Platinum and zinc oxide modified carbon nitride electrode as non-enzymatic highly selective and reusable electrochemical diabetic sensor in human blood Habibulla Imran a,b , Krishnamoorthy Vaishali a , Sindhuraj Antony Francy a , Palinci Nagarajan Manikandan a,b , Venkataraman Dharuman a,⇑ a Molecular Electronics Laboratory, Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630 003, India b Fedesens Centre for Innovation and Instrumentation, Chennai 600024, India article info Article history: Received 15 July 2020 Received in revised form 13 August 2020 Accepted 26 August 2020 Available online 2 September 2020 Keywords: Metal Metal oxide Carbon nitride polymer Glucose Renewable Cost effective abstract Development of non-enzymatic glucose sensor is essential to reduce the cost of diabetes regular monitor- ing. Here, graphitic carbon nitride (g-C 3 N 4 ) is modified with platinum and zinc oxide for non-enzymatic electrochemical glucose sensing in physiological conditions for the first time in the literature. The inter- actions between Pt, g-C 3 N 4 and the ZnO are studied using different physicochemical characterization techniques. The Electrochemical glucose sensing at the ZnO-Pt-gC 3 N 4 occurs at low applied potential of +0.20 V (vs. Ag/AgCl) with high sensitivity 3.34 lA/mM/cm 2 and fast response (5 s) time. This sensor exhibited a wide linear range 0.25–110 mM with lower limit of detection of 0.1 mM. The architectured sensor was evaluated in human blood, serum and urine samples. The sensor is 4 time reusable in whole blood without activity deterioration. This reusable surface helps to reduce the cost of strip. Ó 2020 Elsevier B.V. All rights reserved. 1. Introduction Diabetes, a hyperglycemic chronic disease, occurs due to the accumulation of glucose in the blood above the normal limit 140 mg/dL. This disease affects the human organs and responsible for development of blindness, kidney failure, heart attacks, and stroke and lower limb amputation. This affects majority of the world population and causes several million deaths every year [1,2]. The life span of a diabetic person can be increased by regular and periodic monitoring of the diabetes status with proper medica- tion [3]. Glucometer, a portable hand held instrument, is widely used for the regular bedside and home monitoring of diabetes. The instrument works on the principle of reaction between glucose and glucose oxidase enzyme in presence of redox mediator at an applied potential 600 mV (Ag/AgCl) and current output is recorded amperometrically [4]. Still research is directed towards improving diabetic care by developing non-invasive glucose sensors with low cost, high sensitivity, extended linearity and reusability. Nanoma- terials like metal, metal oxides, single and double walled carbon nanotubes, graphene, and polymer and their composites with high surface-to-volume ratio and biocompatibility have been regularly employed for immobilizing the enzyme glucose oxidase to improve the performance [5–11]. As carbon and its allotropes exist abun- dantly in nature and cost effective, several efforts have been made to develop enzyme based glucose sensors using carbon nano tube (CNT) and graphene materials. Compared to the CNTs and gra- phene nano materials, carbon nitride nano material with alternate carbon and nitrogen in a aromatic ring with 2D structure is shown to possess higher electronic, optical properties due to the presence of nitrogen hetero atom [12,13] and investigated in the fields of battery as super capacitor and sensor fields. In the context of glu- cose sensing, a calorimetric detection of glucose was made on g- C 3 N 4 –GOX [14]. The H 2 O 2 produced from the reaction of glucose oxidase and glucose is detected by the peroxidise activity of g- C 3 N 4 . This sensor showed a linear range from 50 to 100 lM with the lowest detection limit of 1.0 lM. The peroxidase activity of g-C 3 N 4 is improved by doping with Fe and the linear range falls between 0.5 and 10 lM. The H 2 O 2 was catalysed by the Fe- doped-g-C 3 N 4 in the presence of 3,3,5,5-tetramethylbenzidine (TMB) substrate and observed the lowest detection limit of 5 mM [15]. The peroxidase property of C 3 N 4 in the absence [16] and pres- ence [17] of ruthenium metal was recently explored to quantify the H 2 O 2 by fluorescence ratiometric method. In this, o- phenylenediamine (OPD) was catalytically oxidized to OPDox in https://doi.org/10.1016/j.bioelechem.2020.107645 1567-5394/Ó 2020 Elsevier B.V. All rights reserved. ⇑ Corresponding author. E-mail addresses: dharumanudhay@yahoo.com, dharumanv@alagappauniver- sity.ac.in (V. Dharuman). Bioelectrochemistry 137 (2021) 107645 Contents lists available at ScienceDirect Bioelectrochemistry journal homepage: www.elsevier.com/locate/bioelechem