A robust Pt nanozyme for visual isoniazid determination in commercial tablets and biosamples

decomposition, supported by both experimental evidence and density functional theory (DFT) calculations. The biosensor exhibits a broad linear range of 5-35 µM, with a limit of detection (LOD) of 1.46 µM and a limit of quantification (LOQ) of 4.57 µM. It shows acceptable selectivity against common interferents in various sample matrices. Validation in artificial urine samples demonstrated good agreement with high-performance liquid chromatography (HPLC), and spike-and-recovery tests in commercial tablets, urine, and serum yielded satisfactory results. This work establishes a proof-of-concept for a practical Pt-NZ-based colorimetric assay for INH, supporting therapeutic drug monitoring and pharmacokinetic studies.