Biodegradability and anticoagulant properties of chitosan and sulfonated chitosan films coated on TiNi alloys

This study proposes a method of coating chitosan and sulfonated chitosan surface modification films on nickel-titanium shape memory alloys and investigates their biodegradability and anticoagulant properties. Sulfonated chitosan has a similar structure to chitosan, although amino groups convert during the sulfonation process. The biodegradation of chitosan by Escherichia coli DH5 alpha does not occur when the concentration of chitosan is sufficiently high because the electrostatic interactions between the amino groups and phospholipid components damage the cell membranes of E. coli DH5 alpha. By contrast, the biodegradation of sulfonated chitosan is independent of its concentration because the sulfonation process results in a decrease in the number of amino groups present. Bicinchoninic acid protein assay results reveal that the amount of fibrin adhered on the deposited natural chitosan surface is twice that adhered to sulfonated chitosan. (C) 2012 Elsevier B.V. All rights reserved.