Facile synthesis of Au@α-Fe2O3@RGO ternary nanocomposites for enhanced electrochemical sensing of caffeic acid toward biomedical applications

Demonstrated herewith is a novel eco-friendly Au@α-Fe2O3@RGO ternary nanocomposites using chlorophyll as reductants and stabilizers. Systematic characterizations studies confirm Au and α-Fe2O3 nanoparticles are uniformly decorated on the surfaces of reduced graphene oxide (RGO) nanosheets. As a proof-of-concept, the developed Au@α-Fe2O3@RGO ternary nanocomposites were coated on a glass carbon electrode (GCE) and evaluated for electrochemical detection of caffeic acid. The electrochemical mechanism involves the synergistic electrocatalytic activity of Au and α-Fe2O3 towards caffeic acid oxidation, with the RGO serving as an efficient electron shuttling mediator-enhancing the sensor performance. The Au@α-Fe2O3@RGO modified GCE caffeic acid sensor exhibited a wide linear response range of 19-1869 μM, sensitivity of 315 μA μM−1 cm-2, and a detection limit of 0.098 μM at very low potential of 0.21 V. This ternary nanocomposite provides high catalytic performance as well as excellent selectivity toward caffeic acid. To demonstrate real life application of the Fe2O3@RGO modified GCE caffeic acid sensor, caffeic acid in a coffee sample was measured. The α-Fe2O3, Au-NPs, and conductive graphene sheets composites, result in a highly catalytic and stable electrode system, with no pulverization problems. As such, it is demonstrated herewith that the Fe2O3@RGO ternary nanocomposite electrode is rapid, highly stable, and sensitive, with promised for utilization in fabrication of other multifarious biosensors.