Construction of a miniaturized monosaccharide detection system based on measuring electric current and testing its performance using a Bodipy fluorescent dye

This study aims to create a fluorescence-based measurement system to enable the development of miniaturized and low-cost optical biosensors. Alternative to bulky and expensive optical equipment, a custom-made 3D-printed setup was designed and modeled for electrical detection and monitoring of the fluorescence light intensity. The system comprises a blue LED (450 nm) and a photodiode (PD) mounted orthogonally on the top and back of the cell package. The LED is used to optically excite the fluorescent dye particles in a solution, resulting in a fluorescence light that is captured by the PD, yielding a measurable electrical current proportional to the light intensity. This system was used to explore the ratiometric fluorescence quenching of the fluorescent dye Bodipy in the presence of the quencher o-BBV to develop a novel non-enzyme-based glucose sensing platform. The fluorescence quenching of the boron-dipyrromethene (Bodipy) solution was initiated by exposing the mixture of Bodipy (2x10^-6 M) and boronic acid conjugated viologen (o-BBV) (2x10^-3 M) to UV light for 120 seconds. Monitoring the fluorescence intensities of the solutions were performed at various pHs (5.5, 7.4 and 8.0) and temperatures (0°C, 4°C, 25°C, and 37°C) before and after the addition of glucose (30 mM). The results showed that the emission intensity of the Bodipy solution was recovered after the addition of glucose, making it a potential platform for glucose sensing. The measured photodiode current in the developed system is found to be coherent with the intensity of the Bodipy emission measured by the fluorescent spectrometer of the same solution. The advantage of our system is that is possible to measure concentrated samples, whereas a fluorescent spectrometer requires only working with diluted samples. This study provides a proof-of-concept demonstration for a low-cost and miniaturized optical biosensor, offering the potential for further development and optimization.