SERS-Based Aptamer Sensing Strategy for Diabetes Biomarker Detection.

Accurate detection of glucose and insulin is crucial for early diagnosis, classification, and timely prevention of diabetes. In this study, we present a novel surface-enhanced Raman scattering (SERS) aptasensor for glucose and insulin detection. The SERS aptasensor is composed of gold bipyramidal nanoparticles (Au BPs), SH-aptamer-methylene blue (MB), and thiolated polyethylene glycol (SH-PEG). As a SERS substrate, the Au BPs provide abundant "hot spots" for the aptasensor to detect target molecules with reasonable sensitivity. One end of the aptamer is modified with a thiol group to facilitate chemical immobilization of SH-aptamer-MB via the Au-S bond, while the other end is functionalized with MB as a probe molecule. SH-PEG is used to block nonspecific adsorption. Glucose and insulin are specifically trapped by SH-aptamer-MB and cause conformational changes in SH-aptamer-MB, which in turn induce changes in the SERS signal of the modified MB, allowing detection of glucose and insulin. Finally, we validated the usefulness of this method on saliva samples and obtained satisfactory results. The proposed aptasensor exhibits strong selectivity and reliable sensitivity and provides an effective strategy for using SERS in disease biomarkers detection.