Síntese de nanopartículas de cobre e avaliação da ação antimicrobiana

Abstract

Nanoparticles, objects with dimensions between 1 and 100 nanometers, have made a name for themselves in various fields, such as chemistry, materials science, and physics. Due to their low synthesis cost and bactericidal and fungicidal properties, copper nanoparticles are extensively researched and applied in various sectors, including the textile industry. Nanoscience and nanotechnology play crucial roles in developing and using these nanoparticles, enabling the creation of advanced and functional materials in fields such as medicine, electronics, and the pharmaceutical and food industries. The unique characteristics of metallic nanoparticles, such as their high surface area, make them efficient even in small quantities, reducing application costs. The synthesis of copper nanoparticles was carried out using anhydrous copper sulfate, L-ascorbic acid, and gelatin as reagents. They were chosen for their accessibility and low toxicity, aiming to be applied as antimicrobial agents in 100% polyester fabrics. The synthesis process involved the preparation of solutions containing food-grade gelatin and copper sulfate combined with different concentrations of L-ascorbic acid. An additional variation used P.A. gelatin instead of food-grade gelatin. The nanoparticles were characterized in terms of size and structure using spectroscopic techniques. At the end of the synthesis, two mixtures were obtained with a greenish color and another with an orange hue, followed by precipitation without constant stirring. UV/Vis analysis showed absorption of the standard CuNPs using laboratory-grade gelatin in the 583 nm range. The CuNPs with food-grade gelatin showed copper complexes in the 692 nm range without a welldefined absorption. The particle size by the DLS technique revealed that most of the CuNPs had an average diameter of 1790 nm, possibly due to the agglomeration effect of the gelatin, even in the standard synthesis. The standard CuNPs exhibited an average diameter of 545 nm, with a small part measuring 28 nm. Despite the large diameter of the synthesized particles, the CuNPs did not show an inhibition halo against S. aureus. Still, they did reveal a small inhibition zone of 7 ± 0.5 mm against K. pneumoniae, which is an exciting result. On the other hand, the standard synthesis showed a significant halo of inhibition against the bacteria, with a zone of inhibition of 8 ± 0.5 mm and 9 ± 0.5 mm for S. aureus and K. pneumoniae, respectively. As for the application test on 100% polyester fabric, it won’t be possible to carry it out within the time available.