Carbon quantum dots as versatile nanomaterials for improving soil health and plant stress tolerance: a comprehensive...

This review summarizes the synthesis, purification/separation, and characterization techniques for carbon quantum dots (CQDs) and highlights their versatile applications as low-toxicity, multifunctional nanomaterials with particular focus on improving soil health, plant stress tolerance, and promoting sustainable agriculture. Carbon quantum dots (CQDs) have recently emerged as highly versatile nanomaterials with a broad spectrum of applications. This review provides a comprehensive overview of various aspects of CQDs, including their synthesis via both top-down and bottom-up approaches, along with the critical separation and purification techniques required to fully harness their potential. This article highlights the multifaceted roles of both pristine and engineered CQDs in soil and plant systems, with a particular emphasis on soil biochemical processes and different stages of plant life cycle. A special attention has been given to the role of CQDs in enhancing plant tolerance to various biotic and abiotic stresses, such as nutritional imbalance, salinity, drought, heat, and heavy metal stress, with studies showing an improvement in stress tolerance, and considerable increase in seed germination rates when seeds are primed with CQDs. We have also discussed the crucial role of CQDs-mediated gene delivery in plants along with their influence on various soil characteristics. Moreover, the application of CQDs in the detection of agrochemical residues has been discussed with detection sensitivity reported as low as 0.1 µg L^-1 for certain pesticides along with their broader utility in environmental remediation, food safety, and therapeutic applications demonstrating their unique properties and multi-functionality for sustainable use. This review also addresses the emerging concerns surrounding the potential toxicity of CQDs, particularly in plants, the food chain, and human health. While most studies report low toxicity at concentration below 100 mg L^-1, understanding these risks is important to ensure the safe deployment of CQDs in real-world scenarios. In short, advanced research knowledge is provided as a basis for CQDs future development research toward efficient non-toxic delivery system for sustainable agriculture and other applications.

Comprehensive exploration of synthesis methodologies for CQDs. The multifaceted role of CQDs in improving soil health and plant stress tolerance is discussed. Explores the nutritional significance of CQDs-coated fertilizers and their potential to revolutionize agricultural practices. Highlights the diverse application of CQDs in environmental remediation and biomedical field, emphasizing their cross disciplinary impact.