Integrated RSM and machine learning-based green fabrication of a trimetallic Fe₃O₄/ZnO/CuO nanocomposite with antimicrobial activity

A green and sustainable approach was employed to synthesize a trimetallic Fe₃O₄/ZnO/CuO nanocomposite using pumpkin peel extract as a natural reducing and stabilizing agent. Phytochemicals in the extract facilitated metal ion reduction and nanoparticle stabilization. The composite was characterized by UV-Vis, FTIR, XRD, FESEM–EDX, and TEM–SAED and XPS analyses. UV–Vis absorption at 229 and 277 nm and a band gap of 2.85 eV indicated photoactive behavior near visible region. FTIR confirmed metal–oxygen linkages and organic residues, while XRD and SAED verified nanocrystallinity. FESEM and TEM revealed cubic assemblies (150–250nm) composed of 2–5nm spherical particles. Optimal synthesis conditions determined by Response Surface Methodology showed strong model validity (R² = 0.952), supported by machine learning (ML) optimization studies. EDX confirmed Fe, Zn, Cu, and O presence. The nanocomposite exhibited concentration-dependent antimicrobial activity, showing notable antifungal efficacy against A. niger, suggesting potential for environmental and selected biomedical applications pending further safety evaluation.