N-methylene phosphonic acid gelatin encapsulated copper sulfide nanoparticles as smart antibacterial materials

초록

A green and sustainable approach was developed for the synthesis of copper sulfide (CuS) nanoparticles functionalized with N-methylene phosphonic acid gelatin (MPG) as a novel antibacterial nanocomposite. Gelatin was chemically modified via a Schiff base reaction to introduce phosphonic acid groups, enhancing its metal-binding and stabilization properties. The MPG solution facilitated the green synthesis of MPG-decorated CuS nanoparticles (MPG@CuS) through an ultrasonication-assisted process, ensuring effective dispersion and uniform nanoparticle formation. The concentration of MPG was accurately optimized to investigate its effect on nanoparticle morphology and antibacterial efficiency. The successful synthesis and structural characterization of MPG and MPG@CuS nanocomposites were confirmed using ¹H NMR, FTIR, TEM, and UV-Vis spectroscopy. The antibacterial efficacy of the MPG@CuS nanocomposites was evaluated against E. coli (Gram-negative) and S. aureus (Gram-positive) using the agar well diffusion method. The results revealed a dose-dependent improvement in antibacterial activity, with inhibition zone diameters reaching 25 mm for E. coli and 27 mm for S. aureus at 20 % MPG concentration and bacterial reduction percentage of 99 % for both two bacterium strains. This enhanced activity is attributed to the synergistic effects of CuS-induced reactive oxygen species (ROS) generation and the MPG matrix, which ensures uniform nanoparticle dispersion and facilitates strong interactions with bacterial membranes. Overall, the MPG@CuS nanocomposite demonstrates excellent antibacterial performance, scalability, and environmental compatibility, offering promising applications in biomedical and environmental fields as a green and efficient antibacterial material. © 2025 Elsevier B.V.

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