Phytofabricated Flower‐Like Nano‐CuO Reinforced k‐Carrageenan/PVA Films With Antimicrobial and Antioxidant Activity for Tomato Shelf‐Life Extension

Abstract

Growing interest in eco‐friendly, biodegradable food packaging has led to the development of biopolymer films enhanced with nanomaterials. This study explores the green phyto‐assisted biosynthesis of nano copper oxide (nCuO) using Bacopa monnieri (BM) leaf extract, which was subsequently incorporated into kappa‐carrageenan/polyvinyl alcohol (kC/PVA) films for antimicrobial packaging. The nCuO was characterized using UV‐Vis spectroscopy, dynamic light scattering, transmission electron microscopy and zeta potential analysis. The nCuO had a hydrodynamic size of ~ 115 ± 35 nm, a flower‐like structure with clusters ~ 70 ± 35 nm, and a stable colloidal suspension with a zeta potential ~−21 mV. Structural confirmation via FTIR, XRD, SEM/EDS validated the successful and uniform integration of nCuO into the kC/PVA matrix. The resulting nanocomposite films demonstrated improved mechanical properties (peak tensile strength of ~32.38 MPa), enhanced thermal stability, and superior water‐barrier characteristics. Antioxidant activity reached up to 68% (DPPH) and 62% (ABTS) and antimicrobial tests showed superior inhibition against gram‐negative bacteria, due to reactive oxygen species and Cu 2 + ion release. Cu 2 + ions migration studies using representative food simulants showed that the maximum migration (1.63 ± 0.03 mg L − 1 ) remained well below the specific migration limit, confirming the suitability of the developed films for food‐contact applications. Shelf‐life tests with tomatoes showed significantly lower weight loss in coated fruits than in uncoated controls. These results highlight the potential of BM‐based kC/PVA/nCuO films as sustainable, active packaging materials that can help improve food safety and reduce environmental impact.