Design, Synthesis, and Functionalization Strategies of Tailored Carbon Nanodots

Carbon dot-phthalocyanine hybrids: synergistic effects that boost their multifaceted applications

Since their discovery, carbon dots (CDs) have been extensively studied for their potential in diverse applications owing to their unique properties such as high biocompatibility, excellent water solubility, low toxicity, minimal photobleaching, and exceptional chemical versatility. These characteristics position CDs as promising candidates for overcoming the limitations of various molecular compounds. This review provides a comprehensive analysis of the synergistic effects arising from the integration of CDs and phthalocyanines (Pcs) to form hybrids with distinct photophysical and photochemical properties. This study explores recent advances in the development of Pc@CD hybrids, focusing on their synthesis, conjugation strategies, and synergistic effects that impact their performance in several areas, including optical sensing, electrocatalysis, photodynamic processes and photocatalysis. Emphasis is given to chemical methods that enable efficient conjugation and the role of the generation of reactive oxygen species in driving these applications. Additionally, the discussion also addresses key challenges, highlighting innovative solutions and proposing future research directions to fully harness the potential of Pc@CD hybrids in diverse scientific and technological breakthroughs.

Eco-Friendly Multifunctional Hydrogel Sensors Enabled Sustainable and Accurate Human-Machine Interaction System

Wearable epidermic electronics assembled by conductive hydrogels exhibit great application potential for their seamless integration with the human body for human-machine interactions (HMI). However, most multifunctional hydrogel sensors are prone to water loss and become useless e-waste, resulting in a growing threat to the global environment and human health. Inspired by the resurrection plants, this paper introduces the reversible intermolecular forces and physical crosslinking method into the hydrogel system to obtain a fully recyclable multifunctional smart hydrogel sensor (RMSHS), which can be completely recycled in a simple step. Meanwhile, RMSHS possesses admirable biocompatibility, excellent antibacterial ability (S. aureus and E. coli bacterial inhibition rate of 99.8%), rapid self-healing ability, and outstanding sensing performances such as low detection limit, fast response/recovery time (160/200 ms). Intelligent medical rehabilitation and smart HMI systems are developed for medical diagnostics and real-time remote controlling. Moreover, the recyclable triboelectric nanogenerator (R-TENG) intelligent array, designed based on RMSHS, replaces the electrode consumables in traditional TENGs, realizing the generation of green energy and 100% recyclability of electrode materials. RMSHS can be generalized and applied to other remote-controlling platforms, paving the way for large-scale, multi-scenario applications.

Synthesis, Characterization, and Applications of Carbon Dots for Determination of Pharmacological and Biological Samples: A Review

Carbon dots (CDs) are a novel category of carbon-based nanomaterials characterized by their small size, often less than 10 nm. CDs physical, chemical, and optical properties can be tuned using one-pot assembly. Because of their non-toxicity, biocompatibility, chemical and physical responsiveness, photo- and chemical-bleaching resistance, and low cost, nanoparticles have become incredibly versatile. They find various applications in detecting inorganic substances, bio sensing, visualizing cells, studying biological processes in live cells, and aiding in medication delivery. Additionally, CDs exhibit versatility in electronics and energy storage, making them promising candidates for applications in solar cells, light-emitting diodes, and supercapacitors. CDs are more photo stable for hours than typical fluorescent semiconductor quantum dots. Before applying CDs, they must be characterized. Techniques such as UV-VIS spectroscopy, fluorescence spectrophotometry, FT-IR, TEM, XRD, Raman spectroscopy, and NMR are commonly used to assess their photophysical and structural properties. This article review explores the synthesis, characterization applications of CDs in analytical techniques for the determination of various analytes. The article provides a detailed analysis of the different methodologies used to make nanomaterials and devices for the characterization of CDs. It also discusses the challenges that arise when using CDs in analytical techniques for detecting different analytes. The focus of this review is on accurately determining pharmaceutical and biological samples using CDs as sensing probes.

Production of Myco-Nanomaterial Products from Pleurotus ostreatus (Agaricomycetes) Mushroom via Pyrolysis

Background: The study aimed to develop a sustainable method for producing myco-nanomaterials, particularly fluorescent carbon nanodots (CNDs), from freeze-dried Pleurotus ostreatus (Agaricomycetes) mushroom powder via pyrolysis. The goal was to investigate how pyrolysis conditions affect CND characteristics and their potential antimicrobial properties. Mushroom powder was pyrolyzed at temperatures ranging from 150 to 240 °C. The resulting products were analyzed for yield, molecular weight, fluorescence intensity, and estimated CND concentration in relation to the carbon-to-nitrogen (C/N) ratio. Antibacterial activity was tested against Escherichia coli and Staphylococcus epidermidis. Product yield decreased from 13.20% at 150 °C to 0.80% at 240 °C. Molecular weight peaked at 200 °C (623.20 kDa), while maximum fluorescence intensity (739.40 A.U.) was observed at 210 °C. A strong positive correlation (R2 = 0.72) was found between the C/N ratio and estimated CND concentration. Antimicrobial testing revealed notable inhibition of E. coli, associated with higher fluorescence intensity and CND content. Pyrolyzed P. ostreatus mushroom powder offers a promising, eco-friendly platform for producing luminescent, carbonaceous nanomaterials with antibacterial potential. These non-purified, myco-derived nanomaterials may contribute to green nanotechnology development and antimicrobial strategies.

Revolutionizing nanozymes: The synthesis, enzyme-mimicking capabilities of carbon dots, and advancements in catalytic mechanisms

Nanozymes, a revolutionary category of engineered artificial enzymes based on nanomaterials, have been developed to overcome the inherent limitations of natural enzymes, such as the high cost associated with storage and their fragility. Carbon dots (CDs) have emerged as compelling candidates for various applications due to their versatile properties. Particularly noteworthy are CDs with a range of surface functional groups that exhibit enzyme-like behavior, combining exceptional performance with catalytic capabilities. This review explores the methodologies used for synthesizing CDs with enzyme mimicking capabilities, highlighting potential avenues such as doping and hybrid nanozymes to enhance their catalytic efficacy. Moreover, a comprehensive overview of CDs that mimick the activities of various oxidoreductases-like peroxidase, catalase, oxidase/laccase, and superoxide dismutase-like is provided. The focus is on the in-depth exploration of the mechanisms, advancements and practical applications of each oxidoreductase-like function exhibited by CD nanozymes. Drawing upon these exhaustive summaries and analyses, the review identifies the prevailing challenges that hinder the seamless integration of CDs into real-world applications and offers forward-looking perspectives for future directions.

Covalently Coupling Carbon Quantum Dots for Photoluminescence Red Shift Response to pH

Conventional fluorescent pH sensors, despite offering high sensitivity and rapid response, are limited by their reliance on fluorescence intensity changes, hindering applications requiring precise wavelength control. Here, we present a pH sensing strategy based on cross-linked carbon quantum dots (CCL-CQDs) displaying a remarkable pH-dependent red shift in the fluorescence emission wavelength. Amino- and carboxyl-functionalized CQDs were synthesized via a one-step hydrothermal method and further assembled into CCL-CQDs through the condensation reaction between amino groups and glutaraldehyde. The CCL-CQDs displayed excellent pH sensitivity, with their fluorescence emission wavelength exhibiting a linear red shift upon increasing pH (from 2.29 to 7.16). The results of mechanism exploration revealed that H+ induced the cleavage of C═N bonds in the CCL-CQD structure, leading to the formation of -COOH groups and increased surface-oxidized carbon content. This enhanced oxidation generated more surface defects, triggering a wavelength shift in surface-state-related fluorescence emission. This study demonstrates the successful synthesis of pH-sensitive CCL-CQDs with an excellent fluorescence detection performance.

Carbon Nanodots-Based Polymer Nanocomposite: A Potential Drug Delivery Armament of Phytopharmaceuticals

Carbon nanodots (CNDs) have garnered significant attention as viable drug delivery vehicles in recent years, especially in the field of phytomedicine. Although there is much promise for therapeutic applications with phytomedicine, its effectiveness is frequently restricted by its low solubility, stability, and bioavailability. This paper offers a thorough synopsis of the developing field of phytomedicine drug delivery based on CND. It explores CND synthesis processes, surface functionalization strategies, and structural and optical characteristics. Additionally, the advantages and difficulties of phytomedicine are examined, with a focus on the contribution of drug delivery methods to the increased effectiveness of phytomedicine. The applications of CNDs in drug delivery are also included in the review, along with the mechanisms that underlie their improved drug delivery capabilities. Additionally, it looks at controlled-release methods, stability augmentation, and phytomedicine-loading tactics onto CNDs. The potential of polymeric carbon nanodots in drug delivery is also covered, along with difficulties and prospective directions going forward, such as resolving toxicity and biocompatibility issues. In summary, the present review highlights the encouraging contribution of CNDs to the field of drug delivery, specifically in enhancing the potential of phytomedicine for therapeutic purposes.

Unlocking Photosynthetic Potential: Harnessing Rosa roxburghii Derived Carbon Dots as Nanofertilizers for Enhanced Plant Growth

The synthesis of nanomaterials from renewable resources has emerged as an environmentally friendly alternative. This approach helps to reduce the use of chemical fertilizers in agricultural production, further reducing the potential harm to the ecosystem and effectively reducing the burden on the environment. In this work, we synthesized Rosa roxburghii derived carbon dots (CDs) using the microwave hydrothermal method (RR-CDs) and the electrolytic oxidation method (GRR-CDs), and the results showed that RR-CDs had a wider ultraviolet absorption range and emitted blue fluorescence. These properties make RR-CDs more effective as light-harvesting materials in plants, thus promoting photosynthesis. In the cultivation of lettuce, RR-CDs significantly enhanced both the biomass and the quality of the lettuce. In addition, compared to the control group, the chlorophyll content of lettuce treated with RR-CDs increased by 31.83%, the net photosynthetic rate increased by 60.76%, and the electron transport rate of photosystem II increased by 38.72%. Therefore, we found that the microwave hydrothermal method could bring better benefits, with a yield of up to 40.20% after just 2 h of reaction. RR-CDs promote photosynthesis by promoting light conversion and improving nutrient efficiency while also boasting the dual advantages of low cost and easy large-scale production, thus opening up avenues for sustainable agricultural production.

Carbon Dot Synthesis and Purification: Trends, Challenges and Recommendations

Carbon dots (CDs) have rapidly emerged as a new family of carbon-based nanomaterials since their initial discovery two decades ago. Numerous appealing properties, such as precursor and synthesis process flexibility, tunable photoluminescence, and good biocompatibility, have enabled their widespread applications in sensing, catalysis, energy, and biomedical fields. As the field expands, notable efforts have recently focused on mechanistically elucidating the structural formation and optical behavior of CDs. However, the absence of "clean" CDs presents a major obstacle to achieving a solid understanding of these aspects. Often, the claimed CDs are, in fact, a mixture of small molecules, oligomers, nano-sized aggregates, or even microparticles. Such coexistence of impurities markedly impacts the physicochemical properties of resulting CD-based mixtures, hampering the resolution of key mechanistic questions. Here, we aim to address this fundamental shortcoming of the field, going beyond the customary focus of the existing reviews that predominantly cover synthesis, optical performance, and application prospects. We begin with an overview of CD synthesis and then thoroughly examine the purification methods, including filtration, dialysis, electrophoresis, and chromatography. The insights provided here will guide the researchers towards obtaining high-quality CDs, employing proper combinations of available tools, and ultimately paving the way for more demanding applications.

Bio-Inspired Carbon Dots as Malondialdehyde Indicator for Real-Time Visualization of Lipid Peroxidation in Depression

Brain lipidic peroxidation is closely associated with the pathophysiology of various psychiatric diseases including depression. Malondialdehyde (MDA), a reactive aldehyde produced in lipid region, serves as a crucial biomarker for lipid peroxidation. However, techniques enabling real-time detection of MDA are still lacking due to the inherent trade-off between recognition dynamics and robustness. Inspired by the structure of phospholipid bilayers, amphiphilic carbon dots named as CG-CDs targeted to cell membrane are designed for real-time monitoring of MDA fluctuations. The design principle relies on the synergy of dynamic hydrogen bonding recognition and cell membrane targetability. The latter facilitates the insertion of CG-CDs into lipid regions and provides a hydrophobic environment to stabilize the labile hydrogen bonding between CG-CDs and MDA. As a result, recognition robustness and dynamics are simultaneously achieved for CG-CDs/MDA, allowing for in situ visualization of MDA kinetics in cell membrane due to the instant response (<5 s), high sensitivity (9-fold fluorescence enhancement), intrinsic reversibility (fluorescence on/off), and superior selectivity. Subsequently, CG-CDs are explored to visualize nerve cell membrane impairment in depression models of living cells and zebrafish, unveiling the extensive heterogeneity of the lipid peroxidation process and indicating a positive correlation between MDA levels and depression.

Luminous Insights: Harnessing Carbon Nanodots from Black Seed Powder via Pyrolysis for Bioimaging and Antifungal Investigations

This study delves into the fabrication of carbon nanodots (CNDs) through a bottom-up approach, utilizing black seed powder as the precursor material and employing the pyrolysis method. CNDs were synthesized across four distinct temperature settings. The investigation encompasses an extensive characterization of the CNDs, including optical and structural attributes. UV-visible and fluorescence spectroscopy were utilized to assess their optical properties, while FT-IR and XRD analyses confirmed their structural integrity. To elucidate size, shape, and nature, HR-TEM imaging was employed. Furthermore, the functional applications of the synthesized CNDs were explored. The material's antifungal potential was evaluated, and its viability for bioimaging was demonstrated by successfully labeling yeast cells with CNDs. This study underscores the multifaceted nature of CNDs, serving as a bridge between synthesis, comprehensive characterization, and practical applications. In summary, the investigation provides insights into the versatile applications of CNDs derived from black seed powder through pyrolysis. The study contributes to the understanding of their fundamental properties and establishes their potential for both antifungal treatments and cellular bioimaging.

Fluorescent and colorimetric dual-mode recognition of Al3+ in tablets based on chrome azurol S and pH-switchable boron, nitrogen co-doped carbon dots

The synthesis and characterization of pH-sensitive boron and nitrogen co-doped CDs (B, N-CDs) is reported. The fluorescence of B, N-CDs exhibited pH-responsive behavior within the range pH 3.0-6.0, attributed to their controlled aggregation and disaggregation. Interestingly, the fluorescence of B, N-CDs was quenched by the inner filter effect from chrome azurol S (CAS). With the subsequent addition of Al3+, the fluorescence of B, N-CDs was restored due to the formation of blue Al3+-CAS and B, N-CDs-Al3+ complexes. Consequently, a fluorescent and colorimetric dual-mode sensor for Al3+ detection was developed. The proposed sensor enabled Al3+ detection in the ranges and limits of detection of 3.75-22.5 μM and 2.67 μM for the fluorescent mode and 5-20 μM and 4.8 μM for the colorimetric mode, respectively. Furthermore, the efficacy of the sensor was validated through successful detection of Al3+ in tablet samples. The obtained B, N-CDs promised the application in acid condition and the proposed sensor is expected to be applied to in situ on-line detection of Al3+.

Biomass-derived carbon dots with pharmacological activity for biomedicine: Recent advances and future perspectives

Carbon dots (CDs), a type of nanoparticle with excellent optical properties, good biocompatibility, and small size, are finding increasing application across the fields of biology and biomedicine. In recent years, biomass-derived CDs with pharmacological activity (BP-CDs) derived from herbal medicines (HMs), HMs extracts and other natural products with demonstrated pharmaceutical activity have attracted particular attention. Herein, we review recent advances in the development of BP-CDs, covering the selection of biomass precursors, different methods used for the synthesis of BP-CDs from natural sources, and the purification of BP-CDs. Additionally, we summarize the many remarkable properties of BP-CDs including optical properties, biocompatibility and pharmaceutical efficacy. Moreover, the antibacterial, antiviral, anticancer, biosensing, bioimaging, and other applications of BP-CDs are reviewed. Thereafter, we discuss the advantages and disadvantages of BP-CDs and Western drug-derived CDs, highlighting the excellent performance of BP-CDs. Finally, based on the current state of research on BP-CDs, we suggest several aspects of BP-CDs that urgently need to be addressed and identify directions that should be pursued in the future. This comprehensive review on BP-CDs is expected to guide the precise design, preparation, and future development of BP-CDs, thereby advancing the application of BP-CDs in biomedicine.

Advances in Shell and Core Engineering of Carbonized Polymer Dots for Enhanced Applications

ConspectusCarbon dots (CDs), as a novel type of fluorescent nanocarbon material, attract widespread attention in nanomedicine, optoelectronic devices, and energy conversion/storage due to their excellent optical properties, low toxicity, and high stability. They can be classified as graphene quantum dots, carbon quantum dots, and carbonized polymer dots (CPDs). Among these, CPDs exhibit tunable structures and components that allow fine-tuning of their optoelectronic properties, making them one of the most popular types of CDs in recent years. However, the structural complexity of CPDs stimulates deep exploration of the relationship between their unique structure and luminescent performance. As an organic-inorganic hybrid system, the diversity of self-limited quantum state carbon cores and polymer-hybrid shell layers makes understanding the underlying mechanisms and structure-property relationships in CPDs a very challenging task. In this context, elucidating the structural composition of CPDs and the factors that affect their optical properties is vital if the enormous potential of CPDs is to be realized. Achieving controllable structures with predefined optical properties via the adoption of specific functionalization strategies is the prized goal of current researchers in the field.In this Account, we describe the efforts made by our group in the synthesis, mechanism analysis, structural regulation, and functional applications of CPDs, with particular emphasis on the design of CPDs core-shell structures with tailored optoelectronic properties for applications in the fields of optoelectronics and energy. Specifically, through the rational selection of precursors, optimization of reaction conditions, and postmodification strategies for CPDs, we have demonstrated that it is possible to regulate both the carbon core and polymer shell layers, thereby achieving full-spectrum emission, high quantum yield, persistent luminescence, thermally activated delayed fluorescence, and laser action in CPDs. Furthermore, we have established structure-performance relationship in CPDs and proposed a universal strategy for synergistic interactions between hybrid carbon-based cores and surface micronanostructures. In addition, we unveiled a novel luminescence mechanism in cross-linked CPDs, specifically "cross-linking synergistically inducing quantum-state luminescence", which addresses the challenge of efficient circularly polarized luminescence in the liquid and solid phases of CPDs. Subsequently, strong cross-linking, dual-rigidity, and ordering preparation methods were introduced, thereby pioneering tunable laser emission from blue to near-infrared wavelengths. Additionally, we developed a new strategy of "confined composite nanocrystals of CPDs", leading to various high-performance hydrogen evolution catalysts for water electrolysis. The CPDs developed by this strategy not only possessed excellent optical properties but also enabled high efficiencies in field of energy conversion, thus maximizing the utilization of CPDs. Finally, we discuss important new trends in CPD research and development. Overall, this Account summarizes the latest advancements in CPDs in recent years, providing case-studies that enable deep understanding of structure-property-performance relationships and regulation strategies in CPDs, guiding the future expansion and application of CPDs.

A review on green synthesis, biological applications of carbon dots in the field of drug delivery, biosensors, and bioimaging

Since the beginning of nanoscience and nanotechnology, carbon dots (CDs) have been the foundational idea and have dominated the growth of the nano-field. CDs are an intriguing platform for utilization in biology, technology, catalysis, and other fields thanks to their numerous distinctive structural, physicochemical, and photochemical characteristics. Since several carbon dots have already been created, they have been assessed based on their synthesis process, and luminescence characteristics. Due to their biocompatibility, less toxic effects, and most significantly their fluorescent features in contrast to other carbon nanostructures, CDs have several benefits. This review focuses on the most recent advancements in the characterization, applications, and synthesis techniques used for CDs made from natural sources. It will also direct scientists in the creation of a synthesis technique for adjustable carbon dots that is more practical, effective, and environmentally benign. With low toxicity and low cost, CDs are meeting the new era's requirements for more selectivity and sensitivity in the detection and sensing of various things, such as biomaterial sensing, enzymes, chemical contamination, and temperature sensing. Its variety of properties, such as optical properties, chemiluminescence, and morphological analysis, make it a good option to use in bioimaging, drug delivery, biosensors, and cancer diagnosis.

Nanomaterial-Based Sensors for Coumarin Detection

Sensors are widely used owing to their advantages including excellent sensing performance, user-friendliness, portability, rapid response, high sensitivity, and specificity. Sensor technologies have been expanded rapidly in recent years to offer many applications in medicine, pharmaceuticals, the environment, food safety, and national security. Various nanomaterial-based sensors have been developed for their exciting features, such as a powerful absorption band in the visible region, excellent electrical conductivity, and good mechanical properties. Natural and synthetic coumarin derivatives are attracting attention in the development of functional polymers and polymeric networks for their unique biological, optical, and photochemical properties. They are the most abundant organic molecules in medicine because of their biological and pharmacological impacts. Furthermore, coumarin derivatives can modulate signaling pathways that affect various cellular processes. This review covers the discovery of coumarins and their derivatives, the integration of nanomaterial-based sensors, and recent advances in nanomaterial-based sensing for coumarins. This review also explains how sensors work, their types, their pros and cons, and sensor studies for coumarin detection in recent years.

Three-Dimensional Imaging of Bioinspired Lipidic Mesophases Using Multicolored Light-Emitting Carbon Nanodots

Recent progress in the design of carbon nanostructures exhibiting strong multiphoton-excited emission opens new pathways to explore the self-organization of lipids found in living organisms. Phospholipid-based lyotropic myelin figures (MFs) are promising materials as simplified models of biomembranes due to their structural resemblance to a multilamellar sheath insulating the axon. This study demonstrates the possibility of selective labeling of MFs by strongly emitting multicolor phloroglucinol-derived carbon nanodots (PG CNDs). Such dopants are efficiently excited by visible and near-infrared light; therefore, one- and two-photon fluorescence microscopies are incorporated to gain 3D insights into the MFs. Combining nondestructive fluorescence microscopy and spectroscopy techniques along with polarized light microscopy gives details on the stability and morphology of lipidic mesophases. Our findings suggest that PG CNDs can be a viable and simple alternative to conventional fluorescent lipid stains to image biologically relevant phospholipid-based structures.

Metal-organic framework (MOF)/C-dots and covalent organic framework (COF)/C-dots hybrid nanocomposites: Fabrications and applications in sensing, medical, environmental, and energy sectors

Developing new hybrid materials is critical for addressing the current needs of the world in various fields, such as energy, sensing, health, hygiene, and others. C-dots are a member of the carbon nanomaterial family with numerous applications. Aggregation is one of the barriers to the performance of C-dots, which causes luminescence quenching, surface area decreases, etc. To improve the performance of C-dots, numerous matrices including metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), and polymers have been composited with C-dots. The porous crystalline structures, which are constituents of metal nodes and organic linkers (MOFs) or covalently attached organic units (COFs) provide privileged features such as high specific surface area, tunable structures, and pore diameters, modifiable surface, high thermal, mechanical, and chemical stabilities. Also, the MOFs and COFs protect the C-dots from the environment. Therefore, MOF/C-dots and COF/C-dots composites combine their features while retaining topological properties and improving performances. In this review, we first compare MOFs with COFs as matrices for C-dots. Then, the recent progress in developing hybrid MOFs/C-dots and COFs/C-dots composites has been discussed and their applications in various fields have been explained briefly.

Tris-assisted one-step fabrication of functional carbon dots for specific folate receptor positive-expressed cancer cell imaging

Specific staining of cancer cells is momentous for cancer research. Nanoprobe with multivalent recognition is emerging as powerful tools for bioimaging, but the nonspecific cell uptake and complex functional modification procedures are still obstacles for specific detection and convenient synthesis. Carbon dots (CDs) with an intrinsic targeting ability, excellent optical properties and biocompatibility acquired from an efficient one-step fabrication procedure were urgently desired in specific cancer cells visualization. Herein, inspired by the interrelationships between interface and biomolecular mechanisms, we suggested that it was possible to construct CDs with the desired characteristics for folate receptor (FR) positive-expressed cancer cell imaging via rich hydroxyl groups Tris-assisted one-step hydrothermal treatment of folate acid (FA) and l-Arginine (L-Arg) precursors. The prepared small-sized F-CDs were equipped with abundant hydroxyl, pterin and negative charge surface, and possessed environmental friendliness, outstanding photostability and biocompatibility. Moreover, F-CDs had an intrinsic FR positive-expressed cancer cell targeting ability without any post-modification of the ligands. Rich hydroxyl groups play a vital role in endowing the optical properties and biological effects of F-CDs. F-CDs could be used as a promising candidate for FR-expressed cancer cell labeling and tracking. In addition, the caveolae-mediated endocytosis pathway of F-CDs was ascertained. More importantly, experimental results confirmed that the combination of physicochemical properties may provide an efficient strategy to overcome non-specific cell uptake interactions for cell labeling. Our strategy put forward a promising alternative to design fluorescent CDs for extensive chemical and biomedical applications.

Molecularly imprinted polymer photoelectrochemical sensor for the detection of triazophos in water based on carbon quantum dot-modified titanium dioxide

Widely used organophosphorus pesticide triazophos (TAP) can easily cumulate in aquatic system due to its high stability chemically and photochemically and thus posing significant threat to aquatic creatures and humans' health. Urging demand for rapid determining TAP in water has risen. Photoelectrochemical (PEC) sensing turns out to be a good candidate for its simplicity in fabrication and swiftness in detection. Nevertheless, traditional PEC sensors often lack selectivity as their signal generation primarily relies on the oxidation of organic compounds in the electrolyte by photo-induced holes. To address this limitation, molecularly imprinted polymers (MIPs) can be in combined with PEC sensors to significantly enhance the selectivity. Here, we present a novel approach utilizing a PEC sensor enhanced by carbon-modified titanium dioxide molecularly imprinted polymers (MIP/C/TiO2 NTs). Carbon quantum dot (CQD) modification of titanium dioxide nanotube arrays (C/TiO2 NTs) was achieved through a one-step anodization process, effectively enhancing visible light absorption by narrowing the band gap of TiO2, and CQDs also function as sensitizer accelerating charge transfer for improved and stable photocurrent signals during detection. Our method further incorporates MIPs to heighten the selectivity of the PEC sensor. Electro-polymerization using cyclic voltammetry was employed to polymerize MIPs with pyrrole as the functional monomer and triazophos as the target molecule. The resultant MIP/C/TiO2 NT sensor exhibited remarkable sensitivity, with a detection limit of 0.03 nM (S/N = 3), alongside exceptional selectivity and stability for triazophos detection in water. This offers a promising avenue for efficient, cost-effective, and rapid monitoring of pesticide contaminants in aquatic environments, contributing to the broader goals of environmental preservation and public health.

Carbon nanoparticles neutralize carbon dioxide (CO2) in cytotoxicity: Potent carbon emission induced resistance to anticancer nanomedicine and antibiotics

Excessive carbon emissions, especially CO2 release, have been a global concern. Few studies applied nanotechnology to relieve the ecotoxicity of CO2. Here, we applied carbon dots (CDs) to neutralize the CO2. We found CO2 induced the aggregation of CDs, which is of significance for CDs in enhanced fluorescence intensity but decreased CDs function in nanozyme activity, and reduced CDs toxicity to bacteria and cancer cells. Our data suggest the concern of CO2 release in global health in CDs mediated anticancer drug delivery and antibiotics resistance. However, enhanced fluorescence in cells which can be applied for bioimaging or CO2 sensing as simulated investigation by static charged attraction of positively charged CDs with negatively charged soluble HCO3-. Thus, CO2 abrogates the nanomedicine efficacy in cancer cells and antibacterial and may induce drug resistance for patients undergoing chemotherapy or antibiotics therapy. To overcome the resistance, we may apply the CDs for a neutralization of CO2 for impact on anticancer nanomedicine and antibiotics and reducing the ecotoxicity in biological systems.

Celebrating Maurizio Prato's Passion, Talent and Imagination

This Editorial introduces a Special Collection of papers dedicated to Maurizio Prato, featuring prominent examples of his team's efforts to integrate complex frontier research with pioneering achievements in the field of carbon nanostructures and molecular nanoscience.

n-Type Fullerene-Carbon Dots: Synthesis and Electrochemical and Photophysical Properties

The covalent incorporation of C60 and C70 derivatives of the well-known n-type organic semiconductor PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) onto carbon dots (CD) is described. Morphological and structural characterization reveal combined features of both pristine starting materials (CD and PCBM). Electrochemical investigations evidenced the existence of additional reduction processes to that of CD or PCBM precursors, showing rich electron-acceptor capabilities, with multistep processes in an affordable and narrow electrochemical window (ca. 1.5 V). Electronic communication in the obtained nanoconjugated species were derived from steady-state absorption and emission spectroscopies, which showed bathochromically shifted absorptions and emissions well entering the red region. Finally, the lower fluorescence quantum yield of CD-PCBM nanoconjugates, compared with CD, and the fast decay of the observed emission of CD, support the existence of an electronic communication between both CD and PCBM units in the excited state.

Photochemical synthesis, characterization, and electrochemical sensing properties of CD-AuNP nanohybrids

Among the existing nanosystems used in electrochemical sensing, gold nanoparticles (AuNPs) have attracted considerable attention owing to their intriguing chemical and physical properties such as good electrical conductivity, high electrocatalytic activity, and high surface-to-volume ratio. However, despite these useful characteristics, there are some issues due to their instability in solution that can give rise to aggregation phenomena and the use of hazardous chemicals in the most common synthetic procedures. With an aim to find a solution to these issues, recently, we prepared and characterized carbon dots (CDs), from olive solid wastes, and employed them as reducing and capping agents in photo-activated AuNP synthesis, thus creating CD-Au nanohybrids. These nanomaterials appear extremely stable in aqueous solutions at room temperature, are contemporary, and have been obtained using CDs, which are exclusively based on non-toxic elements, with an additional advantage of being generated from an otherwise waste material. In this paper, the synthesis and characterization of CD-Au nanohybrids are described, and the electrochemical experiments for hydroquinone detection are discussed. The results indicate that CD-Au acts as an efficient material for sensing hydroquinone, matching a wide range of interests in science from industrial processes to environmental pollution.

Wavelength-Tuneable Fluorescent Carbon Dots for Nucleic Acid Imaging

Nucleic acid is one of the most important substances in organisms, and its dynamic changes are closely related to physiological processes. Nucleic acid labeling is conducive to providing important information for the early diagnosis and treatment of pathophysiological processes. Here, we utilized the transfer mechanism between carbon sources and CDs to synthesize wavelength-adjustable N-CDs for the nucleic acid image. Along with the increased graphite nitrogen (from 10.6 to 30.1%) gradually by the precise design of the nitrogen structure in carbon sources (e.g., primary amines, secondary amines, tertiary amines, and liking graphite-nitrogen), the energy gap of CDs reduced, resulting in adjustable wavelength from visible to near-infrared range (from 461 nm/527 nm to 650 nm/676 nm). Furthermore, N-CDs exhibited a selective affinity for nucleic acids, especially RNA. Therefore, N-CDs support an efficient platform for real-time tracking of RNA dynamic changes in cells.

A standard procedure for rapid toxicity evaluation of carbon dots both in vitro and in vivo

Carbon dots (CDs) are an emerging class of fluorescent quantum dot nanomaterials that have attracted considerable scientific attention for biomedical or bioimaging applications due to their physicochemical and biochemical properties. With the emergence of massive novel synthetic CDs applying to biomedical fields of science, evaluating their biosafety before any biological application is essential. However, there is no universal protocol or routine procedures for toxicity detection and biosafety assessment of CDs in general biological environments. Herein, we provide an ideal and fast operating system to detect the biotoxicity of CDs, which has been preliminary practiced. Briefly, the obtained CDs will be evaluated by in vitro cytotoxicity assay using cell counting kit-8, lactate dehydrogenase assay kit, and flow cytometry. Meanwhile, the model creature zebrafish is employed to perform in vivo evaluation by measuring body length, hatching rate, heart rate, and morphological observation. Our operating procedure condenses previous scattered biosafety detection methods into a rapid standard evaluation protocol that can be applied to early biotoxicity screening of CDs. This protocol will accelerate CDs biological exploitation and guide future industrialized biosafety assessment in large-scale applications.

Nitrogen-doped Carbon Dots as Efficient Photocatalysts for High Selectivity of Dehalogenative Oxyalkylation of Styrene

Carbon dots (CDs) are a type of carbon-based luminescent material with a zero-dimensional structure and a size of less than 10 nm, which are composed of sp2 /sp3 hybrid carbon nuclei and surface functional groups. Because CDs has strong photoluminescence and good light absorption in the ultraviolet and near visible regions, it is an excellent candidate for photocatalytic applications. However, the use of nonmetallic doped CDs as photosensitizers for direct photocatalytic organic reactions has been limited to several scattered reports. Herein, we present nitrogen-doped carbon dots (N-CDs) that has a capability for not only produce reactive oxygen species (ROS), including superoxide anion radical (O2 ⋅- ) and singlet oxygen (1 O2 ), but also provide an unprecedented high activity of dehalogenative oxyalkylation of styrene with a yield of 93 %. This work develops a novel opportunity to utilize cost-effective and easily accessible CDs for the advancement of photocatalysis.

Dye-Derived Red-Emitting Carbon Dots for Lasing and Solid-State Lighting

Carbon dots are carbon-based nanoparticles renowned for their intense light-emitting capabilities covering the whole visible light range. Achieving carbon dots emitting in the red region with high efficiency is extremely relevant due to their huge potential in biological applications and in optoelectronics. Currently, photoluminescence in such an energy interval is often associated with polyheterocyclic molecular domains forming during the synthesis that, however, present low emission efficiency and issues in controlling the optical features. Here, we overcome these problems by solvothermally synthesizing carbon dots starting from Neutral Red, a common red-emitting dye, as a molecular precursor. As a result of the synthesis, such molecular fluorophore is incorporated into a carbonaceous core while retaining its original optical properties. The obtained nanoparticles are highly luminescent in the red region, with a quantum yield comparable to that of the starting dye. Most importantly, the nanoparticle carbogenic matrix protects the Neutral Red molecules from photobleaching under ultraviolet excitation while preventing aggregation-induced quenching, thus allowing solid-state emission. These advantages have been exploited to develop a fluorescence-based color conversion layer by fabricating polymer-based highly concentrated solid-state carbon dot nanocomposites. Finally, the dye-based carbon dots demonstrate both stable Fabry-Perot lasing and efficient random lasing emission in the red region.

Carbon network-hosted porphyrin as a highly biocompatible nanophotosensitizer for enhanced photodynamic therapy

Photodynamic therapy (PDT) has the characteristics of being simple and non-invasive, and with on-demand light control. However, most photosensitizers exhibit strong hydrophobicity, low quantum yields in water and low tumor selectivity. In this study, carbon network-hosted porphyrins (CPs) with high biocompatibility and efficient singlet oxygen (1O2) generation were developed to reduce the biotoxicity of photosensitizers and avoid quenching caused by hydrophobic aggregation for enhanced PDT. The CPs were prepared by a simple solid-phase synthesis method using porphyrin, green non-toxic citric acid and urea as the raw materials. The CPs exhibited excellent water solubility and high biocompatibility. Even when the concentration reached 1.5 mg mL-1, cells still had good biological activity. By separately fixing the porphyrins in the carbon network, the CPs avoided aggregation-induced inactivation and had high generation efficiency of 1O2. Furthermore, in order to improve the PDT effect, the CPs were modified with the upper nuclear targeting peptide TAT (T-CPs), which was used to target the nucleus and generate 1O2in situ to directly destroy genetic material. The proposed strategy provides a simple and green path to prepare nanophotosensitizers with high biocompatibility and efficient 1O2 generation for PDT.

Assessment of biomass-derived carbon dots as highly sensitive and selective templates for the sensing of hazardous ions

Access to safe drinking water and a hygienic living environment are the basic necessities that encourage healthy living. However, the presence of various pollutants (especially toxic heavy metal ions) at high concentrations in water renders water unfit for drinking and domestic use. The presence of high concentrations of heavy-metal ions (e.g., Pb2+, Hg2+, Cr6+, Cd2+, or Cu2+) greater than their permissible limits adversely affects human health, and increases the risk of cancer of the kidneys, liver, skin, and central nervous system. Therefore, their detection in water is crucial. Due to the various benefits of "green"-synthesized carbon-dots (C-dots) over other materials, these materials are potential candidates for sensing of toxic heavy-metal ions in water sources. C-dots are very small carbon-based nanomaterials that show chemical stability, magnificent biocompatibility, excitation wavelength-dependent photoluminescence (PL), water solubility, simple preparation strategies, photoinduced electron transfer, and the opportunity for functionalization. A new family of C-dots called "carbon quantum dots" (CQDs) are fluorescent zero-dimensional carbon nanoparticles of size < 10 nm. The green synthesis of C-dots has numerous advantages over conventional chemical routes, such as utilization of inexpensive and non-poisonous materials, straightforward operations, rapid reactions, and renewable precursors. Natural sources, such as biomass and biomass wastes, are broadly accepted as green precursors for fabricating C-dots because these sources are economical, ecological, and readily/extensively accessible. Two main methods are available for C-dots production: top-down and bottom-up. Herein, this review article discusses the recent advancements in the green fabrication of C-dots: photostability; surface structure and functionalization; potential applications for the sensing of hazardous anions and toxic heavy-metal ions; binding of toxic ions with C-dots; probable mechanistic routes of PL-based sensing of toxic heavy-metal ions. The green production of C-dots and their promising applications in the sensing of hazardous ions discussed herein provides deep insights into the safety of human health and the environment. Nonetheless, this review article provides a resource for the conversion of low-value biomass and biomass waste into valuable materials (i.e., C-dots) for promising sensing applications.

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.

Microwave-assisted one-step synthesis of water-soluble manganese-carbon nanodot clusters

Using metal coordination to assemble carbon nanodots (CND) into clusters can enhance their photophysical properties for applications in sensing and biomedicine. Water-soluble clusters of CNDs are prepared by one-step microwave synthesis starting from ethylenediaminetetraacetic acid, ethylenediamine and MnCl2·4H2O as precursors. Transmission electron microscopy and powder X-Ray diffraction techniques indicate that the resulting clusters form spherical particles of 150 nm constituted by amorphous CNDs joined together with Mn ions in a laminar crystalline structure. The nanomaterial assemblies show remarkable fluorescence quantum yields (0.17-0.20) and magnetic resonance imaging capability (r1 = 2.3-3.8 mM-1.s-1). In addition, they can be stabilized in aqueous solutions by phosphate ligands, providing a promising dual imaging platform for use in biological systems.

Recent advances and perspectives of functionalized carbon dots in bacteria sensing

Bacterial infectious diseases are severe threats to human health and increase substantial financial burdens. Nanomaterials have shown great potential in timely and accurate bacterial identification, detection, and monitoring to improve the cure rate and reduce mortality. Recently, carbon dots have been evidenced to be ideal candidates for bacterial identification and detection due to their superior physicochemical properties and biocompatibility. This review outlines the detailed recognition elements and recognition strategies with functionalized carbon dots (FCDs) for bacterial identification and detection. The advantages and limitations of different kinds of FCDs-based sensors will be critically discussed. Meanwhile, the ongoing challenges and perspectives of FCDs-based sensors for bacteria sensing are put forward.

Nanoparticle-Based Photothermal Therapy for Breast Cancer Noninvasive Treatment

Rapid advancements in materials science and nanotechnology, intertwined with oncology, have positioned photothermal therapy (PTT) as a promising noninvasive treatment strategy for cancer. The breast's superficial anatomical location and aesthetic significance render breast cancer a particularly pertinent candidate for the clinical application of PTT following melanoma. This review comprehensively explores the research conducted on the various types of nanoparticles employed in PTT for breast cancer and elaborates on their specific roles and mechanisms of action. The integration of PTT with existing clinical therapies for breast cancer is scrutinized, underscoring its potential for synergistic outcomes. Additionally, the mechanisms underlying PTT and consequential modifications to the tumor microenvironment after treatment are elaborated from a medical perspective. Future research directions are suggested, with an emphasis on the development of integrative platforms that combine multiple therapeutic approaches and the optimization of nanoparticle synthesis for enhanced treatment efficacy. The goal is to push the boundaries of PTT toward a comprehensive, clinically applicable treatment for breast cancer.

RNA-Targeting Carbon Dots for Live-Cell Imaging of Granule Dynamics

It is significant to monitor the different RNA granules dynamics and phase separation process inside cells under various stresses, for example, oxidative stress. The current small-molecule RNA probes work well only in fixed cells and usually encounter problems such as insufficient stability and biocompatibility, and thus a specific RNA-targeting fluorescent nanoprobe that can be used in the living cells is urgently desired. Here, the de novo design and microwave-assisted synthesis of a novel RNA-targeting, red-emissive carbon dots (named as M-CDs) are reported by choosing neutral red and levofloxacin as precursors. The as-synthesized M-CDs is water-soluble with a high fluorescence quantum yield of 22.83% and can selectively bind to RNA resulting in an enhanced red fluorescence. More interestingly, such an RNA-targeting, red-emissive M-CDs can be fast internalized into cells within 5 s and thus used for real-time imaging the dynamic process of intracellular stress granules under oxidative stress, revealing some characteristics of granules that have not been identified by previously reported RNA and protein biomarkers. This research paves a new pathway for visualizing bulk RNA dynamics and studying phase-separation behaviors in living cells by rational design of the fluorescent carbon dots in terms of structure and functionality.

A smartphone-based fluorospectrophotometer and ratiometric fluorescence nanoprobe for on-site quantitation of pesticide residue

Cost-effective and user-friendly quantitation at points-of-need plays an important role in food safety inspection, environmental monitoring, and biomedical analysis. This study reports a stand-alone smartphone-based fluorospectrophotometer (the SBS) installed with a custom-designed application (the SBS-App) for on-site quantitation of pesticide using a ratiometric sensing scheme. The SBS can collect fluorescence emission spectra in the wavelength range of 380-760 nm within 5 s. A ratiometric fluorescence probe is facilely prepared by directly mixing the blue-emissive carbon nanodots (the Fe3+-specific fluorometric indicator) and red-emissive quantum dots (the internal standard) at a ratio of 11.6 (w/w). Based on the acetylcholinesterase/choline oxidase dual enzyme-mediated cascade catalytic reactions of Fe2+/Fe3+ transformation, a ratiometric fluorescence sensing scheme is developed. The practicability of the SBS is validated by on-site quantitation of chlorpyrifos in apple and cabbage with a comparable accuracy to the GC-MS method, offering a scalable solution to establish a cost-effective surveillance system for pesticide pollution.

Supramolecular Chemistry of Carbon-Based Dots Offers Widespread Opportunities

Carbon dots are an emerging class of nanomaterials that has recently attracted considerable attention for applications that span from biomedicine to energy. These photoluminescent carbon nanoparticles are defined by characteristic sizes of <10 nm, a carbon-based core and various functional groups at their surface. Although the surface groups are widely used to establish non-covalent bonds (through electrostatic interactions, coordinative bonds, and hydrogen bonds) with various other (bio)molecules and polymers, the carbonaceous core could also establish non-covalent bonds (ππ stacking or hydrophobic interactions) with π-extended or apolar compounds. The surface functional groups, in addition, can be modified by various post-synthetic chemical procedures to fine-tune the supramolecular interactions. Our contribution categorizes and analyzes the interactions that are commonly used to engineer carbon dots-based materials and discusses how they have allowed preparation of functional assemblies and architectures used for sensing, (bio)imaging, therapeutic applications, catalysis, and devices. Using non-covalent interactions as a bottom-up approach to prepare carbon dots-based assemblies and composites can exploit the unique features of supramolecular chemistry, which include adaptability, tunability, and stimuli-responsiveness due to the dynamic nature of the non-covalent interactions. It is expected that focusing on the various supramolecular possibilities will influence the future development of this class of nanomaterials.

Tailoring the Chemical Structure of Nitrogen-Doped Carbon Dots for Nano-Aminocatalysis in Aqueous Media

Amine-rich carbon dots (NCDs) have become promising nano-aminocatalytic platforms in organic synthesis. These nanomaterials can be effectively produced through straightforward bottom-up approaches using inexpensive nitrogen-containing molecular precursors as a starting material. However, to date, there is still a limited understanding of how the molecular features of these precursors affect the catalytic activity of the resulting nanoparticles. This study concerns the production of a new family of NCDs, which use l-arginine and different alkyl diamines as starting materials. The surface amines of all these NCDs were comprehensively characterized, thus allowing us to provide a correlation between the structural features of the nanoparticles and their catalytic performance with a selected amino-catalyzed organic transformation. Importantly, the most active nano-aminocatalysts, namely, NCDs-3, were then used as a basis for the formation of a wide variety of functionalized organic compounds in water under mild reaction conditions.

Enhanced sonodynamic therapy by carbon dots-shelled microbubbles with focused ultrasound

Sonodynamic therapy involving the non-invasive and local generation of lethal reactive oxygen species (ROS) via ultrasound (US) with sonosensitizers has been proposed as an emerging tumor therapy strategy. However, such therapy is usually associated with inertial cavitation and unnecessary damage to healthy tissue because current sonosensitizers have insufficient sensitivity to US. Here, we report the use of a new proposed sonosensitizer, carbon dots (C-dots), to assemble microbubbles with a gas core (C-dots MBs). As the C-dots were directly integrated into the MB shell, they could effectively absorb the energy of inertial cavitation and transfer it to ROS. Our results revealed the appearance of 1O2, •OH, and H2O2 after US irradiation of C-dots MBs. In in vitro experiments, treatment with C-dots MBs plus US induced lipid peroxidation, elevation of intracellular ROS, and apoptosis in 32.5%, 45.3%, and 50.1% of cells respectively. In an animal solid tumor model, treatment with C-dots MBs plus US resulted in a 3-fold and 2.5-fold increase in the proportion of ROS-damaged cells and apoptotic cells, respectively, compared to C-dots MBs alone. These results will pave the way for the design of novel multifunctional sonosensitizers for SDT tumor therapy.

The Importance of the Purification Step and the Characterization of the Products in the Synthesis of Carbon Nanodots

In the synthesis of carbon nanodots (CNDs), the critical step of the purification from the starting materials and unwanted side products is faced. In the exciting race toward new and interesting CNDs, this problem is often underestimated, leading to false properties and erroneous reports. In fact, on many occasions, the properties described for novel CNDs derive from impurities not completely eliminated during the purification process. Dialysis, for instance, is not always helpful, especially if the side products are not soluble in water. In this Perspective, the importance of the purification and characterization steps, in order to obtain solid reports and reliable procedures, is emphasized.

A critical review on the environmental applications of carbon dots

The discovery of zero-dimensional carbonaceous nanostructures called carbon dots (CDs) and their unique properties associated with fluorescence, quantum confinement and size effects have intrigued researchers. There has been a substantial increase in the amount of research conducted on the lines of synthesis, characterization, modification, and enhancement of properties by doping or design of composite materials, and a diversification of their applications in sensing, catalysis, optoelectronics, photovoltaics, and imaging, among many others. CDs fulfill the need for inexpensive, simple, and continuous environmental monitoring, detection, and remediation of various contaminants such as metals, dyes, pesticides, antibiotics, and other chemicals. The principles of green chemistry have also prompted researchers to rethink novel modes of nanoparticle synthesis by incorporating naturally available carbon precursors or developing micro reactor-based techniques. Photocatalysis using CDs has introduced the possibility of utilizing light to accelerate redox chemical transformations. This comprehensive review aims to provide the reader with a broader perspective of carbon dots by encapsulating the concepts of synthesis, characterization, applications in contaminant detection and photocatalysis, demerits and research gaps, and potential areas of improvement.

Enhanced chemodynamic and photoluminescence efficiencies of Fe-O4 coordinated carbon dots via the core-shell synergistic effect

In natural systems like photosynthetic organisms and photo-active enzymes, the spatial organization of chromophores is critical for efficient light harvesting and bio-catalysis. Inspired by nature, a novel modular nanoplatform with both biological imaging and therapeutic functions is constructed by taking advantage of the intrinsic core-shell structure of Fe-decorated carbon dots. Light-harvesting chromophores with deep-red photoluminescence are densely packed into the carbon core. Simultaneously, the atomically dispersed Fe³⁺ catalytic sites accounting for efficient conversion of H₂O₂ to ˙OH are discretely distributed on the shell. Precise control over their spatial distribution leads to the elegant integration and exciting interplay of the functional moieties. On the one hand, incorporating a catalysis shell enhances the emission of chromophores via synergistic shielding and rigidifying effects. On the other hand, visible light excitation of the chromophores significantly increases the catalytic activity and cytotoxicity against cancer cells, ascribed to the promotion of the charge transfer process. This nanoplatform exhibits excellent biocompatibility, bright red fluorescence, and light-regulated cytotoxicity for anti-cancer treatment, promising its applications in smart nanocatalytic medicines and efficient chemodynamic therapy.

Carbon quantum dots with pH-responsive orange-/red-light emission for fluorescence imaging of intracellular pH

N-doped carbon quantum dots (N-CDs) with polyaminobenzene hydrazine as precursor were prepared by solvothermal method for the monitoring of pH fluctuation in HeLa cells via fluorescence imaging. The N-CDs show two emission wavelengths at 582 and 640 nm under different pH with two excitation wavelengths. The fluorescence intensity at 640 nm (λ_ex = 520 nm) and the ratio of F₅₈₂/F₆₄₀ (λ_ex = 470 nm) linearly increase with pH in the range of 2.4 ~ 3.6 (R² = 992) and 5.6 ~ 7.6 (R² = 0.987), respectively. The sensor exhibits high sensitivity and reversibility and anti-interference capability, thus enabling sensing pH change in intracellular environment in real time, as demonstrated by successful monitoring of intracellular pH fluctuation during H₂O₂ stimulation in HeLa cells.

High reactive oxygen species produced from fluorescence carbon dots for anticancer and photodynamic therapies: A review

High-photoluminescence carbon dots (CDs) were synthesized from various sources and various methods using two approaches, namely bottom up and top down, with emission-dependent excitation wavelength. Electronic transition from the higher-occupied molecular orbital (HOMO) state to the lowest-unoccupied molecular orbital(LUMO) state, surface defect states, wider excitation spectrum, higher quantum yield, efficient energy transfer, and element doping affected the fluorescence properties of CDs. Using 102 references listed in this review, the authors studied the relationship between fluorescence mechanism and reactive oxygen species (ROS) produced for photodynamic therapy (PDT) and materials anticancer applications. We described how the radical atom or ROS work as anticancer therapy and PDT and described the chemical reaction of high-resolution fluorescence CDs. We summarized experimental techniques that are used for producing CDs and discussed their characteristics. Finally, conclusions and future prospects in this field are also discussed. The important characteristics of CD-based design for high ROS may usher in new prospects and challenges for high efficiency and stability of PDT and anticancer therapy. In conclusion, we have provided perspectives and challenges of the future development of CD s.

Amine-Rich Carbon Dots as Novel Nano-Aminocatalytic Platforms in Organic Synthesis

The development of novel and effective metal-free catalytic systems, which can drive value-added organic transformations in environmentally benign solvents (for instance, water), is highly desirable. Moreover, these new catalysts need to be harmless, easy-to-prepare, and potentially recyclable. In this context, amine-rich carbon dots (CDs) have recently emerged as promising nano-catalytic platforms. These nitrogen-doped nanoparticles, which show dimensions smaller than 10 nm, generally consist of carbon cores that are surrounded by shells containing numerous amino groups. In recent years, organic chemists have used these surface amines to guide the design of several synthetic methodologies under mild operative conditions. This Concept highlights the recent advances in the synthesis of amine-rich carbon dots and their applications in organic catalysis, including forward-looking opportunities within this research field.

Synthetic carbon nanomaterials for electrochemical energy conversion

Carbon nanomaterials have attracted widespread attention in electrochemical energy conversion due to their large surface area, excellent electrical/thermal conductivity and good chemical stability. However, the structure-activity relationship of carbon nanomaterials remains unclear. This review is thus on the synthesis methods of carbon nanomaterials including two-dimensional graphene, graphene nanoribbons, nanographene, heteroatom doped porous carbon and graphdiyne as electrocatalysts for the hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction in fuel cells, electrolyzers and CO₂ reduction. The correlation between the electronic/chemical properties and electrochemical performance of synthetic carbon nanostructures will be profoundly discussed. Additionally, the emerging challenges and some perspectives on the development of synthetic carbon nanomaterials for electrochemical energy conversion are discussed.