27 research outputs found
Stabilization of Ion Concentration Polarization Using a Heterogeneous Nanoporous Junction
We demonstrate a recycled ion-flux through heterogeneous nanoporous junctions, which induce stable ion concentration polarization with an electric field. The nanoporous junctions are based on integration of ionic hydrogels whose surfaces are negatively or positively charged for cationic or anionic selectivity, respectively. Such heterogeneous junctions can be matched up in a way to achieve continuous ion-flux operation for stable concentration gradient or ionic conductance. Furthermore, the combined junctions can be used to accumulate ions on a specific region of the device.Korea Research Foundation (Grant MOEHRD: KRF-2007-331-D00040)Korean Science and Engineering Foundation (Grant MOST: R01-2007-000-20675-0)Korea Research Foundation (Grant MOEHRD: KRF-J03000)National Research Foundation of Korea (Grant NRF-2009- 352-D00034)National Institutes of Health (U.S.) (EB005743)National Science Foundation (U.S.). (CBET-0347348
Fabrication and characterization of hyaluronic-acid-based antigen sensitive degradable hydrogel
Analytical Expressions Pertaining to the Steady State Concentrations of Glucose, Oxygen and Gluconic Acid in a Composite Membrane Using Genocchi Polynomials
Preparation and characterization of pH-sensitive poly(ethylene oxide) grafted methacrylic acid and acrylic acid hydrogels by Îł-ray irradiation
Synthesis of Poly(ferrocenylsilane) Polyelectrolyte Hydrogels with Redox Controlled Swelling
A superabsorbent hydrogel network based on poly((2-dimethylaminoethyl) methacrylate) and sodium alginate obtained by Îł-radiation: synthesis and characterization
pH Response of Model Diblock and Triblock Copolymer Networks Containing Polystyrene and Poly(2-hydroxyethyl methacrylate- co
Polythiolactone-Based Redox-Responsive Layers for the Reversible Release of Functional Molecules
The development of thin macromolecular layers with incorporated disulfide bonds that can be disrupted and formed again under redox stimulation is of general interest for drug release applications, because such layers can provide rapid and reversible responses to specific biological systems and signals. However, the preparation of such layers from polythiols remains difficult, because of the fast oxidation of thiol groups in ambient conditions. Here we propose water-soluble thiolactone-containing copolymers as stable precursors containing protected thiol groups, allowing us to produce on demand polythiol layers on gold substrates in the presence of amine derivatives. Electrochemical, water contact angle, X-ray photoelectron spectroscopy, and X-ray reflectometry measurements evidence the formation of uniform copolymer layers containing both anchored and free thiol groups. The number of free thiols increases with the content of thiolactone units in the copolymers. In a second step, a thiolated dye, used as a model drug, was successfully grafted on the free thiol groups through disulfide bonds using mild oxidizing conditions, as proved by fluorescence and quartz crystal microbalance measurements. Finally, the reversible release/regrafting of the dye under redox stimulation is demonstrated