Green synthesis, characterization, and antimicrobial evaluation of jackfruit seed starch-capped copper oxide nanoparticles in cold creams

Abstract

Copper oxide nanoparticles (CuO NPs) were synthesized via a green approach by reacting copper sulfate with jackfruit seed starch in its native, annealed, and pregelatinized forms, and were characterized by UV–visible spectrophotometry, Fourier-transform infrared (FTIR) spectroscopy, and X-ray diffractometry (XRD). The copper oxide nanoparticles were made into cream formulations, which were characterized and assess for their antimicrobial efficacy against selected bacterial and fungal species. Optical microscopy revealed large nanoparticle agglomerates in the micrometer range, with sizes as large as 267.70 ± 179.50 μm for the pregelatinized starch-CuO NPs. This observation was further supported by highly textured and rough micro-sized surface structures observed by SEM. However, the nanoparticles exhibited characteristic CuO absorption maxima within the 250–310 nm range. FTIR spectra confirmed the involvement of starch molecules in the formation and stabilization of CuO NPs, as evidenced by the presence of O–H stretching and C–H stretching bands at 3300–3500 cm⁻¹ and 2800–3000 cm⁻¹ , respectively. Similarly, the starch-CuO NPs showed characteristic XRD peaks corresponding to the (110) and (111) crystallographic planes, with an average crystallite size of 32.19 nm. All cream formulations exhibited acceptable appearance, pH, viscosity, and spreadability. The starch-CuO nanoparticle-loaded creams demonstrated notable antibacterial activity against Streptococcus pneumoniae and enhanced antifungal activity against Candida albicans . The findings demonstrate that jackfruit seed starch possesses effective reducing and stabilizing properties for the green synthesis of CuO nanoparticles. Additionally, the resulting nanoparticle-loaded creams show promise as topical antimicrobial formulations for the management of skin infections.