Recent advances in graphene quantum dot-based optical and electrochemical (bio)analytical sensors

Since the day of their origin, the graphene quantum dots (GQDs) have been considered a predominant material for biosensing applications in view of their unique and exciting electronic, physicochemical and optical properties. By combining the quantum-confinement and edge effects of carbon dots with the graphene structure, GQDs have emerged as a wonder material. These photoluminescent QDs possess remarkable biocompatibility, high current density, fast electron mobility, high water solubility, good photochemical stability, and low cytotoxicity, thereby prevailing in the field of sensing. Moreover, the high electron-transfer and easy biomolecule-immobilization capabilities of GQDs make them suitable for developing efficient (bio)analytical sensors. In this direction, the review is proposed to enlighten the scope of GQDs in a variety of optical and electrochemical chemosensors as well as biosensors. Recent advancements pertaining to their synthesis methods, unique properties, and their regulation through heteroatom-doping and surface-functionalization strategies are discussed, along with the current challenges and future prospects.