Peroxidase-like activity of silver nanowires and its application for colorimetric detection of the antibiotic chloramphenicol

Abstract

Different nanomaterials possessing localized surface plasmon resonance (LSPR) such as Ag, Au, Cu, Ti are considered as valuable tools in biomedicine and biotechnology, especially as signal enhancers in different immunoassays. In particular, silver nanoparticles as one of the most effective plasmonic metamaterials are widely used for the development of analytical detection methods, where nanoparticles either act as labels or exhibit intrinsic enzymatic activity (e.g., peroxidase or catalase-like). Silver nanowires (AgNWs) synthesized through polyol synthesis are stable nanomaterials with a highly reactive surface. Here we show that AgNWs possess intrinsic peroxidase-like activity with three commonly used substrates – 3,3’,5,5’-tetramethybenzidine (TMB), o-phenylenediamine (OPD), or diaminobenzidine (DAB) both in precipitating and non-precipitating modes. Moreover, we showed that AgNWs together with OPD can serve as a robust hydrogen peroxide sensor and pH-sensor: AgNW peroxidase-like activity increases linearly with pH. The capabilities of AgNWs as enzyme-like labels were demonstrated in competitive enzyme-linked immunoassay with chloramphenicol (CAP) biosensing with the 0.36 µM (0.15 µg/mL) detection limit. Moreover, the LSPR property of AgNW allows using them as optical labels for the visualization of antibody-hapten interaction – the fact was confirmed with CAP detection in the lateral flow test within the 0.12 ÷ 88 µM working concentration range. Taking into account the unique stability of AgNWs (AgNW were stable for more than two years at room temperature in water without any preservatives and light protection), AgNWs should be considered as robust, convenient, and reliable optical labels for the development of different commercial assays for the wide spectrum of biological applications.