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

• Autor(a) principal: de Lima, Lucas F.
• Data de Publicação: 2022
• Outros Autores: de Freitas, Amanda de S.M., Ferreira, André L., Maciel, Cristiane Carla [UNESP], Ferreira, Marystela, de Araujo, William R.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://dx.doi.org/10.1016/j.snr.2022.100102; http://hdl.handle.net/11449/241651
• topic: Biodegradable material; Enzyme-free sensor; Glucose detection; Low-cost electrochemical sensor; Thermoplastic composite electrodes

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®) 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 µmol 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.