An injectable thermo-responsive hydrogel based cellulose-brush derivative for the sustained release of doxorubicin

A cellulose-grafted-poly(N-isopropylacrylamide) (cellulose-g-PNIPAAm) copolymer with thermo-responsivity was synthesized using homogeneous activators regenerated by electron transfer for atom transfer radical polymerization (ARGET-ATRP). The prepared copolymer dispersed at low concentration in water or phosphate-buffered saline (PBS) at 25 °C could self-assembly into micelles at 37 °C. The size and morphology of these micelles were determined by dynamic light scattering and transmission electron microscopy. The copolymer at a concentration over 4.2% by weight in water formed an injectable thermo-responsive hydrogel that was composed of micelles when the temperature increased to 37 °C. This hydrogel was used to load the anticancer drug doxorubicin (DOX). In vitro release studies demonstrated that this hydrogel released DOX in a sustained manner. Furthermore, this cellulose-based injectable thermo-responsive hydrogel was used in cytotoxicity tests, revealing that it was very biocompatible. Based on the above results, this cellulose-g-PNIPAAm injectable thermo-responsive hydrogel has strong potential for application in smart drug delivery systems.