Smartphone-assisted point-of-care colorimetric biosensor for the detection of urea via pH-mediated AgNPs growth

Smartphone-assisted point-of-care (POC) bioassay has brought a giant leap in personal healthcare sys-tem and environmental monitoring advancements. In this study, we developed a rapid and reliable colorimetric urea biosensor assisted by a smartphone. We employed hydrolysis of urea into NH3 by urease, which activates the reduction power of tannic acid, to generate silver nanoparticles for a dramatic colorimetric response. The proposed urea biosensor was validated in a solution to provide high selec-tivity against various interferents in human urine. It had high sensitivity, with a limit of detection as low as 0.0036 mM, and a high reliability of 99% +/- 2.9% via the standard addition method. The urea biosensor was successfully implanted on a paper to facilitate smartphone-assisted POC readout with a limit of detection of 0.58 mM and wide detection range of 500 mM, whereby direct diagnosis of human urine without dilution was realized. Our smartphone-assisted POC colorimetric urea biosensor will pave the way for daily monitoring systems of renal and hepatic dysfunction diseases. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study developed a rapid and reliable colorimetric urea biosensor assisted by a smartphone, with high selectivity, sensitivity, and reliability. It enables direct diagnosis of human urine and paves the way for daily monitoring systems of renal and hepatic dysfunction diseases.