Comb-Shaped Conjugates Comprising Hydroxypropyl Cellulose Backbones and Low-Molecular-Weight Poly(N-isopropylacryamide) Side Chains for Smart Hydrogels: Synthesis, Characterization, and Biomedical Applications

Hydroxypropyl Cellulose (HPC) possesses a lower critical solution temperature (LCST) above 40 degrees C, while the poly(N-isopropylacrylamide) (P(NIPAAm)) exhibits a LCST of about 32 degrees C. Herein, comb-shaped copolymer Conjugates of HPC backbones and low-molecular-weight P(NIPAAm) side chains (HPC-g-P(NIPAAm) or HPN) were prepared via atom transfer radical polymerization (ATRP) from the bromoisobutyryl-functionalized HPC biopolymers. By changing the composition ratio of HPC and P(NIPAAm), the LCSTs of HPNs can he adjusted to be lower than the body temperature. The MTT assay from the HEK293 cell line indicated that HPNs possess reduced cytotoxicity. Sonic of the hydroxyl groups of HPNs were used as cross-linking sites for the preparation of stable HPN hydrogels. In corn part Soil with the HPC hydrogels, the cross-linked HPN hydrogels possess interconnected pore structures and higher swelling ratios. The in vitro release kinetics of fluorescein isothiocyanate-labeled dextran and BSA (or dextran-FTFC and BSA-FITC) as model drugs from the hydrogels showed that the HPN hydrogels are Suitable for long-term Sustained release of macromolecular drugs at body temperature.