Green wet-chemical synthesis and stabilization of colloidal arsenic nanoparticles using Lonicera suspicata var. johnstonii extract

Arsenic nanoparticles represent a new alternative in the medical field; however, their synthesis, stability, and formation mechanisms are still unclear. Currently, the reported synthetic routes have shown a limited stability, excluding them from the benefits of colloidal systems. Therefore, in this study, we report a green wet-chemical strategy for the synthesis of colloidally stable As 0 nanoparticles from As 2 O 3 using Lonicera suspicata var. johnstonii aqueous extract as a stabilizing platform. NaBH 4 acted as the primary reducing agent, while phytochemicals from the evaluated plant contributed secondary reduction and surface stabilization effects. UV-Vis kinetic analysis revealed a concentration-dependent nucleation process, with nanoparticle formation occurring above 15 mM NaBH 4 . Linearization of ln(A ∞ - A t ) versus time demonstrated first-order behavior with a rate constant of k=0.033 min -1 , suggesting that the formation of AsNPs is mainly controlled by the concentration of As 3+ . Physicochemical characterization confirmed the formation of spherical, polycrystalline rhombohedral AsNPs with an average size of 40.98 ± 3.8 nm and a negative zeta potential (-37.7 mV), indicating strong colloidal stability. FTIR analysis verified the adsorption of plant-derived phenolic metabolites onto the nanoparticle surface, supporting a steric - electrostatic stabilization mechanism. This work provides mechanistic insight into the green synthesis of metalloid nanoparticles and establishes a stable, organically capped AsNP platform with potential biomedical relevance.