Antioxidant coatings with selenium nanoparticles, stabilized by chitosan and nanocellulose, for active paper...

This study develops active food packaging coatings using antioxidant selenium nanoparticles (Se NPs), synthesized via green chemical reduction with cationic cellulose nanofibers (CCNFs) and chitosan (CS) as stabilizers. Se NPs were incorporated into either TEMPO-oxidized or enzymatically hydrolyzed (EH) cellulose nanofibers (CNFs) using blending and in-situ synthesis methods. Se NP incorporated CNF suspensions were coated onto liners with one or two alginate layers, and the best formulation was identified based on CNF type and incorporation method. Antioxidant performance, assessed via DPPH assay, showed 98-99 % radical inhibition in coatings with 10 % Se NP-incorporated CNFs. Antimicrobial activity was less remarkable, but inhibitions of E. coli growth of up to ∼65 % were found for coated papers. Barrier properties were evaluated at different Se NP concentrations and alginate layer numbers. The highest kit value (12) was achieved with two layers of alginate and two layers of 10 % CS- or CCNF-stabilized Se NP-incorporated TEMPO CNFs (STC) via in-situ synthesis. Coated liners also reached air resistance values of ∼2000 Gurley seconds and water vapor transmission rates of ∼150-200 g/m²/day. FESEM imaging confirmed the synergistic effect of alginate and STC in reducing pore size, highlighting its potential for active food packaging.