Obtenção de nanopartículas de óxido de cobre por síntese verde a partir do extrato de folhas de laranjeira e avaliação de sua ação antimicrobiana em filmes de látex de borracha natural

Abstract

Natural rubber latex (NRL) is a plant-derived biopolymer widely used in the manufacture of materials such as gloves and dressings. Due to its use in applications involving direct contact with the skin, NRL must be free from allergenic compounds and, ideally, exhibit antimicrobial properties. In this context, metal oxide nanoparticles (NPs) have attracted increasing interest, as they can be sustainably produced through green synthesis processes and incorporated into polymeric matrices, endowing them with antimicrobial activity. In this context, this study aimed to investigate the experimental parameters involved in the synthesis of copper oxide nanoparticles (CuONPs) using an aqueous extract of orange leaves (Citrus sinensis), employing two copper salts: copper(II) acetate monohydrate (Cu(CH3COO)2 · H2O) and copper(II) nitrate trihydrate ((Cu(NO3)2 · 3H2O). Furthermore, the chemical, morphological, and antimicrobial characteristics of the synthesized NPs were evaluated, as well as their incorporation into NRL and the resulting effects on the antimicrobial properties of the final material, aiming at their application as a biomaterial. Preliminary tests indicated that the orange leaf extract has potential for use in the green synthesis of CuONPs. Under optimized conditions, the extract showed a phenolic compound concentration of 26.73 mg GAE g-1 of leaves and an antioxidant capacity of 80%. The green synthesis results demonstrated that the experimental parameters influence the structural and antimicrobial properties of CuONPs. The ideal parameters for NP synthesis were pH adjusted to 7.0, calcination temperature of 300 °C, and Cu(CH3COO)2 · H2O of 10 g L-1. Cyclic voltammetry analysis revealed that changing the pH of the medium leads to deprotonation of hydroxyl groups in the phenolic compounds from the Citrus sinensis extract, which complex with Cu(II) ions prior to CuONP formation. Finally, the synthesized CuONPs exhibited an average size of 20-30 nm and were successfully incorporated into NRL films, maintaining bacteriostatic activity against Staphylococcus aureus and Escherichia coli strains. The findings not only open new perspectives for innovative biomedical applications but also highlights the importance of sustainability in materials science. [resumo fornecido pelo autor]