Nanopartículas de prata estabilizadas por ácido ricinoléico e seu epóxido aplicadas como sensor de cisteína e agente antimicrobiano

Abstract

The nanoscale production of materials has consolidated its importance in modern science. New synthetic routes using natural products have been developed to make the process more ecofriendly. However, the use of raw natural product requires high temperatures or a long synthesis time. In this study, due to its biodegradability, higher water solubility and availability, we employed ricinoleic acid extracted from castor oil in the ecofriendly synthesis of silver nanoparticles. Ricinoleic acid epoxidation was carried out in order to increase the ricinoleate reducing capacity. The synthesis of silver nanoparticles with ricinoleic acid surfactant (AgSAR) and its epoxidized form (AgSEAR) was optimized to be applied as cysteine sensor and antibacterial agents. Maximum UV-Vis absorbances of 420 nm for AgSAR and 405 nm for AgSEAR were obtained, which indicated nanoparticle formation. The optimal condition of the experiment was the concentration of 0.5 mmol∙L-1 Ag+ and 20 mmol∙L-1 of surfactant in AgSAR synthesis and 0.3 mmol∙L-1 of Ag+ and 20 mmol∙L-1 of the surfactant in AgSEAR synthesis. Synthesis time decreased from 10 days with AgSAR to 6 hours with AgSEAR. The average nanoparticle size was 16.70 nm for AgSAR and 17.80 nm for AgSEAR, respectively, while for DLS 75.42 nm for AgSAR and 82.10 nm for AgSEAR size diameter were observed. This size difference indicates that surfactants are found as micelles around the nanoparticle. The nanoparticles were cysteine selective with a detection limit of 3.49 μmol∙L-1 for AgSAR and 16.67 μmol∙L-1 for AgSEAR. In the antibacterial application, there was total inhibition of growth at a concentration of 18 mg/L for AgSAR and 11 mg/L for AgSEAR.