Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033036 (APC)
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Surface immobilization of the thrombin inhibitor r-hirudin was carried out on two different polymers. Linkage to poly(urethane-graft-acrylic acid) (PAC/PU) was done via carboxylic acid groups, using a water soluble carbodimide, while the immobilization on a modified poly[(ethene-co-vinyl acetate)-graft-vinyl chloride] (PVC/EVA) was achieved via the alcohol groups of the polymer using HDI as spacer. Direct immobilization of r-hirudin leaded to a remarkable loss of thrombin activity. As proved by means of protein chemical analysis, loss of activity was due to a selective coupling via the N-terminal amino group of r-hirudin, which is essential for its thrombin activity. Based on these results we developed an immobilization method via an epsilon-amino group of r-hirudin preserving full biological activity of the r-hirudin coated surface.
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PMID:Immobilization of the thrombin inhibitor r-hirudin conserving its biological activity. 1534 28

An implantable glucose microbiosensor that utilizes an electrodeposited redox polymer/glucose oxidase (GOX) sensing membrane and a highly hydrophilic poly (4-vinyl pyridine-co-acrylic acid) (PVP-PAC) overcoating as an analyte-regulating membrane has been developed. A gold microelectrode was electrodeposited with the redox polymer/GOX composite sensing membrane. Two polymers, a hydrophobic poly (4-vinyl pyridine) (PVP) and a hydrophilic PVP-PAC were investigated as possible analyte-regulating membranes. Each was mounted on the sensing layer via chemical cross-linking with poly(ethylene glycol) diglycidyl ether (PEGDGE). High current sensitivities of approximately 220 nA/mM glucose were obtained in the presence of PVP-PAC. In the case of PVP, much lower sensitivities of approximately 30 nA/mM were observed. However, only the biosensor with PVP-PAC showed excellent selectivity to glucose against interferants like oxygen and ascorbic acid (AA). The dynamic range is from 0 to 30 mM. The response time in amperometric measurements was less than 10 sec. Clinical trials showed good correlation between the readings of the subcutaneously implanted biosensor and blood sugar levels.
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PMID:An interference-free implantable glucose microbiosensor based on use of a polymeric analyte regulating membrane. 1576 68

A simple two-step method was introduced to improve the hydrogel mechanical strength by forming an interpenetrating network (IPN). For this purpose, we synthesized polyacrylate/polyacrylate (PAC/PAC), polyacrylate/polyacrylamide (PAC/PAM), polyacrylamide/polyacrylamide (PAM/PAM) and polyacrylamide/poly(vinyl alcohol) (PAM/PVA) IPN hydrogels. The PAC/PAC IPN and PAC/PAM IPN hydrogels showed compressive strength of 70 and 160kPa, respectively. For the PAM/PAM IPN and PAM/PVA IPN hydrogels, they exhibited excellent tensile strength of 1.2 and 2.8MPa, and elongations at break of 1750% and 3300%, respectively. A strain relaxation was also observed in the case of PAM series IPN hydrogels. From FTIR, TGA and SEM measurements, we confirmed that physical entanglement, hydrogen bonds and chemical crosslinking played major roles in improving hydrogel strength and toughening. The two-step technique contributes to the understanding of ideal networks, provides a universal strategy for designing high mechanical strength hydrogels, and opening up the biomedical application of hydrogels.
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PMID:A simple route to interpenetrating network hydrogel with high mechanical strength. 1966 39