Enzymeless glucose sensor based on disposable Ecoflex?/graphite thermoplastic composite substrate modified with Au@GQDs

Author(s)

Lima, Lucas F. de ; de Freitas, Amanda de S. M. ; Maciel, Cristiane Carla ; Ferreira, Andre L. ; Ferreira, Marystela ; Araujo, William R. de

• Document type: Journal article
• Source: SENSORS AND ACTUATORS REPORTS; v. 4, p. 11-pg., 2022-11-01.

Abstract

There is an increasing demand for robust, affordable, and sensitive analytical devices for clinical diagnostics. Herein, we describe a simple route to produce biodegradable and disposable thermoplastic composite electrodes using the commercial polymer (Ecoflex (R)) and graphite microparticles. The surface of the carbon composite electrode was modified with gold nanoparticles conjugated with graphene quantum dots (Au@GQDs) for sensitive and non-enzymatic glucose sensing. The morphological and structural characterizations of the modified electrochemical device revealed a hydrophilic rough composite surface, with high dispersion of graphite in the polymer matrix and confirmed the successful superficial modification of the working electrode with spherical Au@GQDs nanoparticles. Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were used to electrochemically characterize the modified and nonmodified thermoplastic sensor, demonstrating a 4.5 fold enhancement of the electroactive area, higher heterogeneous electron transfer kinetics, and electrocatalytic properties for glucose sensing when the sensor was modified with Au@GQDs. The electrochemical determination of the glucose was carried out using an amperometric method applying-0.15 V in alkaline conditions (0.1 mol L-1 NaOH). Under optimized conditions, the proposed method presented a high sensitivity (4.85 A L mol(-1)) and a low limit of detection (LOD) of 9.12 mu mol L-1. The Ecoflex:graphite/Au@GQDs sensor was applied for glucose sensing in synthetic saliva samples with recovery values ranging from 97.84% to 105.20%, highlighting the excellent accuracy of the proposed method. Finally, the electrode was subjected to thermal and biological degradation studies and presented disposable and eco-friendly characteristics. Based on these results, we believe that this new thermoplastic composite sensor modified with Au@GQDs can be an excellent candidate for a disposable, low-cost, and enzymeless electrochemical glucose sensor. (AU)

• FAPESP's process: 18/08782-1 - Miniaturized and integrated chemical sensors: new fabrication platforms for biological, clinical and environmental applications
• Grantee: Mauro Bertotti
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 19/02692-3 - Development an optical biossensor by surface plasmonic resonance (SPR) technique for the determination of creatine kinase (CK-MB)
• Grantee: André Lopes Ferreira
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 18/04061-8 - Layer by layer films of polypyrrol and magnetite nanoparticles in the analytical determination of parabens
• Grantee: Lucas Felipe de Lima
• Support Opportunities: Scholarships in Brazil - Master