@article{goli_rojas_oezcam_genzer_2012, title={Generation of Functional Coatings on Hydrophobic Surfaces through Deposition of Denatured Proteins Followed by Grafting from Polymerization}, volume={13}, ISSN={["1525-7797"]}, DOI={10.1021/bm300075u}, abstractNote={Hydrophilic coatings were produced on flat hydrophobic substrates featuring n-octadecyltrichlorosilane (ODTS) and synthetic polypropylene (PP) nonwoven surfaces through the adsorption of denatured proteins. Specifically, physisorption from aqueous solutions of α-lactalbumin, lysozyme, fibrinogen, and two soy globulin proteins (glycinin and β-conglycinin) after chemical (urea) and thermal denaturation endowed the hydrophobic surfaces with amino and hydroxyl functionalities, yielding enhanced wettability. Proteins adsorbed strongly onto ODTS and PP through nonspecific interactions. The thickness of adsorbed heat-denatured proteins was adjusted by varying the pH, protein concentration in solution, and adsorption time. In addition, the stability of the immobilized protein layer was improved significantly after interfacial cross-linking with glutaraldehyde in the presence of sodium borohydride. The amino and hydroxyl groups present on the protein-modified surfaces served as reactive sites for the attachment of polymerization initiators from which polymer brushes were grown by surface-initiated atom-transfer radical polymerization of 2-hydroxyethyl methacrylate. Protein denaturation and adsorption as well as the grafting of polymeric brushes were characterized by circular dichroism, ellipsometry, contact angle, and Fourier transform infrared spectroscopy in the attenuated total reflection mode.}, number={5}, journal={BIOMACROMOLECULES}, author={Goli, Kiran K. and Rojas, Orlando J. and Oezcam, A. Evren and Genzer, Jan}, year={2012}, month={May}, pages={1371–1382} }
 @article{oezcam_roskov_spontak_genzer_2012, title={Generation of functional PET microfibers through surface-initiated polymerization}, volume={22}, ISSN={["1364-5501"]}, DOI={10.1039/c2jm16017j}, abstractNote={In this study, we report on a facile and robust method by which poly(ethylene terephthalate) (PET) surfaces can be chemically modified with functional polymer brushes while avoiding chemical degradation. The surface of electrospun PET microfibers has been functionalized by growing poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) and poly(2-hydroxyethyl methacrylate) (PHEMA) brushes through a multi-step chemical sequence that ensures retention of mechanically robust microfibers. Polymer brushes are grown via “grafting from” atom-transfer radical polymerization after activation of the PET surface with 3-aminopropyltriethoxysilane. Spectroscopic analyses confirm the expected reactions at each reaction step, as well as the ultimate growth of brushes on the PET microfibers. Post-polymerization modification reactions have likewise been conducted to further functionalize the brushes and impart surface properties of biomedical interest on the PET microfibers. Antibacterial activity and protein resistance of PET microfibers functionalized with PDMAEMA and PHEMA brushes, respectively, are demonstrated, thereby making these surface-modified PET microfibers suitable for filtration media, tissue scaffolds, delivery vehicles, and sensors requiring mechanically robust support media.}, number={12}, journal={JOURNAL OF MATERIALS CHEMISTRY}, author={Oezcam, A. Evren and Roskov, Kristen E. and Spontak, Richard J. and Genzer, Jan}, year={2012}, pages={5855–5864} }
 @article{ozcam_roskov_genzer_spontak_2012, title={Responsive PET Nano/Microfibers via Surface-Initiated Polymerization}, volume={4}, ISSN={["1944-8252"]}, DOI={10.1021/am201559f}, abstractNote={Poly(ethylene terephthalate) (PET) is one of the most important thermoplastics in ubiquitous use today because of its mechanical properties, clarity, solvent resistance, and recyclability. In this work, we functionalize the surface of electrospun PET microfibers by growing poly(N-isopropylacrylamide) (PNIPAAm) brushes through a chemical sequence that avoids PET degradation to generate thermoresponsive microfibers that remain mechanically robust. Amidation of deposited 3-aminopropyltriethoxysilane, followed by hydrolysis, yields silanol groups that permit surface attachment of initiator molecules, which can be used to grow PNIPAAm via "grafting from" atom-transfer radical polymerization. Spectroscopic analyses performed after each step confirm the expected reaction and the ultimate growth of PNIPAAm brushes. Water contact-angle measurements conducted at temperatures below and above the lower critical solution temperature of PNIPAAm, coupled with adsorption of Au nanoparticles from aqueous suspension, demonstrate that the brushes retain their reversible thermoresponsive nature, thereby making PNIPAAm-functionalized PET microfibers suitable for filtration media, tissue scaffolds, delivery vehicles, and sensors requiring robust microfibers.}, number={1}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Ozcam, A. Evren and Roskov, Kristen E. and Genzer, Jan and Spontak, Richard J.}, year={2012}, month={Jan}, pages={59–64} }
 @article{yang_ozcam_efimenko_genzer_2011, title={Photochromic materials with tunable color and mechanical flexibility}, volume={7}, ISSN={["1744-683X"]}, DOI={10.1039/c0sm00928h}, abstractNote={Florescence switches based on photochromic compounds have been fabricated previously and identified as potential candidates for information technology. Recently, optically responsive materials with tunable color have been prepared by dissolving photochromic compounds, such as spiropyran (SP), into solutions of various pH or embedding them into sol–gel matrices with adjusted chemical compositions. Here we report on fabricating flexible rubbers with tunable color by embedding SP molecules inside silicone elastomer networks (SENs) based on poly(vinylmethylsiloxane) (PVMS). SP-containing PVMS networks have been further modified either physically by exposing them to ultraviolet/ozone treatment or chemically by attaching functional thiols to the vinyl bonds in PVMS via UV-activated thiol–ene addition. The color hue of the SP–PVMS SENs after exposing to UV light depends on either the UVO dose or the chemical end-functionality of the thiol modifier, respectively. We also present simple methodologies enabling patterning regions in SP-doped SENs with various shapes and colors.}, number={8}, journal={SOFT MATTER}, author={Yang, Hyun-Kwan and Ozcam, A. Evren and Efimenko, Kirill and Genzer, Jan}, year={2011}, pages={3766–3774} }
 @article{ahmed_yang_ozcam_efimenko_weiger_genzer_haugh_2011, title={Poly(vinylmethylsiloxane) Elastomer Networks as Functional Materials for Cell Adhesion and Migration Studies}, volume={12}, ISSN={["1526-4602"]}, DOI={10.1021/bm101549y}, abstractNote={Cell migration is central to physiological responses to injury and infection and in the design of biomaterial implants. The ability to tune the properties of adhesive materials and relate those properties in a quantitative way to the dynamics of intracellular processes remains a definite challenge in the manipulation of cell migration. Here, we propose the use of poly(vinylmethylsiloxane) (PVMS) networks as novel substrata for cell adhesion and migration. These materials offer the ability to tune independently chemical functionality and elastic modulus. Importantly, PVMS networks are compatible with total internal reflection fluorescence (TIRF) microscopy, which is ideal for interrogating the cell-substratum interface; this latter characteristic presents a distinct advantage over polyacrylamide gels and other materials that swell with water. To demonstrate these capabilities, adhesive peptides containing the arginyl-glycyl-aspartic acid (RGD) tripeptide motif were successfully grafted to the surface of PVMS network using a carboxyl-terminated thiol as a linker. Peptide-specific adhesion, spreading, and random migration of NIH 3T3 mouse fibroblasts were characterized. These experiments show that a peptide containing the synergy sequence of fibronectin (PHSRN) in addition to RGD promotes more productive cell migration without markedly enhancing cell adhesion strength. Using TIRF microscopy, the dynamics of signal transduction through the phosphoinositide 3-kinase pathway were monitored in cells as they migrated on peptide-grafted PVMS surfaces. This approach offers a promising avenue for studies of directed migration and mechanotransduction at the level of intracellular processes.}, number={4}, journal={BIOMACROMOLECULES}, publisher={American Chemical Society (ACS)}, author={Ahmed, Shoeb and Yang, Hyun-kwan and Ozcam, Ali E. and Efimenko, Kirill and Weiger, Michael C. and Genzer, Jan and Haugh, Jason M.}, year={2011}, month={Apr}, pages={1265–1271} }
 @article{crowe-willoughby_weiger_ozcam_genzer_2010, title={Formation of silicone elastomer networks films with gradients in modulus}, volume={51}, ISSN={["0032-3861"]}, DOI={10.1016/j.polymer.2009.11.070}, abstractNote={We describe the formation of soft material substrates with position-dependent modulus. Two strategies have been employed in the preparation of such materials. In the first method, we create modulus gradient structures by inter-diffusing two (or more) formulations of silicone elastomers (SE), comprising mixtures of poly(dimethylsiloxane) (PDMS) and poly(vinylmethylsiloxane) (PVMS) with varying molecular weight and content of PDMS, and cross-link them thermally in order to form SE networks. With this method, the resultant substrates exhibit shallow modulus gradients that extend over a few centimeters in length. The second technique is based on employing ultraviolet (UV)-based cross-linking of mercapto-terminated PVMS chains across transparency lithographic masks. We demonstrate that the shape and “sharpness” of the modulus on the substrate depends solely on the position-dependent transparency of the mask to the UV light. As a part of the study we provide detailed material characterization of networks formed by the PDMS–PVMS and PVMS-SH chains.}, number={3}, journal={POLYMER}, author={Crowe-Willoughby, Julie A. and Weiger, Katherine L. and Ozcam, Ali E. and Genzer, Jan}, year={2010}, month={Feb}, pages={763–773} }
 @article{arifuzzaman_oezcam_efimenko_fischer_genzer_2009, title={Formation of surface-grafted polymeric amphiphilic coatings comprising ethylene glycol and fluorinated groups and their response to protein adsorption}, volume={4}, ISSN={["1559-4106"]}, DOI={10.1116/1.3114502}, abstractNote={Amphiphilic polymer coatings were prepared by first generating surface-anchored polymer layers of poly(2-hydroxyethyl methacrylate) (PHEMA) on top of flat solid substrates followed by postpolymerization reaction on the hydroxyl terminus of HEMA’s pendent group using three classes of fluorinating agents, including organosilanes, acylchlorides, and trifluoroacetic anhydride (TFAA). The distribution of the fluorinated groups inside the polymer brushes was assessed by means of a suite of analytical probes, including contact angle, ellipsometry, infrared spectroscopy, atomic force microscopy, and near-edge x-ray absorption fine structure spectroscopy. While organosilane modifiers were found to reside primarily close to the tip of the brush, acylchlorides penetrated deep inside PHEMA thus forming random copolymers P(HEMA-co-fHEMA). The reaction of TFAA with the PHEMA brush led to the formation of amphiphilic diblocks, PHEMA-b-P(HEMA-co-fHEMA), whose bottom block comprised unmodified PHEMA and the top block was made of P(HEMA-co-fHEMA) rich in the fluorinated segments. This distribution of the fluorinated groups endowed PHEMA-b-P(HEMA-co-fHEMA) with responsive properties; while in hydrophobic environment P(HEMA-co-fHEMA) segregated to the surface, when in contact with a hydrophilic medium, PHEMA partitioned at the brush surface. The surface activity of the amphiphilic coatings was tested by studying the adsorption of fibrinogen (FIB). While some FIB adsorption occurred on most coatings, the ones made by TFAA modification of PHEMA remained relatively free of FIB.}, number={2}, journal={BIOINTERPHASES}, author={Arifuzzaman, Shafi and Oezcam, Ali E. and Efimenko, Kirill and Fischer, Daniel A. and Genzer, Jan}, year={2009}, month={Jun}, pages={FA33–FA44} }
 @article{ozcam_efimenko_jaye_spontak_fischer_genzer_2009, title={Modification of PET surfaces with self-assembled monolayers of organosilane precursors}, volume={172}, ISSN={["1873-2526"]}, DOI={10.1016/j.elspec.2009.03.012}, abstractNote={Abstract We report on a facile, robust and rapid method by which poly(ethylene terephthalate) (PET) surfaces can be chemically modified while avoiding chemical degradation. Specifically, we demonstrate that brief exposure of PET surfaces to ultraviolet/ozone (UVO) generates a large surface concentration of hydrophilic moieties that serve as points of chemical attachment, thereby facilitating subsequent chemisorption of organosilane precursors. The feasibility of this methodology is tested by decorating UVO-modified PET surfaces with semifluorinated organosilane (SFOS) molecules, which serve to alter the surface energy of PET without compromising its bulk characteristics. The physico-chemical properties of the SFOS layers attached to PET are studied with a palette of experimental probes, including near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle, atomic force microscopy (AFM), and ellipsometry. Experimental results indicate that ≈2 min of UVO treatment is optimal for covering PET with dense self-assembled monolayers (SAMs) of SFOS. Longer UVO treatment times contaminate and correspondingly roughen PET surfaces with low-molecular-weight organic compounds (LMWOCs) generated from degradation of the topmost PET material. As a consequence, SFOS SAMs attached to the LMWOC layer readily wash off from UVO-treated PET.}, number={1-3}, journal={JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA}, author={Ozcam, Ali E. and Efimenko, Kirill and Jaye, Cherno and Spontak, Richard J. and Fischer, Daniel A. and Genzer, Jan}, year={2009}, month={May}, pages={95–103} }
 @article{aberg_ozcam_majikes_seyam_spontak_2008, title={Extended chemical crosslinking of a thermoplastic polyimide: Macroscopic and microscopic property development}, volume={29}, ISSN={["1022-1336"]}, DOI={10.1002/marc.200800230}, abstractNote={Abstract}, number={17}, journal={MACROMOLECULAR RAPID COMMUNICATIONS}, author={Aberg, Christopher M. and Ozcam, Ali E. and Majikes, Jacob M. and Seyam, Mohamed A. and Spontak, Richard J.}, year={2008}, month={Sep}, pages={1461–1466} }
 @article{ozcam_cheng_2005, title={A discretization based smoothing method for solving semi-infinite variational inequalities}, volume={1}, number={2}, journal={Journal of Industrial and Management Optimization}, author={Ozcam, B. and Cheng, H.}, year={2005}, pages={219–233} }
 @article{tang_ozcam_stout_khan, title={Effect of pH on protein distribution in electrospun PVA/BSA composite nanofibers}, volume={13}, number={5}, journal={Biomacromolecules}, author={Tang, C. and Ozcam, A. E. and Stout, B. and Khan, S. A.}, pages={1269–1278} }