Biomass-derived carbon quantum dots as fluorescent probes for biosensing: a review

The conversion of biomass waste into value-added carbon quantum dots (CQDs) has been recognized as a green synthetic pathway in CQD manufacturing. The distinctive nanostructure of biomass-derived carbon quantum dots (BCQDs) confers superior fluorescence properties and biocompatibility, rendering them highly promising as fluorescent probes for biosensing applications. The preparation of BCQD fluorescent probes using biomass as the primary carbon source not only realizes the high-quality recycling of waste resources but also has excellent biocompatibility and fluorescence emission stability, which has received great attention from researchers. This review offers a comprehensive analysis of BCQDs, encompassing various carbon sources including both waste and non-waste renewable materials. It systematically examines three fundamental properties, two primary synthesis techniques, three distinct luminescence mechanisms, three sensing mechanisms, nitrogen and sulfur elemental doping strategies enhancing quantum yield (QY), as well as the most recent advancements in the biosensing applications of BCQDs. Additionally, this review identifies existing research challenges and suggests prospective directions for future investigation in this emerging domain.