The FRET-Based APTA Sensor/Cy3 Complex for Glucose Determination

This study developed a sensitive and cost-effective fluorescent probe based on the Förster Resonance Energy Transfer (FRET) method to monitor blood glucose levels. The APTA sensor/Cy3 probe consisted of cadmium telluride quantum dots modified with thioglycolic acid (CdTe-TGA QDs), a thiol-glucose-aptamer, and a Cy3-labeled aptamer. Due to the well-matched emission spectrum of the CdTe QDs and the absorption spectrum of Cy3, the FRET system decreased fluorescence intensity. However, glucose molecules quenched it when introduced to the system. The linear relationship between fluorescence intensity and glucose concentration was established with a detection limit of 7.72 × 10⁻⁹ M. The APTA sensor/Cy3 complex demonstrated excellent selectivity and specificity toward glucose and a high recovery rate of 96.00–101.11% in human serum and urine using the spiking method. The structural and morphological characteristics of the APTA sensor/Cy3 complex were confirmed by UV–visible spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), atomic force microscopy (AFM), and dynamic light scattering (DLS) analyses. The results suggest that the FRET-based APTA sensor/Cy3 complex would lead to the development of fluorescent probes for screening biological metabolites in clinical diagnostics and research.