A detection system for serum cholesterol based on the fluorescence color detection of beta-cyclodextrin-capped gold nanoclusters

Cholesterol is one of the major markers for cardiovascular diseases. Herein, a portable cholesterol measurement system based on fluorescence color detection was constructed by combining the high sensitivity of fluorescence analysis with the ease of color sensing to determine low levels of serum cholesterol. Cyclodextrin capping gold nanoclusters with blue-green emission were used as fluorescent probes because cholesterol exposure induced fluorescence enhancement of the probe due to the host-guest inclusion interaction between cholesterol and the cavity of cyclodextrin. The integrated sensing system consisted of modules including a microprocessor, a power supply, an LED light with a constant current source, an RGB color sensor, a display, and a darkroom. All the modules except the display screen were placed in a 3D printing darkroom to avoid interference from ambient light. An RGB color sensor TCS230 was applied to capture the RGB signals of the fluorescent color of the probe solution before and after cholesterol addition. Then the obtained RGB signals were converted into the signals in Hue, Saturation, and Value (HSV) color space with a central control chip STM32F407. The Hue value of the fluorescent color of the solution can discriminate the concentration change of cholesterol. Experimental results demonstrate that the system responds linearly to cholesterol in the concentration range of 20.00 ∼ 150.00 μmol·L-1 with a detection limit of 16.07 μmol·L-1 (3σ, n = 3). The detection of the system has good consistency and accuracy compared with the standard instrument, showing potential for the detection of low levels of serum cholesterol.