Thermoresponsive Cellulose Nanocrystals Protecting Macrophage Cells From Oxidative Stress

Abstract

Cellulose nanocrystals (CNCs) were grafted with poly(N-isopropylacrylamide) (PNIPAM) chains, by means of the grafting from route, using the TEMED/KPS redox pair as free-radical initiators. The confirmation of grafting was revealed by 13C NMR spectra. In a test with murine macrophages (RAW 264.7 cell line), CNC-g-PNIPAM copolymers did not affect cell viability nor RAW cell oxide nitric production. Raw cells exposed to oxidative stress induced by H2O2 decreased the cell viability (~ 60%) and increased lipid peroxidation, as revealed by malondialdehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD) levels. The most effective protection against the oxidative damage, with cell viability of 100%, was provided by 50 µg mL-1 of CNC-g-PNIPAM synthesized with 1:1 CNC:NIPAM mass ratio. Furthermore, there was no significant difference between the levels of GSH, MDA and SOD between cells treated with the modified CNC and cells not exposed to peroxide. These results indicate that the antioxidant properties of CNC-g-PNIPAM may be useful in possible applications in health treatments.