Yazar "John, Vijay T." seçeneğine göre listele
Listeleniyor 1 - 11 / 11
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Arsenic (V) removal with modifiable bulk and nano p(4-vinylpyridine)-based hydrogels: The effect of hydrogel sizes and quarternization agents(Elsevier, 2011) Şahiner, Nurettin; Özay, Özgür; Aktaş, Nahit; Blake, Diane A.; John, Vijay T.Macrogels and nanogels (5 x 6 mm and 370 nm dimensions, respectively) based on 4-vinylpyridine (p-(4VP)) were prepared using redox and microemulsion techniques. The p(4-VP)-based materials were quaternized with HCl/alkyhalides having different chain lengths to tune the charges (macro and nanogels) and size of nanogels. By developing positive charge on the p(4-VP) materials, they behaved as ion exchangers and used in removal of As(V) from aqueous environments. The prepared p(4-VP) materials were also rendered responsive to magnetic field by in situ incorporation of magnetic metal nanoparticles inside macro p(4-VP) hydrogels and by encapsulation of separately prepared magnetic ferrites by nanosized p(4-VP) particles. Nanoparticles quaternized with HCl (p(4-VP)-HCl) (1 g) removed over 95% of As(V) from a stock solution (10 mg L-1 1000 mL) in 15 min whereas bulk hydrogels removed >82% of the As(V) from an equivalent solution in similar to 12 h. Parameters effecting the As(V) removal, including pH, temperature and ionic strength, were also investigated. The synthesized magnetic p(4-VP) composites could be reused after elution with NaOH and regeneration with quaternization agents; these procedures were facilitated using an externally applied magnetic field. The Langmuir and Freundlich adsorption isotherms were also applied to study the removal of As(V) from aqueous environments. (C) 2011 Elsevier B.V. All rights reserved.Öğe COLL 246-Hyaluronic acid hydrogel particles with micron and nano dimensions and their applications in drug delivery(Amer Chemical Soc, 2009) Ilgın, Pınar; Özay, Hava; Aktaş, Nahit; John, Vijay T.; Blake, Diane A.; Ayyala, Ramesh S.; Şahiner, Nurettin[Anstract Not Available]Öğe COLL 490-Colloidal p(4-VP) particles and composites for biomedical application(Amer Chemical Soc, 2009) Özay, Özgür; Aktaş, Nahit; Dülger, Başaran; Sılan, Coşkun; John, Vijay T.; Şahiner, Nurettin[Anstract Not Available]Öğe Colloidal drug carries from (sub)micron hyaluronic acid hydrogel particles with tunable properties for biomedical applications(Elsevier Sci Ltd, 2010) Ilgin, Pinar; Avci, Gulden; Sılan, Coşkun; Ekici, Sema; Aktas, Nahit; Ayyala, Ramesh S.; John, Vijay T.Hyaluronic acid (HA) hydrogel particles were synthesized in a single step employing water-in-oil microemulsion system. The HA particles were formed in the micro-environments of aqueous HA solution in oil by chemical crosslinking with divinyl sulfone (DVS). To produce magnetic field responsive HA-composite particles, iron magnetic nanoparticles were introduced into microemulsion system during synthesis to obtain HA-magnetic composites. For this purpose, iron nanoparticles were separately synthesized and mixed with linear HA followed by chemical crosslinking of linear HA with DVS in the micro-environments to envelope magnetic metal nanoparticles in the emulsion system. Scanning electron microscopy (SEM), dynamic light scattering (DLS) studies, and zeta potentials measurement were performed for particle size, charge and morphological characterization. Additionally. HA particles were chemically modified to induce desired functional groups on the particle surface and utilized for potential drug delivery vehicles. Trimethoprim (TMP) a bacteriostatic antibiotic drug were used as a model drug for the release studies in phosphate buffer solution (PBS) at pH 7.4 from bare HA, magnetic HA-composite and modified HA hydrogel particles. (C) 2010 Elsevier Ltd. All rights reserved.Öğe Creation of a Drug-Coated Glaucoma Drainage Device Using Polymer Technology(Amer Medical Assoc, 2009) Şahiner, Nurettin; Kravitz, Daniel J.; Qadir, Rabah; Blake, Diane A.; Haque, Salima; John, Vijay T.; Margo, Curtis E.Objective: To create and test a slow-release antifibrotic drug-coated glaucoma drainage device using in vitro and in vivo experiments. Methods: A slow-release device incorporating mitomycin C in poly(2-hydroxyethyl methacrylate) disks was developed using redox-polymerization techniques. A standardized preparation of this drug delivery device was attached to the Ahmed glaucoma valve (model FP7; New World Medical, Inc, Rancho Cucamonga, California). Semicircular disks (5 x 6 mm) of P(HEMA)-mitomycin C containing varying concentrations of mitomycin C per gram dry weight of the gel were attached to the lower half of an Ahmed glaucoma valve plate. Water was pumped through the modified Ahmed glaucoma valve at a rate comparable to that of aqueous humor outflow, and mitomycin C release was measured. Modified and unmodified Ahmed glaucoma valves were implanted in a rabbit model, and drug release and fibrosis were assessed after 3 months. Results: The P(HEMA)-mitomycin C device released mitomycin C in vitro over 1 to 2 weeks. Studies in rabbits revealed that mitomycin C was released from the disks during the 3-month implantation. Histologic analysis demonstrated a significant reduction in inflammatory reaction and fibrosis in the resulting blebs. Conclusion: Our slow-release drug-coated glaucoma drainage device decreased fibrosis and inflammation in the resulting bleb in a rabbit model. Clinical Relevance: This device could reduce the failure rate of glaucoma drainage devices.Öğe Highly Porous Acrylonitrile-Based Submicron Particles for UO22+ Absorption in an immunosensor Assay(Amer Chemical Soc, 2012) Şahiner, Nurettin; Yu, Haini; Tan, Grace; He, Jibao; John, Vijay T.; Blake, Diane A.Our laboratory has previously reported an antibody-based assay for hexavalent uranium (UO22+) that could be used on-site to rapidly assess uranium contamination in environmental water samples (Melton, S. J.; et al. Environ. Sci. Technol. 2009, 43, 6703-6709). To extend the utility of this assay to less-characterized sites of uranium contamination, we required a uranium-specific adsorbent that would rapidly remove the uranium from groundwater samples, while leaving the concentrations of other ions in the groundwater relatively unaltered. This study describes the development of hydrogel particles containing amidoxime groups that can rapidly and selectively facilitate the uptake of uranyl ions. A miniemulsion polymerization technique using SDS micelles was employed for the preparation of the hydrogel as linked submicrometer particles. In polymerization, acrylonitrile was used as the initial monomer, ethylene glycol dimethacrylate as the crosslinker and 2-hydroxymethacrylate, 1-vinyl-2-pyrrolidone, acrylic acid, or methacrylic acid were added as co-monomers after the initial seed polymerization of acrylonitrle. The particles were characterized by transmission electron spectroscopy, scanning electron microscopy (SEM) and cryo-SEM. The amidoximated particles were superior to a commercially available resin in their ability to rapidly remove dissolved UO22+ from spiked groundwater samples.Öğe Hydrogel networks for metal nanoparticle syntheses and their applications in catalysis(Amer Chemical Soc, 2009) Özay, Hava; Aktaş, Nahit; Baran, Yakup; John, Vijay T.; Şahiner, NurettinÖğe Magnetic hydrogel syntheses and their applications in the environment for the removal of toxic metal ions(Amer Chemical Soc, 2009) Özay, Özgür; Önder, Alper; Şahan, Tekin; Aktaş, Nahit; Baran, Yakup; John, Vijay T.; Şahiner, Nurettin[Anstract Not Available]Öğe PMSE 489-Poly(4-vinylpyridine) based nanoparticle syntheses and their applications to functional materials(Amer Chemical Soc, 2008) Özay, Özgür; Aydin, Fatma; Ekici, Sema; Yıldız, Mustafa; Baran, Yakup; Tan, Grace; John, Vijay T.[Anstract Not Available]Öğe POLY 225-Acrylonitrile-based functional hydrogel particles(Amer Chemical Soc, 2008) Şahiner, Nurettin; Yu, Haini; Tan, Grace; He, Jibao; John, Vijay T.; Blake, Diane A.Öğe POLY 545-Modifiable hydrogel particles based on acrylonitrile core and various shells(Amer Chemical Soc, 2009) Ilgın, Pınar; John, Vijay T.; Şahiner, Nurettin[Anstract Not Available]
