Single-atom Rh nanozyme: An efficient catalyst for highly sensitive colorimetric detection of acetylcholinesterase activity and adrenaline

In this work, a single-atom nanozyme-Rh-N/C was constructed with excellent tetra-enzyme mimic activities including laccase-(Km = 0.10 mM), oxidase (OXD; Km = 0.19 mM)-, superoxide dismutase (SOD)-and catalase (CAT)-like activities. Meanwhile, the laccase-and oxidase-mimic activities of Rh-N/C display excellent stability and reusability even under long storage time (2 months) and reuses for 10 times with just a minor loss of activity (maintained above 96.0%). Two biosensors have been designed and assembled based on the versatile simulated enzymatic activities of Rh-N/C. Firstly, a novel colorimetric biosensor was manufactured from the oxidase mimetic activity of Rh-N/C for the determination of acetylcholinesterase (AChE) activity, which shows a good linear response over a range of 0.001&1.0 mU/mL with the detection limit (LOD) of 3.2 & 10-4 mU/mL. Additionally, based on laccase-like activity of Rh-N/C, a sensitive colorimetric Rh-N/C-based biosensor was constructed for determining adrenaline with a low LOD of 0.106 mu g/mL. Thus, this work broadens the arsenal of single-atom nanozyme and discovers their prospects in biosensors.

Automated summary

In this study, a single-atom nanozyme-Rh-N/C with tetra-enzyme mimic activities was constructed. The Rh-N/C showed stable and reusable laccase and oxidase mimic activities, even after 2 months of storage and 10 times of reuse with minimal loss of activity (maintained above 96.0%). Two biosensors were designed based on the versatile enzymatic activities of Rh-N/C, including a colorimetric biosensor for acetylcholinesterase activity determination and a sensitive Rh-N/C-based biosensor for adrenaline detection. This work expands the application of single-atom nanozyme and explores their potential in biosensors.