Recent advances in carbon dots for electrochemical sensing and biosensing: A systematic review

Carbon dots (CDs) are a class of emerging carbon-based nanomaterials with an average particle size of less than 10 nm. CDs have received considerable attention due to their outstanding characteristics, such as conjugated structure, excellent fluorescent properties, high electrical conductivity, exceptional biocompatibility, negligible toxicity, superior water dispersion, ease of synthesis and feasibility of surface modification. In light of these unique properties, a wide variety of potential applications of CDs have been proposed, including sensing, bioimaging, drug delivery, optoelectronics, photocatalysis, energy storage and conversion, etc. In the field of sensing, CDs are widely used as modified materials to fabricate sensors by simple drop-casting, electrodeposition and inkjet printing process. The analytical performances in electrochemical sensing and biosensing rival or surpass those of other carbon-based nanomaterials, such as graphene and carbon nanotubes. To date, the availability of a comprehensive review focused on electrochemical sensing platform based on CDs with the information on recent progress, analytical performance, and application prospects is lacking. In this review, we aim to summarize the advances in the application of CDs in electrochemical sensing platform for determining environmental contaminants (endocrine disrupting chemicals, heavy metals, pesticides and antibiotics) and biomolecules (proteins, metabolites and amino acids) over the last 5 years. Besides, the challenges and future research directions for CDs-based sensors are discussed.