Smartphone assisted portable biochip for non-invasive simultaneous monitoring of glucose and insulin towards precise diagnosis of prediabetes/diabetes

Abstract

Diabetes is a chronic disease with metabolic disorders. Prediabetes is a condition in which the blood glucose levels are not high enough to be diagnosed as diabetes, but insulin resistance and β-cell dysfunction are simultaneously present. Glucose and insulin are important biomarkers for diagnosing diabetes/prediabetes. It is critical and essential to monitor glucose and insulin levels to achieve the early and precise diagnosis, timely prevention and scientific management of diabetes/prediabetes. Here, an electrochemical aptasensor on screen-printed carbon electrode (SPCE) was developed for non-invasive simultaneous real-time detection of glucose and insulin in saliva. Two thiolated aptamers specific to glucose and insulin, respectively, were fabricated onto gold nanoparticles (AuNPs) decorated SPCE through Au–S bonds to form the sensing interface terminated with redox probes methylene blue (SPCE-AuNPs-GluApt-MB and SPCE-AuNPs-InsApt-MB). With the electrochemical signal readout on SPCE, the sensing interface responded to glucose linearly in the range of 0.1–50 mM with a detection limit of 0.08 mM, and responded linearly to insulin in the range of 0.05–15 nM with a detection limit of 0.85 nM. Integration of a SPCE based sensing interface with a portable wireless biochip, the continuous real-time detection of glucose and insulin in saliva was successfully realized with smartphone signal readout in a non-invasive way, demonstrating its potential as a non-invasive and reliable tool for precise diagnosis of diabetes/prediabetes in a point of care fashion.