Newly designed hydrogel with both sensitive thermoresponse and biodegradability

Abstract

The synthesis and characterization of thermoresponsive hydrogels on the basis of N‐isopropylacrylamide (IPAAm) copolymers crosslinked with biodegradable poly(amino acids) are described. This hydrogel was prepared with two kinds of reactive IPAAm‐based copolymers containing poly(amino acids) as the side‐chain groups and activated ester groups. We introduced the graft chains by decarboxylation polymerization of amino acid N‐carboxyanhydrides initiated from lateral amino groups in the PIPAAm copolymer. The hydrogels easily crosslinked with degradable poly(amino acid) chains by only mixing the copolymer aqueous solutions. The gelling method in this study would provide some of the following innovative features: (1) no necessary removal of unreacted monomers and so forth, (2) simpler loading of drugs into the hydrogels (only mixing when gelling), and (3) easier insertion into the body. On the basis of the swelling ratio measurement of the hydrogel, large volume changes dependent on temperature changes were observed. Moreover, the enzymatic temperature‐dependent degradation was confirmed. The results suggested that these hydrogels could be used for an injectable or implantable matrix of temperature‐modulated drug release. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 779–787, 2003

Thermoresponsive Polymers for Biomedical Applications

“…Another interesting approach utilizing biological structures for drug delivery has been taken by several groups using amino acid based hydrogels [78,79]. Yoshida et al produced PNIPAAm hydrogels with polyamino acid crosslinked chains to produce thermoresponsive degradable hydrogels [78].…”

“…Yoshida et al produced PNIPAAm hydrogels with polyamino acid crosslinked chains to produce thermoresponsive degradable hydrogels [78]. Hatefi and Amsden wrote a detailed review on biodegradable injectable drug delivery systems commenting on the numerous approaches and methods for in situ formation and drug release [35].…”

New Hydrolysis-Dependent Thermosensitive Polymer for an Injectable Degradable System

“…reported the synthesis of the NIPAAm copolymers cross-linked with biodegradable poly(amino acid). 19 Lee et. al.…”

Thermoresponsive hyperbranched polyethylenimines with isobutyramide functional groups

“…2 To date, the fundamental composition in nearly all the thermoresponsive materials was the linear polymers with LCST property. [3][4][5] In other words, even though the thermoresponsive materials had some specific topology, such as hydrogel, 6 star or grafted polymer, [7][8][9] and polymeric micelles, 10,11 their LCST properties were only contributed by their fundamental composition of the thermoresponsive linear polymer, and were independent on their specific topology. Only very recently, perfectly branched and welldefined dendrimers exhibiting the LCST in aqueous media were addressed, and the LCSTs were significantly dependent on the spheroid-like geometry of dendrimers.…”