Natural polymers drug carriers Natural polymers drug carriers

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Macromolecular-based drug carriers have attracted increasing interest because of their potential applications in cancer diagnosis, imaging, and treatment. Especially, natural polymers show excellence in drug carriers.

Keratin graft copolymers

Keratin is a cysteine-rich structural protein formed in the epithelial cells of higher vertebrates, and possesses excellent biological compatibility and low toxicity to cells. Furthermore, keratin is rich in lysine and arginine, which enables it to be cleaved in vivo by trypsin, an essential protease found in the body that is generally overexpressed in inflamed and tumorous tissues. The problem of using keratin as a drug carrier is that keratin cannot be well dissolved in mild aqueous media due to strong inter- and intra-molecular hydrogen bonding. In our works, poly(ethylene glycol), poly-[N-(2-hydroxypropyl)methacrylamidewere grafted on to the keratin backbone endowing with good resolvability and synthetic polymer properties. These keratin copolymers served as excellent carriers, showing good effects.

 J. Mater. Chem., 2012, 22, 19964–19973

Dextran graft copolymers

Dextran is a water-soluble, biodegradable, nonimmunogenic, and nontoxic glucose polymer that can be enzymatic digestion in the human body. Dextran and its derivatives have been exploited extensively in biomedical, biotechnological, and pharmaceutical fields. In our works, dextran graft poly (N-methacryloylglycylglycine) copolymer tyrosine conjugates (dextran-g-PMAGGCONHTyr) were synthesized and characterized. The graft copolymers were labeled with 125I, and pharmacokinetics studies showed a rapid clearance of 125I-labeled graft copolymers from the blood pool. And then biodistribution and the effect of the numbers of -COOH groups on the graft copolymers on the biodistribution were investigated. In order to improve the blood clearance time of Dex-g-PMAGGCONHTyr copolymers, PHPMA is introduced into the Dex-g-PMAGGCONHTyr copolymers. The results showed a striking prolonged clearance time. The PHPMA-modified dextran graft copolymer Dex-g-P(HPMA-co-MAGGCONHTyr) is a potentially excellent radiotherapy carrier, which can be applied to in vivo efficient radiotherapy for tumors in the further.

        

 Biomacromolecules, 2011, 12, 1851–1859, Polym. Chem., 2011, 2, 1872–1878