Tripodal N ₄ O ₃ Schiff Base‐Capped AgNPs for Fluorescent‐Colorimetric Selective Detection of Pb ²⁺ Ion: Antimicrobial and Anticancer Activity, Biosensor Imaging, and Analytical Applications

ABSTRACT The synthesis, characterization, and application of a tripodal N 4 O 3 Schiff base (NTT)‐capped silver nanoparticle (NTT@AgNPs) as a fluorescent‐colorimetric chemosensor for the sensitive and selective detection of Pb 2+ ions have been effectively demonstrated in this work. The NTT ligand successfully capped silver nanoparticles, producing a stable hybrid nanomaterial with unique optical and structural properties. Extensive spectroscopic (UV–vis, fluorescence, FT‐IR, and NMR), morphological (SEM, TEM, and XRD), and thermal (TGA and DTG) analyses confirmed the efficient synthesis and stability of the nanomaterial. NTT@AgNPs exhibited remarkable optical selectivity toward Pb 2 + with very low detection limits (4.52 × 10 − 7 M for colorimetric detection and 4.98 × 10 − 7 M for fluorometric detection), along with excellent resistance to interference from competing metal ions and high recovery rates (97%–100.67%) in real environmental water samples, demonstrating superior analytical performance compared to many previously reported Schiff base‐capped AgNP sensors. The sensor′s potential practical applications have been further demonstrated by its exceptional reversibility and strong resistance to interference in the presence of EDTA. Its usefulness was confirmed by the reliable detection of Pb 2+ in real water samples with low relative standard deviations and good recovery rates. The rigid tripodal N 4 O 3 Schiff base framework provides strong metal chelation, structural stability, and low cytotoxicity to the AgNPs, enabling the NTT@AgNPs hybrid to function as a multifunctional platform for both selective Pb 2 + sensing and biomedical applications.