carbon quantum dots

Overview

Carbon quantum dots (CQDs), also referred to as carbon dots (CDs), are a class of zero-dimensional carbon-based nanomaterials typically ranging from 1 to 10 nanometers in diameter. First discovered in 2004 as a byproduct of carbon nanotube purification, they have since emerged as a versatile and increasingly important nanomaterial platform in biomedical, analytical, and materials science. Their defining properties include strong photoluminescence, tunable emission spectra, high photostability, low cytotoxicity, and exceptional biocompatibility — characteristics that distinguish them favorably from traditional heavy-metal-based semiconductor quantum dots such as cadmium selenide. The surface of carbon quantum dots can be richly functionalized with Amino Acids, carboxyl, hydroxyl, and amine groups, enabling precise conjugation with drugs, targeting ligands, and other nanomaterials.

The photophysical behavior of CQDs arises from a combination of quantum confinement effects and surface state emissions, though the exact mechanistic contributions remain an active area of investigation. Their optical properties are highly sensitive to surface chemistry and particle size, making them tunable across the visible and near-infrared (NIR) spectrum. This tunability, combined with inherent biocompatibility and the possibility of green synthesis routes from natural precursors, has positioned carbon quantum dots as compelling candidates for bioimaging, drug delivery, biosensing, phototherapy, and food safety monitoring. They interact with a broad range of biological molecules, including adenosine triphosphate and Amino Acids, and have demonstrated activity in pathways relevant to mitophagy, neuroinflammation, and cancer biology.

Focus of Latest Publications

Recent literature reflects a rapidly expanding and diverse portfolio of applications for carbon quantum dots, spanning acute lung injury immunotherapy, neurodegenerative disease research, food safety, cancer drug delivery, and enzymatic sensing.

Theranostics and immunotherapy A significant study published in Bioactive Materials (2026) engineered mitochondrially targeted palladium-loaded carbon dots derived from Siraitia grosvenorii (CPs@SS31) to treat acute lung injury (ALI). This system integrated photothermal therapy (PTT) with induction of mitophagy — the selective autophagic clearance of damaged mitochondria — and immunoregulation, achieving synergistic therapeutic enhancement. The use of a near-infrared source was central to activating the photothermal component, and the design deliberately coupled CQD functionality with immunomodulatory capacity, demonstrating that carbon quantum dots can serve as scaffolds for multi-mechanism therapeutic platforms. This work highlights the relevance of mitophagy as a targetable biological process in inflammatory lung pathology.

Neurotoxicity and Parkinson's disease A study in Chemico-Biological Interactions (2026) examined the paradoxical role of CQDs in the context of Parkinson's disease. While carbon quantum dots have been proposed as theranostic nanoplatforms for PD diagnosis and treatment, this investigation revealed that CQDs can exacerbate Parkinson's disease-like pathology through microglia-mediated neuroinflammatory responses. This finding underscores the urgent need for rigorous mechanistic safety evaluations before therapeutic deployment, bridging the gap between the therapeutic potential and the neurotoxic risks of CQDs. The study positions neuroinflammation, rather than direct neuronal cytotoxicity, as a key pathway of concern.

Cancer Drug Delivery Research published in Analytical Chemistry (2026) utilized AMPS (2-acrylamido-2-methylpropanesulfonic acid)-derived carbon dots as drug delivery vehicles for riluzole in three-dimensional glioblastoma (GBM) spheroids. Non-tumoral 3D astrocyte spheroids served as control samples, allowing investigators to compare molecular responses in tumoral versus healthy neural tissue. This study exemplifies how CQDs can be chemically tailored from specific precursors to optimize delivery of neuroactive compounds in spatially complex tumor models.

A complementary study in Chembiochem (2026) developed luminescent Fe₃O₄ nanohybrid particles (Fe₃O₄@GUCDs) incorporating carbon dots synthesized from a glucose-urea mixture. These hybrid nanoparticles combined the magnetic responsiveness of an Fe₃O₄ core (saturation magnetization: 33.5 emu g⁻¹) with the photoluminescent properties of the CDs, enabling intra-cellular imaging alongside combinatorial chemo-photothermal cancer therapy using MCF-7 cells as a model. This work demonstrates a strategy analogous to Caelyx (liposomal doxorubicin), combining passive targeting with multimodal therapeutic activation.

Food Safety and Authentication Two studies demonstrate the utility of CQDs in food science. Research in Spectrochimica Acta Part A (2026) developed a multiple carbon quantum dots-enhanced excitation-emission matrix (MCQDs-EEM) fluorescence strategy for rapid identification of Anhua dark tea from different production years, leveraging phenolic content differences as a discriminating spectral signature. Separately, a study in Food Chemistry (2026) constructed a starch-based ratiometric fluorescence hydrogel incorporating CQDs paired with europium ions (Eu³⁺) for the visual, nondestructive detection of methyl parathion contamination on food surfaces, with CQDs serving as the primary detection fluorophore and Eu³⁺ as the background reference signal.

Biosensing and Enzymatic Detection In Talanta (2026), carbon dots with outstanding fluorescent properties were integrated with Fe/Co/Cu layered double hydroxide nanosheets exhibiting peroxidase-mimicking activity to build a dual-signal ratiometric fluorescence and colorimetric assay for monoamine oxidase B (MAO-B) — an enzyme clinically relevant to Parkinson's disease and psychiatric pharmacology. The dual-signal design improved detection robustness over single-channel methods.

Drug Interaction and Green Synthesis Research in the Journal of Molecular Graphics and Modelling (2026) synthesized carbon dots from Tribulus terrestris leaves via a chemical-free, greener method and investigated their interactions with the anti-inflammatory drug aceclofenac using both experimental and computational approaches, emphasizing the biocompatibility advantages of naturally derived CQDs.

Cryoprotective Food Applications A study in Food Research International (2026) innovatively combined CDs with konjac glucomannan to modify corn starch, developing a novel antifreeze gel system for cryoprotective coating of beef. CQDs contributed structural and functional properties to the gel matrix beyond their optical role, illustrating their materials versatility.

Key Publications

Jun Engineering Hydrophobic and Hydrophilic Carbon Quantum Dots from Curcumin for Spatially Controlled Liposome Integration. (Langmuir : the ACS journal of surfaces and colloids, 2026, PMID 42244174): "Carbon quantum dots (CQDs) are widely explored for bioimaging, drug delivery, and theranostic applications due to their tunable fluorescence, biocompatibility, and adaptable surface chemistry."
Jun Multiple carbon quantum dots-enhanced excitation-emission matrix fluorescence strategy for accurate vintage discrimination of Anhua dark tea. (Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2026, PMID 41722367): "a multiple carbon quantum dots-enhanced excitation-emission matrix (MCQDs-EEM) fluorescence strategy was developed for the rapid identification of Anhua dark tea from different production years."
May Carbon quantum dots exacerbate Parkinson's disease-like pathology through microglia-mediated neuroinflammatory responses with toxicological implications. (Chemico-biological interactions, 2026, PMID 41791449): "Recently, carbon quantum dots (CQDs) emerge as promising nanoplatforms for PD theragnostic, but their paradoxical role in exacerbating neuroinflammation and neurodegeneration shows the urgent need for mechanistic safety evaluations to bridge their therapeutic potential and neurotoxic risks."
May A ratiometric fluorescence sensor based on starch/polyacrylamide/deep eutectic solvent hydrogel for visual and nondestructive detection of methyl parathion on foods. (Food chemistry, 2026, PMID 41825382): "Herein, a starch-based ratiometric fluorescence hydrogel was constructed by introducing carbon quantum dots and Eu3+ as the detection and background fluorescence source, respectively."
May 3D Glioblastoma Molecular Responses to Carbon Dot-Delivered Riluzole Probed by Synchrotron FTIR. (Analytical chemistry, 2026, PMID 42009312): "Here, we report 2-acrylamido-2-methylpropanesulfonic acid (AMPS)-derived carbon dots (CDs) as vehicles for riluzole delivery in three-dimensional (3D) glioblastoma (GBM) spheroids, with 3D astrocyte spheroids employed as nontumoral control samples."
May Dual-signal assay based on carbon dots and Fe/Co/Cu layered double hydroxide nanosheets for efficient monoamine oxidase B sensing. (Talanta, 2026, PMID 41475227): "Here, we reported a dual-signal ratiometric fluorescence and colorimetric method for the analysis of MAO-B by integrating carbon dots (CDs) with outstanding fluorescent properties and Fe/Co/Cu layered double hydroxide (Fe/Co/Cu-LDH) nanosheets exhibiting prominent peroxidase-mimicking activity, for the first time."
May Mechanistic insights into carbon dot-aceclofenac interactions: An experimental and theoretical approach. (Journal of molecular graphics & modelling, 2026, PMID 41722416): "In this study, carbon dots (CDs) were synthesized from Tribulus terrestris leaves (TTLF) through a greener, chemical-free method, underscoring environmental sustainability and their biocompatibility."
May Carbon dots/konjac glucomannan/starch anti-freezing gel: development and cryoprotective coating for beef preservation. (Food research international (Ottawa, Ont.), 2026, PMID 41794488): "This study innovatively combined carbon dots (CDs) with konjac glucomannan (KGM) to modify corn starch (S), thereby developing a novel antifreeze gel system."
Apr Luminescent Fe3O4 Nanohybrid for Intra-Cellular Imaging and Combinatorial Chemo-Photothermal Therapy in Cancer. (Chembiochem : a European journal of chemical biology, 2026, PMID 42011112): "The resultant Fe3O4@GUCDs (FCDs) hybrid NPs not only validate excellent magnetic responsive properties (Ms=33.5 emu g-1) from the magnetic (Fe3O4) core, but also exhibit intriguing photo luminescent properties, including excellent photo stability from the CDs produced from glucose-urea mixture."
Apr Near infrared enhanced palladium loaded siraitia grosvenorii carbon dots amplify mitophagy for acute lung injury immunotherapy. (Bioactive materials, 2026, PMID 41810016): "Here, the mitochondrial targeted palladium loaded siraitia grosvenorii derived carbon dots (CPs@SS31) were engineered designed to integrate PTT, mitophagy induction, and immunoregulation for synergistic enhanced ALI therapy."