Smartphone-assisted colorimetric detection of uric acid based on the enhanced peroxidase-like activity of Cu doping Prussian blue.

Monitoring uric acid (UA) level in body fluids is of great significance for clinical diagnosis and treatment of related diseases. Herein, we introduce a simple smartphone-assisted colorimetric sensing platform for detection of UA. The experiment exhibited that the peroxidase-like activity of copper-doped Prussian blue (CuPB) could be enhanced by the doping of Cu element on Prussian blue. CuPB displayed excellent peroxidase-like activity and efficiently catalyze the oxidation of 2,2-diazo-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) in the presence of HO to generate a colored radical cation ABTS, resulting in a absorbance and color-based RGB intensity dual signal output. Hence, a reliable colorimetric and color-based-smartphone assay for detection of UA was constructed based on CuPB-mediated the peroxidase-like activity and UA-trigged inhibition of the ABTS oxidation reaction catalyzed by CuPB. The color change is collected by the built-in camera of smartphone, and the RGB intensity of sample images was processed by Image J. The sensing platform was used for highly sensitive colorimetric and portable detection of UA in human urine within 6 min with a wide range of linear response from 0.1 to 80 μM, a limit of quantitation of 0.10 μM and a low limit of detection of 0.041 μM (3σ rule). This work demonstrates a novel and versatile strategy to develop superior peroxidase mimics and holds great potential for rapid and portable detection of UA in urine, healthcare and clinical diagnosis, and also open promising avenues for the nursing point detection of UA.