DoE-Assisted Green Synthesis of Silver Nanoparticles Using Peel Extract from Nephelium lappaceum: Systematic Size Optimization Enabling Antibacterial and Antioxidant Activity

Abstract

Green-synthesized silver nanoparticles (AgNPs) exhibit outstanding antibacterial and antioxidant potential for designing and developing nanomedicines and medical devices. Nephelium lappaceum or rambutan contains polyphenol-based phytochemicals, which suggests its suitability for the green synthesis of NPs. However, the lack of a systematic approach directly impacts the robustness and reproducibility of the process. Design of experiments can address these challenges in obtaining NPs with the desired quality profile. In this work, we demonstrated the advantages of a Plackett–Burman model in the semi-automated green synthesis of AgNPs using N. lappaceum peel extract. The extract concentration was the only significant factor affecting the particle size. The optimized NPs exhibited triangular and hexagonal morphologies and a hydrodynamic diameter of 80 nm after 24 h without a stabilizing agent, representing 1.2% prediction error according to the model’s equation. The in vitro antioxidant capacity was confirmed through the ABTS radical scavenging assay. The AgNPs displayed a minimum inhibitory concentration of 23.5 µg mL−1 against Escherichia coli and Staphylococcus aureus. Overall, this work highlights the synergistic role between a DoE-assisted green synthesis, the phytochemicals from N. lappaceum peel extract, and the formed AgNPs, positioning this systematic approach as a sustainable and efficient process for novel antibacterial and antioxidant agents.