Sparse silver loading on chitosan–boron carbon nitride framework: a sustainable route to multifunctional nanomaterials

The design of multifunctional nanomaterials capable of addressing both environmental and biomedical challenges is a growing focus in modern materials science. In this study, we report the synthesis of a silver nanoparticle-embedded on chitosan-boron carbon nitride (Ag@CS-BCN), crosslinked with glutaraldehyde, <i>via</i> a multi-step process. The structural, morphological, elemental, and stability characteristics of the synthesised nanohybrid systematically investigated using spectroscopic and microscopic techniques. The catalytic performance of Ag@CS-BCN was evaluated for the reduction of 4-nitrophenol (4-NP) and the degradation of methyl orange (MO) and rhodamine B (RhB), persistent organic pollutants of environmental concern. The nanocomposite exhibited rapid catalytic activity, achieving >94% degradation within minutes (4-NP: 5 min, 99.82%; MO: 3 min, 94.50%; RhB: 7 min, 98.89%), and demonstrated recyclability for up to three consecutive cycles with minimal loss in performance. Beyond environmental applications, Ag@CS-BCN displayed potent antimicrobial efficacy against both Gram-positive and Gram-negative bacterial strains. Importantly, cytotoxicity studies revealed selective anticancer activity, with an IC₅₀ value of 45.73 μg mL^-1 against HeLa cancer cells and substantially lower toxicity toward normal 3T3 fibroblasts (IC₅₀ = 446.6 μg mL^-1). Overall, the Ag@CS-BCN nanohybrid demonstrates significant promise as a multiple-purpose material for environmental remediation and biomedical applications, particularly in nanocatalysis, antimicrobial, and targeted anticancer therapy, thereby offering an innovative platform for sustainable and therapeutic technologies.