The method of Chhangte et al. was adopted with slight modifications. Twenty grams of Psidium guajava leaves and fruit were weighed, sliced into small pieces with a knife, and gently pounded using a mortar and pestle. 100 mL of distilled water was added to extract, and more of its juice was filtered with Whatman No. 1 filter paper and set aside for copper nanoparticles synthesis as a stabilizing and capping agent. While stirring, a drop of H2SO4 was added to adjust the pH to 4-5, and the stirring continued until the color changed from green to pale blue, confirming the synthesis of green CuNPs. The green-synthesized P.g-CuNPs were then subjected to centrifugation to obtain colloidal particles.