Chitosan is natural polysaccharide which is easily extracted from Crustaceans such as crabs and lobsters. Utilization of chitosan for medical uses has been attempted owing to its wound healing property. Chitosan may be solubilized only under acidic conditions and is difficult to convert sol/gel state, which made its application difficult. NeTech was able to improve solubility of chitosan to make it soluble under neutral conditions by introducing photo-reactive moiety to chitosan. This enabled to control sol/gel conversion by light irradiation.
Photo-reactive chitosan (PRC) thus obtained gives highly viscous solution in water which can easily be applied to external wound and/or to tissue after surgical treatments. On irradiation of light between 365 and 500 nm, it converts to insoluble adhesive gel within short period of time as shown in Fig. 1).