Fabrication and characterization of Cu–ZnO–cellulose acetate electrospun nanocomposite membranes for dual-function photocatalytic degradation and microbial inhibition

Abstract

Antimicrobial resistance is a growing global health threat, motivating the design of materials with enhanced, broad-spectrum antimicrobial performance under practical conditions. Zinc oxide (ZnO) nanoparticles are attractive for their intrinsic antimicrobial activity, but their photocatalytic efficacy is typically limited to UV irradiation due to a wide band gap. Here, Cu-doped ZnO (Cu_xZn_100−xO) nanohybrids were synthesized via co-precipitation with varying Cu contents (x = 0, 3, 5, 7, 10) and calcination temperatures (450 °C and 650 °C) to enable visible-light activation and synergistic antimicrobial activity. XRD, FTIR, SEM-EDX, UV-vis DRS, and AAS analyses confirmed the successful incorporation of Cu, along with corresponding changes in morphology and band gap modulation. The 7% Cu-doped ZnO prepared at 450 °C exhibited the lowest band gap and the highest photocatalytic activity toward methylene blue under visible light, alongside the strongest antioxidant capacity (IC₅₀ = 151 μg mL⁻¹). Antimicrobial activity assessed by agar well diffusion demonstrated superior inhibition zones for 7% Cu–ZnO compared to pure ZnO across gram-positive (Staphylococcus aureus, MRSA), gram-negative (Escherichia coli, Salmonella typhi, Shigella sonnei), and fungal (Candida albicans) strains. Cu doping markedly enhanced the antimicrobial performance of ZnO nanofiber mats. The 7% Cu–ZnO mats exhibited significantly larger inhibition zones against both Gram-positive and Gram-negative bacteria as well as C. albicans compared to pure ZnO mats, confirming their superior broad-spectrum activity. 7% Cu-doped ZnO processed at 450 °C functions as a visible-light-active, broad-spectrum antimicrobial nanohybrid, and its incorporation into cellulose acetate nanofibers provides a cost-effective, scalable membrane platform for advanced antimicrobial and photocatalytic applications.