Green synthesis and optimization of selenium nanoparticles using chitosan or cationic cellulose nanofibers

Spherical selenium nanoparticles (Se NPs) were synthesized by green chemical reduction method using biocompatible chitosan (CS) or as reported herein for the first time, cationic cellulose nanofibers (CCNFs) as stabilizers. CNFs were cationized using (3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC), followed by high-pressure homogenization. The anionic demand of the CCNFs was found to be 2000 +/- 2 mu eq/g and the degree of substitution was 0.25 +/- 0.01. The optimization of Se NP synthesis was done using response surface methodology with controlled composite design. Two response surface models were developed to optimize the size and stability of CS-Se NPs and CCNF-Se NPs. Concentrations of Na2SeO3, ascorbic acid, and CS or CCNFs were used as three variables, and their interaction was studied as a function of size and zeta potential. The results indicate that the variables fitted into the model and was validated using a combined contour plot of size and zeta potential. From the model, CS-Se NPs of size and zeta potential in the range between 10 and 70 nm and 30-40 mV were synthesized, while CCNF-Se NPs of size and zeta potential in the range between 50 and 85 nm and 30-35 mV were synthesized. EDX spectra confirmed elemental Se formation, and XRD pattern verified the presence of alpha-monoclinic Se crystallites. Additionally, the FTIR spectra confirmed the interaction between the stabilizing agent and Se NPs. Thus, CS- and CCNF-stabilized Se NPs were sustainably synthesized making them suitable for incorporation into CNFs and can be used as an active agent in food packaging application.