Chitosan, a mucopolysaccharide of marine origin, was studied for its safety and hemostatic potential. Its surface was treated with glutaraldehyde, carbodiimide, and plasma glow discharge to elicit effects of enzyme degradation. Of the seven enzymes used, leucine amino peptidase caused maximum degradation. Autoclaving appeared to be an ideal sterilizing method as it caused least decrease in tensile strength and effected a negligible rate of hemolysis. Sterilizing with glutaraldehyde with a physiologic pH retained the maximum tensile strength of chitosan. In vivo toxicity tests indicated that it is nontoxic, and the sterilized films were free of pyrogen. Coagulation and hemagglutination tests showed that the hemostatic mechanism of chitosan seems to be independent of the classical coagulation cascade and appears to be an interaction between the cell membrane of erythrocytes and chitosan.
Among biomaterials used as implants in human body, sutures constitute the largest groups of materials having a huge market exceeding $1.3 billion annually. Sutures are the most widely used materials in wound closure and have been in use for many centuries. With the development of the synthetic absorbable polymer, poly(glycolic acid) (PGA) in the early 1970s, a new chapter has opened on absorbable polymeric sutures that got unprecedented commercial successes. Although several comparative evaluations of suture materials have been published, there were no serious attempts of late on a comprehensive review of production, properties, biodegradability, and performance of suture materials. This review proposes to bring to focus scattered data on chemistry, properties, biodegradability, and performance of absorbable polymeric sutures.
This paper reports the use of fluorescent gold nanoclusters synthesized using bovine serum albumin (Au-BSA) for the sensing of copper ions in live cells. The fluorescence of the clusters was found to be quenched by Cu(2+) enabling its detection in cells. The selectivity of the nanosensor was demonstrated in the presence of several cations excluding Hg(2+). We did not study the effect of Hg(2+) since it was reported earlier. The present study suggests that Cu(2+) induced fluorescence quenching is due to its binding to BSA rather than the fluorescence quenching by metal-metal interaction as in the case of Hg(2+). The Au-BSA showed excellent selectivity to Cu(2+) at various pH conditions. The 'turn off' of fluorescence can be retrieved by a Cu(2+) chelator glycine. Our results showed that gold clusters can be used as a 'turn off' sensor for copper and a 'turn on' sensor for glycine. Under the experimental conditions, the probe showed a response for Cu(2+) over a range of 100 μM to 5 mM with a detection limit of 50 μM. The role of Cu(2+) in the misfolding and disassembly of Prion Protein (PrP) leading to various maladies is well ascertained. The methodology we reported here seems to be useful in supplementing other techniques in predicting disease conditions involving Cu(2+).
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