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 system 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 NH by urease, which activates the reduction power of tannic acid, to generate silver nanoparticles for a dramatic colorimetric response.