177,290 research outputs found
Conformation of human plasma proteins at polymer surfaces: the effectiveness of surface heparinization
No full textStudies were made on the adsorption of two human plasma proteins, albumin (HSA) and fibrinogen (HFg), onto three different polymeric surfaces: commercial pellethane R 2363-80AE (PU); pellethane crosslinked with a poly(amido-amine) (PUPA); and heparinized PUPA, using in situ ATR/FTIR spectroscopy (attenuated total reflection Fourier transform infrared spectroscopy). Conformational changes were found to occur on the two proteins upon adsorption onto bare PU and PUPA and the protein unfolding on bare PU was also found to be time dependent. On the contrary, the two proteins do not change conformation when they are adsorbed onto the heparinized surface, emphasising the effectiveness of surface heparinizatio
An insulin releasing system responsive to glucose: thermodynamic evaluation of permeability properties
No full textTwo weak poly(acid)s, poly(acrylic acid) (PAA) and poly(N-acryloyl-glycine) (P1), were graft-copolymerized onto porous cellulose membrane and their protonation behavior in aqueous media was studied by potentiometric techniques. Comparison with the corresponding free polymers in solution showed the same basicity constants during the protonation of ionized carboxyl groups, and the large potentiometric hysteresis loops observed for the grafts were indicative of specific interactions with the cellulose substrate. This was confirmed by FT-IR spectroscopic analysis at low pH. The polymeric membrane system, containing immobilized glucose oxidase, was synthesized for the purpose of insulin delivery in response to glucose concentration. The porosity of the membrane was controlled by the charge-state conformations of the grafted chains. The formation of gluconic acid in the presence of glucose caused a drop in pH which led to neutralization of the negatively charged carboxyl groups. The decrease in electrostatic repulsion caused the extended macromolecular chain to assume a coil-like form and opened the membrane pores to insulin
Physiochemical characterization and coating of polyurethane with a new heparin adsorbing material
No full textThe coating of polyurethane devices was obtained by using a solution of a new heparin-adsorbing material. PUPA. The structure of the coated material was investigated at different depths by FTIR techniques. The bond with heparin is electrostatic, as revealed by subtracting the spectrum of the native PUPA from that of the heparinized sample
Thermodynamics of protonation and Cu(II) complex formation with polymers containing different basic groups.
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