Graphene oxide-based smart sensors: Synthesis, functionalization strategies, and biosensing applications

Graphene oxide and its nanocomposites exhibit extensive surface coverage, exceptional conductivity, and excellent functionalization properties, making them a revolutionary platform for electrochemical biosensing. This review highlights the advancements made in the preparation and functionalization of GO-based nanocomposites and their hybridization with polymers, metal oxides, and noble metals, as well as biomolecules for developing sensitive sensing platforms. We describe covalent and non-covalent methods of functionalization, as well as hybrid systems and doping, which contribute to the selectivity, sensitivity, and stability of sensing techniques. Emphasis is placed on electrochemical graphene oxide-based sensors for biomolecules, heavy metals, pharmaceuticals, and disease biomarkers, with applications in medical, environmental, and food analysis. The aspects of characterization methods, material stability, and reproducibility, as well as real-world integration issues, along with emerging trends such as wearable and flexible sensors, and environment-friendly syntheses, aim to provide researchers working on the future of nano-carbon sensors with a basis for the fabrication of scalable, innovative materials for translation.