@article{mccord_muddiman_khaledi_2017, title={Perfluorinated alcohol induced coacervates as extraction media for proteomic analysis}, volume={1523}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2017.06.025}, abstractNote={We describe a novel method for using hexafluoroisopropanol (HFIP) induced coacervates with a variety of surfactants to extract proteins from a yeast whole cell lysate and conduct a global proteomic investigation on the extracted proteins. Yeast whole cell lysates were prepared and proteins were extracted using two workflows: 1) Proteins were extracted into the coacervate generated from the mixture of HFIP, surfactant, and cell lysate. 2) Proteins were extracted from cell lysate using a surfactant solution, and HFIP was added to the supernatant to generate a coacervate phase with concentrated proteins. Both initial extractions were followed by a modified filter-aided sample preparation (FASP) cleanup. The methodology yields significant protein concentrations in the coacervate phase (2–3 orders of magnitude increase in concentration) and an increase in proteome sequence coverage (+5%), membrane proteins identifications (+50%), and identification of proteins from low abundance cellular subfractions (>10% of total IDs).}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={McCord, James P. and Muddiman, David C. and Khaledi, Morteza G.}, year={2017}, month={Nov}, pages={293–299} }
 @article{weisner_khaledi_2016, title={Organic synthesis in fluoroalcohol-water two-phase systems}, volume={18}, ISSN={["1463-9270"]}, DOI={10.1039/c5gc01463h}, abstractNote={Higher yields were observed for Friedel Crafts benzylations of arenes in HFIP–Water two phase systems that in pure solvents.}, number={3}, journal={GREEN CHEMISTRY}, author={Weisner, Nathaniel and Khaledi, Morteza G.}, year={2016}, pages={681–685} }
 @article{jenkins_collins_khaledi_2016, title={Perfluorinated Alcohols Induce Complex Coacervation in Mixed Surfactants}, volume={32}, ISSN={["0743-7463"]}, DOI={10.1021/acs.langmuir.5b04701}, abstractNote={Recently, we reported a unique and nearly ubiquitous phenomenon of inducing simple and complex coacervation in solutions of a broad variety of individual and mixed amphiphiles and over a wide range of concentrations and mole fractions. This paper describes a novel type of biphasic separation in aqueous solutions of mixed cationic-anionic (catanionic) surfactants induced by hexafluoroisopropanol (HFIP). The test cases included mixtures of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) (surfactants with different carbon chain lengths) as well as dodecyltrimethylammonium bromide (DTAB) with SDS (surfactants with the same carbon chain lengths). The CTAB-SDS-HFIP coacervate systems can be produced at many different mole ratios of surfactant, but DTAB-SDS-HFIP formed only coacervates at equimolar (1:1) mole ratios of DTAB and SDS. The phase-transition behavior of both systems was studied over a wide range of surfactant and HFIP concentrations at the stoichiometric (1:1) mole ratio of cationic/anionic surfactants. The chemical compositions of each of the two phases (aqueous-rich and coacervate phases) were studied with regard to the concentrations of HFIP, water, and individual surfactants. It is revealed that the surfactant-rich phase (coacervate phase) contains a large percentage of fluoroalcohol relative to the aqueous phase and is enriched in both surfactants but contains a small percentage of water. Surprisingly, the concentration of water in the coacervate phase increases as the total HFIP concentration is increased while the concentration of HFIP in the coacervate phase remains relatively constant, which means a larger amount of water associated with HFIP molecules is extracted into the coacervate phase, which results in the growth of the phase. The volume of the coacervate phase increases with an increase in surfactant concentration and total HFIP %. The coacervate phase is highly enriched in the two amphiphilic ions (DTA(+) and DS(-)) whereas the two counterions (Br(-) and Na(+)) primarily reside in the aqueous-rich phase. The results suggest the formation of a catanionic complex in the coacervate phase through ion pairing with a concomitant release of the surfactant counterions (Na(+) and Br(-)) into the aqueous-rich phase. Finally, the fluorocarbon alcohol systems are contrasted with the effects of aliphatic alcohols in the mixed catanionic surfactant systems. Isopropanol does not have the same interactions as HFIP with respect to solubilization, aggregation, and phase separation of the oppositely charged surfactants.}, number={10}, journal={LANGMUIR}, author={Jenkins, Samuel I. and Collins, Christopher M. and Khaledi, Morteza G.}, year={2016}, month={Mar}, pages={2321–2330} }
 @article{nejati_khaledi_2015, title={Perfluoro-Alcohol-Induced Complex Coacervates of Polyelectrolyte-Surfactant Mixtures: Phase Behavior and Analysis}, volume={31}, ISSN={["0743-7463"]}, DOI={10.1021/acs.langmuir.5b00444}, abstractNote={Perfluorinated alcohols and acids such as hexafluoroisopropanol (HFIP), trifluoroethanol, trifluoroacetic acid, pentafluoropropionic acid, and heptafluorobutyric acid induce coacervation and phase separation in aqueous solutions of a wide variety of individual and mixed amphiphiles [ Khaledi Langmuir 2013 , 29 , 2458 ]. This paper focuses on HFIP-induced complex coacervate formation in the mixtures of anionic polyelectrolytes, such as sodium salt of poly(methacrylic acid) (PMA) or poly(acrylic acid) (PAA) and cationic surfactants of alkyltrimethylammonium bromides. In purely aqueous media and over a wide concentration range, mixtures of PMA and CTAB form the catanionic complex (CTA(+)PM(-)) that is insoluble in water (white precipitate). Upon addition of a small percentage of HFIP, the mixture goes through phase transition and formation of two distinctly clear liquid phases. The phase diagram for the HFIP-PMA-CTAB coacervate system was studied. The coacervate volume was determined as a function of system variables such as charge ratio as well as total and individual concentrations of the system components. These results, combined with the chemical composition analysis of the separated aqueous top-phase and coacervate bottom-phase, shed light on the coacervation mechanism. The results suggest that exchange of counterions and ion-pair formation play critical roles in the coacervation process. This process facilitated by HFIP through solvation of the head groups and dehydration of the hydrophobic moieties of the catanionic complex. Because of the presence of HFIP, coacervation occurs over a wide range of concentrations and charge ratios of the oppositely charged polyelectrolyte and surfactant.}, number={20}, journal={LANGMUIR}, author={Nejati, Mahboubeh M. and Khaledi, Morteza G.}, year={2015}, month={May}, pages={5580–5589} }
 @article{fu_khaledi_2014, title={Characterization and Classification of Pseudo-Stationary Phases in Micellar Electrokinetic Chromatography Using Chemometric Methods}, volume={86}, ISSN={["1520-6882"]}, DOI={10.1021/ac403231h}, abstractNote={Two types of chemometric methods, principal component analysis (PCA) and cluster analysis, are employed to characterize and classify a total of 70 pseudostationary phases (54 distinct systems and 16 decoy systems) in micellar electrokinetic chromatography (MEKC). PCA excels at removing redundant information for micellar phase characterization and retaining principal determinants for phase classification. While PCA is useful in the characterization of micelle selectivities, it is ineffective in defining the grouping of micellar phases. Hierarchical clustering yields a complete dendrogram of cluster structures but provides only limited cluster characterizations. The combination of these two chemometric methods leads to a comprehensive interpretation of the micellar phase classification. Moreover, the k-means analysis can further discern subtle differences among those closely located micellar phases. All three chemometric methods result in similar classifications with respect to the similarities and differences of the 70 micelle systems investigated. These systems are categorized into 3 major clusters: fluoro-surfactants represent cluster I, identified as strong hydrogen bond donors and dipolar but weak hydrogen bond acceptors. Cluster II includes sulfonated acrylamide/acrylate copolymers and surfactants with trimethylammonium head groups, characterized by strong hydrophobicity (v) and weak hydrogen bond acidity (b). The last cluster consists of two subclusters: clusters III and IV. Cluster III includes siloxane-based polymeric micelles, exhibiting weak hydrophobicity and medium hydrogen bond acidity and basicity (a), and the cluster IV micellar systems are characterized by their strong hydrophobicity and medium hydrogen bond acidity and basicity but rather weak dipolarity. Cluster III differs from cluster IV by its slightly weaker hydrophobicity and hydrogen bond donating capability. The classification by chemometric methods is in good agreement with the classification by the micellar selectivity triangle (MST) ( Fu, C.; Khaledi, M. G. J. Chromatogr., A 2009 , 1216 , 1891 - 1900 ).}, number={5}, journal={ANALYTICAL CHEMISTRY}, author={Fu, Cexiong and Khaledi, Morteza G.}, year={2014}, month={Mar}, pages={2371–2379} }
 @article{khaledi_jenkins_liang_2013, title={Perfluorinated Alcohols and Acids Induce Coacervation in Aqueous Solutions of Amphiphiles}, volume={29}, ISSN={["0743-7463"]}, DOI={10.1021/la303035h}, abstractNote={We have discovered that water-miscible perfluorinated alcohols and acids (FA) can induce simple and complex coacervation in aqueous solutions of a wide range of amphiphilic molecules such as synthetic surfactants, phospholipids, and bile salts as well as polyelectrolytes. This unique phenomenon seems to be nearly ubiquitous, especially for complex coacervate systems composed of mixed catanionic amphiphiles. In addition, coacervation and aqueous phase separation were observed over a wide range of surfactants concentrations and for different mole fractions of the oppositely charged amphiphile.}, number={8}, journal={LANGMUIR}, author={Khaledi, Morteza G. and Jenkins, Samuel I. and Liang, Shuang}, year={2013}, month={Feb}, pages={2458–2464} }
 @article{fu_khaledi_2009, title={Micellar selectivity triangle for classification of chemical selectivity in electrokinetic chromatography}, volume={1216}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2008.12.085}, abstractNote={A novel micellar selectivity triangle (MST) is developed and used to characterize and classify the chemical selectivities of pseudo-phases in electrokinetic chromatography (EKC). The MST scheme is, in concept, similar to the widely known solvent selectivity triangle (SST) originally developed by Snyder. However, the MST is based on linear solvation energy relationships. Thus it incorporates the solvation characteristics of both the pseudo-phase and the bulk solvent; while the SST is basically for classification of pure solvents. The similarities and differences of these pseudo-phases are determined by the relative scales of hydrogen bond donating ability (Xb), hydrogen bond accepting ability (Xa) and dipolarity (Xs). The MST scheme is used for characterization and classification of a wide range of pseudo-phases such as micelles, polymers, vesicles, liposomes, as well as mixed systems such as mixed micelles, mixed polymer–surfactants, organically modified pseudo-phases, etc. Over seventy pseudo-phases were examined and four clusters of pseudo-phases with different selectivity patterns are recognized that include pseudo-phases with strong hydrogen bond acidities (e.g. fluorinated micelles or micelles modified with fluorinated alcohols), strong hydrogen bond acceptor pseudo-phases (such as bile salts, liposomes, microemulsions, as well as biphasic octanol–water system), strong dipolar phase of a class of polymeric pseudo-phase, and pseudo-phases with intermediate hydrogen bonding and dipolarity [like sodium dodecyl sulfate (SDS) and its analogs as well as organically modified SDS]. The MST scheme is also useful in identifying pseudo-phases that closely resemble the selectivities of octanol–water for determination of octanol–water partition coefficients by EKC.}, number={10}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Fu, Cexiong and Khaledi, Morteza G.}, year={2009}, month={Mar}, pages={1891–1900} }
 @article{fu_khaledi_2009, title={Selectivity patterns in micellar electrokinetic chromatography Characterization of fluorinated and aliphatic alcohol modifiers by micellar selectivity triangle}, volume={1216}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2009.01.041}, abstractNote={The usefulness of the micellar selectivity triangle (MST) for prediction and interpretation of separation patterns in micellar electrokinetic chromatography (MEKC) separations is presented. In addition, we demonstrate the capability of controlling selectivity properties of micelles through addition of organic modifiers with known solvation properties as predicted by MST. The examples are modification of the hydrogen bond donor (HBD) micelle of lithium perfluorooctanesulfonate, the hydrogen bond acceptor (HBA) micelle of tetradecyltrimethylammonium bromide, and the sodium dodecyl sulfate micelles with intermediate hydrogen bonding properties with two hydrophobic organic modifiers. One is an aliphatic alcohol, n-pentanol that can act as both a HBA and a HBD; by contrast, the other organic modifier is a fluorinated alcohol, hexafluoroisopropanol that is a strong HBD modifier and would enhance the hydrogen bond donor strength of micelles. A test sample composed of 20 small organic solutes representing HBA, HBD, and non-hydrogen bond aromatic compounds was carefully selected. The trends in retention behavior of these compounds in different micelles are consistent with the selectivity patterns predicted by the MST scheme. To the best of our knowledge, this is the first report on the unique selectivity of fluorinated alcohols as modifiers in MEKC. These results demonstrate the usefulness of the MST scheme for identifying pseudo-phases with highly similar or different selectivities and can serve as a guide for judicious selection of modifiers to create pseudo-phases with desired selectivity behavior on a rational basis.}, number={10}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Fu, Cexiong and Khaledi, Morteza G.}, year={2009}, month={Mar}, pages={1901–1907} }
 @article{jalali-heravi_shen_hassanisadi_khaledi_2005, title={Artificial neural network modeling of peptide mobility and peptide mapping in capillary zone electrophoresis}, volume={1096}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2005.09.043}, abstractNote={Recently, we have developed an artificial neural network model, which was able to predict accurately the electrophoretic mobilities of relatively small peptides. To examine the robustness of this methodology, a 3-3-1 back-propagation artificial neural network (BP-ANN) model was developed using the same inputs as the previous model, which were the Offord's charge over mass term (Q/M2/3), corrected steric substituent constant (Es,c) and molar refractivity (MR). The data set consisted of 102 peptides with a larger range of size than that of our earlier report – up to 42 amino acid residues as compared to 13 amino acids in the initial study – that also included highly charged and hydrophobic peptides. The entire data set was obtained from the published result by Janini and co-workers. The results of this model are compared with those obtained using multiple linear regressions (MLR) model developed in this work and the multi-variable model released by Janini et al. Better predictive ability of the BP-ANN model over the MLR indicates the non-linear characteristics of the electrophoretic mobility of peptides. The present model exhibits better robustness than the MLR models in predicting CZE mobilities of a diverse data set at different experimental conditions. To explore the utility of the ANN model in simulation of the CZE peptide maps, the profiles for the endoproteinase digests of melittin, glucagon and horse cytochrome C is studied in the present work.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Jalali-Heravi, M and Shen, Y and Hassanisadi, M and Khaledi, MG}, year={2005}, month={Nov}, pages={58–68} }
 @article{carrozzino_khaledi_2005, title={PH effects on drug interactions with lipid bilayers by liposome electrokinetic chromatography}, volume={1079}, ISSN={["1873-3778"]}, DOI={10.1016/j.chroma.2005.04.008}, abstractNote={Liposome electrokinetic chromatography (LEKC) provides convenient and rapid methods for studying drug interactions with lipid bilayers using liposomes as a pseudostationary phase. LEKC was used to determine the effects of pH on the partitioning of basic drugs into liposomes composed of zwitterionic phosphatidylcholine (PC), anionic phosphatidylglycerol (PG), and cholesterol, which mimic the composition of natural cell membranes. An increase in pH results in a smaller degree of ionization of the basic drugs and consequently leads to a lower degree of interaction with the negatively charged membranes. From the LEKC retention data, the fractions of drugs distributed in the bulk aqueous and the liposome phase were determined at various pH values. Finally, lipid mediated shifts in the ionization constants of drugs were examined.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Carrozzino, JM and Khaledi, MG}, year={2005}, month={Jun}, pages={307–316} }
 @article{jalali-heravi_shen_hassanisadi_khaledi_2005, title={Prediction of electrophoretic mobilities of peptides in capillary zone electrophoresis by quantitative structure-mobility relationships using the offord model and artificial neural networks}, volume={26}, ISSN={["1522-2683"]}, DOI={10.1002/elps.200410308}, abstractNote={The aim of this work was to explore the usefulness of empirical models and multivariate analysis techniques in predicting electrophoretic mobilities of small peptides in capillary zone electrophoresis (CZE). The data set consists of electrophoretic mobilities, measured at pH 2.5, for 125 peptides ranging in size between 2 and 14 amino acids. Among the existing empirical models, the Offord model (i.e., µ ≡ Q/M2/3) gave the best correlation for the data set. A quantitative structure‐mobility relationship (QSMR) was developed using the Offord's charge‐over‐mass term (Q/M2/3) as one descriptor combined with the corrected steric substituent constant (Es, c) and molar refractivity (MR) descriptors to account for the steric effects and bulkiness of the amino acid side chains. The multilinear regression (MLR) of the data set showed an improvement in the predictive ability of the model over the simple Offord's relationship. A 3–4–1 back propagation artificial neural networks (BP‐ANN) model resulted in a significant improvement in the predictive ability of the QSMR over the MLR treatment, especially for peptides of higher charges that contain basic amino acids arginine, histidine, and lysine. The improved correlations by the BP‐ANN analysis suggest the existence of nonlinear characteristic in the mobility‐charge relationships.}, number={10}, journal={ELECTROPHORESIS}, author={Jalali-Heravi, M and Shen, Y and Hassanisadi, M and Khaledi, MG}, year={2005}, month={May}, pages={1874–1885} }
 @article{carrozzino_fuguet_helburn_khaledi_2004, title={Characterization of small unilamellar vesicles using solvatochromic pi* indicators and particle sizing}, volume={60}, ISSN={["0165-022X"]}, DOI={10.1016/j.jbbm.2004.04.014}, abstractNote={A suite of small unilamellar vesicles (SUVs) composed of mixtures of phospholipids and cholesterol (CH) or the synthetic surfactant dihexadecyl phosphate (DHP) and cholesterol was investigated using a homologous series of solvatochromic pi* indicators coupled with size exclusion methods and photon correlation spectroscopy (PCS). The solvatochromic method, which is based on the measurement of solvent-dependent shifts in lambda(max) from UV-Vis spectra of solubilized indicators, was used to quantify the dipolarity and polarizability (pi*) of probe solvation environments. The partitioning of the series of individual di-n-alkyl-p-nitroaniline (DNAP) pi* indicators in PG(24)PC(46)Chol(30) and DHP(70)Chol(30) SUVs was examined as a function of the head group structure as well as the method of dye-vesicle preparation. Solubilization of the larger more hydrophobic probes in the bilayer portion of PG(24)PC(46)Chol(30) SUVs was aided through physical entrapment. Such physical methods were not needed for the smaller indicators or for the range of indicators in the DHP(70)Chol(30) dispersions. Extrusion and size-exclusion chromatographic methodologies for the preparation of physically entrapped dopants in SUVs of fixed size range demonstrated that the larger (longer alkyl chain) dopants in the series resided in PG(24)PC(46)Chol(30) liposomes with a wider range of sizes, while the smaller more polar solutes tended to be entrapped in smaller vesicles with a narrower size range.}, number={2}, journal={JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS}, author={Carrozzino, JM and Fuguet, E and Helburn, R and Khaledi, MG}, year={2004}, month={Aug}, pages={97–115} }
 @article{carrozzino_khaledi_2004, title={Interaction of basic drugs with lipid bilayers using liposome electrokinetic chromatography}, volume={21}, ISSN={["1573-904X"]}, DOI={10.1007/s11095-004-7685-3}, abstractNote={{"Label"=>"PURPOSE", "NlmCategory"=>"OBJECTIVE"} This study explores factors influencing the interactions of positively charged drugs with liposomes using liposome electrokinetic chromatography (LEKC) for the development of LEKC as a rapid screening method for drug-membrane interactions. {"Label"=>"METHODS", "NlmCategory"=>"METHODS"} Liposomes were prepared and the retention factors were measured for a series of basic drugs under a variety of buffer conditions, including various buffer types, concentrations, and ionic strengths as well as using different phospholipids and liposome compositions. LEKC retention is compared with octanol-water partitioning. {"Label"=>"RESULTS", "NlmCategory"=>"RESULTS"} The interaction of ionizable solutes with liposomes decreased with increasing ionic strength of the aqueous buffer. The type of buffer also influences positively charged drug partitioning into liposomes. Varying the surface charge on the liposomes by the selection of phospholipids influences the electrostatic interactions, causing an increase in retention with increasing percentages of anionic lipids in the membrane. Poor correlations are observed between LEKC retention and octanol-water partitioning. {"Label"=>"CONCLUSIONS", "NlmCategory"=>"CONCLUSIONS"} These studies demonstrate the overall buffer ionic strength at a given pH is more important than buffer type and concentration. The interaction of positively charged drugs with charged lipid bilayer membranes is selectively influenced by the pKa of the drug. Liposomes are more biologically relevant in vitro models for cell membranes than octanol, and LEKC provides a unique combination of advantages for rapid screening of drug-membrane interactions.}, number={12}, journal={PHARMACEUTICAL RESEARCH}, author={Carrozzino, JM and Khaledi, MG}, year={2004}, month={Dec}, pages={2327–2335} }
 @article{burns_khaledi_2004, title={Predictions of micelle-water partition coefficients and retention in micellar electrokinetic chromatography from solute structure. 2. Fragmental constant approach}, volume={76}, ISSN={["1520-6882"]}, DOI={10.1021/ac0498718}, abstractNote={The fragmental constant approach (FCA) was used to calculate water-sodium dodecyl sulfate (SDS) micelle partition coefficients, K(mw), for uncharged solutes from their structure. Subsequently, the availability of K(mw) values allows prediction of retention factor, k, in micellar electrokinetic chromatography (MEKC) using the simple relationship k = K(mw)phi, where phi is the phase ratio. The FCA model describes a micelle-water partition coefficient as the sum of the partition coefficients of the constituent atomic/molecular fragments, measured by fragmental constant values, f (i), as well as correction factors to account for various "intramolecular effects" that cause deviations from the predicted partition coefficients as, log K(mw) = sum(n)(i=1)aif i+sum(m)(i=1)kiCm. The fragmental constants for a set of 41 fragments were determined using a training set of 229 aromatic solutes and 198 aliphatic compounds. The K(mw) of the aromatic compounds in the training set were determined by MEKC, while the K(mw) of the aliphatic solutes were estimated using the linear solvation energy relationship (LSER) for the SDS micelles. The fragments consisted of both aromatic fragments (i.e., directly attached to an aromatic ring) and aliphatic fragments. The FCA predictions agree nicely with the observed and LSER partition coefficient values, even for complex molecular structures such as beta-blocker drugs. The results show the great potential of the FCA for a priori prediction of retention behavior in MEKC from solute structure.}, number={18}, journal={ANALYTICAL CHEMISTRY}, author={Burns, ST and Khaledi, MG}, year={2004}, month={Sep}, pages={5451–5458} }
 @article{mckeon_khaledi_2003, title={Evaluation of liposomal delivery of antisense oligonucleotide by capillary electrophoresis with laser-induced fluorescence detection}, volume={1004}, ISSN={["0021-9673"]}, DOI={10.1016/S0021-9673(03)00721-0}, abstractNote={Two widely used commercial cationic liposome formulations, Lipofectamine and Escort, were evaluated for drug delivery efficacy with capillary electrophoresis coupled with laser-induced fluorescence detection using a fluorescein conjugated 2'-O-methyl-phosphorothioate (Me-PS) antisense oligonucleotide and the HeLa cell line. Binding constants were estimated by monitoring changes in the electrophoretic mobility of the oligonucleotide with the liposome solution in the running buffer. From these changes in mobility, the binding constants for Lipofectamine and Escort liposomes with Me-PS oligomer were estimated to be 1139 and 590 M(-1), respectively. Additionally, intracellular concentrations and gene expression were quantified for the liposome formulations.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={McKeon, J and Khaledi, MG}, year={2003}, month={Jul}, pages={39–46} }
 @article{malek_khaledi_2003, title={Monitoring liposome-mediated delivery and fate of an antisense drug in cell extracts and in single cells by capillary electrophoresis with laser-induced fluorescence}, volume={24}, ISSN={["0173-0835"]}, DOI={10.1002/elps.200390122}, abstractNote={Abstract}, number={6}, journal={ELECTROPHORESIS}, author={Malek, AH and Khaledi, MG}, year={2003}, month={Mar}, pages={1054–1062} }
 @article{quang_malek_khaledi_2003, title={Separation of peptides and proteins by capillary electrophoresis using acidic buffers containing tetraalkylammonium cations and cyclodextrins}, volume={24}, ISSN={["1522-2683"]}, DOI={10.1002/elps.200390103}, abstractNote={Abstract}, number={5}, journal={ELECTROPHORESIS}, author={Quang, CY and Malek, A and Khaledi, MG}, year={2003}, month={Mar}, pages={824–828} }
 @article{agbodjan_khaledi_2003, title={Study of solute partitioning into cationic vesicles of dihexadecyldimethylammonium bromide using electrokinetic chromatography}, volume={1004}, ISSN={["0021-9673"]}, DOI={10.1016/S0021-9673(03)00853-7}, abstractNote={A cationic vesicular pseudo-stationary phase was used in electrokinetic chromatography. The stable cationic lipid bilayer, composed of a double chain cationic surfactant, dihexadecyldimethylammonium bromide was prepared in deionized water, with no buffer additive. The chromatographic characteristics of this novel pseudo-phase are presented. A linear solvation energy relationship was successfully used to characterize the interaction of neutral solutes with the cationic vesicles. This study was complemented by the determination of changes in the free energy for transfer of various groups from the aqueous phase into the bilayer.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Agbodjan, AA and Khaledi, MG}, year={2003}, month={Jul}, pages={145–153} }
 @article{leonard_khaledi_2002, title={A mixed ionic block copolymer-surfactant pseudostationary phase in micellar electrokinetic chromatography}, volume={25}, ISSN={["1615-9314"]}, DOI={10.1002/1615-9314(20021101)25:15/17<1019::AID-JSSC1019>3.0.CO;2-C}, abstractNote={A mixture of a tri-block copolymer, poly(methyl methacrylate-ethyl acrylate-methacrylic acid), commercially known as Elvacite 2669, and sodium dodecyl sulfate (SDS) micelle was investigated as pseudo-stationary phase in Micellar Electrokinetic Chromatography (MEKC). The properties of the mixed system were characterized using surface tension and conductance experiments, as well as absorbance and fluorescence solvatochromic studies using ET(30) and pyrene as the probes. In this mixed system the SDS has a critical micelle concentration of 2 mM and the fluorescence data indicates that it has a microenvironment similar to SDS alone. Additionally, the solvation properties of the individual and the mixed systems were compared using linear solvation energy relationships (LSER). As compared to the SDS micelles, the mixed pseudo-phase is a weaker hydrogen bond donor and has stronger polarizability properties. The functional group selectivities in the mixed pseudo phase are different from that in the SDS micelle. The functional group selectivities of non-hydrogen bonding and hydrogen bonding solutes provide further support for the LSER findings.}, number={15-17}, journal={JOURNAL OF SEPARATION SCIENCE}, author={Leonard, MS and Khaledi, MG}, year={2002}, month={Dec}, pages={1019–1026} }
 @article{burns_agbodjan_khaledi_2002, title={Characterization of solvation properties of lipid bilayer membranes in liposome electrokinetic chromatography}, volume={973}, ISSN={["0021-9673"]}, DOI={10.1016/S0021-9673(02)00955-X}, abstractNote={The nature of solute interactions with biomembrane-like liposomes, made of naturally occurring phospholipids and cholesterol, was characterized using electrokinetic chromatography (EKC). Liposomes were used as a pseudo-stationary phase in EKC that provided sites of interactions for uncharged solutes. The retention factors of uncharged solutes in liposome EKC are directly proportional to their liposome-water partition coefficients. Linear solvation energy relationship (LSER) models were developed to unravel the contributions from various types of interactions for solute partitioning into liposomes. Size and hydrogen bond acceptor strength of solutes are the main factors that determine partitioning into lipid bilayers. This falls within the general behavior of solute partitioning from an aqueous into organic phases such as octanol and micelles. However, there exist subtle differences in the solvation properties of liposomes as compared to those of octanol and various micellar pseudo-phases such as aggregates of sodium dodecyl sulfate (SDS), sodium cholate (SC), and tetradecylammonium bromide (TTAB). Among these phases, the SDS micelles are the least similar to the liposomes, while octanol, SC, and TTAB micelles exhibit closer solvation properties. Subsequently, higher correlations are observed between partitioning into liposomes and the latter three phases than that into SDS.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Burns, ST and Agbodjan, AA and Khaledi, MG}, year={2002}, month={Oct}, pages={167–176} }
 @article{bui_khaledi_2002, title={Determination of vesicle-water partition coefficients by electrokinetic chromatography: Study of temperature effect}, volume={253}, ISSN={["1095-7103"]}, DOI={10.1006/jcis.2002.8496}, abstractNote={Vesicular electrokinetic chromatography was used to investigate solute partitioning from the aqueous phase into dihexadecyl hydrogen phosphate (DHP) vesicles. Retention factors of neutral solutes are related to their partition coefficients between the aqueous phase and vesicles (K(vw)). The K(vw) of the aromatic test solutes were readily obtained from the slopes of the linear relationships between retention factors versus DHP concentrations. The technique offers the advantages of speed, automation, and small sample size for determination of partition coefficients. The K(vw) values of 43 uncharged solutes were measured at below as well as above the phase transition temperatures. The logarithms of partition coefficients (log K(vw)) of solutes at 71 degrees C (above T(c)) were slightly higher than those at 36 degrees C (below T(c)). The solvation characteristics of DHP were also studied using linear solvation energy relationships at the two temperatures.}, number={2}, journal={JOURNAL OF COLLOID AND INTERFACE SCIENCE}, author={Bui, HH and Khaledi, MG}, year={2002}, month={Sep}, pages={397–401} }
 @article{burns_khaledi_2002, title={Rapid determination of liposome-water partition coefficients (K-lw) using liposome electrokinetic chromatography (LEKC)}, volume={91}, ISSN={["0022-3549"]}, DOI={10.1002/jps.10119}, abstractNote={Liposome Electrokinetic Chromatography (LEKC) provides a simple and facile approach for determining liposome-water partition coefficients, Klw. LEKC is a Capillary Electrophoresis (CE) technique where liposomes are incorporated into a buffer solution and act as a pseudostationary phase providing sites of interaction for solutes. The retention factors of solutes in LEKC are directly proportional to Klw. This article describes how LEKC can be used to determine Klw for both neutral and charged solutes. The Klw values for a group of neutral aromatic compounds, beta-blockers, and other drugs are reported. In addition, the usefulness of two quantitative structure partition relationships (QSPR) for estimation of Klw is demonstrated. One is the logarithmic linear relationship between liposome water and octanol-water partition coefficients (Pow). The other is the Linear Solvation Energy Relationship (LSER). The calculated Klw values from the two QSPR agree nicely with the observed values and with one another.}, number={7}, journal={JOURNAL OF PHARMACEUTICAL SCIENCES}, author={Burns, ST and Khaledi, MG}, year={2002}, month={Jul}, pages={1601–1612} }
 @article{deterding_cutalo_khaledi_tomer_2002, title={Separation and characterization of human high-density apolipoproteins using a nonaqueous modifier in capillary electrophoresis-mass spectrometry}, volume={23}, ISSN={["1522-2683"]}, DOI={10.1002/1522-2683(200207)23:14<2296::AID-ELPS2296>3.0.CO;2-I}, abstractNote={The separation and characterization of human apolipoproteins and their isoforms was investigated using capillary electrophoresis (CE) in combination with mass spectrometry (MS). The focus of these analyses was the major protein constituents of plasma high‐density lipoproteins, apolipoprotein A‐I and A‐II. Using aqueous buffers in CE, no separation between apolipoprotein A‐I and A‐II was observed. With the addition of 10–20% acetonitrile, however, the two species could be separated. Furthermore, multiple peaks for each of the apolipoprotein species were observed under these CE conditions. In order to identify and characterize the components, these separations were then coupled with online mass spectrometric detection (CE‐MS). Our CE‐MS results suggest that the multiple components observed in the acetonitrile‐containing CE separation appear to be oxidized forms of the proteins in addition to native forms of the apolipoprotein A‐I and A‐II. These data are in agreement with previous reports that the methionine residues of the high‐density lipoproteins (HDLs) are sensitive to oxidation, which in turn, alters their lipid binding characteristics and secondary structure. In addition to oxidized forms of the proteins, apolipoprotein A‐II contained additional components, which varied in mass by 128 Da. The structural differences between these components were determined by proteolytic digestion and tandem MS. Using these techniques, we determined that these components were due to truncation of the C‐terminal glutamine amino acid residue on apolipoprotein A‐II. These results demonstrate that CE in combination with MS is a promising technique for screening and characterizing isomers of plasma apolipoproteins.}, number={14}, journal={ELECTROPHORESIS}, author={Deterding, LJ and Cutalo, JM and Khaledi, M and Tomer, KB}, year={2002}, month={Jul}, pages={2296–2305} }
 @article{kelly_burns_khaledi_2001, title={Prediction of retention in micellar electrokinetic chromatography from solute structure. 1. Sodium dodecyl sulfate micelles}, volume={73}, DOI={10.1021/ac01059444}, number={24}, journal={Analytical Chemistry}, author={Kelly, K. A. and Burns, S. T. and Khaledi, M. G.}, year={2001}, pages={6057–6062} }
 @article{mckeon_cho_khaledi_2001, title={Quantitation of intracellular concentration of a delivered morpholino oligomer by capillary electrophoresis-laser-induced fluorescence: Correlation with upregulation of luciferase gene expression}, volume={293}, ISSN={["1096-0309"]}, DOI={10.1006/abio.2001.5087}, abstractNote={Antisense oligonucleotides have shown great promise over the past several years as viable drugs to combat various forms of cancer and viral diseases. However, quantitative detection to monitor cellular association is difficult using conventional methods such as radiolabeling of the oligonucleotide or fluorescence confocal microscopy. In this paper quantitation of intracellular concentration of the morpholino oligonucleotide is investigated using capillary electrophoresis coupled with laser-induced fluorescence detection (CE-LIF). HeLa cells, which produce luciferase as the antisense oligomer enters the cell, were scrape-loaded with varying concentrations of the morpholino antisense. The intracellular antisense concentration measured by CE-LIF was found to correlate with those obtained with the cellular functional assay based on upregulation of luciferase. Intracellular concentrations of the antisense were found to be in the range of 6 to 29 nmol/g total cell protein, depending on the amounts that were scrape-loaded. To our best knowledge, this is the first reported quantitative correlation between delivered antisense concentration in a cell extract and the subsequent antisense upregulation of gene expression.}, number={1}, journal={ANALYTICAL BIOCHEMISTRY}, author={McKeon, J and Cho, MJ and Khaledi, MG}, year={2001}, month={Jun}, pages={1–7} }
 @article{mckeon_khaledi_2001, title={Quantitative nuclear and cytoplasmic localization of antisense oligonucleotides by capillary electrophoresis with laser-induced fluorescence detection}, volume={22}, ISSN={["0173-0835"]}, DOI={10.1002/1522-2683(200109)22:17<3765::AID-ELPS3765>3.0.CO;2-Y}, abstractNote={We demonstrate the use of simple extraction procedures to separate nuclear and cytoplasmic material from cell extracts, which have been scrape‐loaded with a 2‐O‐methyl phosphorothioate antisense oligonucleotide. Separation and quantitation of the fluorescein‐labeled antisense and the flourescein isothiocyanate (FITC)‐dextran (molecular weight 40 000) as an internal standard is done using capillary electrophoresis coupled with laser‐induced fluorescence detection (CE‐LIF). The bulky FITC‐dextran is unable to penetrate the nuclear membrane thereby making it a quantitative indicator of any overlap between the nuclear and cytoplasmic materials during separation of the two phases. Using this procedure, the fluorescein‐labeled phosphorothioate oligomer was quantitated at 4.1×10–13and 3.4×10–14 mol antisense/νg‐total cellular protein in the nuclear and cytoplasmic extracts respectively following scrape‐load delivery of the phosphorothioate to a batch of confluent HeLa cells at a concentration of 0.5 νM (5×10–10 total moles of oligomer). Additionally, gene expression was monitored by measurement of the luciferase reporter protein activity. Scrape‐load, spontaneous and liposomal delivery were investigated and compared for subcellular distribution of the oligomer and subsequent gene expression.}, number={17}, journal={ELECTROPHORESIS}, author={McKeon, J and Khaledi, MG}, year={2001}, month={Oct}, pages={3765–3770} }
 @article{agbodjan_bui_khaledi_2001, title={Study of solute partitioning in biomembrane-mimetic pseudophases by electrokinetic chromatography: Dihexadecyl phosphate small unilamellar vesicles}, volume={17}, ISSN={["0743-7463"]}, DOI={10.1021/la001120n}, abstractNote={Solute partitioning into vesicles of dihexadecyl hydrogen phosphate (DHP) was investigated by electrokinetic chromatography (EKC). The ionic double-chain surfactant forms bilayer structures that mimic a biological membrane when dispersed in aqueous media. The linear solvation energy relationship (LSER) was used to gain insights about the nature of interactions and parameters that influence the partitioning process into vesicles, micelles, and n-octanol. The Gibbs free energies of transfer of selected functional groups from aqueous to vesicular phases were compared to those in micellar pseudophases of sodium dodecyl sulfate (SDS) and sodium dodecyl phosphate (SDP). Size and hydrogen bond acceptor strength of solutes are the main factors that determine their partitioning behavior, while dipolarity and polarizability play minor, yet significant, roles. It was determined that the cohesiveness of solute microenvironments in DHP vesicles is between those for micells and n-octanol. Vesicles are weaker hydrogen b...}, number={10}, journal={LANGMUIR}, author={Agbodjan, AA and Bui, H and Khaledi, MG}, year={2001}, month={May}, pages={2893–2899} }
 @article{jouyban-gharamaleki_khaledi_clark_2000, title={Calculation of electrophoretic mobilities in water-organic modifier mixtures in capillary electrophoresis}, volume={868}, ISSN={["0021-9673"]}, DOI={10.1016/S0021-9673(99)01258-3}, abstractNote={In order to correlate/predict electrophoretic mobility data in the mixture of water+organic modifier four equations have been presented and examined. The experimental mobilities of five analytes were determined in a water-methanol mixture. These data have been used to assess the accuracy and predictability of the models. Also, some previously published mobility data in water-organic modifier mixtures has been employed for further evaluation of the models. The models produced accurate results and the means of percentage deviations were in the range of 0.66-1.30.}, number={2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Jouyban-Gharamaleki, A and Khaledi, MG and Clark, BJ}, year={2000}, month={Feb}, pages={277–284} }
 @article{trone_mack_goodell_khaledi_2000, title={Characterization of chemical selectivity in micellar electrokinetic chromatography VI. Effects of surfactant counter-ion}, volume={888}, ISSN={["0021-9673"]}, DOI={10.1016/S0021-9673(00)00515-X}, abstractNote={Linear solvation energy relationships and free energy of transfer data were used to evaluate the influence of the surfactant counter-ion on selectivity in micellar electrokinetic chromatography. It was determined that selectivity differences are dependent on the valency of the counter-ion but not the type of counter-ion. Monovalent surfactants, sodium dodecyl sulfate (SDS) and lithium dodecyl sulfate, have nearly identical selectivity behavior. The divalent surfactants, magnesium didodecyl sulfate and copper didodecyl sulfate also show very similar behavior. However, when the divalent counter-ion species is compared to SDS under similar conditions, significant differences are observed. Most notably, the utilization of divalent counter-ion species of dodecyl sulfate surfactants causes the micelles to become more hydrophobic and a weaker hydrogen bond donating pseudo-stationary phases. It is believed that the divalent counter-ions reduce the electrostatic repulsion between the surfactant head groups and therefore, increase the chain packing of the monomers in the micelle aggregates. This reduces the degree of hydration of the micellar palisade layer leading to a decreased ability of the micelle to participate in polar/polarizable and hydrogen bonding interactions with solute molecules.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Trone, MD and Mack, JP and Goodell, HP and Khaledi, MG}, year={2000}, month={Aug}, pages={229–240} }
 @article{trone_khaledi_2000, title={Characterization of chemical selectivity in micellar electrokinetic chromatography: V. The effect of the surfactant hydrophobic chain}, volume={12}, ISSN={["1040-7685"]}, DOI={10.1002/1520-667x(2000)12:8<433::aid-mcs1>3.0.co;2-r}, abstractNote={The influence of the surfactant hydrophobic chain on selectivity in micellar electrokinetic chromatography was investigated using two sets of surfactants. A series of three sarcosinate surfactants (sodium N-lauroyl sarcosinate, sodium n−myristoyl sarcosinate, and sodium N-parmitoyl sarcosinate) with C11, C13, and C15 hydrocarbon tails were compared. In addition, sodium dodecyl sulfate and sodium tetradecyl sulfate were investigated to determine the chain length effect for sodium sulfate surfactants. Linear solvation energy relationships as well as free energy of transfer studies were used to predict the selectivity differences. The results suggest that although the surfactant chain length can have some effect, the magnitude of this influence seems to be dependent on the head group. © 2000 John Wiley & Sons, Inc. J Micro Sep 12: 433–441, 2000}, number={8}, journal={JOURNAL OF MICROCOLUMN SEPARATIONS}, author={Trone, MD and Khaledi, MG}, year={2000}, pages={433–441} }
 @article{trone_leonard_khaledi_2000, title={Congeneric behavior in estimations of octanol-water partition coefficients by micellar electrokinetic chromatography}, volume={72}, ISSN={["0003-2700"]}, DOI={10.1021/ac990852l}, abstractNote={Linear Solvation Energy Relationships (LSERs) are used to explain the congeneric behavior observed when using Micellar Electrokinetic Chromatography (MEKC) to estimate the octanol-water partition coefficient scale of solute hydrophobicity. Such studies provide useful insights about the nature of solute interactions that are responsible for the sources of congeneric relationships between MEKC retention and log Po/w. It was determined that solute dipolarity/polarizability and hydrogen-bonding character play the most important roles in the congeneric behavior observed for many surfactant systems. The individual dipolarity/polarizability and hydrogen-bonding contributions to the free energy of transfer were also investigated.}, number={6}, journal={ANALYTICAL CHEMISTRY}, author={Trone, MD and Leonard, MS and Khaledi, MG}, year={2000}, month={Mar}, pages={1228–1235} }
 @article{zhou_merrick_khaledi_tomer_2000, title={Detection and sequencing of phosphopeptides affinity bound to immobilized metal ion beads by matrix-assisted laser desorption/ionization mass spectrometry}, volume={11}, ISSN={["1879-1123"]}, DOI={10.1016/S1044-0305(00)00100-8}, abstractNote={Consecutive enzymatic reactions of analytes which are affinity bound to immobilized metal ion beads with subsequent direct analysis of the products by matrix-assisted laser desorption/ionization mass spectrometry have been used for detecting phosphorylation sites. The usefulness of this method was demonstrated by analyzing two commercially available phosphoproteins, beta-casein and alpha-casein, as well as one phosphopeptide from a kinase reaction mixture. Agarose loaded with either Fe3+ or Ga3+ was used to isolate phosphopeptides from the protein digest. Results from using either metal ion were complementary. Less overall suppression effect was achieved when Ga3+-loaded agarose was used to isolate phosphopeptides. The selectivity for monophosphorylated peptides, however, was better with Fe3+-loaded agarose. This technique is easy to use and has the ability to analyze extremely complicated phosphopeptide mixtures. Moreover, it eliminates the need for prior high-performance liquid chromatography separation or radiolabeling, thus greatly simplifying the sample preparation.}, number={4}, journal={JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY}, author={Zhou, W and Merrick, BA and Khaledi, MG and Tomer, KB}, year={2000}, month={Apr}, pages={273–282} }
 @misc{wang_khaledi_2000, title={Enantiomeric separations by nonaqueous capillary electrophoresis}, volume={875}, ISSN={["1873-3778"]}, DOI={10.1016/S0021-9673(00)00110-2}, abstractNote={This paper reviews the recent advances in enantioseparations by nonaqueous capillary electrophoresis (NACE) and the effect of organic solvents on mobility of enantiomers, separation selectivity and resolution. In general, the enantioseparation systems in NACE are similar to those of aqueous capillary electrophoresis (CE) except pure organic solvents are used. The influence of important parameters such as concentration and type of chiral selectors, apparent pH, ionic strength, temperature, and control of electroosmotic flow is discussed. In addition, the reported applications of NACE separations of racemates are presented.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Wang, F and Khaledi, MG}, year={2000}, month={Apr}, pages={277–293} }
 @article{zhou_tomer_khaledi_2000, title={Evaluation of the binding between potential anti-HIV DNA-based drugs and viral envelope glycoprotein gp120 by capillary electrophoresis with laser-induced fluorescence detection}, volume={284}, ISSN={["0003-2697"]}, DOI={10.1006/abio.2000.4651}, abstractNote={The fusion of the human immunodeficiency virus (HIV) with the target cell was assisted by the interaction between the viral envelope glycoprotein HIV-1 gp120 and a chemokine receptor. Studies have shown that the efficiency of the binding depends on the presence of the V3 loop of the gp120 which is known to interact with polyanions, such as phosphorothioate oligodeoxynucleotides (Sd, potential anti-HIV drugs). In this study, capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was used to systematically evaluate binding between Sd and HIV-1 gp120. A 25-mer fluorescently tagged phosphorothioate oligodeoxynucleotide (GEM) was employed as a probe to study this interaction. The dissociation constant (K(d)) between GEM and gp120 was determined to be 0.98 nM by Scatchard analysis. The competition constants (K(c)) of a set of Sd that compete with GEM for binding to gp120 were also determined. The results showed that the interaction had a strong dependence on the sulfur phosphorothioate backbone. Chain length and the sequence of Sd also affect the ability of binding to gp120. The ability to study the protein-drug binding in the solution with minimal sample consumption makes CE-LIF very attractive for biological studies.}, number={2}, journal={ANALYTICAL BIOCHEMISTRY}, author={Zhou, W and Tomer, KB and Khaledi, MG}, year={2000}, month={Sep}, pages={334–341} }
 @article{trone_khaledi_2000, title={Influence of ester and amide-containing surfactant headgroups on selectivity in micellar electrokinetic chromatography}, volume={21}, ISSN={["0173-0835"]}, DOI={10.1002/1522-2683(20000701)21:12<2390::AID-ELPS2390>3.0.CO;2-K}, abstractNote={The selectivity differences between six anionic surfactans in micellar electrokinetic chromatography (MEKC) are presented and the structural influence of the surfactant head‐group is investigated. It was determined that the surfactant structure can have a significant impact on retention and selectivity. Linear solvation energy relationships (LSERs) are used to study the role of solute size, polarity/polarizability, and hydrogen bonding characteristics in determining retention and selectivity. While both the solute size and hydrogen bond accepting ability were found to be the most important factors in solute retention, the hydrogen bonding characteristic of the solutes have the largest influence on selectivity differences between surfactants.}, number={12}, journal={ELECTROPHORESIS}, author={Trone, MD and Khaledi, MG}, year={2000}, month={Jul}, pages={2390–2396} }
 @article{miller_shea_khaledi_2000, title={Separation of acidic solutes by nonaqueous capillary electrophoresis in acetonitrile-based media - Combined effects of deprotonation and heteroconjugation}, volume={888}, ISSN={["0021-9673"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0034604766&partnerID=MN8TOARS}, DOI={10.1016/S0021-9673(00)00467-2}, abstractNote={Nonaqueous capillary electrophoresis (NACE) is a chemical separation technique that has grown in popularity over the past few years. In this report, we focus on the combination of heteroconjugation and deprotonation in the NACE separation of phenols using acetonitrile (ACN) as the buffer solvent. By preparing various dilute buffers consisting of carboxylic acids and tetrabutylammonium hydroxide in ACN, selectivity may be manipulated based on a solute's dissociation constant as well as its ability to form heterogeneous ions with the buffer components. ACN's low viscosity, coupled with its ability to allow for heteroconjugation, often leads to rapid and efficient separations that are not possible in aqueous media. In this report, equations are derived showing the dependence of mobility on various factors, including the pKa of the analyte, the pH and concentration of the buffer, and the analyte-buffer heteroconjugation constant (Kf). The validity of these equations is tested as several nitrophenols are separated at different pH values and concentrations. Using nonlinear regression, the Kf values for the heteroconjugate formation between the nitrophenols and several carboxylate anions are calculated. Also presented in this report are the NACE separations of the 19 chlorophenol congeners and the 11 priority pollutant phenols (used in US Environmental Protection Agency methods 604, 625/1625 and 8270B).}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Miller, JL and Shea, D and Khaledi, MG}, year={2000}, month={Aug}, pages={251–266} }
 @article{trone_khaledi_2000, title={Statistical evaluation of linear solvation energy relationship models used to characterize chemical selectivity in micellar electrokinetic chromatography}, volume={886}, ISSN={["0021-9673"]}, DOI={10.1016/S0021-9673(00)00416-7}, abstractNote={Characterization of retention and selectivity differences between surfactants in micellar electrokinetic chromatography (MEKC) using linear solvation energy relationships (LSERs) has been given a significant amount of attention in the last four years. This report evaluates the validity of using the two LSER models that have been used to fit retention in MEKC in the literature. The results and the fit of the revised model and parameters developed by Abraham and coworkers are compared to the original model developed by Kamlet, Taft, and coworkers. LSERs can generally only be used as a comparative tool to describe the selectivity differences between surfactant systems used in MEKC. With this in mind, it was determined that the results of both models essentially provide the same information about these differences. However, the revised model and parameters have been found to yield a statistically better fit of the MEKC retention data as well as providing more chemically sound LSER coefficients.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Trone, MD and Khaledi, MG}, year={2000}, month={Jul}, pages={245–257} }
 @article{wang_khaledi_1999, title={Capillary electrophoresis chiral separation of basic pharmaceutical enantiomers with different charges using sulfated beta-cyclodextrin}, volume={11}, ISSN={["1040-7685"]}, DOI={10.1002/(SICI)1520-667X(1999)11:1<11::AID-MCS2>3.0.CO;2-P}, abstractNote={A negatively charged cyclodextrin, sulfated β-cyclodextrin [β-CD-(SO4−)4], was used as a chiral selector for capillary electrophoresis separations of basic pharmaceutical enantiomers. The charges of the basic enantiomers were controlled by adjusting the buffer pH. At pH 2.5, basic compounds are positively charged and interact stronger with the negatively charged CD than with neutral CDs, owing to the extra electrostatic interaction. This additional interaction is very useful for chiral separations of the enantiomers that interact weakly with the neutral CDs. For example, chiral separations of acebutolol, metanephrine, normetanephrine, nafronyl, labetalol, and nadolol were achieved at this pH. For labetalol and nadolol that have two chiral centers, three of the four isomers were separated. The capillary surface was dynamically coated with poly(vinyl alcohol) (PVA) to reduce the possible interactions between solutes and the capillary wall, to improve efficiency and reduce the electroosmotic flow (EOF) for enhancing resolution. PVA reduced the interactions between the analytes and the chiral selector; nevertheless, peak tailing was observed owing to the electrodispersion for the compounds that interact too strongly with the anionic CD. At pH 11.6, most of the basic test compounds (except those having phenol groups) are neutral and have weaker interactions with the negatively charged CD. The separation efficiency increased dramatically for all analytes at higher pH owing to the absence of electrodispersion. The existence of the neutral PVA polymer in the buffer solution increased the solubility of the neutral hydrophobic amines and reduced the solute–CD complexation. Chiral separations of a large number of compounds were achieved at a single concentration of the charged cyclodextrin. ©1999 John Wiley & Sons, Inc. J Micro Sep 11: 11–21, 1999}, number={1}, journal={JOURNAL OF MICROCOLUMN SEPARATIONS}, author={Wang, F and Khaledi, MG}, year={1999}, pages={11–21} }
 @article{trone_khaledi_1999, title={Characterization of chemical selectivity in micellar electrokinetic chromatography. 4. Effect of surfactant headgroup}, volume={71}, ISSN={["1520-6882"]}, DOI={10.1021/ac9809736}, abstractNote={The influence of surfactant headgroups on migration behavior in micellar electrokinetic chromatography is examined. Using linear solvation energy relationships (LSER) and functional group selectivity studies, the effect of six anionic headgroups on chemical selectivity is characterized. The sodium dodecyl surfactants of the sulfate [SO4-], sulfonate [SO3-], carboxylate [CO2-], carbonyl valine [OC(O)NHCH(CH(CH3)2)CO2-], and sulfoacetate [OC(O)CH2SO3-] anions are investigated. Solute size and the hydrogen-bond-donating ability of the micellar phase play the most significant roles in solute retention in all of the surfactants studied. While solute-micelle hydrogen bonding plays a dominant role in the observed selectivity, the dipolarity and polarizability of the micellar phase also have a small influence. The results also suggest that the hydrogen-bond-accepting ability for surfactants is inversely proportional to the proton acidity (pKa) of its headgroup. The observed hydrogen-bond-donating ability and dipolarity of surfactant systems are believed to be a result of the water that resides near the micelle surface.}, number={7}, journal={ANALYTICAL CHEMISTRY}, author={Trone, MD and Khaledi, MG}, year={1999}, month={Apr}, pages={1270–1277} }
 @article{qian_zhou_khaledi_tomer_1999, title={Direct analysis of the products of sequential cleavages of peptides and proteins affinity-bound to immobilized metal ion beads by matrix-assisted laser desorption/ionization mass spectrometry}, volume={274}, ISSN={["1096-0309"]}, DOI={10.1006/abio.1999.4268}, abstractNote={Consecutive enzymatic reactions on analytes affinity-bound to immobilized metal ion beads with subsequent direct analysis of the products by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry have been used for detecting protein synthesis errors occuring at the N-terminus. The usefulness of this method was demonstrated by analyzing two commercially available recombinant HIV proteins with affinity tags at the N-terminus, and histatin-5, a peptide with multiple histidine residues. The high specificity, sensitivity, and speed of analysis make this method especially useful in obtaining N-terminal sequencing information of histidine-tagged recombinant proteins.}, number={2}, journal={ANALYTICAL BIOCHEMISTRY}, author={Qian, XH and Zhou, W and Khaledi, MG and Tomer, KB}, year={1999}, month={Oct}, pages={174–180} }
 @article{ward_khaledi_1999, title={Efficiency studies in nonaqueous capillary electrophoresis}, volume={859}, ISSN={["0021-9673"]}, DOI={10.1016/S0021-9673(99)00839-0}, abstractNote={Nonaqueous capillary electrophoresis (NACE) is a relatively new area with several advantages that include enhanced efficiency and improved detection sensitivity. The goal of this study was to investigate the influence of NACE compared to aqueous CE on the separation efficiency of oligosaccharides. The applied voltage and buffer concentration were optimized for the aqueous and nonaqueous buffer media to minimize the band broadening effects of Joule heating and electrophoretic dispersion. At the optimized conditions a 1.5-fold enhancement in efficiency was obtained with the nonaqueous buffer medium.}, number={2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Ward, VL and Khaledi, MG}, year={1999}, month={Oct}, pages={203–219} }
 @article{malek_khaledi_1999, title={Expression and analysis of green fluorescent proteins in human embryonic kidney cells by capillary electrophoresis}, volume={268}, ISSN={["0003-2697"]}, DOI={10.1006/abio.1998.2975}, abstractNote={The green fluorescent protein (GFP) has attracted much interest as a reporter for gene expression. In this paper, application of capillary electrophoresis with laser-induced fluorescent (CE-LIF) for quantitation of green fluorescence protein in cellular extracts and single cells is investigated. The S65T mutant form of GFP protein was successfully expressed in human embryonic kidney (HEK293) cells, and its production was confirmed by fluorescence microscopy and CE-LIF. The mass limit of detection for the mutant S65T was 5.3 x 10(-20) mol, which was better than that for the wild-type GFP by a factor of six. Detection of a small amount of GFP is difficult by conventional techniques such as fluorescent microscopy due to interference from cell autofluorescence at low GFP concentrations. The HEK293 cells were transfected with the GFP plasmid that produced S65T-GFP. Transient production of S65T protein was detected 2 h after the transfection and reached a maximum after 48 h. The protein concentration began to decrease significantly after 96 h. Single cell analysis of HEK293 cells after transfection with GFP plasmid indicate a nonuniform production of S65T-GFP protein among cells.}, number={2}, journal={ANALYTICAL BIOCHEMISTRY}, author={Malek, A and Khaledi, MG}, year={1999}, month={Mar}, pages={262–269} }
 @article{wang_khaledi_1999, title={Non-aqueous capillary electrophoresis chiral separations with sulfated beta-cyclodextrin}, volume={731}, ISSN={["0378-4347"]}, DOI={10.1016/S0378-4347(99)00217-0}, abstractNote={This paper reports the application of an anionic cyclodextrin (CD), sulfated β-cyclodextrin with a degree of substitution of four (β-CD-(SO4−)4, in chiral separations of pharmaceutical enantiomers by non-aqueous capillary electrophoresis (NACE). Upon complexation with the anionic CD, electrophoretic mobilities of the basic enantiomers decreased, however, both separation selectivity and resolution were enhanced. The advantage of NACE chiral separations over the aqueous CE with the charged CD is that higher electric field strength and higher ionic strength could be applied due to the characteristics of the solvent formamide. The higher ionic strength leads to stacking of peaks and reduces the electrodispersion caused by the mobility mismatch between β-CD-(SO4−)4–analyte complexes and the co-ions in the running buffer. As a result, better peak shapes and higher separation efficiency were obtained. Comparing with NACE chiral separations with neutral CDs, lower concentration of β-CD-(SO4−)4 was needed due to the fact that the electrostatic attraction caused stronger binding between β-CD-(SO4−)4 and the enantiomers. The effects of the experimental parameters, such as concentration of the CD, apparent pH (pH*), degree of substitutions of the CDs, percentage of water in mixed solvent systems, and type of solvents were also studied.}, number={2}, journal={JOURNAL OF CHROMATOGRAPHY B}, author={Wang, F and Khaledi, MG}, year={1999}, month={Aug}, pages={187–197} }
 @article{malek_khaledi_1999, title={Steroid analysis in single cells by capillary electrophoresis with collinear laser-induced fluorescence detection}, volume={270}, ISSN={["1096-0309"]}, DOI={10.1006/abio.1999.3096}, abstractNote={Capillary electrophoresis with collinear laser-induced fluorescence detection was used for the analysis of steroids in single R2C cells. Progesterone secretion was monitored from cultured cells and subsequently detected in single cells. Mass detection limit of 10(-18) mol for dansylated steroids was achieved with the 325-nm line of a helium-cadmium laser. Dansylhydrazine proved to be an effective fluorescent tag for derivatization of steroids outside and inside the biological cell. Fluorescence microscopy indicates that a dimethyl sulfoxide-containing physiological buffer was sufficient to incorporate the tag inside the cell for subsequent steroid derivatization.}, number={1}, journal={ANALYTICAL BIOCHEMISTRY}, author={Malek, A and Khaledi, MG}, year={1999}, month={May}, pages={50–58} }
 @inbook{khaledi_1998, title={Applications of micellar electrokinetic chromatography in quantitative structure-activity relationship studies: Estimation of log P-ow and bioactivity}, volume={146}, ISBN={0471148512}, booktitle={High-performance capillary electrophoresis: theory, techniques, and applications}, publisher={New York: John Wiley & Sons}, author={Khaledi, M. G.}, year={1998}, pages={999–1014} }
 @inbook{kelly_khaledi_1998, title={Capillary electrochromatography}, volume={146}, ISBN={0471148512}, booktitle={High-performance capillary electrophoresis: theory, techniques, and applications}, publisher={New York: John Wiley & Sons}, author={Kelly, K. A. and Khaledi, M. G.}, year={1998}, pages={277–299} }
 @article{wang_khaledi_1998, title={Capillary electrophoresis chiral separations of basic compounds using cationic cyclodextrin}, volume={19}, ISSN={["0173-0835"]}, DOI={10.1002/elps.1150191209}, abstractNote={Abstract}, number={12}, journal={ELECTROPHORESIS}, author={Wang, F and Khaledi, MG}, year={1998}, month={Sep}, pages={2095–2100} }
 @article{khaledi_bumgarner_hadjmohammadi_1998, title={Characterization of mixed micellar pseudostationary phases in electrokinetic chromatography using linear solvation energy relationships}, volume={802}, ISSN={["1873-3778"]}, DOI={10.1016/S0021-9673(97)01157-6}, abstractNote={The influence of mixed micellar systems on retention and selectivity in micellar electrokinetic chromatography is examined using linear solvation energy relationships (LSER). Systems that were investigated include mixed bile salts [sodium deoxycholate (SDC) and sodium cholate (SC)] and mixed sodium dodecyl sulfate (SDS)–bile salt systems (e.g., SDS–SC and SDS–SDC). The retention behavior in individual and mixed micellar systems is primarily determined by size and hydrogen bond acceptor strengths of solutes. Through a comparative study of the LSER coefficients in the individual and mixed micellar systems, it was concluded that hydrogen bonding interactions have a significant effect on selectivity of these pseudostationary phases in electrokinetic chromatography. The interactive properties of the mixed micelles are different from the constituent individual micelles, however, the overall characteristics are closer to one of the bile salt micelles in the mixture even at the equimolar compositions.}, number={1}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Khaledi, MG and Bumgarner, JG and Hadjmohammadi, M}, year={1998}, month={Apr}, pages={35–47} }
 @book{khaledi_1998, title={High-performance capillary electrophoresis: Theory, techniques, and applications}, ISBN={0471148512}, publisher={New York: John Wiley & Sons}, author={Khaledi, M. G.}, year={1998} }
 @inbook{khaledi_1998, title={Micellar electrokinetic chromatography}, volume={146}, ISBN={0471148512}, booktitle={High-performance capillary electrophoresis: theory, techniques, and applications}, publisher={New York: John Wiley & Sons}, author={Khaledi, M. G.}, year={1998}, pages={77–140} }
 @inbook{miller_khaledi_1998, title={Nonaqueous capillary electrophoresis}, volume={146}, ISBN={0471148512}, booktitle={High-performance capillary electrophoresis: theory, techniques, and applications}, publisher={New York: John Wiley & Sons}, author={Miller, J. L. and Khaledi, M. G.}, year={1998}, pages={525–555} }
 @article{wang_khaledi_1998, title={Nonaqueous capillary electrophoresis chiral separations with quaternary ammonium beta-cyclodextrin}, volume={817}, ISSN={["0021-9673"]}, DOI={10.1016/S0021-9673(98)00484-1}, abstractNote={Chiral separation of nonsteroidal anti-inflammatory drugs (profens), 1,1′-binaphthyl-2,2′-diyl-hydrogen phosphate, N-[1-(1-naphthyl)ethyl]phthalamic acid, and derivatized amino acids by a cationic cyclodextrin, quaternary ammonium β-cyclodextrin (QA-β-CD), was investigated by capillary electrophoresis (CE) in both aqueous and nonaqueous media. Several profens and amino acids could only be separated by QA-β-CD in pure formamide system. No chiral separation of the profens was achieved in the following solvents: N-methylformamide, methanol, dimethyl sulfoxide, and water; however, chiral separations of most of the amino acids were obtained in all of these solvents. The effects of other experimental parameters such as the CD concentration and apparent pH (pH*) were also investigated. The first application of nonaqueous CE chiral separation of ketoprofen in a commercially available sample, Actron, was also examined. In addition, the reversal of electroosmotic flow by QA-β-CD was observed in water, formamide, N-methylformamide, methanol, and dimethyl sulfoxide media.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Wang, F and Khaledi, MG}, year={1998}, month={Aug}, pages={121–128} }
 @article{ward_khaledi_1998, title={Nonaqueous capillary electrophoresis with laser induced fluorescence detection}, volume={718}, ISSN={["0378-4347"]}, DOI={10.1016/S0378-4347(98)00330-2}, abstractNote={This paper describes the use of nonaqueous capillary electrophoresis (NACE) with laser induced fluorescence (LIF) to improve detection sensitivity. The nonaqueous medium is conducive to lower detection limits due to the minimization of quenching effects. The nonaqueous solvent, N-methylformamide, produced the best detection limit with a 2-fold enhancement using NACE–LIF as compared to aqueous CE. N-methylformamide also gave the best fluorescent signal enhancement (6-fold) among the five nonaqueous solvents tested using steady-state fluorescence. The extent (or degree) of enhancement in fluorescence intensity seems to be related to the viscosity and/or polarity of the solvent.}, number={1}, journal={JOURNAL OF CHROMATOGRAPHY B}, author={Ward, VL and Khaledi, MG}, year={1998}, month={Oct}, pages={15–22} }
 @article{miller_khaledi_shea_1998, title={Separation of hydrophobic solutes by nonaqueous capillary electrophoresis through dipolar and charge-transfer interactions with pyrylium salts}, volume={10}, ISSN={["1040-7685"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0001258994&partnerID=MN8TOARS}, DOI={10.1002/(SICI)1520-667X(1998)10:8<681::AID-MCS7>3.0.CO;2-6}, abstractNote={In this study, the use of pyrylium salts for the separation of uncharged hydrophobic solutes in nonaqueous capillary electrophoresis (NACE) is examined. In an aprotic solvent such as acetonitrile, large polarizable compounds selectively interact with planar organic cations, thereby facilitating the analysis of solutes that have low solubilities in aqueous or mixed solvents. Presented in this article are the separations of polycyclic aromatic hydrocarbons (PAHs) that were achieved through dipolar and charge-transfer interactions with various substituted pyrylium cations. It was found that the number of rings contained in the PAH molecule, the presence of functional groups on the molecule, the concentration of the pyrylium cation, and the number of phenyl substituents on the pyrylium ring affected the electrophoretic mobility of the solute–cation complex. © 1998 John Wiley & Sons, Inc. J Micro Sep 10: 681–685, 1998}, number={8}, journal={JOURNAL OF MICROCOLUMN SEPARATIONS}, author={Miller, JL and Khaledi, MG and Shea, D}, year={1998}, pages={681–685} }
 @misc{khaledi_1997, title={Micelles as separation media in high-performance liquid chromatography and high-performance capillary electrophoresis: overview and perspective}, volume={780}, ISSN={["0021-9673"]}, DOI={10.1016/S0021-9673(97)00610-9}, abstractNote={The use of micelles in high-performance liquid chromatography and capillary electrophoresis is reviewed. In the first part, an overview of micellar liquid chromatography (MLC) is provided. Since the first introduction of the technique by Armstrong and Henry [D.W. Armstrong and S.J. Henry, J. Liq. Chromatogr., 3 (1980) 657; D.W. Armstrong, Sep. Purif. Methods 14 (1985) 213] in 1980, the technique has received much attention due to its numerous capabilities and advantages, such as simultaneous separation of charged and uncharged solutes, rapid gradient capability, direct on-column injection of physiological fluids, unique separation selectivity, high reproducibility, robustness, enhanced luminescence detection, low cost and safety. The main shortcoming of the technique is poor chromatographic efficiency. Nevertheless, MLC is superior to ion-pair LC and ion-exchange LC for the separation of charged molecules and mixtures of charged and uncharged solutes. The roles of micelles and organic modifiers in controlling retention and selectivity in MLC is described. The differences between MLC and reversed-phase LC in terms of chromatographic hehavior and scope of application are examined. A main focus of this overview is on micellar electrokinetic chromatography (MEKC). In 1984, Terabe et al. [S. Terabe, K. Otsuka, K. Ichikawa, A. Tsuchiya and T. Ando, Anal. Chem. 56 (1984) 111; S. Terabe, K. Otsuka and T. Ando, Anal. Chem. 57 (1985) 834] reported the use of micelles in buffer solutions for capillary electrophoresis (CE). MEKC was primarily developed for the separation of uncharged solutes, but it has grown far beyond its initial intent. The scope of applications covers wide groups of organic, inorganic and biochemical compounds that are of interest in various disciplines, such as pharmaceutical, clinical, biotechnological, environmental sciences and others. This is due to its unique advantages, such as high efficiency, speed, ease of method development, feasibility of incorporating various chemistries to influence retention and selectivity, small sample size and low cost. The instrumental set-up in MEKC is the same as that for CE. However, charged organized media such as micelles are incorporated in the buffer solution and act as a pseudo-stationary phase. Unchanged solutes are separated on the basis of their differential partitioning into the micellar pseudo-stationary phase. The roles of various parameters on the overall chromatographic behavior are described. Special attention is given to the characterization of selectivity of pseudo-stationary phases on MEKC.}, number={1-2}, journal={JOURNAL OF CHROMATOGRAPHY A}, author={Khaledi, MG}, year={1997}, month={Sep}, pages={3–40} }
 @article{miller_khaledi_shea_1997, title={Separation of polycyclic aromatic hydrocarbons by nonaqueous capillary electrophoresis using charge-transfer complexation with planar organic cations}, volume={69}, ISSN={["0003-2700"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-0031569134&partnerID=MN8TOARS}, DOI={10.1021/ac960734n}, abstractNote={In this study, we examine the use of charge-transfer interactions between polycyclic aromatic hydrocarbons (PAHs) and planar organic cations in nonaqueous capillary electrophoresis. Since the separations are performed in a purely nonaqueous medium, this method also facilitates the analysis of solutes that have low solubilities in aqueous or mixed media. Presented in this study are the separations of PAHs as well as the quantitative structure-migration relationships that assisted in achieving a better understanding of the forces through which the PAH molecules interact with the acceptor cation. It was found that, in addition to charge-transfer interactions, electrostatic and dispersive forces play an important role in PAH-cation binding.}, number={6}, journal={ANALYTICAL CHEMISTRY}, author={Miller, JL and Khaledi, MG and Shea, D}, year={1997}, month={Mar}, pages={1223–1229} }