Studying the synthesis, antimicrobial activity, and phenol red removal of gelatin-stabilized copper nanoparticles

This study presents a synthesis method for environmentally friendly copper nanoparticles using ascorbic acid and gelatin as key components. The influence of precursor concentration, reductant amount, and stabilizer on the process was systematically investigated to obtain optimal results for the synthesis. The optimal parameters for forming copper nanoparticles, including 20 g per L gelatin, 19.3 mM (AcO)₂Cu, and 41.5 mM ascorbic acid, were determined using a central composite design of the response surface methodology. Successful generation of pure copper nanoparticles with both spherical and cylindrical shapes, whose sizes were 43.1 and 105.2 nm, respectively, was confirmed by X-ray diffraction analysis and transmission electron microscopy. The synthesized nanomaterial was stable for a two-week storage time after which they gradually oxidized into Cu²⁺ ions. During antimicrobial activity testing, the synthesized nanoparticles displayed distinctive ability to inhibit the growth of Gram-positive bacteria (<i>Lactobacillus fermentum</i>, <i>Bacillus subtilis</i>, and <i>Staphylococcus aureus</i>), Gram-negative bacteria (<i>Escherichia coli</i>), and cancer cells (A549, Hep-G2, KB, and MCF7). Copper nanoparticles synthesized by chemical reduction demonstrated notable inhibitory activity against various pathogenic fungi that affect plants, including <i>Fusarium solani</i>, <i>Rhizoctonia solani</i>, and <i>Colletotrichum gloeosporioides</i>. Additionally, the catalytic activity of the produced nanomaterial with a bandgap energy of 2.14 eV and a specific surface area of 40.6 m² g^-1 was explored in the degradation of phenol, a common dye used in laboratories and industries. An optimized phenol red removal of 94.4% was achieved after a 540 second reaction time using response surface methodology, specifically a central composite design with an optimal dosage of copper nanoparticles at 31.5 ppm, a NaBH₄ concentration of 53.1 mM, and a pH of 7.5.