Enhanced radical scavenging activity of polyhydroxylated C60 functionalized cellulose nanocrystals

A first demonstration of conjugated polyhydroxylated fullerene (C₆₀(OH)₃₀) on the surface of cellulose nanocrystals (CNC)s is reported. These nanohybrids display favourable antioxidant performance and are an attractive alternative to derivatized fullerene nanocages reported previously. UV–Vis measurements indicated that the C₆₀(OH)₃₀-CNC system scavenged 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals to a greater degree than C₆₀(OH)₃₀ alone, due to the nucleation of C₆₀(OH)₃₀ on the surface of CNC and high colloidal stability of the engineered nanohybrid. A mechanism for the 2-stage process of the radical reaction with C₆₀(OH)₃₀-CNC is proposed, and modelled by pseudo-first order kinetics. Successful grafting of C₆₀(OH)₃₀ on CNC was confirmed by FTIR, while TEM revealed the morphology of the system with a grafting degree of 20.8 % C₆₀(OH)₃₀. Zeta potential measurements of C₆₀(OH)₃₀-CNC in aqueous solution showed a high stability in the pH range 4.0-8.0, indicating functionality of the CNC based antioxidant system as a biocompatible and sustainable protocol with potential for use in personal care applications.