BIOSINTESIS NANOPARTIKEL ZINK OKSIDA MENGGUNAKAN EKSTRAK BIJI PEPAYA (Carica papaya L.) SEBAGAI AGEN ANTIMIKROBA

Abstract

Green synthesis of nanoparticles using plant extracts has emerged as an environmentally friendly method for producing antimicrobial materials. The utilization of papaya seed extract (Carica papaya L.) as a reducing and stabilizing agent in the synthesis of zinc oxide (ZnO) nanoparticles remains limited. This study aimed to synthesize ZnO nanoparticles using papaya seed extract and to evaluate their structural properties, optical characteristics, colloidal stability, thermal behavior, and antimicrobial activity. The synthesis was carried out using zinc nitrate as a precursor at pH 8 under controlled heating, followed by purification and drying. Characterization results showed an absorption peak at 367 nm with a band gap energy of 3.38 eV. X-ray diffraction analysis confirmed a hexagonal wurtzite crystal structure with an average crystallite size of 45 nm. The particles exhibited a nearly spherical morphology with sizes ranging from 20-80 nm. A zeta potential value of -23.46 mV indicated moderate colloidal stability. Thermal analysis revealed the presence of residual phytochemical compounds adsorbed on the surface of the ZnO nanoparticles. Antimicrobial activity testing showed an increase in the inhibition zone diameter with increasing nanoparticle concentration. At a concentration of 25 mg/mL, the inhibition zone diameters against S. aureus, S. epidermidis, and C. albicans were 13.76 ± 0.88 mm, 12.25 ± 0.85 mm, and 14.88 ± 0.18 mm, respectively. These values decreased at lower concentrations, with the lowest activity observed at 0.375 mg/mL. These findings indicate that papaya seed extract has potential as a natural bioreducing agent in the green synthesis of ZnO nanoparticles for environmentally friendly antimicrobial nanotechnology applications.