A fluorescent biosensor based on graphene quantum dots/zirconium-based metal-organic framework nanocomposite as a peroxidase mimic for cholesterol monitoring in human serum

In this study, graphene quantum dots/zirconium-based metal?organic framework (GQDs/UiO-66) nanocomposite was synthesized via a solvothermal procedure in one pot. The photocatalytic activity of the prepared GQDs/UiO-66 nanocomposite in peroxidase-like reactions was investigated using colorimetric and spectrofluorometric techniques. The photocatalytic activity of the nanocomposite in peroxidase mimetic-based fluorescence analysis of H2O2 based on H2O2-terephthalic acid reaction was considerably enhanced in comparison with its components. Owing to the fact that H2O2 could be produced as a result of enzymatic oxidation of cholesterol, and there is a linear relationship between the fluorescence intensity and cholesterol concentration, a fluorescent biosensor was developed for indirect determination of the cholesterol. In the optimal condition, the calibration plot was linear in the concentration range between 0.04 and 1.60 ?mol L-1, with a detection limit of 0.01 ?mol L-1. The method validation was checked by analyzing the NIST SRM 1952a-2, as a certified reference material, and the evolved technique was successfully used for cholesterol quantification in human serum samples.

Automated summary

A nanocomposite of graphene quantum dots/UiO-66 metal-organic framework was synthesized through a solvothermal method, exhibiting enhanced photocatalytic activity in peroxidase mimetic-based fluorescence analysis of H2O2. By developing a fluorescent biosensor, a linear relationship between fluorescence intensity and cholesterol concentration was utilized for indirect determination of cholesterol, showing promising results for cholesterol quantification in human serum samples.