@article{moses_brewer_kraemer_fuierer_lowe_agbasi_sauthier_franzen_2007, title={Detection of DNA hybridization on indium tin oxide surfaces}, volume={125}, ISSN={["0925-4005"]}, DOI={10.1016/j.snb.2007.03.009}, abstractNote={Indium tin oxide (ITO) surfaces were modified with ssDNA by coupling oligonucleotides to a monolayer of 12-phosphonododecanoic acid (12-PDA) on ITO surfaces. This coupling involved the formation of an amide bond between the carboxylic acid moiety of 12-PDA to the amine group of a 5′-aminopropyl-labeled single strand of DNA. The self-assembled monolayer of 12-PDA and surface-attached oligonucleotides were characterized by X-ray photoelectron and reflectance FTIR spectroscopy. Detection of selective surface DNA hybridization was achieved by labeling the target ssDNA with gold nanoparticles. The presence of gold nanoparticles was probed using X-ray photoelectron spectroscopy, stripping voltammetry, atomic force microscopy, thermography, photoelectrochemistry (chronoamperometry) and cyclic voltammetry (CV). CV was used to successfully detect DNA hybridization for nanoparticle concentrations as low as 10 pM when using the gold nanoparticles bound to an ITO electrode as catalysts for the electrochemical oxidation of FeCl2. The studies described here provided the basis for surface attachment methodology for various electrochemical and thermographic sensing methods that use ITO thin films as a substrate.}, number={2}, journal={SENSORS AND ACTUATORS B-CHEMICAL}, author={Moses, Selina and Brewer, Scott H. and Kraemer, Stephan and Fuierer, Ryan R. and Lowe, Lisa B. and Agbasi, Chiamaka and Sauthier, Marc and Franzen, Stefan}, year={2007}, month={Aug}, pages={574–580} }
 @article{glomm_moses_brennaman_papanikolas_franzen_2005, title={Detection of adsorption of Ru(II) and Os(II) polypyridyl complexes on gold and silver nanoparticles by single-photon counting emission measurements}, volume={109}, ISSN={["1520-6106"]}, DOI={10.1021/jp049184k}, abstractNote={The present study describes a new application of ruthenium(II) tris(bipyridine) (Ru(bpy)3(2+)) and osmium(II) tris(bipyridine) (Os(bpy)3(2+)) as phosphorescent labels for the quantification of surface binding of molecules to gold and silver nanoparticles. The fraction of Ru(bpy)3(2+) and Os(bpy)3(2+) that is in solution can be distinguished from the surface-bound fraction by the relative lifetimes and integrated emission yields as determined by time-correlated single-photon counting (TCSPC) spectroscopy. Complementary steady-state measurements were carried out to confirm surface attachment of the phosphorescent label molecules. Although the emission of solutions of Ru(bpy)3(2+) and Os(bpy)3(2+) is quenched proportional to the concentration of 10 nm Au or 20 nm Ag nanoparticles, the quenching is static and not diffusional quenching observed in Stern-Volmer plots. The results demonstrate that time-resolved spectroscopy provides a rapid method for the measurement of surface binding of labeled molecules on metallic nanoparticles. While steady-state measurements require the preparation of a series of samples with varying quencher concentrations and a reference, the method described herein requires a single sample plus reference. The mechanism for phosphorescence quenching on Au and Ag nanoparticles is discussed in terms of energy and electron transfer theories.}, number={2}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Glomm, WR and Moses, SJ and Brennaman, MK and Papanikolas, JM and Franzen, S}, year={2005}, month={Jan}, pages={804–810} }
 @article{moses_brewer_lowe_lappi_gilvey_sauthier_tenent_feldheim_franzen_2004, title={Characterization of single- and double-stranded DNA on gold surfaces}, volume={20}, ISSN={["0743-7463"]}, DOI={10.1021/la0492815}, abstractNote={Single- and double-stranded deoxy ribonucleic acid (DNA) molecules attached to self-assembled monolayers (SAMs) on gold surfaces were characterized by a number of optical and electronic spectroscopic techniques. The DNA-modified gold surfaces were prepared through the self-assembly of 6-mercapto-1-hexanol and 5'-C(6)H(12)SH -modified single-stranded DNA (ssDNA). Upon hybridization of the surface-bound probe ssDNA with its complimentary target, formation of double-stranded DNA (dsDNA) on the gold surface is observed and in a competing process, probe ssDNA is desorbed from the gold surface. The competition between hybridization of ssDNA with its complimentary target and ssDNA probe desorption from the gold surface has been investigated in this paper using X-ray photoelectron spectroscopy, chronocoulometry, fluorescence, and polarization modulation-infrared reflection absorption spectroscopy (PM-IRRAS). The formation of dsDNA on the surface was identified by PM-IRRAS by a dsDNA IR signature at approximately 1678 cm(-)(1) that was confirmed by density functional theory calculations of the nucleotides and the nucleotides' base pairs. The presence of dsDNA through the specific DNA hybridization was additionally confirmed by atomic force microscopy through colloidal gold nanoparticle labeling of the target ssDNA. Using these methods, strand loss was observed even for DNA hybridization performed at 25 degrees C for the DNA monolayers studied here consisting of attachment to the gold surfaces by single Au-S bonds. This finding has significant consequence for the application of SAM technology in the detection of oligonucleotide hybridization on gold surfaces.}, number={25}, journal={LANGMUIR}, author={Moses, S and Brewer, SH and Lowe, LB and Lappi, SE and Gilvey, LBG and Sauthier, M and Tenent, RC and Feldheim, DL and Franzen, S}, year={2004}, month={Dec}, pages={11134–11140} }
 @article{lowe_brewer_kramer_fuierer_qian_agbasi-porter_moses_franzen_feldheim_2003, title={Laser-induced temperature jump electrochemistry on gold nanoparticle-coated electrodes}, volume={125}, ISSN={["0002-7863"]}, DOI={10.1021/ja036672h}, abstractNote={Laser-induced temperature jumps (LITJs) at gold nanoparticle-coated indium tin oxide (ITO) electrodes in contact with electrolyte solutions have been measured using temperature-sensitive redox probes and an infrared charge-coupled device. Upon irradiation with 532 nm light, interfacial temperature changes of ca. 20 degrees C were recorded for particle coverages of ca. 1 x 1010 cm-2. In the presence of a redox molecule, LITJ yields open-circuit photovoltages and photocurrents that are proportional to the number of particles on the surface. When ssDNA was used to chemisorb nanoparticles to the ITO surface, solution concentrations as low as 100 fM of target ssDNA-modified nanoparticles could be detected at the electrode surface.}, number={47}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Lowe, LB and Brewer, SH and Kramer, S and Fuierer, RR and Qian, GG and Agbasi-Porter, CO and Moses, S and Franzen, S and Feldheim, DL}, year={2003}, month={Nov}, pages={14258–14259} }