SERS-Based\nAptamer Sensing Strategy for Diabetes Biomarker\nDetection

Accurate\ndetection of glucose and insulin is crucial for early\ndiagnosis, classification, and timely prevention of diabetes. In this\nstudy, we present a novel surface-enhanced Raman scattering (SERS)\naptasensor for glucose and insulin detection. The SERS aptasensor\nis composed of gold bipyramidal nanoparticles (Au BPs), SH-aptamer-methylene\nblue (MB), and thiolated polyethylene glycol (SH-PEG). As a SERS substrate,\nthe Au BPs provide abundant “hot spots” for the aptasensor\nto detect target molecules with reasonable sensitivity. One end of\nthe aptamer is modified with a thiol group to facilitate chemical\nimmobilization of SH-aptamer-MB via the Au–S bond, while the\nother end is functionalized with MB as a probe molecule. SH-PEG is\nused to block nonspecific adsorption. Glucose and insulin are specifically\ntrapped by SH-aptamer-MB and cause conformational changes in SH-aptamer-MB,\nwhich in turn induce changes in the SERS signal of the modified MB,\nallowing detection of glucose and insulin. Finally, we validated the\nusefulness of this method on saliva samples and obtained satisfactory\nresults. The proposed aptasensor exhibits strong selectivity and reliable\nsensitivity and provides an effective strategy for using SERS in disease\nbiomarkers detection.