High-efficiency production of multifunctional silver nanoparticles from Lagenaria siceraria Sandıklı ecotype via hydrothermal synthesis for biomedical and dielectric applications with phytochemical profiling

Abstract Green synthesis of silver nanoparticles (AgNPs) offers a sustainable alternative to conventional, toxic chemical methods. This study investigates a combined hydrothermal-assisted green synthesis approach for AgNPs, utilizing a synergistic combined exocarp-mesocarp extract of Lagenaria siceraria sourced from the Sandıklı region of Turkiye. The principal methodological innovation of this work lies in the simultaneous utilization of both anatomical layers to maximize the phytochemical reducing and capping capacity, rather than simply relying on their synergistic effects. The phytochemical profile of the extract was comprehensively analyzed via LC-MS/MS, alongside quantitative assessments of total phenolic (TPC) and flavonoid (TFC) contents. Synthesized AgNPs were characterized using SEM-EDX, XRD, UV-Vis, FTIR, TGA, contact angle, and dielectric measurements. Biological performance was evaluated through total antioxidant/oxidant capacity (TAC/TOC), oxidative stress index (OSI), and antimicrobial assays against Escherichia coli, Staphylococcus aureus, and Candida albicans. LC-MS/MS revealed a rich bioactive profile dominated by quinic, protocatechuic, and caffeic acids. This integrated synthesis protocol enabled the high-yield (98% based on AgNO₃) production of highly crystalline, face-centered cubic (FCC) AgNPs with an average size of ~ 25 nm and a distinct surface plasmon resonance at 422 nm. FTIR and TGA confirmed the effective capping and thermal stability provided by the phytochemicals. While the plant extract (LSE) exhibited robust antioxidant activity comparable to Vitamin C, the synthesized AgNPs demonstrated a significant increase in TOC and OSI ( p < 0.05), indicating a shift toward a pro-oxidant character. Antimicrobial tests revealed that the AgNPs exhibited superior inhibitory activity against Gram-negative E. coli compared to the penicillin control, while showing moderate activity against S. aureus and C. albicans due to their complex cell wall structures. The Sandıklı ecotype of L. siceraria serves as a highly efficient, dual-action (reducing and capping) agent within this combined synthesis framework, highlighting the potential of the resulting nanomaterials not only for targeted antimicrobial applications but also as high-dielectric-performance materials for advanced electronic applications.