VOLUME 18 (Supplement)

Optimization of ultrasonic-assisted green synthesis of Au-ZnO bimetallic nanoparticles using pineapple (Ananas comosus) peels extract

Bimetallic nanoparticles are composed of two metals with specific activities that produce a greater effect when combined. Gold and zinc oxide nanoparticles provide various pharmacological applications such as antibacterial, anticancer, antimicrobial, and antioxidant. In the biosynthesis of bimetallic nanoparticles, appropriate temperature and power are the factors evaluated to produce optimized bimetallic nanoparticles (BNPs) using a certain synthesis method. This study aimed to determine the optimum temperature (Celsius) and sonication power (watts) for the green synthesis of Au-ZnO bimetallic nanoparticles by the phenolic compounds contained in Ananas comosus peels extract as reducing and capping agents using an ultrasonic-assisted method. The A. comosus peels were collected, dried, and extracted using 95% ethanol and water (50:50). The extract was then tested using ferric chloride and potassium dichromate to confirm the presence of phenolic compounds. The Au-ZnO BNPs were green-synthesized under varying temperatures (60 - 80°C) and sonication power (60 – 180 watts). The Au-ZnO BNPs were characterized using UV-Vis spectroscopy, SEM-EDX, and FTIR. The BNPs were also subjected to in vitro assays for DPPH scavenging activity and UV protection property. Results indicated that the absorbance peaks at 315 nm and 545 nm for ZnO NPS and Au NPS while the Au-ZnO NPS obtained from different temperatures and sonication power showed characteristic peaks between 320 to 345 nm and between 530 to 540 nm, respectively. The inhibitory concentration (IC50) for the DPPH scavenging activity for Au NPS, ZnO NPS, and the Au-ZnO BNPs were calculated to be 346.38, 67.68, and 11.26 – 808.68 μg/mL, respectively. The Au-ZnO BNPs C1, C4, C7, and C9 showed good UV protection properties with UPF values 18.96, 18.08, 14.79, and 17.02, respectively. Results of the optimization indicated that the Au-ZnO BNPs synthesized under low temperature (60°C) and low sonication power (60 watts) exhibited the highest DPPH scavenging activity and UV protection property.