Recent developments in three-dimensional graphene-based electrochemical sensors for food analysis

Background: Food contaminants, which can occur at every stage of food production, has been considered as a spotlight. Its harmful effects on the human health points to the necessity of a rapid, sensitive, accurate and multianalyte analytical system to measure the undesirable components in foodstuff. At present, many researchers have focused more attention on the electrochemical sensor technique in food analysis. The requirements for high sensitivity and accuracy facilitate the development of electrode materials. However, many challenges and breakthroughs for the design of electrode materials still needs to be resolved. Scope and approach: Three-dimensional (3D) graphene with the interconnected ordered framework exhibited extraordinary properties, such as a large specific surface area, sufficient spaces and free binder, which determines that this could be a promising electrode material for the electrochemical sensor. However, the 3D graphenebased electrochemical sensor possesses the disadvantages of insufficient sensitivities, long dynamic response, weak repeatability, and especially, poor selectivity. Due to these issues, the preparation methods have been constantly improved. In addition, multitudinous nanomaterials (i.e., metal and metal compounds, metal-organic frameworks, polymers, carbon-based materials, etc.) have also successively been introduced to the 3D graphenebased electrode. The reasonable design and preparation of these materials endowed the electrochemical sensor with unique advantages of low-cost, convenience, high sensitivity, excellent selectivity and high efficiency for the detection of analytes. Therefore, the applications in food analysis has been enlarged, mainly including heavymetal ions, pesticide residues, food additives, pathogenic bacteria, etc. Key findings and conclusions: In the long-term process, the porous structure of 3D graphene can still easily collapse, and the multivariate material on the surface of the electrode can also easily fall off, which affects the method sensitivity, accuracy andservice life of the electrode. In the present study, focused was given to two aspects, which included the optimization of doped material types and manufacturing, and the preparation method, in order to solve these problems, and provide helpful insights for the future design and fabrication of electrode materials. In conclusion, through the investigation of literatures, there is still a lack of understanding of interaction mechanisms between 3D graphene-based nanocomposites and analytes. The future study should be placed on the research of theoretical mechanisms in order to improve the method sensitivity, accuracy and practicability.