A green carbon dot@silver nanoparticle hybrid: as a turn-on fluorescent probe for the detection and quantification of cholesterol and glucose

Cholesterol and glucose are two important biomarkers that are linked to different human diseases. In this work, we have designed a turn-on fluorescent biosensor based on carbon dots hybridized by AgNPs (CD@AgNPs). <i>Oliveria decumbens</i> Vent. extract was used as a rich carbon source for the green synthesis of carbon dots, which exhibited excitation-dependent fluorescence with maximum emission at 409 nm under 350 nm excitation. In this approach, hydrogen peroxide, a by-product of enzymatic reactions between oxidase enzymes and analytes, etches AgNPs, leading to fluorescence recovery. The designed biosensor showed a great linear range (2-60 μM for cholesterol and 4-250 μM for glucose) with very low limits of detection (3 μM for cholesterol and 38 μM for glucose), which are lower than the concentrations of these biomarkers in human body fluids. The great selectivity and sensitivity of the designed biosensor enable it to be used for the detection of biomarkers in complex media such as artificial human plasma in only 30 min. This work could open new avenues for researchers in the fields of sustainability and biomedicine, where green and accurate biosensors are required.