A nonenzymatic electrochemical glucose sensor based on molecularly imprinted polymer and its application in measuring saliva glucose.

Diabetes mellitus (DM) is often diagnosed by invasive or enzymatic methods being progressively somewhat undesirable. If salivary glucose (SG) level correlates with blood glucose (BG), it could be useful for early DM detection. In this work, a molecular imprinted polymer (MIP) approach was used to develop an electrochemical non-enzymatic sensor to determine SG in micro-molar levels. The MIP based Screen printed gold electrode (Au-SPE) was prepared by electropolymerizing Acrylamide/Bis-Acrylamide (AAM/NNMBA) in the presence of glucose (G) as a template. The Cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques were employed for the electrochemical measurements with Ferri/Ferrocyanide as redox probe in phosphate buffer saline. Morphological characterizations of the elaborated sensors were performed by using atomic force microscopy (AFM) and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS). Important parameters influencing the MIP sensor performances such as extraction, incubation time, potential range and number of CV cycles, were studied and optimized. Under optimum conditions, the sensor could effectively detect glucose avoiding interferences of structural similar substances like lactose and sucrose. In a working range from 0.5 to 50 μg/mL, it exhibits a detection and quantification limits of 0.59 μg/mL and 1.9 μg/mL, respectively. Additionally, the real saliva glucose determination was compared to those of finger prick blood with satisfactory results (R2 = 0.99) by using partial least squares (PLS) statistical technique. Correspondingly, this work has demonstrated a cheap, simple and effective sensing platform for non-enzymatic glucose detection thus making it a promising tool for future evolution of accurate and reliable non-invasive DM diagnosis.