Enzyme mimics of Os/Ag nanoparticles for colorimetric detection of biothiols by smartphone

In this study, Os/Ag nanoparticles (Os/Ag NPs) with smaller Km and almost five times Vmax compared to Os NPs were prepared. This not only reduced the cost of nanozyme, but also improved the catalytic ability. Addition of L-Cysteine or glutathione (GSH) resulted in inhibitory effect on the peroxidase-like activity of Os/Ag nanozyme. Therefore, the L-Cysteine and GSH could be detected by absorption spectra method with limit of detection (LOD) of 0.22 μM and 0.2 μM, respectively. Moreover, a colorimetric sensing system for L-Cysteine and GSH based on portable paper strip and smartphone was fabricated with LOD of 1.72 μM and 1.4 μM, respectively. Furthermore, this method can be used in fetal bovine serum with recovery rates ranging from 89.42 Scheme illustration for the colorimetric detection of L-Cysteine and GSH by use of smartphone