A Cholesterol Optical Fiber Sensor Based on CQDs-COD/CA Composite

A novel optical fiber biosensor based on carbon quantum dots (CQDs) fluorescent probe was developed for cholesterol sensing, in which CQDs-COD/CA composite acted as the sensitive film. The electron charge transfer between H₂O₂ and CQDs resulting from the specific reaction of cholesterol and cholesterol oxidase leads to fluorescence quenching. The fluorescence properties and surface morphology of CQDs-COD complex and complex sensitive film were characterized by Scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier transformation infrared (FTIR), fluorescence and ultraviolet spectroscopy. The fluorescence response of the sensor to cholesterol solution in micromole and millimole concentration ranges was studied, and the linear relations were obtained with $\text{R}^{2} = 0.99022$ and 0.99638, respectively. The results obtained in this study showed that the CQDs-COD/CA composite sensor has good biocompatibility and selectivity for cholesterol.

I. Introduction

Cholesterol mainly comes from the daily diet and plays an important role in building cell membranes, maintaining normal cell activities and building cell structure. The concentration of cholesterol in healthy people ranges over 1.16-2.02 mg/ml [1]. An anemia will be caused and resistance will be reduced when the cholesterol concentration is too low. However, if the concentration is too high, obesity will be caused and the risk of cardiovascular diseases will be increased [2]. Therefore, it is very important to measure cholesterol content and control the cholesterol concentration in the normal range, which has important practical significance for clinical disease diagnosis and prevention.