Enzyme‐Free Detection of Glucose in Blood and Saliva Using Silver Decorated Poly( o ‐phenylenediamine) Nanostructure

ABSTRACT An ultra‐sensitive non‐enzymatic electrochemical glucose sensor was developed using a self‐assembled monolayer of poly(o‐phenylenediamine) with ─NH 2 functional groups on a glassy carbon electrode (GCE), followed by the successful decoration of silver nanoparticles via thermal reduction of silver nitrate. The surface morphology of the prepared layer was evaluated from the FESEM images and EDAX elemental mapping. The electrochemical properties of monolayer formation and then silver decoration on GCE were analyzed by cyclic voltammetry (CV) in 25 mL of 0.1 M aqueous NaOH electrolyte. The silver decorated poly(o‐phenylenediamine) nanostructure on GCE was found to exhibit sensing response in CV measurement via reversible oxidation of glucose in 0.1 M aqueous NaOH electrolyte, especially at very low concentrations. The limit of detection was calculated as 5.5×10 −7 mg dL −1 , having an excellent sensitivity of 4.4 µA µL‐1 cm −2 within the linearity range of 0–80 µL of 72 mg dL −1 (4 mM) glucose. A selective response toward glucose over common interfering biomolecules, viz., ascorbic acid, uric acid, dopamine, fructose, lactose, sucrose, Cl − , K + , and albumin was observed from the linear sweep voltammetric measurement. Using the developed sensor, the glucose level in raw human blood was also verified with an average accuracy of ∼ 101 % and it was also possible to measure the glucose concentration in human saliva.