Robust Pt nanozyme for visual isoniazid determination in commercial tablets and biosamples

Abstract

A reliable method for isoniazid (INH) determination is critical for personalized tuberculosis therapy. In this study, we developed a robust colorimetric biosensor using a peroxidase (POD)-like platinum nanozyme (Pt-NZ) as the signal transducer. Pt-NZ features simple preparation, batch-to-batch reproducibility, and catalytic efficiency comparable to other Pt-based nanozymes. Mechanistic investigations confirmed that •OH dominate the H2O2 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 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 high 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.