Au@carbon dot nanoconjugates as a dual mode enzyme-free sensing platform for cholesterol

In this report, we present a novel application of gold-carbon dot nanoconjugates (Au@CDs) of an average size of around 12.6 nm as a sensor for the detection of cholesterol. The Au particles perform the dual function of displaying colorimetric sensing, and fluorescence quenching in response to cholesterol in the concentration range of 10-100 ppm (0.208-2.08 mM), wherein the carbon dots act as the fluorescent entity. Interestingly, the nanoconjugates were observed to show a high specificity to cholesterol resulting in their precipitation. A visible change in colour of the assay mixture along with fluorescence quenching was seen in the reaction mixture on treatment with cholesterol. The synthesized nanoconjugates had high selectivity towards cholesterol, even in the presence of interfering analytes, and a minimum detection limit of 0.12 ppm (0.0025 mM) in the linear range of 50-300 ppm (1-6.25 mM). We anticipate that these Au@CDs can be employed for the fabrication of enzyme-free strip-based biosensors for the detection of cholesterol.