Chitosan–Antipyrine Schiff Base Nanocomposites With ZnO or Ag Nanoparticles: Synthesis, Characterization, and Dye Adsorption With Preliminary Biological Assessment

Abstract

ABSTRACT A novel chitosan Schiff base derivative (CSB) was synthesized by chemically modifying chitosan with antipyrine. This modified matrix was subsequently used to prepare nanocomposites through the encapsulation of zinc oxide (CSB/ZnO) and silver (CSB/Ag) nanoparticles. Fourier‐transform infrared spectroscopy (FTIR), x‐ray diffraction (XRD), elemental analysis, and electron microscopy confirmed Schiff base formation and a degree of substitution of 71.35%. Nanoparticle incorporation produced distinct changes in surface morphology and porosity. The materials exhibited excellent performance in removing Reactive Blue 19 (Remazol Brilliant Blue R) from synthetic wastewater. Under optimized batch conditions using an initial dye concentration of 50 mg/L and a contact time of 60 min, removal efficiencies reached 97.40% for CSB, 98.80% for CSB/ZnO, and 99.09% for CSB/Ag, compared with 47.12% for unmodified chitosan. Biological assessments demonstrated dose‐dependent antibacterial activity against Gram‐positive ( B. cereus and S. aureus ) and Gram‐negative ( Escherichia coli and P. aeruginosa ) bacteria, as well as antifungal activity against A. niger and C. albicans . In vitro MTT assays were performed to investigate the cytotoxic effects of CSB and its nanocomposites against MCF‐7 and HepG2 cancer cell lines and normal cells. These results support further investigation of the prepared nanocomposites for water purification and potential biomedical applications.