Antimony-doped tin oxide nanoparticles as peroxidase mimics for paper-based colorimetric detection of glucose using smartphone read-out

Antimony-doped tin oxide nanoparticles (ATO NPs) were loaded on a filter paper where they act as a peroxidase mimic without electrochemical or photochemical assistance. The peroxidase mimicking activity is distinctly improved compared to most known nanomaterials and to natural horseradish peroxidase. The catalytic properties depend on the amount of antimony doped into the ATO NPs. A glucose assay was worked out that is based on (a) the oxidation of glucose by glucose oxidase under formation of H 2 O 2 , (b) the oxidation of 3,3,5,5-tetramethybenzidine (TMB) catalyzed by ATO NPs to form blue-green colored oxidized TMB on the surface of the paper. The coloration was analyzed with a smartphone. The method has a 21 μM limit of detection and a linear range that extends from 0.5 to 80 mM. Antimony-doped tin oxide nanoparticles (ATO NPs) combined with 3,3,5,5-tetramethybenzidine (TMB) and triethylamine were coated on the filter paper. After addition of sample solution, the blue-green colored oxidized TMB was generated and recorded by a digital camera.