Carbon Dots as a Potential Therapeutic Agent for the Treatment of Cancer-Related Anemia

T-2 toxin induces anemia via disrupting erythroid commitment and differentiation

T-2 toxin, a stable and highly toxic secondary metabolite produced by Fusarium, is known to have strong cytotoxicity and threaten multiple systems. However, its effect on the hematopoietic system and the mechanisms of anemia induction remains unclear. Here, we establish the acute T-2 toxin poisoning mouse model at concentrations ranging between 0.5 and 4 mg/kg. Our results show that T-2 toxin exposure causes severe anemia in mice, as indicated by significant reductions in red blood cell count and hemoglobin levels. Further analysis indicates that T-2 toxin profoundly disrupts the homeostasis of hematopoietic stem cells and their commitment to the erythroid lineage and subsequent erythroid differentiation, thus significantly inhibiting the formation of erythroblasts and reticulocytes. In humans, cells are exposed to T-2 toxin at concentrations of 0.25-1 ng/mL for 13 days. T-2 toxin strongly inhibits erythropoiesis and promotes the formation of abnormal nucleated erythroblasts. Mechanistically, high concentration of T-2 toxin induces apoptosis, while lower levels arrest the cell cycle at the G1/S phase. Overall, our findings reveal the hematotoxic effects of T-2 toxin and shed light on the mechanisms underlying T-2 toxin induced anemia, providing valuable guidance for developing strategies to mitigate T-2 toxin poisoning.

Rational design of near-infrared carbon dots as polarity-sensitive fluorescent probes for imaging of lipid droplets

Polarity plays important roles in establishing and reflecting numerous complex physiological functions and pathological effects associated with energy metabolism and cell signaling. Monitoring the variations in polarity, particularly the polarity of lipid droplets (LDs), is of great significance in biomedical research and clinical diagnosis. Herein, a novel near-infrared (NIR) carbon dots (CDs)-based fluorescent nanoprobe is presented to serve the stringent requirements of polarity targeting and imaging with high sensitivity, superior photostability, excellent permeability and biocompatibility. The absorption and emission wavelength shifts were in response to an increased ambient polarity (Δf), in which the emission reached to the NIR region near 800 nm with the maximum emission wavelength located around 700 nm. This nanoprobe can specifically colocalize with LDs with a high correlation coefficient of 0.96 and effectively image the polarity changes in LDs and living cells. This work presents effective strategies and foundations for the construction of NIR CDs, helps in the design of polarity selective probes, and has implications for accelerating the development of polarity-related processes for disease diagnosis.

Green biomass carbon points with efficient broad-spectrum antibacterial activity and widespread application

With low toxicity and good biocompatibility, carbon dots (CDs) are widely used in the fields of biosensing and drug delivery. In recent years, they have demonstrated excellent antimicrobial properties, thus becoming another research hotspot in the antimicrobial field. However, most of the studies showed that CDs were effective in inhibiting Gram-positive bacteria but ineffective against Gram-negative bacteria. In this study, macadamia nutshell (MNS)-CDs were prepared from the hard shells of macadamia nuts by a one-step hydrothermal method, and their appearance, morphology, structural composition, antimicrobial properties, and toxicity were investigated. The results showed that the MNS-CDs were spherical particles with an average diameter of about 4.25 nm, with hydrophilic groups, a hemolysis rate of less than 2%, good biocompatibility, and excellent antimicrobial properties against both Gram-negative and Gram-positive bacteria. The antimicrobial mechanism of these materials was also investigated. The inhibition of Gram-negative bacteria by MNS-CDs was mainly due to electrostatic interactions, while the inhibition of Gram-positive bacteria was mainly based on activated oxygen sterilization. Furthermore, MNS-CDs achieved good antimicrobial effects when applied in the fields of water purification, plates, fabrics, and food packaging, indicating that the prospects of their broad application are good.

Mung bean-derived carbon dots suppress ferroptosis of Schwann cells via the Nrf2/HO-1/GPX4 pathway to promote peripheral nerve repair

Schwann cells (SCs) can potentially transform into the repair-related cell phenotype after injury, which can promote nerve repair. Ferroptosis occurs in the SCs of injured tissues, causing damage to the SCs and exacerbating nerve injury. Targeting ferroptosis in SCs is a promising therapeutic strategy for effective repair; however, research on ferroptosis in the peripheral nervous system remains limited. In this study, we generated and characterized novel distinctive carbon dots, mung bean-derived carbon dots (MB-CDs). Our results demonstrated that MB-CDs have the advantages of low toxicity, good biocompatibility, high stability, the specific effect of ferric ions (Fe3+) on fluorescence, and antioxidant activity. We demonstrated that MB-CDs promoted functional recovery after peripheral nerve injury (PNI), preventing gastrocnemius atrophy. Further research indicated that MB-CDs boosted the repair-related phenotypes of SCs. We used lipopolysaccharide (LPS) to induce an inflammatory model of SCs and co-cultured them with MB-CDs. Then, we examined the effects of MB-CDs by dividing the cells into four groups: the control group (CTRL), MB-CD treatment group (CDs-SCs), LPS treatment group (LPS-SCs), and LPS and MB-CD treatment group (LPS-CDs). RNA sequencing of LPS-CDs and LPS-SCs indicated that LPS-CDs significantly upregulated heme oxygenase-1 (HO-1) expression. Furthermore, western blotting and immunofluorescence techniques demonstrated that MB-CDs suppressed the ferroptosis of SCs via the Nrf2/HO-1/GPX4 signaling pathway after PNI. Overall, this study further uncovered the connection between ferroptosis and the repair-related phenotypes of SCs, filling this gap in the existing knowledge; accordingly, they may be promising agents for treating PNI.

Surface Engineering Enabled Capacitive Gas-Phase Water Molecule Sensors in Carbon Nanodots

Gas-phase water molecule sensors are essential in scientific, industrial, and environmental applications, playing a crucial role in ensuring human safety, monitoring pollution, and optimizing processes. However, developing gas-phase water sensors with high sensitivity remains a significant challenge. Herein, the effect of molecular adsorption on capacitive response is explored, and a facile surface engineering strategy to achieve sensitive carbon nanodots (CDs)-based sensors for H2O is demonstrated.hydrophilic raw precursor is utilized to prepare the hydrophilic CDs and further employ these CDs as active media in the capacitive sensors, demonstrating how surface adsorption influences the capacitive response to H2O molecules. By applying surface engineering, the molecular affinity potential of CDs is regulated, resulting in sensors that exhibit a broad detection range from 11% to 98% relative humidity (RH), with a remarkable sensitivity of 3.3 × 105 pF/RH and an impressive response of 1.8 × 108% at 98% RH. These CDs-based sensors present great potential for applications in respiratory monitoring, information exchange, contactless recognition of finger trajectories, etc. The findings unveil the unique influence of molecular affinity on capacitive response, opening new avenues for the design and applications of highly sensitive molecular sensors.

Biogenic fluorescent carbon dot-decorated mesoporous organosilica nanoparticles for enhanced bioimaging and chemotherapy

Hybrid materials possess the unique properties of their individual components, enabling their use in multiple synergistic applications. In this study, we synthesized biogenic fluorescent carbon dots (CDs) decorated with biodegradable periodic mesoporous organosilica nanoparticles (BPMO), creating BPMO@CDs. The CDs, approximately 9.8 nm in diameter, were derived from Musa paradisiaca cv. Awak juice using a rapid microwave method, exhibiting a spherical shape and green and red luminescence. The resulting BPMO@CDs are spherical, around 100 nm in size, and maintain high pore volume and surface area. The elemental chemical state in the BPMO@CDs remains consistent with that of pure BPMO. Our findings demonstrate that BPMO@CDs achieve efficient cellular uptake rates of 46.74% in MCF7 cells and 17.07% in L929 cells, with preserved fluorescence within the cells. The optical properties of the CDs are retained in the BPMO@CDs, allowing for detection upon cellular uptake. Additionally, when loaded with anticancer drugs, the BPMO@CDs significantly enhance the cytotoxicity against MCF7 breast cancer cells, highlighting their potential for synergistic bioimaging and chemotherapy applications.

Therapeutic potential of naturally derived carbon dots in sepsis-associated acute kidney injury

BACKGROUND

Sepsis is a life-threatening infectious disease characterized by an uncontrolled inflammatory response and consequent multi-organ dysfunction. The kidneys, as primary excretory organs with high blood flow, are particularly susceptible to damage during sepsis. Nonetheless, the existing treatment options for sepsis-associated acute kidney injury (SA-AKI) are still restricted. Nanomedicine, especially carbon dots (CDs), has attracted considerable interest lately for outstanding biomedical characteristics.

METHODS

To avoid the generation of toxic effects, the natural CDs derived from Ziziphi Spinosae Semen (Z-CDs) were synthesized employing a hydrothermal method. The free radical scavenging capabilities of Z-CDs were evaluated by utilizing ABTS assay, NBT method, and Fenton reaction. A lipopolysaccharide (LPS)-stimulated RAW 264.7 cell model was used to explore the therapeutic potential of Z-CDs on cellular oxidative stress and inflammation. The CuSO4-induced zebrafish inflammation model and LPS-exposed SA-AKI mouse model were employed to assess the therapeutic efficacy of Z-CDs in vivo.

RESULTS

The synthesized Z-CDs exhibited distinctive unsaturated surface functional groups, which confer exceptional biocompatibility and the ability to scavenge free radicals. Moreover, Z-CDs were particularly effective in eliminating excess reactive oxygen species (ROS) in cells, thus protecting mitochondrial function from oxidative damage. Notably, Z-CDs have demonstrated significant therapeutic benefits in protecting kidney tissue in SA-AKI mouse model with minimizing side effects. In mechanism, Z-CDs effectively reduced ROS production, thereby alleviating inflammatory responses in macrophages through the suppression of the NF-κB pathway.

CONCLUSIONS

This study developed a multifunctional nanomedicine derived from traditional medicinal herb, providing a promising pathway for the advancement of innovative drug therapies to treat SA-AKI.

Fluorescence-Switchable Iron-Doped Nanodot Assembly as a Robust Redox Dyshomeostasis Amplifier for Noninvasive Treatment of Deep-Seated Tumors

Carbon dots (CDs) have been recognized as promising candidates for cancer diagnosis and therapy, owing to their intrinsic fluorescence properties and facile functionalization pathways. However, such tiny-sized CDs tend to be rapidly excreted by the kidney and/or hepatobiliary system before reaching the tumor site, which may significantly weaken their performance in tumor theranostics. Here, fluorescence switchable iron-doped carbon dot assemblies (FCDDs) are developed with an average size of ≈120 nm for passive tumor targeting. After lesional enrichment, FCDDs can be dissembled into Fe-doped CDs (FCDs) with fluorescence switched on, in response to the upregulated glutathione (GSH) in the tumor microenvironment. The ultrasmall FCDs are able to penetrate into the deep region of solid tumors and generate reactive oxygen species (ROS) through the Fenton reaction. Such ROS accumulation and GSH deprivation caused by FCDDs can effectively trigger the irreversible apoptosis and ferroptosis of tumor cells. Meanwhile, the resultant intracellular redox dyshomeostasis induces prominent immunogenic cell death to prevent metastasis. Tumor-specific fluorescence imaging not only enables cancerous tissue probing but also assists in monitoring the treatment effectiveness. Taken together, this paradigm exemplifies a practical approach to improve the functionality of CDs toward clinical applications and may inspire more facile designs toward upcoming translational medicines.

Eco-Friendly Synthesized Carbon Dots from Chinese Herbal Medicine: A Review

Chinese herbal medicines and their extracts will produce nano-components of charcoal drugs after high-temperature carbonization, and the process is similar to that of carbon dots (CDs). Chinese herbal medicine-derived CDs (CHM-CDs) are a new carbon-based nanomaterial with a particle size of less than 10 nm discovered in charcoal drugs in recent years. CHM-CDs possess a range of beneficial traits, such as minimal toxicity, strong water solubility, superior biocompatibility, and remarkable photoluminescence capabilities. Additionally, they exhibit multifaceted pharmacological activity in the absence of drug loading. Over the past half-decade, numerous publications have presented evidence suggesting that CHM-CDs exhibit a wide array of pharmacological effects. These primarily encompass hemostatic capabilities, neuroprotection, anti-infective, antitumor, immunomodulatory effects and hypoglycemic activity. Notably, they have been associated with circulatory system, digestive system, nervous system, immune system, endocrine system, urinary system and skeletal system. This article systematically reviews the modern pharmacological effects and potential mechanisms of CHM-CDs, offering insights into current challenges and proposing directions for future advancements. As such, it serves as a vital reference for the clinical application of CHM-CDs.

Novel carbon dots with dual Modulatory effects on the bone marrow and spleen as a potential therapeutic candidate for treating spinal cord injury

Spinal cord injury triggers leukocyte mobilization from the peripheral circulation to the injury site, exacerbating spinal cord damage. Simultaneously, bone marrow hematopoietic stem cells (HSCs) and splenic leukocytes rapidly mobilize to replenish the depleted peripheral blood leukocyte pool. However, current treatments for spinal cord injuries overlook interventions targeting peripheral immune organs and tissues, highlighting the need to develop novel drugs capable of effectively regulating peripheral immunity and treating spinal cord injuries. In this study, we designed, synthesized, and characterized novel Ejiao carbon dots (EJCDs) that inhibit myeloid cell proliferation and peripheral migration by promoting HSC self-renewal, and distinct differentiation into erythroid progenitors in vitro and in vivo. Additionally, EJCDs attenuate the immune response in the spleen, leukocytes' reservoir, following spinal cord injury by diminishing the local infiltration of monocytes and macrophages while promoting motor function recovery. These effects are mediated through the downregulation of CCAAT enhancer binding protein-β expression in the spleen and the upregulation of FZD4 protein expression in Lin- Sca-1+ c-kit+ cells (LSKs) within the bone marrow. Our findings demonstrate that EJCDs effectively reduce myeloid cell infiltration post-spinal cord injury and promote neurological recovery, making them promising therapeutic candidates for treating spinal cord injuries.

Solution-Processed Near Unit Carbon Dots-Based Deep-Blue Electroluminescent Light-Emitting Diodes with External Quantum Efficiency over 10

Deep-blue electroluminescent light-emitting diodes (ELEDs) are crucial for various applications, including solid-state lighting, high-density information storage, and vibrant displays. Currently, the development of conventional deep-blue ELEDs is predominantly based on multilayer evaporation structures. Despite significant technological progress, the fabrication of electroluminescent devices via low-cost solution processing has still not fully been realized. Given that, a novel approach for their development based on deep-blue emission carbon dots (CDs) has been proposed in this study. The as-prepared CDs exhibited a quantum yield close to 100% and a high exciton binding energy. The CDs-based ELEDs provided deep-blue emission at a wavelength of 450 nm, with CIE coordinates of (0.15, 0.07), closely approaching the standard color of the Rec. 2020 specification (0.131, 0.046). These results provide sufficient evidence that the devices fabricated in this work are one of the highest-performing CDs-based ELEDs developed so far, providing a quantum efficiency of over 10%.

Recent Advances of Carbon Dots: Synthesis, Plants Applications, Prospects, and Challenges

Nanomaterials and nanotechnology have garnered significant attention in the realm of agricultural production. Carbon dots (CDs), as a class of nanomaterials, play a crucial role in the field of plant growth due to their excellent properties. This review aims to summarize recent achievements on CDs, focusing on their methods of preparation and applications in plants systems. The effects of CDs on seed germination, growth, photosynthesis, nutritional quality, and stress resistance were studied. It has been demonstrated that CDs can promote seed germination and growth, as well as improve photosynthetic efficiency, ultimately leading to increase plants yield. The nutritional quality of the plants treated with CDs was significantly improved. Specifically, the levels of essential mineral elements, vitamins, amino acids, and other constituents that are beneficial to human health increased notably. Additionally, CDs show positive effects on augmenting plant resistance against environmental stresses, such as drought conditions, heavy metal toxicity, and high salinity. Finally, the prospects and challenges of the application of CDs in plant systems are also discussed, which provide a scientific basis for the future application of CDs in agricultural production.

Functionalized Carbon Dots With Intrinsic Wnt/β-Catenin Inhibition to Synergistically Promote 5-Fluorouracil Chemotherapy

Background

5-fluorouracil (5-FU) is the most widely used anti-pyrimidine drug that exerts its cytotoxic effect by causing DNA damage. The Wnt/β-catenin pathway has been considered a promising strategy to improve chemosensitivity by enhancing the DNA damage response of chemotherapy drugs. Combination therapies against cancers could inevitably affect endogenous levels of ribonucleotides (RNs) and deoxyribonucleotides (dRNs) which are critical for DNA synthesis and repair. However, exploring satisfactory Wnt/β-catenin inhibitors for synergistic therapy through regulating RNs and dRNs remains challenging.

Methods and Results

Here, aloe vera-derived carbon dots (A-CDs) with good bioactivity were synthesized via a one-step hydrothermal process, demonstrating both intrinsic Wnt/β-catenin inhibition and bioimaging capabilities to overcome the limitations of conventional Wnt/β-catenin inhibitors. The as-prepared A-CDs were further served as the transport vehicle for 5-FU, facilitating synergistic combination therapy by inhibiting the Wnt/β-catenin pathway, which could possibly accelerate nucleotide imbalance of dATP, ATP, TMP, and dUMP, ultimately leading to enhanced 5-FU efficiency. Additionally, the tumor-targeted material (HA-CDs@5-FU) was synthesized by modifying hyaluronic acid (HA) onto CDs@5-FU and exhibited superior antitumor efficacy in vivo with negligible side effects.

Conclusion

Overall, this study provided a novel strategy for Wnt/β-catenin inhibition and synergistic therapy, providing insights into the application of nano-agents in cancer therapy.

Nucleolus-Targeting Carbon Dot Nanocomplexes for Combined Photodynamic/Photothermal Therapy

The low cure rate and high mortality associated with cancer pose significant threats to human health. Photodynamic and photothermal therapies have emerged as promising treatment strategies for various types of cancers. In this study, we successfully synthesized a novel type of carbon dot (CD) using 1,2,4-aminobenzene and ethylenediamine as precursors. Surprisingly, these CDs exhibited outstanding nucleolus-targeting capabilities coupled with a remarkable photothermal effect. Through the integration of these nucleolus-targeting CDs with indocyanine green (ICG) and folic acid (FA), we created CDs-ICG-FA nanocomplexes suitable for combined photodynamic and photothermal therapy. In vitro experiments demonstrated that CDs-ICG-FA maintained a robust photothermal ability, achieving a conversion efficiency of up to 34.3%. Furthermore, CDs-ICG-FA generated abundant reactive oxygen species, effectively inducing cancer cell death and demonstrating its potential for photodynamic therapy. In MCF-7 cancer cells, CDs-ICG-FA exhibited a pronounced synergistic photothermal/photodynamic anticancer effect. Subsequent in vivo experiments in mice revealed that CDs-ICG-FA could selectively accumulate at tumor sites, significantly inhibiting tumor growth upon exposure to an 808 nm laser. These findings suggest that the developed nucleolus-targeting CDs-ICG-FA hold promising potential for cancer targeting and the application of combined photothermal/photodynamic therapy.

Low toxicity ginsenoside Rg1-carbon nanodots as a potential therapeutic agent for human non-small cell lung cancer

Here ginsenoside Rg1 was used to synthesise Rg1 carbon nanodots via a one-step hydrothermal method. The surface of the Rg1 carbon nanodots is rich in hydrophilic functional groups with good water solubility and biocompatibility. The Rg1 carbon nanodots exhibited a high inhibitory effect on the proliferation, migration, and proapoptotic ability of non-small cell lung cancer A549 cells. The changes in the levels of ROS, Ca2+, and MMP in A549 cells after the administration of Rg1 carbon nanodots were evaluated and further correlated with relevant proteins in the caspase apoptotic pathway. Proteomic screening revealed that the Rg1 carbon nanodots could regulate A549 cell apoptosis by activating the expression of MAPK pathway-related proteins. In the in vivo experiment, the therapeutic efficacy of the Rg1 carbon nanodots in inhibiting tumour growth was much higher than that of commonly used chemotherapy drugs, with negligible toxicity and side effects. Immunohistochemical staining showed that the expression of caspase- and MAPK pathway-related proteins in mouse tumour tissues was consistent with that at the cellular level. The results suggest that Rg1 carbon nanodots can promote tumour apoptosis and represent a potential therapeutic agent for human non-small-cell lung cancer.

Effectively alleviate rheumatoid arthritis via maintaining redox balance, inducing macrophage repolarization and restoring homeostasis of fibroblast-like synoviocytes by metformin-derived carbon dots

Overproduction of reactive oxygen species (ROS), elevated synovial inflammation, synovial hyperplasia and fibrosis are the main characteristic of microenvironment in rheumatoid arthritis (RA). Macrophages and fibroblast-like synoviocytes (FLSs) play crucial roles in the progression of RA. Hence, synergistic combination of ROS scavenging, macrophage polarization from pro-inflammatory M1 phenotype towards M2 anti-inflammatory phenotype, and restoring homeostasis of FLSs will provide a promising therapeutic strategy for RA. In this study, we successfully synthesized metformin-derived carbon dots (MCDs), and investigated the antirheumatic effect in vivo and in vitro. Designed MCDs could target inflamed cells and accumulate at the inflammatory joints of collagen-induced arthritis (CIA) rats. In vivo therapeutic investigation suggested that MCDs reduced synovial inflammation and hyperplasia, ultimately prevented cartilage destruction, bone erosion, and synovial fibrosis in CIA rats. In addition, MCDs eliminated the cellular ROS in M1 phenotype macrophages in RA microenvironment through the enzyme-like catalytic activity as well as inhibiting NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome signaling pathway, effectively polarizing them into the M2 phenotype to realize the anti-inflammatory effect. Furthermore, MCDs could inhibit the proliferation, migration, and fibrosis of inflamed FLSs. Mechanistically, MCDs restored the homeostasis of FLSs while reducing the level of synovial inflammation by blocking IL-6/gp130 signaling pathway. Combined with preferable biocompatibility, MCDs offer a prospective treatment approach for RA.

Therapeutic Potential of Carbon Dots Derived from Phytochemicals as Nanozymes Exhibiting Superoxide Dismutase Activity for Anemia

Anemia is a potentially life-threatening blood disorder caused by an insufficient erythroblast volume in the circulatory system. Self-renewal failure of erythroblast progenitors is one of the key pathological factors leading to erythroblast deficiency. However, there are currently no effective drugs that selectively target this process. In this work, we present a carbon dot (CP-CDs) derived from phytochemicals that significantly promotes the self-renewal of erythroblast progenitors for anemia therapy. As a superoxide dismutase (SOD)-like nanozyme, CP-CDs significantly activate the hypoxia response and JAK/STAT3 pathways in erythroid cells by reprogramming the oxidative stress state. This results in unique erythropoiesis-enhancing properties by promoting the generation of erythroid progenitor cells. Moreover, CP-CDs protect mature red blood cells by inhibiting oxidative stress-induced damage and improving the immune-inflammatory microenvironment. In vivo, CP-CDs showed a promising therapeutic effect in mouse and zebrafish models of anemia with minimal adverse effects, indicating significant translational medical value. Collectively, this study not only illustrates a successful approach for nanomedicine-enhanced anemia therapy but also enhances our understanding of the interaction between nanomedicine and the self-renewal of erythroblast progenitors.

Donkey-Hide Gelatin-Derived Carbon Dots Activate Erythropoiesis and Eliminate Oxidative Stress for Aplastic Anemia Treatment

Aplastic anemia (AA) is a life-threatening hematologic disease with limited therapeutic options. Stalled erythropoiesis and oxidative stress-induced hemocyte apoptosis are the main pathological features of AA, yet therapeutic agents that address these issues remain elusive. In this study, we report distinctive donkey-hide gelatin-derived carbon dots (G-CDs) that enable erythropoiesis activation and oxidative stress elimination to tackle refractory AA. We demonstrate that G-CDs can promote the proliferation and erythroid differentiation of hematopoietic stem cells as well as erythrocyte maturation, activating the whole process of erythropoiesis. Moreover, G-CDs display multienzyme-like activities and dramatically alleviate the oxidative stress of bone marrow and peripheral blood via catalytic scavenging of multiple reactive oxygen species, reconstructing the hematopoietic microenvironment. Intravenously or orally administered to AA mice induced by chemotherapy drugs, G-CDs significantly boost the level of red blood cells and hemoglobin and lead to the complete recovery of hematopoietic function, showing better therapeutic performance than clinically approved erythropoietin (EPO) without adverse effects. By collaboratively addressing the issues of stalled erythropoiesis and oxidative stress, the G-CDs-based intervention strategy may offer a powerful paradigm for clinical AA management.

Blazing Carbon Dots: Unfolding its Luminescence Mechanism to Photoinduced Biomedical Applications

Carbon dots (CDs) are carbon-based nanomaterials that have garnered immense attention owing to their exceptional photophysical and optoelectronic properties. They have been employed extensively for biomedical imaging and phototherapy due to their superb water dispersibility, low toxicity, outstanding biocompatibility, and exceptional tissue permeability. This review summarizes the structural classification of CDs, the classification of CDs according to precursor sources, and the luminescence mechanism of CDs. The modification in CDs via various doping routes is comprehensively reviewed, and the effect of such alterations on their photophysical properties, such as absorbance, photoluminescence (PL), and reactive oxygen species generation ability, is also highlighted. This review strives to summarize the role of CDs in cellular imaging and fluorescence lifetime imaging for cellular metabolism. Subsequently, recent advancements and the future potential of CDs as nanotheranostic agents have been discussed. Herein, we have discussed the role of CDs in photothermal, photodynamic, and synergistic therapy of anticancer, antiviral, and antibacterial applications. The overall summary of the review highlights the prospects of CD-based research in bioimaging and biomedicine.

Targeting erythroid progenitor cells for cancer immunotherapy

Immunotherapy, especially immune checkpoint blockade therapy, represents a major milestone in the history of cancer therapy. However, the current response rate to immunotherapy among cancer patients must be improved; thus, new strategies for sensitizing patients to immunotherapy are urgently needed. Erythroid progenitor cells (EPCs), a population of immature erythroid cells, exert potent immunosuppressive functions. As a newly recognized immunosuppressive population, EPCs have not yet been effectively targeted. In this review, we summarize the immunoregulatory mechanisms of EPCs, especially for CD45+ EPCs. Moreover, in view of the regulatory effects of EPCs on the tumor microenvironment, we propose the concept of EPC-immunity, present existing strategies for targeting EPCs, and discuss the challenges encountered in both basic research and clinical applications. In particular, the impact of existing cancer treatments on EPCs is discussed, laying the foundation for combination therapies. The aim of this review is to provide new avenues for improving the efficacy of cancer immunotherapy by targeting EPCs.

Carbon Quantum Dots in Biomedical Applications: Advances, Challenges, and Future Prospects

Carbon quantum dots (CQDs) represent a rapidly emerging class of nanomaterials with significant potential in biomedical applications due to their tunable fluorescence, high biocompatibility, and versatile functionalization. This review focuses on the recent progress in utilizing CQDs for drug delivery, bioimaging, biosensing, and cancer therapy. With their unique optical properties, such as tunable fluorescence, high quantum yield, and photostability, CQDs enable precise bioimaging and sensitive biosensing. Their small size, biocompatibility, and ease of surface functionalization allow for the development of targeted drug delivery systems, enhancing therapeutic precision and minimizing side effects. In cancer therapy, CQDs have shown potential in photodynamic and photothermal treatments by generating reactive oxygen species under light exposure, selectively targeting cancer cells while sparing healthy tissues. Furthermore, CQDs’ ability to penetrate biological barriers including the blood–brain barrier opens new possibilities for delivering therapeutic agents to hard‐to‐reach areas, such as tumors or diseased tissues. However, challenges such as optimizing synthesis, ensuring long‐term stability, and addressing safety concerns in biological environments remain critical hurdles. This review discusses current efforts to overcome these barriers and improve CQD performance in clinical settings, including scalable production methods and enhanced biocompatibility. As research progresses, CQDs are expected to play an important role in improving healthcare by offering more targeted treatment options and contributing to advancements in personalized medicine.

Green carbon dots derived from Zingiberis Rhizoma Carbonisatum alleviate ovalbumin-induced allergic rhinitis

Background

Allergic rhinitis (AR) affects up to 40% of the population, leading to significant healthcare expenditures. Current mainstream treatments, while effective, can lead to side effects and do not address the underlying immunological imbalances. Zingiberis Rhizoma Carbonisatum (ZRC), the partially charred product of Zingiberis Rhizoma (ZR), has been widely used clinically in China since ancient times to treat respiratory disorders.

Methods

Inspired by the similarity between high-temperature pyrolysis and carbonization processing of herbal medicine, ZRC derived CDs (ZRC-CDs) were extracted and purified through several procedures. Then, the physicochemical characteristics of CDs were delineated through a suite of characterization methods. Moreover, our investigation zeroed in on elucidating the ameliorative impacts of CDs on ovalbumin-induced rat models alongside their underlying mechanisms.

Results

ZRC-CDs with particle sizes ranging from 1.0 to 3.5 nm and rich surface functional groups. Additionally, we observed that ZRC-CDs significantly attenuated nasal symptoms and pathological damage in ovalbumin-induced AR rats, and modulated lipid metabolism and type 2 inflammatory responses. They also inhibit PI3K/AKT and JAK/STAT pathways, which are associated with metabolism and inflammation. Importantly, ZRC-CDs demonstrated high biocompatibility, underscoring their potential as a novel therapeutic agent.

Conclusion

ZRC-CDs offer a promising alternative for AR treatment and could help facilitate broader clinical use of the ZRC. In addition, the exploration of the inherent bioactivity of CDs can help to broaden their biological applications.

Carbon dot-based nanomaterials with enzyme-like activity for fluorescence imaging and potential combination with therapy of cancer

Carbon dot-based nanomaterials (o-CDs@Mn) were fabricated by assembling fluorescent o-CDs with enzyme-like activity and Mn nanoparticles with photothermal properties for realizing fluorescence imaging and combined therapy of cancer. Due to the inherent optical properties of o-CDs, o-CDs@Mn can be effectively used for bioimaging. In addition, o-CDs@Mn possess peroxidase-like (POD-like) and glutathione (GSH) degradation capabilities, which can effectively deplete excessive H2O2 and GSH in the tumor microenvironment (TME), generating ·OH and reduced GSSH for regulating the TME and triggering ROS-mediated apoptosis in cancer cells. More importantly, it is synergistically supplemented with fluorescence imaging and photothermal therapy (PTT), which realizes the integration of monitoring and combined treatment, providing a promising potential pathway for accurate and efficient cancer treatment.

Facile Synthesis and Multiple Application of Ultralong-Afterglow Room Temperature Phosphorescence Aggregate Carbon Dots from Simple Raw Materials

Owing to the ultralong afterglow, room temperature decay phosphorescence nanomaterials have aroused enough attention. In the work, by simple one-pot solid-state thermal decomposition reaction, aggregate carbon dots (CDs) was prepared from trimesic and boric acid. Based on the intermolecular hydrogen bonds and intramolecular π-π stacking weak interaction from precursors, CDs was encapsulated in boron oxide matrix and formed aggregation. The aggregate state of CDs facilitated the triplet excited states (Tn), which could induce the room temperature decay phosphorescence properties. By careful investigation, under different excitation wavelengths at 254 and 365 nm, the aggregate CDs showed > 15 s and > 3 s room temperature phosphorescence emission in the naked eye, which was associated with 1516.12 ms and 718.62 ms lifetime respectively. And the aggregate CDs exhibited widespread application in encoding encryption, optical anti-counterfeiting and fingerprint identification etc. The interesting aggregate CDs revealed unexpected ultralong-afterglow room temperature decay phosphorescence properties and the work opened a window for constructing ultralong-afterglow room temperature decay phosphorescence aggregate CDs nanomaterials.

A nanocarbon-enabled hybridization strategy to construct pharmacologically cooperative therapeutics for augmented anticancer efficacy

The drug design principles are of great value in developing nanomedicines with favorable functionalities. Herein we propose a nanocarbon-enabled hybridization strategy to construct a pharmacologically cooperative nanodrug for improved cancer therapy in the light of pharmacophore hybridization in medicinal chemistry and the synthetic principles of nanocarbons. An antioxidant defense pharmacological inhibitor and a co-nucleation precursor are structurally hybridized into nanodrugs (SCACDs) via forming carbon quantum dots. These SCACDs elicit dual enhanced bioactivities, including superior sonocatalytic activity that arose from the appropriate band structure of the pharmacophoric carbon cores, and more than an order of magnitude higher antioxidant defense inhibitory activity than the pharmacological inhibitor via conveying the bioactive pharmacophores from the molecular level to nanoscale. In vivo, SCACDs possess a long body retention and desirable biodistribution to eliminate melanoma cells at a very low injection dose. The present study provides a viable yet effective strategy for the development of pharmacologically cooperative nanodrugs to achieve remarkably improved therapeutic efficacy.

Carbon Dots: A Review with Focus on Sustainability

Carbon dots (CDs) are an emerging class of nanomaterials with attractive optical properties, which promise to enable a variety of applications. An important and timely question is whether CDs can become a functional and sustainable alternative to incumbent optical nanomaterials, notably inorganic quantum dots. Herein, the current CD literature is comprehensively reviewed as regards to their synthesis and function, with a focus on sustainability aspects. The study quantifies why it is attractive that CDs can be synthesized with biomass as the sole starting material and be free from toxic and precious metals and critical raw materials. It further describes and analyzes employed pretreatment, chemical-conversion, purification, and processing procedures, and highlights current issues with the usage of solvents, the energy and material efficiency, and the safety and waste management. It is specially shown that many reported synthesis and processing methods are concerningly wasteful with the utilization of non-sustainable solvents and energy. It is finally recommended that future studies should explicitly consider and discuss the environmental influence of the selected starting material, solvents, and generated byproducts, and that quantitative information on the required amounts of solvents, consumables, and energy should be provided to enable an evaluation of the presented methods in an upscaled sustainability context.

Blocking Metallothionein-2 Expression by Copper-Doped Carbon Dots Induces Cellular Antioxidant System Collapse for Antitumor Therapy

The insufficient antioxidant reserves in tumor cells play a critical role in reactive oxygen species (ROS)-mediated therapeutics. Metallothionein-2 (MT-2), an intracellular cysteine-rich protein renowned for its potent antioxidant properties, is intricately involved in tumor development and correlates with a poor prognosis. Consequently, MT-2 emerges as a promising target for tumor therapy. Herein, we present the development of copper-doped carbon dots (Cu-CDs) to target MT-2 to compromise the delicate antioxidant reserves in tumor cells. These Cu-CDs with high tumor accumulation and prolonged body retention can effectively suppress tumor growth by inducing oxidative stress. Transcriptome sequencing unveils a significant decrease in MT-2 expression within the in vivo tumor samples. Further mechanical investigations demonstrate that the antitumor effect of Cu-CDs is intricately linked to apolipoprotein E (ApoE)-mediated downregulation of MT-2 expression and the collapse of the antioxidant system. The robust antitumor efficacy of Cu-CDs provides invaluable insights into developing MT-2-targeted nanomedicine for cancer therapies.

Broadband Negative Photoconductive Response in Carbon Nanodots

Due to the broadband response and low selectivity of external light, negative photoconductivity (NPC) effect holds great potential applications in photoelectric devices. Herein, different photoresponsive carbon nanodots (CDs) are prepared from diverse precursors and the broadband response from the NPC CDs are utilized to achieve the optoelectronic logic gates and optical imaging for the first time. In detail, the mcu-CDs which are prepared by the microwave-assisted polymerization of citric acid and urea possess the large specific surface area and abundant hydrophilic groups as sites for the adsorption of H2O molecules and thereby present a high conductivity in dark. Meanwhile, the low affinity of mcu-CDs to H2O molecules permits the light-induced desorption of H2O molecules by heat effect and thus endow the mcu-CDs with a low conductivity under illumination. The easy absorption and desorption of H2O molecules contribute to the extraordinary NPC of mcu-CDs. With the broadband NPC response in CDs, the optoelectronic logic gates and flexible optical imaging system are established, achieving the applications of "NOR" or "NAND" logic operations and high-quality optical images. These findings unveil the unique optoelectronic properties of CDs, and have the potential to advance the applications of CDs in optoelectronic devices.

Novel Carbon Quantum Dots Precisely Trigger Ferroptosis in Cancer Cells through Antioxidant Inhibition Synergistic Nanocatalytic Activity

High levels of glutathione (GSH) are an important characteristic of malignant tumors and a significant cause of ineffective treatment and multidrug resistance. Although reactive oxygen species (ROS) therapy has been shown to induce tumor cell death, the strong clearance effect of GSH on ROS significantly reduces its therapeutic efficacy. Therefore, there is a need to develop new strategies for targeting GSH. In this study, novel carbon quantum dots derived from gentamycin (GM-CQDs) were designed and synthesized. On the basis of the results obtained, GM-CQDs contain sp2 and sp3 carbon atoms as well as nitrogen oxygen groups, which decrease the intracellular levels of GSH by downregulating SLC7A11, thereby disrupting redox balance, mediating lipid peroxidation, and inducing ferroptosis. Transcriptome analysis demonstrated that GM-CQDs downregulated the expression of molecules related to GSH metabolism while significantly increasing the expression of molecules related to ferroptosis. The in vivo results showed that the GM-CQDs exhibited excellent antitumor activity and immune activation ability. Furthermore, because of their ideal biological safety, GM-CQDs are highly promising for application as drugs targeting GSH in the treatment of malignant tumors.

Red/NIR-I-Fluorescence Carbon Dots Based on Rhein with Active Oxygen Scavenging and Colitis Targeting for UC Therapeutics

Ulcerative colitis (UC) is a chronic inflammatory disease with uncontrolled inflammation and demage to the intestinal barrier. Rhein, a bioactive compound in traditional Chinese medicine, has anti-inflammatory and intestinal repair effect. However, their clinical application is limited by their hydrophobicity and poor bioavailability. L-arginine, as a complement to NO, has synergistic and attenuating effects. In this paper, red/NIR-I fluorescent carbon dots based on rhein and doped with L-arginine (RA-CDs), which are synthesized by a hydrothermal process without any organic solvents, are reported. RA-CDs preserve a portion of the functional group of the active precursor, increase rhein solubility, and emit red/NIR-I light for biological imaging. In vitro experiments show that RA-CDs scavenge excessive reactive oxygen species (ROS), protect cells from oxidative stress, and enable the fluorescence imaging of inflamed colons. In a DSS-induced UC mouse model, both delayed and prophylactic treatment with RA-CDs via intraperitoneal and tail vein injections alleviate UC severity by reducing intestinal inflammation and restoring the intestinal barrier. This study highlights a novel strategy for treating and imaging UC with poorly soluble small-molecule drugs.

Preparation of edible antibacterial films based on corn starch /carbon nanodots for bioactive food packaging

Packaging plays an important role in protecting food from environmental impacts. However, traditional petroleum-based packaging has difficulty in meeting the antimicrobial and antioxidant requirements of prepared foods. This study introduced carbon dots (CDs), prepared by using carrot as a precursor, into corn starch (CS) to construct a bio-friendly composite film with high freshness retention properties. The scavenging of DPPH radicals reached 92.77 % at a CDs concentration of 512 µg/mL, and the antimicrobial activity of CS/5% CDs against Escherichia coli and Staphylococcus aureus was increased to 99.9 %. Notably, the homogeneous doping of CDs creates a dense surface and high carbon content inside the film, which promotes the elasticity and thermal stability of the composite film. Finally, we encapsulated deep-fried meatballs in CS-CDs films. The results showed that the CS-CDs films effectively protected the quality of deep-fried meatballs, and have excellent potential for application in food preservation.

Self-Assembled DNA Nanospheres Driven by Carbon Dots for MicroRNAs Imaging in Tumor via Logic Circuit

DNA nanostructures with diverse biological functions have made significant advancements in biomedical applications. However, a universal strategy for the efficient production of DNA nanostructures is still lacking. In this work, a facile and mild method is presented for self-assembling polyethylenimine-modified carbon dots (PEI-CDs) and DNA into nanospheres called CANs at room temperature. This makes CANs universally applicable to multiple biological applications involving various types of DNA. Due to the ultra-small size and strong cationic charge of PEI-CDs, CANs exhibit a dense structure with high loading capacity for encapsulated DNA while providing excellent stability by protecting DNA from enzymatic hydrolysis. Additionally, Mg2+ is incorporated into CANs to form Mg@CANs which enriches the performance of CANs and enables subsequent biological imaging applications by providing exogenous Mg2+. Especially, a DNAzyme logic gate system that contains AND and OR Mg@CANs is constructed and successfully delivered to tumor cells in vitro and in vivo. They can be specifically activated by endogenic human apurinic/apyrimidinic endonuclease 1 and recognize the expression levels of miRNA-21 and miRNA-155 at tumor sites by logic biocomputing. A versatile pattern for delivery of diverse DNA and flexible logic circuits for multiple miRNAs imaging are developed.

Sleep deprivation boosts O2·- levels in the brains of mice as visualized by a Golgi apparatus-targeted ratiometric fluorescence nanosensor

Sleep deprivation (SD) is highly prevalent in the modern technological world. Emerging evidence shows that sleep deprivation is associated with oxidative stress. At the organelle level, the Golgi apparatus actively participates in the stress response. In this study, to determine whether SD and Golgi apparatus stress are correlated, we rationally designed and fabricated a novel Golgi apparatus-targeted ratiometric nanoprobe called Golgi dots for O2·- detection. This probe exhibits high sensitivity and selectivity in cells and brain slices of sleep-deprived mice. Golgi dots can be readily synthesized by coprecipitation of Golgi-F127, an amphiphilic polymer F127 modified with a Golgi apparatus targeting moiety, caffeic acid (CA), the responsive unit for O2·-, and red emissive carbon nanodots (CDs), which act as the reference signal. The fluorescence emission spectrum of the developed nanoprobe showed an intense peak at 674 nm, accompanied by a shoulder peak at 485 nm. As O2·- was gradually added, the fluorescence at 485 nm continuously increased; in contrast, the emission intensity at 674 nm assigned to the CDs remained constant, resulting in the ratiometric sensing of O2·-. The present ratiometric nanoprobe showed high selectivity for O2·- monitoring due to the specific recognition of O2·- by CA. Moreover, the Golgi dots exhibited good linearity with respect to the O2·- concentration within 5 to 40 μM, and the limit of detection (LOD) was ~ 0.13 μM. Additionally, the Golgi dots showed low cytotoxicity and an ability to target the Golgi apparatus. Inspired by these excellent properties, we then applied the Golgi dots to successfully monitor exogenous and endogenous O2·- levels within the Golgi apparatus. Importantly, with the help of Golgi dots, we determined that SD substantially elevated O2·- levels in the brain.

Fluorescent multichannel sensor array based on three carbon dots derived from Tibetan medicine waste for the quantification and discrimination of multiple heavy metal ions in water

A fluorescent multichannel sensor array has been established based on three carbon dots derived from Tibetan medicine waste for rapid quantification and discrimination of six heavy metal ions. Due to the chelation between metal ions and carbon dots (CDs), this fluorescence "turn off" mode sensing array can quantify six metal ions as low as "μM" level. Moreover, the six heavy metal ions display varying quenching effects on these three CDs owing to diverse chelating abilities between each other, producing differential fluorescent signals for three sensing channels, which can be plotted as specific fingerprints and converted into intuitive identification profiles via principal component analysis (PCA) and hierarchical cluster analysis (HCA) technologies to accurately distinguish Cu2+, Fe3+, Mn2+, Ag+, Ce4+, and Ni2+ with the minimum differentiated concentration of 5 μM. Valuably, this sensing array unveils good sensitivity, exceptional selectivity, ideal stability, and excellent anti-interference ability for both mixed standards and actual samples. Our contribution provides a novel approach for simultaneous determination of multiple heavy metal ions in environmental samples, and it will inspire the development of other advanced optical sensing array for simultaneous quantification and discrimination of multiple targets.

Herbal Medicine-Inspired Carbon Quantum Dots with Antibiosis and Hemostasis Effects for Promoting Wound Healing

Bleeding and bacterial infections are crucial factors affecting wound healing. The usage of herbal medicine-derived materials holds great potential for promoting wound healing. However, the uncertain intrinsic effective ingredients and unclear mechanism of action remain great concerns. Herein, inspired by the herbal medicine Ligusticum wallichii, we reported the synthesis of tetramethylpyrazine-derived carbon quantum dots (TMP-CQDs) for promoting wound healing. Of note, the use of TMP as the precursor instead of L. wallichii ensured the repeatability and homogeneity of the obtained products. Furthermore, TMP-CQDs exhibited high antibacterial activity. Mechanically, TMP-CQDs inhibited the DNA repair, biosynthesis, and quorum sensing of the bacteria and induced intracellular reactive oxygen species (ROS). Moreover, TMP-CQDs could accelerate blood coagulation through activating factor VIII and promoting platelet aggregation. Effective wound healing was achieved by using TMP-CQDs in the Staphylococcus aureus-infected mouse skin wound model. This study sheds light on the development of herbal medicine-inspired materials as effective therapeutic drugs.

Multifunctional Carbon Dots for Biomedical Applications: Diagnosis, Therapy, and Theranostic

Designing suitable nanomaterials is an ideal strategy to enable early diagnosis and effective treatment of diseases. Carbon dots (CDs) are luminescent carbonaceous nanoparticles that have attracted considerable attention. Through facile synthesis, they process properties including tunable light emission, low toxicity, and light energy transformation, leading to diverse applications as optically functional materials in biomedical fields. Recently, their potentials have been further explored, such as enzyme-like activity and ability to promote osteogenic differentiation. Through refined synthesizing strategies carbon dots, a rich treasure trove for new discoveries, stand a chance to guide significant development in biomedical applications. In this review, the authors start with a brief introduction to CDs. By presenting mechanisms and examples, the authors focus on how they can be used in diagnosing and treating diseases, including bioimaging failure of tissues and cells, biosensing various pathogenic factors and biomarkers, tissue defect repair, anti-inflammation, antibacterial and antiviral, and novel oncology treatment. The introduction of the application of integrated diagnosis and treatment follows closely behind. Furthermore, the challenges and future directions of CDs are discussed. The authors hope this review will provide critical perspectives to inspire new discoveries on CDs and prompt their advances in biomedical applications.

Study of bismuth metal organic skeleton composites with photocatalytic antibacterial activity

A composite based on Ag and carbon quantum dot (CQDs) doped bismuth metal organic framework (CAU-17) was synthesized by a one-step thermal solvent in situ growth. The microstructure, chemical composition, morphology, photogenerated electron-hole pairs, and photocatalytic activity of the composite were characterized. The produced composite with its unique energy band structure, enhances the visible light absorption and effectively delays the recombination of the photogenerated carriers. On the other hand, the modification with CQDs increases the concentration and transport rate of photogenerated carriers mainly attributed to their superior electron transport capacity and light trapping ability. The photocatalytic antibacterial effect of CAU-17/Ag/CQDs against common Gram-positive, Gram-negative bacteria (Staphylococcus aureus, Escherichia coli) and drug-resistant bacteria (methicillin-resistant Staphylococcus aureus), as well as its inhibition against HepG2 tumor cell were investigated. The results showed that CAU-17/Ag/CQDs exhibited a photocatalytic antibacterial effect with an inactivation rate as high as 99.9 %. At the low dose (0.2 mg/mL), CAU-17/Ag/CQDs indicated a significant inhibition against bacterial growth 20 min after visible light exposure, whereas at the concentration of 0.5 mg/mL, CAU-17/Ag/CQDs completely killed all the tested bacteria. At the concentration of 0.8 mg/mL, the inhibition rate against HepG2 tumor cells reached 75 %. The excellent photocatalytic property of the as prepared composite contributed to the doping of Ag and CQDs, which fundamentally altered the morphology and energy band distribution. Such a composite can be developed into an effective photocatalytic disinfection system and applied to water purification systems, biofilm rejection, combating different antibiotic resistances, and tumor therapy.

Carbonized Platycladus orientalis Derived Carbon Dots Accelerate Hemostasis through Activation of Platelets and Coagulation Pathways

Achieving rapid and effective hemostasis remains a multidisciplinary challenge. Here, distinctive functional carbon dots derived from carbonized Platycladus orientalis (CPO-CDs) are developed using one-step hydrothermal method. The negatively charged surface of CPO-CDs retains partial functional groups from CPO precursor, exhibiting excellent water solubility and high biocompatibility. Both rat liver injury model and tail amputation model have confirmed the rapid and effective hemostatic performance of CPO-CDs on exogenous hemorrhage. Further, on endogenous blood-heat hemorrhage syndrome rat model, CPO-CDs could inhibit hemorrhage and alleviate inflammation response. Interestingly, the excellent hemostasis performance of CPO-CDs is ascribed to activate exogenous coagulation pathway and common coagulation pathway. More importantly, metabolomics of rat plasma suggests that the hemostasis effect of CPO-CDs is closely related to platelet functions. Therefore, the designed in vitro experiments are performed and it is discovered that CPO-CDs significantly promote platelets adhesion, activation, and aggregation. Further, the underlying mechanism investigation suggests that Src/Syk signal pathway plays a key role in platelets activation triggered by CPO-CDs. Overall, CPO-CDs with rapid and excellent hemostatic performance are discovered for the first time, which could be an excellent candidate for the treatment of hemorrhagic diseases.

Cell-Derived N/P/S-Codoped Fluorescent Carbon Nanodots with Intrinsic Targeting Ability for Tumor-Specific Phototheranostics

Combining targeting ability, imaging function, and photothermal/photodynamic therapy into a single agent is highly desired for cancer theranostics. Herein, we developed a one-for-all nanoplatform with N/P/S-codoped fluorescent carbon nanodots (CNDs) for tumor-specific phototheranostics. The CNDs were prepared via a one-pot hydrothermal process using cancer cells as sources of carbon, nitrogen, phosphorus, and sulfur. The obtained N/P/S-codoped CNDs exhibit wide light absorption in the range of 200-900 nm and excitation-dependent emission with high photostability. Importantly, the cancer cell-derived N/P/S-codoped CNDs have outstanding biocompatibility and naturally intrinsic targeted ability for cancer cells as well as dual photothermal/photodynamic effects under 795 nm laser irradiation. Moreover, the photothermal conversion efficiency and singlet oxygen (1O2) generation efficiency were calculated to be 52 and 34%, respectively. These exceptional properties enable CNDs to act as fine theranostic agents for targeted imaging and photothermal-photodynamic synergistic therapy within the NIR therapeutic window. The CNDs prepared in this work are promising for construction as a universal tumor phototheranostic platform.

Multifunctional Tumor-Targeting Carbon Dots for Tumor Microenvironment Activated Ferroptosis and Immunotherapy in Cancer Treatment

As an emerging cancer treatment strategy, ferroptosis is distinguished by the perturbation of lipid metabolism equilibrium and the accumulation of lipid peroxidation. However, the efficacy is consistently hindered by excessive GSH in the tumor microenvironment (TME). Here, this work designed and prepared multifunctional tumor-targeting carbon dots (FG-CDs@Cu) for ferroptosis and immunotherapy. Cu2+ in FG-CDs@Cu rapidly depletes high concentrations of GSH and inhibits glutathione peroxidase 4 (GPX4) expression in an acidic TME. Meanwhile, the generated Cu+ produced reactive oxygen species (ROS) through Fenton-like reaction. Due to the high efficiency of ROS production and GSH depletion, ferroptosis mediated by oxidative stress is significantly enhanced by FG-CDs@Cu in vivo, which can induce immunogenic cell death and promote CD8+ T cell infiltration. Meanwhile, the generated O2 effectively improves the hypoxic environment of the cells and leads to the reduction of hypoxia factor-1α (HIF-1α) expression, which activates the transformation of tumor-promoting M2-type tumor-associated macrophages (TAMs) to tumor-inhibiting M1-type TAMs, further enhancing the immune response and ferroptosis. The in vivo tests suggested that FG-CDs@Cu could efficiently suppress tumor growth in the mouse model and did not cause obvious toxicity. The combination with antiprogrammed death-ligand 1 (αPD-L1) synergy immune therapy could effectively restrain the growth of distal tumors, suggesting the significant potential of FG-CDs@Cu in augmenting ferroptosis and immunotherapy for efficacious cancer treatment.

Potential Efficacy of Herbal Medicine-Derived Carbon Dots in the Treatment of Diseases: From Mechanism to Clinic

Carbon dots (CDs), a crucial component of nanomaterials, are zero-dimensional nanomaterials with carbon as the backbone structure and smaller than 10 nm. Due to their beneficial characteristics, they are widely used in biomedical fields such as biosensors, drug delivery, bio-imaging, and interactions with DNA. Interestingly, a novel type of carbon dot, generated by using herbal medicines as synthetic raw materials, has emerged as the most recent incomer in the family of CDs with the extensive growth in the number of materials selected for carbon dots synthesis. Herbal medicine-derived carbon dots (HM-CDs) have been employed in the biomedical industry, and are rapidly emerging as "modern nanomaterials" due to their unique structures and exceptional capabilities. Emerging trends suggest that their specific properties can be used in bleeding disorders, gastrointestinal disorders, inflammation-related diseases, and other common intractable diseases including cancer, menopausal syndrome, central nervous system disorders, and pain of various forms and causes. In addition, HM-CDs have been found to have organ-protective and antioxidant properties, as evidenced by extensive studies. This research provides a more comprehensive understanding of the biomedical applications of HM-CDs for the aforementioned disorders and investigates the intrinsic pharmacological activities and mechanisms of these HM-CDs to further advance their clinical applications.

Natural biomass-derived carbon dots as a potent solubilizer with high biocompatibility and enhanced antioxidant activity

Numerous natural compounds exhibit low bioavailability due to suboptimal water solubility. The solubilization methods of the modern pharmaceutical industry in contemporary pharmaceutical research are restricted by low efficiency, sophisticated technological requirements, and latent adverse effects. There is a pressing need to elucidate and implement a novel solubilizer to ameliorate these challenges. This study identified natural biomass-derived carbon dots as a promising candidate. We report on natural fluorescent carbon dots derived from Aurantia Fructus Immatures (AFI-CDs), which have exhibited a remarkable solubilization effect, augmenting naringin (NA) solubility by a factor of 216.72. Subsequent analyses suggest that the solubilization mechanism is potentially contingent upon the oration of a nanostructured complex (NA-AFI-CDs) between AFI-CDs and NA, mediated by intermolecular non-covalent bonds. Concomitantly, the synthesized NA-AFI-CDs demonstrated high biocompatibility, exceptional stability, and dispersion. In addition, NA-AFI-CDs manifested superior free radical scavenging capacity. This research contributes foundational insights into the solubilization mechanism of naringin-utilizing AFI-CDs and proffers a novel strategy that circumvents the challenges associated with the low aqueous solubility of water-insoluble drugs in the field of modern pharmaceutical science.

Carbon Dots Derived from Traditional Chinese Medicines with Bioactivities: A Rising Star in Clinical Treatment

In the field of carbon nanomaterials, carbon dots (CDs) have become a preferable choice in biomedical applications. Based on the concept of green chemistry, CDs derived from traditional Chinese medicines (TCMs) have attracted extensive attention, including TCM charcoal drugs, TCM extracts, and TCM small molecules. The design and preparation of CDs from TCMs (TCMs-CDs) can improve the inherent characteristics of TCMs, such as solubility, particle size distribution, and so on. Compared with other precursor materials, TCMs-CDs have outstanding intrinsic bioactivities and potential pharmacological effects. However, the research of TCMs-CDs in biomedicine is not comprehensive, and their mechanisms have not been understood deeply either. In this review, we will provide concise insights into the recent development of TCMs-CDs, with a major focus on their preparation, formation, precursors, and bioactivities. Then we will discuss the perfect transformation from TCMs to TCMs-CDs. Finally, we discuss the opportunities and challenges for the application of TCMs-CDs in clinical treatment.

Zero-Dimensional Carbon Nanomaterials for Fluorescent Sensing and Imaging

Advances in nanotechnology and nanomaterials have attracted considerable interest and play key roles in scientific innovations in diverse fields. In particular, increased attention has been focused on carbon-based nanomaterials exhibiting diverse extended structures and unique properties. Among these materials, zero-dimensional structures, including fullerenes, carbon nano-onions, carbon nanodiamonds, and carbon dots, possess excellent bioaffinities and superior fluorescence properties that make these structures suitable for application to environmental and biological sensing, imaging, and therapeutics. This review provides a systematic overview of the classification and structural properties, design principles and preparation methods, and optical properties and sensing applications of zero-dimensional carbon nanomaterials. Recent interesting breakthroughs in the sensitive and selective sensing and imaging of heavy metal pollutants, hazardous substances, and bioactive molecules as well as applications in information encryption, super-resolution and photoacoustic imaging, and phototherapy and nanomedicine delivery are the main focus of this review. Finally, future challenges and prospects of these materials are highlighted and envisaged. This review presents a comprehensive basis and directions for designing, developing, and applying fascinating fluorescent sensors fabricated based on zero-dimensional carbon nanomaterials for specific requirements in numerous research fields.

The Preparation of Golgi Apparatus-Targeted Polymer Dots Encapsulated with Carbon Nanodots of Bright Near-Infrared Fluorescence for Long-Term Bioimaging

As a vital organelle in eukaryotic cells, the Golgi apparatus is responsible for processing and transporting proteins in cells. Precisely monitoring the status of the Golgi apparatus with targeted fluorescence imaging technology is of enormous importance but remains a dramatically challenging task. In this study, we demonstrate the construction of the first Golgi apparatus-targeted near-infrared (NIR) fluorescent nanoprobe, termed Golgi-Pdots. As a starting point of our investigation, hydrophobic carbon nanodots (CNDs) with bright NIR fluorescence at 674 nm (fluorescence quantum yield: 12.18%), a narrow emission band of 23 nm, and excellent stability were easily prepared from Magnolia Denudata flowers using an ultrasonic method. Incorporating the CNDs into a polymer matrix modified with Golgi-targeting molecules allowed for the production of the water-soluble Golgi-Pdots, which showed high colloidal stability and similar optical properties compared with pristine CNDs. Further studies revealed that the Golgi-Pdots showed good biocompatibility and Golgi apparatus-targeting capability. Based on these fascinating merits, utilizing Golgi-Pdots for the long-term tracking of the Golgi apparatus inside live cells was immensely successful.

Synthetic strategies, properties and sensing application of multicolor carbon dots: recent advances and future challenges

Recently, carbon dots (CDs) as newly developed carbon-based nanomaterials due to advantages such as excellent photostability and easy surface functionalization have generated wide application prospects in fields such as biological imaging and chemical sensing. The multicolor emission carbon dots (M-CDs) were acquired through the selection of different carbon source precursors, change of synthesis conditions and synthesis environment. Therefore, the aim of this review is to summarize the latest research progress in polychromatic CDs from the perspectives of synthesis strategies, luminescent mechanisms, luminescent properties and applications. This review focuses on how to prepare MCDs by changing raw materials and synthesis conditions such as reaction temperature, synthesis time, synthesis pH, and synthesis solvent. This review also presents the optical properties of MCDs, concentration effects, solvent effects, pH effects, elemental doping, and surface passivation on them, as well as their creative applications in the field of sensing applications. It is anticipated that this review will serve as a guide for the development of multifunctional M-CDs and inspire future research on controllable design and preparation of M-CDs.

Carbon Quantum Dots Derived from Herbal Medicine as Therapeutic Nanoagents for Rheumatoid Arthritis with Ultrahigh Lubrication and Anti-inflammation

As a typical chronic inflammatory joint disease with swelling and pain syndromes, rheumatoid arthritis (RA) is closely related to articular lubrication deficiency and excessive proinflammatory cytokines in its progression and pathogenesis. Herein, inspired by the dual effects of joint lubrication improvement and anti-inflammation to treat RA, two novel potential therapeutic nanoagents have been developed rationally by employing herbal medicine-derived carbon quantum dots (CQDs), i.e., safflower (Carthamus tinctorius L.) CQDs and Angelica sinensis CQDs, yielding ultrahigh lubrication and anti-inflammation bioefficacy. In vitro experimental results show that the two nanoagents display excellent friction reduction due to their good water solubility and spherical structure. Using RA rat models, it is indicated that the nanoagents significantly relieved swelling symptoms and inhibited the expression of related inflammatory cytokines, including IL-1, IL-6, and TNF-α, indicating their extraordinary anti-inflammation bioefficacy. Thus, combining the lubricating and anti-inflammation bioefficacy of CQDs derived from herbal medicine is an attractive strategy to develop new nanoagents for RA treatment.

Single-particle dispersion of carbon dots in the nano-hydroxyapatite lattice achieving solid-state green fluorescence

Carbon dots (CDs), as new carbon nanomaterials, have potential applications in multiple fields due to their superior optical properties, good biocompatibility, and easy preparation. However, CDs are typically an aggregation-caused quenching (ACQ) material, which has a huge limitation on the practical application of CDs. To solve this problem, in this paper, CDs were prepared by the solvothermal method using citric acid and o-phenylenediamine as precursors and dimethylformamide as solvent. Then using CDs as nucleating agents, solid-state green fluorescent CDs were synthesized by in situ growth of nano-hydroxyapatite (HA) crystals on the surface of CDs. The results show that CDs are stably dispersed single-particlely in the form of bulk defects in the nano-HA lattice matrices with a dispersion concentration of 3.10%, and solid-state green fluorescence of CDs is achieved with a stable emission wavelength peak position near 503 nm, which provides a new solution to the ACQ problem. CDs-HA nanopowders were further used as LED phosphors to obtain bright green LEDs. In addition, CDs-HA nanopowders showed excellent performance in cell imaging (mBMSCs and 143B) applications, which provides a new scheme for further applications of CDs in the field of cell imaging and even in vivo imaging.

Optical Properties of Carbon Dots Synthesized by the Hydrothermal Method

In this study, the optical and structural properties of carbon dots (CDs) synthesized using a hydrothermal method were investigated. CDs were prepared from various precursors such as citric acid (CA), glucose, and birch bark soot. The SEM and AFM results show that the CDs are disc-shaped nanoparticles with dimensions of ~7 nm × 2 nm for CDs from CA, ~11 nm × 4 nm for CDs from glucose, and ~16 nm × 6 nm for CDs from soot. The TEM images of CDs from CA showed stripes with a distance of 0.34 nm between them. We assumed that the CDs synthesized from CA and glucose consisted of graphene nanoplates located perpendicular to the disc plane. The synthesized CDs contain oxygen (hydroxyl, carboxyl, carbonyl) and nitrogen (amino, nitro) functional groups. CDs have strong absorption in the ultraviolet region in the range of 200-300 nm. All CDs synthesized from different precursors displayed bright luminescence in the blue-green region of the spectrum (420-565 nm). We found that the luminescence of CDs depended on the synthesis time and type of precursors. The results show that the radiative transitions of electrons occur from two levels with energies ~3.0 eV and ~2.6 eV, which are due to the presence of functional groups.