Silica-templated porous nanoparticles with multifunctional surface groups for sensitive colorimetric detection of glucose and hydrogen peroxide

Abstract

Artificial nanozymes have arisen as promising catalytic materials providing superior stability, economic feasibility, and tunable activity compared with natural enzymes. In the present study, a single-step pyrolysis method was employed to obtain metformin-ZnCl<inf>2</inf>-thiourea nanoparticles (MZT-NPs) where colloidal silica acted as a structural template facilitating the development of a porous architecture and improved surface reactivity. Metformin was served as the precursor for carbon and nitrogen, while thiourea provided sulfur together with supplementary nitrogen functionalities. Zinc chloride acted the same as a dopant improving catalytic competence of the resulting nanomaterial. Comprehensive analysis employing FT-IR, UV–Vis, SEM, EDX, PXR, and DLS established that the MZT-NPs contained well-defined functional groups, exhibited strong optical absorption, maintained a uniform structure, and incorporated elements effectively. Catalytic performance assessments demonstrated that the MZT-NPs exhibit strong peroxidase-mimicking behavior efficiently facilitating o-phenylenediamine (OPD) oxidation by hydrogen peroxide colorimetric quantification. When operated under optimized experimental conditions (acetate buffer, 2 × 10⁵ μM, pH 4.0, 60 °C) the system achieved a low detection limit of 2.97 μM and displayed a linear detection range spanning 10–800 μM. Upon integration with glucose oxidase (GOx), MZT-NPs facilitated sensing of glucose through the enzymatic release of hydrogen peroxide. This approach produced a linear calibration range from 100 to 600 μM and a detection limit as low as 28 μM. The system exhibited high selectivity with glucose generating a relative response of 88 % compared to various common interferents like citric acid, ascorbic acid, uric acid, lactose, fructose, and sucrose. In real sample analysis, the sensor recorded a glucose concentration of 5220 ± 80 μM closely matching results from a commercial kit (5390 ± 60 μM) with an average deviation of 170 μM. These findings demonstrate that MZT-NPs are a cost-effective, sensitive, and selective nanozyme platform with significant potential for clinical glucose and hydrogen peroxide detection.