Highly active carbon dots based nanozyme for enhanced cholesterol detection and antibacterial activity

Recently, nanozyme have emerged as promising direction for chemical sensing, biomedicine, environmental monitoring. However, the novel nanozyme with better catalytic activity and specificity is urgently required realized great application performance. Herein, Fe doped carbon dots (Cit-Fe-CDs) with peroxidase (POD) like activity are synthesized by hydrothermal treatment of ferric ammonium citrate. Due to the strong coordination capacity between Fe(III) and citric acid, the Cit-Fe-CDs exhibited excellent POD activity. Namely the catalytic constant (Kcat) K cat ) and catalytic efficiency ( K cat /Km) K m ) are determined, which are much higher than previous work. Highly effective colorimetric detection of cholesterol in human serum have been realized by the POD activity of Cit-Fe-CDs. Under optimal conditions, the linear range is determined to be 10 and 100 mu M with a detection limit (LOD) of 0.061 mu M. The LOD is two orders of magnitude lower than most of the existing analysis method. Since substantial amounts of free radicals are involved in the catalytic cycle of POD activity, excellent antibacterial activity against Methicillin-Resistant Staphylococcus aureus (MRSA) should be realized by Cit-Fe-CDs. Notably, about 99.999 % inactivation rate towards MRSA can be realized by 125 mu g/mL Cit-Fe-CDs, which showcases promising prospects in addressing bacterial resistance concerns. And we have confirmed that the antibacterials mechanism is related to the generation of hydroxyl radicals by the excellent POD activity of Cit-Fe-CDs.