In this study, silver–histidine-immobilized Laponite nanodisks are developed for use as alternative antibacterial agents for food contact materials. The silver–histidine complex Ag(HHis)+ is immobilized onto Laponite RD nanoparticles through an ion-exchange reaction. The resulting silver–histidine-immobilized Laponite nanodisks (Ag(HHis)+LP) are characterized by inductively coupled plasma optical emission spectroscopy, X-ray diffraction, transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy, dynamic light scattering, and zeta potential analysis to confirm the successful immobilization of the Ag(HHis)+ complex onto the Laponite surfaces. The transparent antibacterial food coatings based on Ag(HHis)+LP nanodisks and cellulose nanofibers (CNF) are subsequently developed. The antibacterial activities of the Ag(HHis)+LP dispersion, the Ag(HHis)+LP-CNF dispersion, and the Ag(HHis)+LP-CNF nanocomposite films are evaluated against E. coli and S. aureus using minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays, Modify BSEN 1276:2019 method, and the JIS Z 2801:2010 method, respectively. The Ag(HHis)+LP-CNF nanocomposite films exhibit favorable mechanical, optical, and barrier properties, and the nanocomposite coatings can be applied to green grape berries as a model fruit without altering their genuine physical appearance. Furthermore, the migration test of the coated green grape berries reveals that residual silver ions detected in the grape pulp are below the ICP-OES detection limit of 0.0076 ppm, and the coatings are fully removable with water. Notably, the optimal Ag(HHis)+LP-CNF nanocomposite coating, formulated with an initial Ag+ concentration of 100 ppm, can effectively suppress bacterial contamination and extend the shelf life of green grape berries up to 21 days.
Sukaiem et al. (Tue,) studied this question.