Carbon-based quantum dots for fluorescence imaging of cells and tissues

ZnCl2 Enabled Synthesis of Highly Crystalline and Emissive Carbon Dots with Exceptional Capability to Generate O2⋅–

Structural features regulated photoluminescence intensity and cell internalization of carbon and graphene quantum dots for bioimaging

Carbon-based quantum dots (CbQDs), encompassing carbon quantum dots (CQDs) and graphene quantum dots (GQDs), are an emerging class of nanomaterials with strong potential to serve as multifunctional fuel additives for compression ignition (CI) engines. This is the first focused critical review to consolidate and evaluate the combustion, performance, and emissions impacts of CbQDs in diesel-based fuels. Compared to broader carbonaceous nanomaterials, CbQDs offer unique advantages, including tunable surface functionality, nanoscale dispersion stability, and catalytic radical-generation potential. The review systematically analyzes experimental findings on the influence of CQDs and GQDs on ignition delay, fuel reactivity, brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), and key exhaust emissions including carbon monoxide (CO), unburned hydrocarbons (UHC), particulate matter (PM), and nitrogen oxides (NOx). Results indicate that CbQDs can reduce BSFC and emissions of CO, UHC, and PM by up to 6.8%, 31%, 45% and 90% respectively, while enhancing BTE by up to 6.6% depending on formulation and dosing. However, NOx behavior remains formulation-dependent and often presents trade-offs. Despite encouraging outcomes, the review identifies major gaps in mechanistic understanding, standardization, and real-world validation. Key directions for future work are proposed, including deeper diagnostics, techno-economic analysis, and environmental risk assessments to support scalable deployment. This synthesis offers essential guidance for researchers and developers advancing next-generation, nanotechnology-enhanced diesel engine technologies.

Carbon-based quantum dots and their nanocomposites have sparked immense interest for researchers as sensors due to their attractive physico-chemical properties caused by edge effects and quantum confinement. In this review article, we have discussed the synthesis and application of nanocomposites of graphene quantum dots (GQDs) and carbon quantum dots (CQDs). Different synthetic strategies for CQDs, GQDs, and their nanocomposites, are categorized as top-down and bottom-up approaches which include laser ablation, arc-discharge, chemical oxidation, ultrasonication, oxidative cleavage, microwave synthesis, thermal decomposition, solvothermal or hydrothermal method, stepwise organic synthesis, carbonization from small molecules or polymers, and impregnation. A comparison of methodologies is presented. The environmental application of nanocomposites of CQDs/GQDs and pristine quantum dots as sensors are presented in detail. Their applications envisage important domains dealing with the sensing of pollutant molecules. Recent advances and future perspective in the use of CQDs, GQDs, and their nanocomposites as sensors are also explored.

Chapter 28 - Physical properties of quantum dots

Recent advances in agricultural and marine waste-derived carbon dots for clean energy technologies

While previous research has primarily focused on nanoparticles larger than 20 nm for promoting migrasome formation, this study shifts the emphasis to nanoparticles smaller than 10 nm. Our findings reveal the significant impact of these sub-10 nm carbon-based quantum dots, specifically carbon quantum dots (CQD), graphene quantum dots (GQD), and graphitic oxide quantum dots (GOQDs), on migrasome formation, mitochondrial integrity, and platelet function. We establish a clear correlation between the application of these nanoparticles and the induction of migrasomes. Furthermore, our results indicate that CQD, GQD, and GOQDs enhance migrasome formation by upregulating phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), cholesterol, and GTP-RhoA. Additionally, these nanoparticles provide mitochondrial protection through a process called mitocytosis and promote increased platelet aggregation. This study represents a pioneering effort to connect various types of nanoscale graphene materials with the dynamic behavior of migrasomes, thereby advancing our understanding of nanoscale materials and their biological implications.Graphical Supplementary InformationThe online version contains supplementary material available at 10.1186/s12951-025-04010-9.

Luminescent quantum dots: Synthesis, optical properties, bioimaging and toxicity

Surface functionality and formation mechanisms of carbon and graphene quantum dots

Carbon based quantum dots (CQDs) have found their applications in various areas due to their unique properties such as photoluminescence (PL) properties, good water solubility and biocompatibility, high chemical stability, low toxicity, environmental friendliness and light bleaching resistance. Herein, a novel functional sensing platform based on bright green fluorescent nitrogen-doped carbon quantum dots (N-CQDs) was prepared for the detection of a variety of ions. Using black tea as a new carbon source, ethylenediamine as nitrogen source and surface modifier, nitrogen doped carbon quantum dots (N-CQDs) with low crystallinity, spherical and uniformly dispersed graphite structure were prepared. Its diameter distribution is between 1.0 and 3.0 nm. Unlike the other transition metal ions such as Al3+, Cu2+, Cd2+ , Hg2+, Ni2+, Fe2+, Zn2+ , and Ag +, as well as the main group metal ions such as Na +, K + , Mg2+, Ca2+ , and Ba2+ , the addition of Pb2+ to the aqueous solution of the as prepared CQDs leads to the significant quenching of the fluorescence centered at 450 nm. Such quantitative quenching effect was used to develop a CQDs sensor that is able to detect the trace amount of Pb2+ in the aqueous solution. The sensor exhibits a detection limit of 13.3 nmol/L for Pb2+ , and the quenching efficiency reaches 70.2%. The quenching mechanism was also discussed. The results in the present work indicate the Pb2+ sensor developed from the tea based CQDs may find broad application in the real time monitoring of water quality and other environmental samples.

Carbon dots, also known as carbon quantum dots or graphene quantum dots (C-dots), have garnered significant attention due to their promising applications in various fields such as energy, catalysis, bioimaging, and nanomedicine. Typically, C-dots exhibit zero-dimensional characteristics with hybridized carbon structures at the core and functional groups like hydroxyl and carboxyl at the edges.In this talk, I will highlight our recent advancements in utilizing ionic complexes based on C-dots for electrochemical applications, serving as supporting electrolytes and anionic dopants. We've developed nano-sized multivalent C-dot polyanions through a hydrothermal oxidation process of carbon nanofibers, forming complexes with alkali cations such as Li+, Na+, and K+. Consequently, we investigated the potential applications of ionic complexes based on C-dot as electrolytes for lithium-ion batteries and electrochromic devices. The ionic complexes demonstrate low Coulombic energy, exceptional thermal/electrochemical stability, and good ionic conductivity when dissolved in both aqueous and organic solvents. Molecular dynamics simulation with the electrochemical characterization reveals that the ionic complexes provide highly abundant free metal cations with highly stable C-dot polyanions and negligible ion pairs in solution. Furthermore, we have successfully implemented a novel approach to fabricate nanoarchitectures based on C-dots as an electrode-active material with outstanding electrochemical catalytic activity which is suitable for electrochemical biosensors and H2O2 reduction. Figure 1

Morphological insights into uncompetitive fluorescence of coal-based carbon dots and strategies for improvement

Carbon dots (CDs), including carbon quantum dots, graphene quantum dots, carbon nanodots, and polymer dots, have gained significant attention due to their unique structural and fluorescence characteristics. This review provides a comprehensive overview of the classification, structural characteristics, and fluorescence properties of CDs, followed by an exploration of various fluorescence sensing mechanisms and their applications in gene detection, nucleolus imaging, and gene delivery. Furthermore, the functionalization of CDs with diverse surface ligand molecules, including dye molecules, nucleic acid probes, and metal derivatives, for sensitive nucleic acid detection is systematically examined. Fluorescence imaging of the cell nucleolus plays a vital role in examining intracellular processes and the dynamics of subcellular structures. By analyzing the mechanism of fluorescence and structure-function relationships inherent in CDs, the nucleolus targeting abilities of CDs in various cell lines have been discussed. Additionally, challenges such as the insufficient organelle specificity of CDs and the inconsistent mechanisms underlying nucleolus targeting have also been highlighted. The unique physical and chemical properties of CDs, particularly their strong affinity toward deoxyribonucleic acid (DNA), have spurred interest in gene delivery applications. The use of nuclear-targeting peptides, polymers, and ligands in conjunction with CDs for improved gene delivery applications have been systematically reviewed. Through a comprehensive analysis, the review aims to contribute to a deeper understanding of the potential and challenges associated with CDs in biomedical applications.

Nanosized fluorescent carbon particles, namely, carbon dots (CDs), are a kind of fluorescent material that has drawn increasing attention in recent years. CDs have size-, surface chemistry-, and wavelength-dependent luminescence emission, which is different from traditional semiconductor-based quantum dots. Moreover, with excellent chemical stability, good biocompatibility, low toxicity, up-conversion emission, resistance to photo bleaching, as well as easy chemical modifications, CDs are promising for substantial applications in numerous areas: bioimaging, sensors, and energy-related devices. Herein, three kinds of fluorescent dots are reviewed: graphene quantum dots (GQDs), carbon nanodots (CNDs) and polymer dots (PDs). After the first reported CDs prepared from electrophoretic analysis and purification of fluorescent carbon nanotube fragments, there were hundreds of publications focusing on fluorescent CDs. Bioimaging was one of the most common applications of the CDs; therefore, in this review, most of the chosen reference papers were related to bioimaging based on CDs.

Photoactivation in CdSe/ZnS quantum dots (QDs) on UV/Vis light exposure improves photoluminescence (PL) and photostability. However, it was not observed in fluorescent carbon quantum dots (CDs). Now, photoactivated fluorescence enhancement in fluorine and nitrogen co-doped carbon dots (F,N-doped CDs) is presented. At 1.0 atm, the fluorescence intensity of F,N-doped CDs increases with UV light irradiation (5 s-30 min), accompanied with a blue-shift of the fluorescence emission from 586 nm to 550 nm. F,N-doped CDs exhibit photoactivated fluorescence enhancement when exposed to UV under high pressure (0.1 GPa). F,N-doped CDs show reversible piezochromic behavior while applying increasing pressure (1.0 atm to 9.98 GPa), showing a pressure-triggered aggregation-induced emission in the range 1.0 atm-0.65 GPa. The photoactivated CDs with piezochromic fluorescence enhancement broadens the versatility of CDs from ambient to high-pressure conditions and enhances their anti-photobleaching.