Co–N–C single-atom nanozymes with oxidase-like activity for highly sensitive detection of biothiols

Biothiol detection is of great importance for clinical disease diagnosis. Previous nanozyme-based colorimetric sensors for biothiol detection showed unsatisfactory catalytic activity, which led to a high detection limit. Therefore, developing new nanozymes with the high catalytic activity for biothiol detection is extremely necessary. Recently, single-atom nanozymes (SAzymes) have attracted much attention in biosensing due to their 100% atom utilization and excellent catalytic activity. Most previous works focus on the peroxidase-like activity of Fe-based SAzymes by using unstable and destructive H2O2 as the oxidant. It is essential to develop new SAzymes with high oxidase-like activity for biosensing to break through the limitation. Herein, Co–N–C SAzymes with high oxidase-like activity are explored. Furthermore, Co–N–C SAzymes are used as a biosensor for colorimetric detection of biothiols (GSH/Cys) based on the inhibition of thiols toward the oxidase-like activity of Co–N–C SAzymes, which showed high sensitivity with a low detection limit of 0.07 µM for GSH and 0.06 µM for Cys. Besides, the method showed good reproducibility and high selectivity against other amino acids. This work offers new insights using Co–N–C SAzymes in the biosensing field.