Chemically modified gelatin derivatives: synthetic strategies, physicochemical properties, biodegradation, drug delivery and biomedical applications.

Gelatin, the hydrolysate of collagen, has been used as a food ingredient as well as a pharmaceutical excipient since ancient times. Of late, it has attracted renewed interest as a constituent of drug delivery systems (DDS) because of its amicability to easily transform into various structural forms such as hydrogel, nanoparticles, and microsphere among others. Further, to meet the requirements for the fabrication of DDS, researchers have attempted various kinds of chemical modifications of the native gelatin. Some of the major chemical modification strategies of gelatin include amination, thiolation, PEGylation, acrylation and selenation, among others. Increasing evidences so far have established that chemically modified derivatives of gelatin exhibit superior physicochemical properties compared to native gelatin to support drug delivery applications such as higher drug loading efficiency and improved drug release kinetics, biocompatibility, biodegradability and pharmacokinetic profile. Accordingly, chemically modified derivatives of gelatin have been preferred over native gelatin for biomedical applications. Moreover, the growing popularity of chemically modified derivatives of gelatin has prompted their commercial production. In view of these considerations, a dedicated review article summarizing the biochemistry of gelatin, various synthetic strategies used for the preparation of chemically modified derivatives of gelatin, mechanistic discussion on the superiority of the Physicochemical properties of gelatin derivatives along with recent progress and concerns linked to their biomedical applications, is warranted. The present review article addresses this objective by providing a comprehensive, critical, and up-to-date summary of chemically modified derivatives of gelatin.