Hybrid Bio–Inorganic pH-Responsive Selenium Nanoparticles from Cinnamomum tamala for Targeted Aflatoxin B1 Suppression

Controlling aflatoxin B 1 -producing Aspergillus flavus using conventional antifungal agents is challenging. Therefore, a pH-responsive chitosan-functionalized selenium nanoparticle hybrid system (CC-SeNPs@Ch), activated via chitosan protonation under acidic conditions, was developed using Cinnamomum tamala leaf extract for targeted anti-aflatoxigenic activity. In this study, we report the green synthesis of selenium nanoparticles (SeNPs) using C . tamala leaf extract and their transformation into a smart bio–inorganic hybrid system through chitosan functionalization (CC-SeNPs@Ch). The synthesized CC-SeNPs@Ch were comprehensively characterized using UV–Vis spectroscopy, dynamic light scattering (DLS), zeta potential, X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses, confirming the formation of crystalline and spherical hybrid nanoparticles with a hydrodynamic size of 120–140 nm, positive surface charge (+28 mV), and enhanced colloidal stability following chitosan functionalization. Their antifungal, anti-aflatoxigenic, cytotoxic, and zebrafish biocompatibility profiles were subsequently evaluated. CC-SeNPs@Ch exhibited pronounced pH-dependent antifungal activity, with the lowest MIC (33.68 ± 0.41 μg/mL) and MFC (40.03 ± 0.96 μg/mL) observed under acidic conditions (pH 5), relevant to the fungal growth microenvironments. Mechanistic investigations revealed that the hybrid nanomaterial induced intracellular ROS accumulation, depleted membrane ergosterol, disrupted fungal growth, and significantly suppressed AFB 1 biosynthesis. In vitro cytotoxicity studies demonstrated selective anticancer activity toward MDA-MB-231 cells with an IC 50 value of 44 μg/mL and a selectivity index (SI) of 1.81, while zebrafish embryo assays established a NOEC of 125 μg/mL and LOEC of 150 μg/mL. This wide safety margin between effective antifungal concentrations and toxicity thresholds underscores the potential application of CC-SeNPs@Ch in food-safety and anti-aflatoxigenic systems. Overall, this study demonstrates that the pH-responsive CC-SeNPs@Ch hybrid nanoplatform effectively suppresses aflatoxigenic A. flavus and AFB 1 production while maintaining acceptable biocompatibility, highlighting their potential application in food-safety and anti-aflatoxigenic systems.