Developing a Portable Autofluorescence Detection System and Its Application in Biological Samples

Abstract

Advanced glycation end-products (AGEs) are complex compounds closely associated with several chronic diseases, especially diabetes mellitus (DM). Current methods for detecting AGEs are not suitable for screening large populations, or for long-term monitoring. This paper introduces a portable autofluorescence detection system that measures the concentration of AGEs in the skin based on the fluorescence characteristics of AGEs in biological tissues. The system employs a 395 nm laser LED to excite the fluorescence of AGEs, and uses a photodetector to capture the fluorescence intensity. A model correlating fluorescence intensity with AGEs concentration facilitates the detection of AGEs levels. To account for the variation in optical properties of different individuals' skin, the system includes a 520 nm light source for calibration. The system features a compact design, measuring only 60 mm × 50 mm × 20 mm, and is equipped with a miniature STM32 module for control and a battery for extended operation, making it easy for subjects to wear. To validate the system's effectiveness, it was tested on 14 volunteers to examine the correlation between AGEs and glycated hemoglobin, revealing a correlation coefficient of 0.49. Additionally, long-term monitoring of AGEs' fluorescence and blood sugar levels showed a correlation trend exceeding 0.95, indicating that AGEs reflect changes in blood sugar levels to some extent. Further, by constructing a multivariate predictive model, the study also found that AGEs levels are correlated with age, BMI, gender, and a physical activity index, providing new insights for predicting AGEs content and blood sugar levels. This research supports the early diagnosis and treatment of chronic diseases such as diabetes, and offers a potentially useful tool for future clinical applications.

Keywords: advanced glycation end-products (AGEs); diabetes management; fluorescence monitoring; portable detection system.

Figure 1

Structural design of the portable autofluorescence detection system. (a) Schematic of the device worn on the arm, with dimensions of 60 mm × 50 mm × 20 mm, secured with an elastic band. (b) Actual device displaying various modules. (c) Three-dimensional structural design illustrating the 395 nm excitation module with a bandpass filter emitting light onto the forearm to stimulate AGEs’ fluorescence; the emitted fluorescence is then received by the detector through a 520 nm long pass filter.

Figure 2

Compact integrated charging and discharging module dimensions: 16.00 mm × 12.00 mm × 2.60 mm.

Figure 3

ELISA measurement and regression analysis of glycated hemoglobin and AGEs. (a) The ELISA process with coating plates, incubation, antibody-antigen complex formation, addition of labeling enzymes, microplate reading, and application of termination liquid. (b) The regression analysis demonstrating the relationship between glycated hemoglobin concentration and AGEs’ fluorescence, with a correlation coefficient of 0.61, a p-value of 0.015, and a coefficient of determination (R²) of 0.38.

Figure 4

Investigation of AGEs content and real-time blood glucose levels over time. (a) Fluorescence intensity of AGEs content for Volunteers 1, 2, and 3 measured at different times. (b) Blood glucose levels of Volunteers 1, 2, and 3 measured at different times.

Figure 5

Analysis of influencing factors on AGEs content in human skin. (a) Correlation heatmap between AGEs, age, BMI, gender, and physical activity; (b) validation of AGEs prediction model using age, BMI, gender, and physical activity.