Composite PEDOT-PSS based highly sensitive electrochemical sensors for sensing glucose from human saliva

Here we report two composites, especially two different 2D materials and Au nanoparticle composite with conducting polymer PEDOT-PSS as electrodes for highly sensitive, cost effective and reliable biosensors. Conducting polymer composite electrodes of AuNP/WS2/PEDOT-PSS and AuNP/GO/PEDOT-PSS were prepared by electrochemical deposition and were studied using various structural and electrochemical techniques. XRD, FTIR and SEM have been used for structural characterization which confirmed the elemental compositions of these composite electrodes. Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV) were used to examine the charge transfer kinetics and electroactive properties of the modified electrodes. Impedance spectra analysis had shown the reduced charge transfer resistance and diffusive property of AuNP/WS2/PEDOT-PSS electrodes compared to AuNP/GO/PEDOT-PSS. To demonstrate biosensing advantages of these electrodes, interaction between covalently immobilized glucose oxidase (GlOx) enzyme and D-glucose was monitored via chronoamperometry and CV. GlOx/AuNP/WS2/PEDOT-PSS/ITO yielded wider linear range from 0.74 to 440.67 mu M towards the oxidation of glucose with high selectivity and lower limit of detection (LOD) of 1 mu M. AuNP/GO/ PEDOT-PSS/ITO composite electrode exhibited linearity in the range 3.84-373.33 mu M and LOD 2.33 mu M. Better sensitivity and wider linear range of GlOx/AuNP/WS2/PEDOT-PSS/ITO has been assigned to special layered structure as sheets formed by incorporation of WS2 to PEDOT-PSS. Validation of the glucose sensors has shown satisfactory results using real saliva samples. Study suggests use of conducting polymer, 2D layered material and metal nanoparticle composite electrodes based sensors offer wider linearity range and higher sensitivity for stable, reliable, cost- effective sensor electrodes which can be used easily in non-clinical diagnostics.