Silane-Functionalized MgO Nanoflake-Reinforced PLA–Curcumin Nanocomposite Films for Active Grape Packaging

Abstract

Hydrothermally synthesized magnesium oxide (MgO) nanoflakes (NFs) were developed as functional nanofillers for biodegradable active food packaging. X-ray diffraction confirmed a face-centered cubic crystal structure with an average crystallite size of 21.5 nm, while transmission electron microscopy revealed a flake-like morphology with particle sizes of 90–110 nm. The MgO NFs exhibited concentration-dependent antibacterial activity against Staphylococcus aureus and Escherichia coli , with greater susceptibility observed for E. coli . Toxicity assessment using Artemia salina nauplii and RAW 264.7 macrophage cells demonstrated excellent biocompatibility without significant cytotoxicity up to 50 µg mL⁻¹. Surface-functionalized MgO, modified with 3-(glycidyloxypropyl)trimethoxysilane, was incorporated into polylactic acid/curcumin (PLA-CRU) films at 1–3% via solvent casting. FTIR, XRD, and SEM analyses confirmed improved interfacial compatibility, enhanced crystallinity, and uniform nanoparticle dispersion within the polymer matrix. The PLA-CRU-3% F-MgO film exhibited complete inhibition of both bacterial strains and the highest antioxidant activity. During grape storage, the nanocomposite films reduced weight loss, maintained pH and titratable acidity, preserved antioxidant capacity, and effectively delayed fruit deterioration. Overall, the PLA-CRU-3% F-MgO nanocomposite demonstrates strong potential as a biodegradable active packaging material for extending the shelf life and microbiological safety of fresh fruits.

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