Bioinspired CuO nanoparticles from Melissa officinalis for antibacterial electrospun nanofiber food packaging

Abstract This study investigates green-synthesized copper oxide nanoparticles (CuONPs) via lemon balm extract and their incorporation into polyacrylonitrile (PAN) nanofibers for food packaging applications. UV-Vis spectroscopy indicates the successful formation of CuONPs, characterized by a characteristic absorption peak at 250–350 nm and minimal aggregation. Photoluminescence (PL) analysis revealed an intense emission peak at 350–450 nm, indicating the presence of oxygen vacancies that enhance photocatalytic activity and reactive oxygen species generation. FT-IR spectroscopy confirmed Cu–O stretching vibrations at 542–588 cm⁻¹ and hydroxyl groups at 3398–3451 cm⁻¹, demonstrating the role of phenolic substances as reducing and capping agents. XRD analysis confirmed phase-pure monoclinic CuONPs with the most intense peak at 2θ = 35.5° corresponding to the (200) plane. TEM revealed rod-shaped nanoparticles with diameters of 10.6–17.7 nm, while SEM showed particles of 30–50 nm. EDX spectroscopy validated elemental composition with no impurities detected. Incorporation of CuONPs into PAN nanofibers at 0.3, 0.7, and 1.0 wt.% produced dose-dependent improvements. PAN/1.0CuONPs nanofibers achieved an ultimate tensile strength of 18.7 MPa and 690% elongation, representing 38% enhancement over pure PAN. The TGA demonstrated improved thermal stability, with the onset of degradation delayed to 330–340 °C. Antibacterial testing against Staphylococcus aureus , Escherichia coli , and Listeria monocytogenes showed that PAN/1.0CuO nanofibers exhibited zones of inhibition of 29.4 ± 0.3 mm, 31.4 ± 0.7 mm, and 25.2 ± 0.3 mm, representing a 5-fold enhancement over pure PAN. DPPH assay revealed 88% radical-scavenging capacity. These findings establish CuONPs-incorporated PAN nanofibers as promising candidates for active food packaging with superior mechanical, thermal, antibacterial, and antioxidant properties.