AIE multifunctional probe empowering colorimetric-fluorescence dual-mode biosensor for early diabetic screening

Diabetes mellitus (DM) is a serious chronic disease characterized by abnormally high blood glucose (Glu) levels, which can cause organ malfunction and metabolic disturbances. However, traditional biomarkers like Glu face limitations due to intraday fluctuations and inability to detect early stages of DM. To tackle these challenges, this study has introduced a colorimetric-fluorescence dual-mode biosensor utilizing α-glucosidase (α-GAA), which enables early diabetes screening without being influenced by physiological fluctuations in blood glucose levels. Specifically, chitosan-modified copper nanoclusters (Cu NC@CS-Ce³⁺: AP-CuCC) with exceptional peroxidase (POD) activity and Ce³⁺-induced aggregate-induced luminescence (AIE) properties have been synthesized. The targeted hydrolysis of the α-GAA substrate, 4-nitrophenyl-α-D-glucopyranoside (pNGP), results in the formation of p-nitrophenol (p-NP) and Glu. While p-NP statically quenches an increase in AP-CuCC fluorescence signal, Glu facilitates the production of H₂O₂ by glucose oxidase during AP-CuCC POD enzyme reactions, triggering colorimetric changes in the reaction. The detection limits for colorimetric and fluorescence measurements were determined to be 0.03 U/L and 0.02 U/L, respectively. By integrating fluorescence analysis, this method cleverly mitigates the confusing effects of normal blood Glu levels on colorimetric outcomes, allowing for the consideration of abnormal Glu levels as a supplementary diagnostic tool. Compared to relying solely on colorimetry, this dual-mode approach reduces false positive rates by 50% and false negative rates by 25%. Leveraging the sensor's colorimetric and fluorescent capabilities provides a versatile platform for precise and reliable evaluation of aberrant expression markers across various clinical settings.