One-step hydrothermal synthesis of chiral carbon dots and their effects on mung bean plant growth

An assessment of nanotechnology-based interventions for cleaning up toxic heavy metal/metalloid-contaminated agroecosystems: Potentials and issues

Heavy metals (HMs) are among the most dangerous environmental variables for a variety of life forms, including crops. Accumulation of HMs in consumables and their subsequent transmission to the food web are serious concerns for scientific communities and policy makers. The function of essential plant cellular macromolecules is substantially hampered by HMs, which eventually have a detrimental effect on agricultural yield. Among these HMs, three were considered, i.e., arsenic, cadmium, and chromium, in this review, from agro-ecosystem perspective. Compared with conventional plant growth regulators, the use of nanoparticles (NPs) is a relatively recent, successful, and promising method among the many methods employed to address or alleviate the toxicity of HMs. The ability of NPs to reduce HM mobility in soil, reduce HM availability, enhance the ability of the apoplastic barrier to prevent HM translocation inside the plant, strengthen the plant's antioxidant system by significantly enhancing the activities of many enzymatic and nonenzymatic antioxidants, and increase the generation of specialized metabolites together support the effectiveness of NPs as stress relievers. In this review article, to assess the efficacy of various NP types in ameliorating HM toxicity in plants, we adopted a 'fusion approach', in which a machine learning-based analysis was used to systematically highlight current research trends based on which an extensive literature survey is planned. A holistic assessment of HMs and NMs was subsequently carried out to highlight the future course of action(s).

The characterization of plant derived-carbon dots and its responses on chlorophyll a fluorescence kinetics, radical accumulation in guard cells, cellular redox state and antioxidant system in chromium stressed-Lactuca sativa

Based on their chemical structure and catalytic features, carbon dots (CDs) demonstrate great advantages for agricultural systems. The improvements in growth, photosynthesis, nutrient assimilation and resistance are provided by CDs treatments under control or adverse conditions. However, there is no data on how CDs can enhance the tolerance against chromium toxicity on gas exchange, photosynthetic machinery and ROS-based membrane functionality. The present study was conducted to evaluate the impacts of the different concentrations of orange peel derived-carbon dots (50-100-200-500 mg L-1 CD) on growth, chlorophyll fluorescence, phenomenological fluxes between photosystems, photosynthetic performance, ROS accumulation and antioxidant system under chromium stress (Cr, 100 μM chromium (VI) oxide) in Lactuca sativa. CDs removed the Cr-reduced changes in growth (RGR), water content (RWC) and proline (Pro) content. Compared to stress, CD exposures caused an alleviation in carbon assimilation rate, stomatal conductance, transpiration rate, carboxylation efficiency, chlorophyll fluorescence (Fv/Fm) and potential photochemical efficiency (Fv/Fo). Cr toxicity disrupted the energy fluxes (ABS/RC, TRo/RC, ETo/RC and DIo/RC), quantum yields and, efficiency (ΨEo and φRo), dissipation of energy (DIo/RC) and performance index (PIABS and PItotal). An amelioration in these parameters was provided by CD addition to Cr-applied plants. Stressed plants had high activities of superoxide dismutase (SOD), peroxidase (POX) and ascorbate peroxidase (APX), which could not prevent the increase of H2O2 and lipid peroxidation (TBARS content). While all CDs induced SOD and catalase (CAT) in response to stress, POX and enzyme/non-enzymes related to ascorbate-glutathione (AsA-GSH) cycle (APX, monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR), the contents of AsA and, GSH) were activated by 50-100-200 mg L-1 CD. CDs were able to protect the AsA regeneration, GSH/GSSG and GSH redox status. The decreases in H2O2 content might be attributed to the increased activity of glutathione peroxidase (GPX). Therefore, all CD applications minimized the Cr stress-based disturbances (TBARS content) by controlling ROS accumulation, antioxidant system and photosynthetic machinery. In conclusion, CDs have the potential to be used as a biocompatible inducer in removing the adverse effects of Cr stress in lettuce plants.

Colloidal Chiral Carbon Dots: An Emerging System for Chiroptical Applications

Chiral CDots (c-CDots) not only inherit those merits from CDots but also exhibit chiral effects in optical, electric, and bio-properties. Therefore, c-CDots have received significant interest from a wide range of research communities including chemistry, physics, biology, and device engineers. They have already made decent progress in terms of synthesis, together with the exploration of their optical properties and applications. In this review, the chiroptical properties and chirality origin in extinction circular dichroism (ECD) and circularly polarized luminescence (CPL) of c-CDots is briefly discussed. Then, the synthetic strategies of c-CDots is summarized, including one-pot synthesis, post-functionalization of CDots with chiral ligands, and assembly of CDots into chiral architectures with soft chiral templates. Afterward, the chiral effects on the applications of c-CDots are elaborated. Research domains such as drug delivery, bio- or chemical sensing, regulation of enzyme-like catalysis, and others are covered. Finally, the perspective on the challenges associated with the synthetic strategies, understanding the origin of chirality, and potential applications is provided. This review not only discusses the latest developments of c-CDots but also helps toward a better understanding of the structure-property relationship along with their respective applications.

The environmental impact of mask-derived microplastics on soil ecosystems

During the COVID-19 pandemic, a significant increased number of masks were used and improperly disposed of. For example, the global monthly consumption of approximately 129 billion masks. Masks, composed of fibrous materials, can readily release microplastics, which may threaten various soil ecosystem components such as plants, animals, microbes, and soil properties. However, the specific effects of mask-derived microplastics on these components remain largely unexplored. Here, we investigated the effects of mask-derived microplastics (grouped by different concentrations: 0, 0.25, 0.5, and 1 % w/w) on soil physicochemical properties, microbial communities, growth performance of lettuce (Lactuca sativa L. var. ramosa Hort.) and earthworm (Eisenia fetida) under laboratory conditions for 80 days. Our findings suggest that mask-derived microplastics reduced soil bulk density while increasing the mean weight diameter of soil aggregates and modifying nutrient levels, including organic matter, potassium, nitrogen, and phosphorus. An increase in the abundance of denitrification bacteria (Rhodanobacteraceae) was also observed. Mask-derived microplastics were found to reduce lettuce germination, and a hormesis effect of low-concentration stimulation and high-concentration inhibition was observed on biomass, chlorophyll, and root activity. While the mortality of earthworms was not significantly affected by the mask-derived microplastics, but their growth was inhibited. Collectively, our results indicate that mask-derived microplastics can substantially impact soil properties, plant growth, and earthworm health, with potential implications for soil ecosystem functionality.

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.

Fabrication of a bifunctional fluorescent chiral composite based on magnetic Fe3O4/chiral carbon dots@hierarchical porous metal-organic framework

Considering the selective pharmacological activity and ecotoxicity of chiral drugs, the development of chiral materials with the dual functions of enantiomeric recognition and adsorption is of great significance. Herein, a novel bifunctional chiral composite (Fe3O4/CCDs@HP-ZIF-8) which does not contain expensive and rare fluorescent chiral ligands or metal ions, was constructed for the first time by encapsulating chiral carbon dots (CCDs) and magnetic Fe3O4 nanoparticles into hierarchical porous metal-organic frameworks (HP-MOFs). Fe3O4/CCDs@HP-ZIF-8, which integrates fluorescent chiral property, magnetism, and hierarchical porosity, shows enormous potential in enantiomeric recognition and adsorption. Fluorescence detection results demonstrate that Fe3O4/CCDs@HP-ZIF-8 presents different fluorescence quenching for naproxen enantiomers. The limits of detection are determined to be 0.05 μM for S-naproxen (S-Nap) and 0.30 μM for R-naproxen (R-Nap), respectively. Furthermore, the isothermal, kinetic, and thermodynamic adsorption behaviors of Fe3O4/CCDs@HP-ZIF-8 to naproxen enantiomers were systematically studied. Due to its hierarchical porosity, the composite exhibits higher adsorption capacity to naproxen enantiomers compared to the non-hierarchical porous composite. Studies of enantiomeric recognition and adsorption mechanisms affirm that the synergistic effect of multiple mechanisms exists between Fe3O4/CCDs@HP-ZIF-8 and naproxen enantiomers. Finally, the satisfactory recoveries and relative standard deviations in the actual sample assays demonstrate the practicality of Fe3O4/CCDs@HP-ZIF-8 for S-Nap detection. This non-destructive functionalization method creates an innovative pathway for developing advanced multifunctional chiral materials, holding great promise for enantiomeric recognition and adsorption.

Preparation of Chiral Carbon Quantum Dots and its Application

Chiral carbon quantum dots (cCQDs) , as a new type of carbon nano-functional material with tunable emission wavelength, superior photostability, low toxicity, biocompatibility and chirality, are playing an increasingly important role in the fields of chemistry, biology and medicine. This paper reviews the preparation methods (one-step and two-step), optical properties (UV, fluorescence, chirality) and applications in chiral catalysis, chiral recognition, targeted imaging as well as other fields, while lists some of the issues and challenges in the research of chiral carbon quantum dots. Finally, due to its good fluorescence and other properties, it is expected that chiral carbon quantum dots will have broad commercial prospects in future applications.

Electrostatics Control Nanoparticle Interactions with Model and Native Cell Walls of Plants and Algae

A lack of mechanistic understanding of nanomaterial interactions with plants and algae cell walls limits the advancement of nanotechnology-based tools for sustainable agriculture. We systematically investigated the influence of nanoparticle charge on the interactions with model cell wall surfaces built with cellulose or pectin and performed a comparative analysis with native cell walls of Arabidopsis plants and green algae (Choleochaete). The high affinity of positively charged carbon dots (CDs) (46.0 ± 3.3 mV, 4.3 ± 1.5 nm) to both model and native cell walls was dominated by the strong ionic bonding between the surface amine groups of CDs and the carboxyl groups of pectin. In contrast, these CDs formed weaker hydrogen bonding with the hydroxyl groups of cellulose model surfaces. The CDs of similar size with negative (-46.2 ± 1.1 mV, 6.6 ± 3.8 nm) or neutral (-8.6 ± 1.3 mV, 4.3 ± 1.9 nm) ζ-potentials exhibited negligible interactions with cell walls. Real-time monitoring of CD interactions with model pectin cell walls indicated higher absorption efficiency (3.4 ± 1.3 10-9) and acoustic mass density (313.3 ± 63.3 ng cm-2) for the positively charged CDs than negative and neutral counterparts (p < 0.001 and p < 0.01, respectively). The surface charge density of the positively charged CDs significantly enhanced these electrostatic interactions with cell walls, pointing to approaches to control nanoparticle binding to plant biosurfaces. Ca2+-induced cross-linking of pectin affected the initial absorption efficiency of the positively charged CD on cell wall surfaces (∼3.75 times lower) but not the accumulation of the nanoparticles on cell wall surfaces. This study developed model biosurfaces for elucidating fundamental interactions of nanomaterials with cell walls, a main barrier for nanomaterial translocation in plants and algae in the environment, and for the advancement of nanoenabled agriculture with a reduced environmental impact.

Chiral Carbon Dots and Chiral Carbon Dots with Circularly Polarized Luminescence: Synthesis, Mechanistic Investigation and Applications

Chiral carbon dots (CCDs) can be widely used in various fields such as chiral recognition, chiral catalysis and biomedicine because of their unique optical properties, low toxicity and good biocompatibility. In addition, CCDs with circularly polarized luminescence (CPL) can be synthesized, thus broadening the prospects of CCDs applications. Since the research on CCDs is still in its infancy, this paper reviews the chiral origin, formation mechanism, chiral evolution, synthesis and emerging applications of CCDs, with a special focus on CCDs with CPL activity. It is hoped that it will provide some reference to solve the current problems faced by CCDs. Finally, the opportunities and challenges of the current research on CCDs are described, and their future development trends have also been prospected.

Recent Progress on Chiral Carbon Dots: Synthetic Strategies and Biomedical Applications

The discovery of chiral carbon dots (Ch-CDs) has opened up an exciting new research direction in the field of carbon dots. It not only retains the chirality of the precursor and exhibits highly symmetric chiral optical properties but also has properties such as chemical stability, antibacterial and antitumor properties, and good biocompatibility of carbon dots. Based on these advantages, the application of Ch-CDs in the biomedical field has attracted significant interest among researchers. However, a comprehensive review of the selection of precursors for Ch-CDs, preparation methods, and applications in biomedical fields is still lacking. Here, we summarize their precursor selection and preparation methods based on recent reports on Ch-CDs and provide the first comprehensive review for specific applications in biomedical engineering, such as biosensing, bioimaging, drug carriers, antibacterial and antibiofilm, and enzyme activity modulation. Finally, we discuss application prospects and challenges that need to be overcome. We hope this review will provide valuable guidance for researchers to prepare novel Ch-CDs and facilitate their application in biomedical engineering.

Green carbon dots derived from Atractylodes macrocephala: A potential nanodrug for treating alcoholic gastric ulcer

Alcoholic gastric ulcer is a common acute gastric injury disease. The drugs currently used in clinical practice not only cannot fundamentally treat gastric injury, but also have serious side effects. There is an urgent demand for the discovery of a mild drug to treat alcoholic gastric ulcers. Herein, the green carbon dots derived from charred Atractylodes macrocephala (CAM-CDs) were acquired and have been proven to be safe and effective in alleviating alcoholic gastric ulcers at an inhibition rate up to 60%. CAM-CDs can markedly attenuate the gastric mucosa damage such as mucosal defect, bleeding and inflammatory cell infiltration by histopathological examination. Serum and tissue inflammatory cytokine measurements, as well as immunohistochemistry results, indicate that its mechanism of gastric mucosal protection may involve the reduction of IL-1β and TNF-α by regulating inflammatory signaling pathway of the NF-κB/NLRP3 axis, as well as elevation of IL-10 levels. CAM-CDs also can reduce oxidative stress markers (MDA), increase PGE2 and mucin secretion (MUC5AC), and it simultaneously exerts slight inhibition of hydrogen potassium ATPase and pepsin activity to protect gastric mucosa, as well as increases the microbial diversity and regulates species composition of gut microbiota in rats with gastric ulcer. Our work provides a new perspective on utilizing carbon-based nanomaterials in the development of new mild drugs.

Physiological Functions of Carbon Dots and Their Applications in Agriculture: A Review

Carbon dots are carbon-based nanoparticles, which have the characteristics of a simple preparation process, photoluminescence, biocompatibility, an adjustable surface function, water solubility, and low-level toxicity. They are widely used in biological applications, such as imaging, biosensing, photocatalysis, and molecular transfer. They have also aroused great interest among researchers in agriculture, and there has been significant progress in improving crop growth and production. This review presents the physiological functions of carbon dots for crop growth and development, photosynthesis, water and nutrient absorption, and abiotic stress resistance and their applications in improving the ecological environment and agriculture as biosensors, and future application prospects and research directions of carbon dots in agriculture.

Recent developments, applications and challenges for carbon quantum dots as a photosynthesis enhancer in agriculture

Since the world's population is expanding, mankind may be faced with a huge dilemma in the future, which is food scarcity. The situation can be mitigated by employing sustainable cutting-edge agricultural methods to maintain the food supply chain. In recent years, carbon quantum dots (CQD), a member of the well-known carbon-based nanomaterials family, have given rise to a new generation of technologies that have the potential to revolutionise horticulture and agriculture research. CQD has drawn much attention from the research community in agriculture owing to their remarkable properties such as good photoluminescence behaviour, high biocompatibility, photo-induced electron transfer, low cost, and low toxicity. These unique properties have led CQD to become a promising material to increase plant growth and yield in the agriculture field. This review paper highlights the recent advances of CQD application in plant growth and photosynthesis rate at different concentrations, with a focus on CQD uptake and translocation, as well as electron transfer mechanism. The toxicity and biocompatibility studies of CQD, as well as industrial scale applications of CQD for agriculture are discussed. Finally, the current challenges of the present and future perspectives in this agriculture research are presented.

Circular Polarized Light Emission in Chiral Inorganic Nanomaterials

Chiral inorganic nanostructures strongly interact with photons changing their polarization state. The resulting circularly polarized light emission (CPLE) has cross-disciplinary importance for a variety of chemical/biological processes and is essential for development of chiral photonics. However, the polarization effects are often complex and their interpretation is dependent on the several structural parameters of the chiral nanostructure. CPLE in nanostructured media has multiple origins and several optical effects are typically convoluted into a single output. Analyzing CPLE data obtained for nanoclusters, nanoparticles, nanoassemblies, and nanocomposites from metals, chalcogenides, perovskite, and other nanostructures, it is shown here that there are several distinct groups of nanomaterials for which CPLE is dominated either by circularly polarized luminescence (CPL) or circularly polarized scattering (CPS); there are also many nanomaterials for which they are comparable. The following points are also demonstrated: 1) CPL and CPS contributions involve light-matter interactions at different structural levels; 2) contribution from CPS is especially strong for nanostructured microparticles, nanoassemblies, and composites; and 3) engineering of materials with strongly polarized light emission requires synergistic implementation of CPL and CPS effects. These findings are expected to guide development of CPLE materials in a variety of technological fields, including 3D displays, information storage, biosensors, optical spintronics, and biological probes.

Nitrogen-doped carbon dots enhanced seedling growth and salt tolerance with distinct requirements of excitation light

Numerous nanomaterials with optical properties have demonstrated excellent capacities to enhance plant growth and stress tolerance. However, the corresponding mechanisms have only been partially characterized, especially the excitation-light dependencies of different actions. Here, nitrogen-doped carbon dots (N-CDs) were developed to explore the excitation-light dependence in N-CD-induced growth enhancement and salt tolerance. Compared to the control, N-CDs induced significant enhancements in Arabidopsis thaliana growth under excitation light, including fresh/dry weight of shoot (21.07% and 16.87%), chlorophyll content (9.17%), soluble sugar content (23.41%), leaf area (28.68%), total root length (34.07%) and root tip number (46.69%). In the absence of excitation light, N-CD-treated seedlings exhibited little differences in these parameters, except the enhancements in root length (24.51%) and root tip number (10.24%). On the other hand, N-CD-treatment could improve seedling salt tolerance with or without excitation light. Under salt stress (150 mM NaCl), in the presence of excitation light, the N-CDs treatment significantly increased shoot/root fresh weight and chlorophyll content by 43.29%, 50.66% and 22.59%, and reduced malondialdehyde (MDA) content and relative conductivity by 17.59% and 32.58% compared to the control group. In the absence of excitation light, significant enhancements in shoot/root fresh weight (34.22%, 32.60%) and chlorophyll content (10.45%), and obvious decreases in MDA content (28.84%) and relative conductivity (16.13%) were also found. These results indicated that N-CDs only induced growth enhancement under excitation light, but they improved salt tolerance with and without excitation light, suggesting that the two effects occurred via distinct signaling pathways. This study revealed the excitation-light dependencies of nanomaterial-involved agriculture applications, providing insight into designing more efficient nanomaterials in the future.

Preparation of nitrogen-doped carbon dots and their enhancement on lettuce yield and quality

Nanotechnology is an effective way to stimulate the yield potential of crops. Various nano-fertilizers and nano-carriers are gradually being developed to bring about a technological revolution in the agricultural industry. As a biocompatible water-soluble nanomaterial, carbon dots (CDs) have attracted the attention of researchers for applications in agriculture. In this study, we prepared nitrogen-doped CDs (N-CDs) as a type of water-soluble carbon nanofertilizer by a one-pot hydrothermal method, and investigated its effects on lettuce biomass and quality. 100 and 200 mg L-1 of N-CDs substantially promoted lettuce biomass accumulation (41.70%), elevated lettuce nutrient content, as well as promoted the accumulation of major nutrients. Moreover, 100 mg L-1 N-CDs increased the chlorophyll a content by 12.68%, significantly increased the electron transport rate (ETR) by 38.61%, significantly increased the light energy conversion efficiency (Y(II)) by 31.24% and increased the Rubisco activity by 60.61%, which are important reasons for its increase in actual photosynthesis rate. N-CDs also have a positive effect on plant nitrogen metabolism by promoting the activity of glutamine synthetase. The significant benefits of N-CDs on lettuce make them have great potential for agricultural yield increase and quality improvement.

Effects of plastic-derived carbon dots on germination and growth of pea (Pisum sativum) via seed nano-priming

Seed nano-priming is a promising technology employed in the agronomic field to promote seed germination and plant growth. However, the effects of carbon dots (CDs) on plant development via seed nano-priming remain unclear. In the present study, CDs synthesized from non-biodegradable plastic wastes were adopted as a nano-priming agent for pea (Pisum sativum) seed treatment. The results demonstrated positive effects of seed priming at all CD concentrations (0.25-2 mg/mL), including accelerated seed germination rate, increased shoot and root elongation, biomass accumulation, and root moisture level compared to the control groups. Surface erosion of seed coat was observed after CD priming, which effectively promoted seed imbibition capability. CD penetration, internalization, and translocation were confirmed using transmission electron microscopy. Furthermore, the CD-plant interaction significantly enhanced seed antioxidant enzyme activity, as well as augmented root vigor, chlorophyll content, and carbohydrate content. These findings exhibit great potential of waste-derived CDs as nano-priming agents for seed germination and seedling development in a cost-effective and sustainable manner.

Cysteine-Derived Chiral Carbon Quantum Dots: A Fibrinolytic Activity Regulator for Plasmin to Target the Human Islet Amyloid Polypeptide for Type 2 Diabetes Mellitus

The fibrillization and deposition of the human islet amyloid polypeptide (hIAPP) are the pathological hallmark of type 2 diabetes mellitus (T2DM), and these insoluble fibrotic depositions of hIAPP are considered to strongly affect insulin secretion by inducing toxicity toward pancreatic islet β-cells. The current strategy of preventing amyloid aggregation by nanoparticle-assisted inhibitors can only disassemble fibrotic amyloids into more toxic oligomers and/or protofibrils. Herein, for the first time, we propose a type of cysteine-derived chiral carbon quantum dot (CQD) that targets plasmin, a core natural fibrinolytic protease in humans. These CQDs can serve as fibrinolytic activity regulators for plasmin to cleave hIAPP into nontoxic polypeptides or into even smaller amino acid fragments, thus alleviating hIAPP's fibrotic amyloid-induced cytotoxicity. Our experiments indicate that chiral CQDs have opposing effects on plasmin activity. The l-CQDs promote the cleavage of hIAPP by enhancing plasmin activity at a promotion ratio of 23.2%, thus protecting β-cells from amyloid-induced toxicity. In contrast, the resultant d-CQDs significantly inhibit proteolysis, decreasing plasmin activity by 31.5% under the same reaction conditions. Second harmonic generation (SHG) microscopic imaging is initially used to dynamically characterize hIAPP before and after proteolysis. The l-CQD promotion of plasmin activity thus provides a promising avenue for the hIAPP-targeted treatment of T2DM to treat low fibrinolytic activity, while the d-CQDs, as inhibitors of plasmin activity, may improve patient survival for hyperfibrinolytic conditions, such as those existing during surgeries and traumas.

Fabrication of Carbon-Based Quantum Dots via a "Bottom-Up" Approach: Topology, Chirality, and Free Radical Processes in "Building Blocks"

The discovery of carbon-based quantum dots (CQDs) has allowed opportunities for fluorescence bioimaging, tumor diagnosis and treatment, and photo-/electro-catalysis. Nevertheless, in the existing reviews related to the "bottom-up" approaches, attention is mainly paid to the applications of CQDs but not the formation mechanism of CQDs, which mainly derived from the high complexities during the synthesis of CQDs. Among the various synthetic methods, using small molecules as "building blocks", the development of a "bottom-up" approach has promoted the structural design, modulation of the photoluminescence properties, and control of the interfacial properties of CQDs. On the other hand, many works have demonstrated the "building blocks"-dependent properties of CQDs. In this review, from one of the most important variables, the relationships among intrinsic properties of "building blocks" and photoluminescence properties of CQDs are summarized. The topology, chirality, and free radical process are selected as descriptors for the intrinsic properties of "building blocks". This review focuses on the induction and summary of recent research results from the "bottom-up" process. Moreover, several empirical rules pertaining thereto are also proposed.

Chiral Carbon Dots: Synthesis and Applications in Circularly Polarized Luminescence, Biosensing and Biology

Chiral carbon dots (CDs) are a novel luminescent zero-dimensional carbon-based nanomaterial with chirality. They not only have the advantages of good biocompatibility, multi-color-emission, easy functionalization, but also exhibits highly symmetrical chiral optical characteristics, which broadens their applicability to enantioselectivity of some chiral amino acids like cysteine and lysine, asymmetric catalysis as well as biomedicine in gene expression and antibiosis. In addition, the exploration of the excited state chirality of CDs has developed its excellent circularly polarized luminescence (CPL) properties, opening up a new application scenario like recognition of chiral light sources and anti-counterfeit printing with information encryption. This review mainly focuses on the mature synthesis approaches of chiral CDs, including chiral ligand method and supramolecular self-assembly method, then we consider emerging applications of chiral CDs in CPL, biosensing and biological effect. Finally, we concluded with a perspective on the potential challenges and future opportunities of such fascinating chiral CDs.

Machine Learning-Assisted Carbon Dot Synthesis: Prediction of Emission Color and Wavelength

Carbon dots (CDs) have attracted great attention in a range of applications due to their bright photoluminescence, high photostability, and good biocompatibility. However, it is challenging to design CDs with specific emission properties because the syntheses involve many parameters, and it is not clear how each parameter influences the CD properties. To help bridge this gap, machine learning, specifically an artificial neural network, is employed in this work to characterize the impact of synthesis parameters on and make predictions for the emission color and wavelength for CDs. The machine reveals that the choice of reaction method, purification method, and solvent relate more closely to CD emission characteristics than the reaction temperature or time, which are frequently tuned in experiments. After considering multiple models, the best performing machine learning classification model achieved an accuracy of 94% in predicting relative to actual color. In addition, hybrid (two-stage) models incorporating both color classification and an artificial neural network k-ensemble model for wavelength prediction through regression performed significantly better than either a standard artificial neural network or a single-stage artificial neural network k-ensemble regression model. The accuracy of the model predictions was evaluated against CD emission wavelengths measured from experiments, and the minimum mean average error is 25.8 nm. Overall, the models developed in this work can effectively predict the photoluminescence emission of CDs and help design CDs with targeted optical properties.

Hydrothermal synthesis of chiral carbon dots

Nanocolloids that are cumulatively referred to as nanocarbons, attracted significant attention during the last decade because of facile synthesis methods, water solubility, tunable photoluminescence, easy surface modification, and high biocompatibility. Among the latest development in this reserach area are chiral nanocarbons exemplified by chiral carbon dots (CDots). They are expected to have applications in sensing, catalysis, imaging, and nanomedicine. However, the current methods of CDots synthesis show often contradictory chemical/optical properties and structural information that required a systematic study with careful structural evaluation. Here, we investigate and optimize chiroptical activity and photoluminescence of L- and D-CDots obtained by hydrothermal carbonization of L- and D-cysteine, respectively. Nuclear magnetic resonance spectroscopy demonstrates that they are formed via gradual dehydrogenation and condensation reactions of the starting amino acid leading to particles with a wide spectrum of functional groups including aromatic cycles. We found that the chiroptical activity of CDots has an inverse correlation with the synthesis duration and temperature, whereas the photoluminescence intensity has a direct one, which is associated with degree of carbonization. Also, our studies show that the hydrothermal synthesis of cysteine in the presence of boric acid leads to the formation of CDots rather than boron nitride nanoparticles as was previously proposed in several reports. These results can be used to design chiral carbon-based nanoparticles with optimal chemical, chiroptical, and photoluminescent properties.

Improving Plant Photosynthesis through Light-Harvesting Upconversion Nanoparticles

Nanotechnology is considered as an emerging effective means to augment plant photosynthesis. However, there is still a lot of work to be done in this field. Here, we applied the upconversion nanoparticles (UCNPs) on lettuce leaves and found that the UCNPs were able to transport into the lettuce body and colocalize with the chloroplasts. It was proved that UCNPs could harvest the near-infrared light of sunlight and increase the electron transfer rate in the photosynthesis process, thus increasing the photosynthesis rate. The gene expression analysis showed that more than 90% of gene expression in photosynthesis was upregulated. After spraying the UCNP solution on the leaves of lettuce and placing the lettuce under sunlight for 1 week, the wet/dry weight of the leaves increased by 53.33% and 45.71%, respectively. This nanoengineering of light-harvesting UCNPs may have great potential for applications in agriculture.

Sustainable agronomic response of carbon quantum dots on Allium sativum: Translocation, physiological responses and alternations in chromosomal aberrations

The revolutionary growth in the usage of carbon quantum dots (CQDs) in different areas have ultimately directed their discharge in the environment and further augmented the exposure of agricultural crops to these released particles. Therefore, the aim of current study is to evaluate the uptake, translocation and phytotoxicity of blue emissive CQDs on Allium sativum plant. The genotoxicity and cytotoxicity assessment of CQDs towards Allium sativum roots was estimated as function of three different concentrations. Considering the role of CQDs in promoting seed germination at 50 ppm concentration, a greenhouse experiment was performed to evaluate their effect on plant growth. Systematic investigations have shown the translocation of CQDs and their physiological response in terms of increased shoot length wherein P-CQDs exhibited more accumulation into Allium sativum parts. Our investigations unfold the opportunity to utilize Aegle marmelos fruit derived CQDs as a growth regulator in variety of other food plants.

Potential of chitosan/carbon nanoparticles and chitosan/lignocellulose nanofiber composite as growth media for peatland paddy seeds

Indonesia has committed to restoring degraded peatlands by revegetating them with paddy plants using paludiculture systems. Nanofertilizers derived from chitosan and oil palm biomass can be used to enhance paddy growth. This study analyzed the potential growth media of chitosan nanocomposite films for paddy seeds grown in tropical peatland. Chitosan nanocomposites were synthesized by reinforcing chitosan with activated carbon nanoparticles (ACNPs), nonactivated carbon nanoparticles (n-ACNPs), and lignocellulose nanofibers (LCNFs). All carbon nanoparticles were reversibly aggregated, whereas LCNFs did not have a tendency to aggregate but were entangled. The highest specific surface area and pore volume are on EFB ACNPs, followed by OPT LCNFs and EFB n-ACNPs. Both nanocomposites' tensile strength and elastic modulus value were reduced with an average of 45.77% and 34.00%, respectively, because of the lack of nano- and micro-aggregates formation, good dispersion, and incompatibility. In a germination test, chitosan nanocomposites provided the best growth patterns for the Dendang paddy variety, whereas, in a greenhouse test, the nanocomposites had the best growth patterns for the Indragiri paddy variety. Chitosan/empty fruit bunch ACNP nanocomposites grown in a germinator had the highest growth normality (100.00%), highest maximum growth potential (100.00%), and highest height average (11.27 cm). In the greenhouse test, chitosan/oil palm trunk n-ACNPs achieved the highest growth natality (16.44%) and growth rate (65.74%). All chitosan nanocomposites had a synergetic biofertilizing effect on fungi and mycorrhiza. Chitosan nanocomposites can be used as a growth regulator for peatland paddy varieties and can accelerate peatland restoration in tropical areas.

Impact of Graphene Quantum Dot Edge Morphologies on Their Optical Properties

The optoelectronic properties of functionalized graphene quantum dots (GQDs) have been explored by simulating electronic structure of three different shapes of GQDs containing exclusively zigzag or armchair edges in both pristine and functionalized forms. Absorption spectra and transition densities for the low-lying excited states are evaluated by using time-dependent density functional theory and compared for different functionalization species. The functionalization position dictates the optical properties of square GQDs, where isomers with CH₂ in the intermediate positions (excluding corner and center positions) have higher electronic transition energies and exciton delocalization than other isomers. Rhombic GQDs with all armchair edges exhibit high steric flexibility, and their complete passivation results in the largest structural deformation from planarity and strongest red-shifts. A steady red-shift in the absorption energy is observed following the order F, CH₃, Cl, and Br substitutions. This suggests that the steric effects due to large van der Waals radii overcome electronegative effects.

Design, Synthesis, and Application of Carbon Dots With Synergistic Antibacterial Activity

The diversity of bacteria and their ability to acquire drug resistance lead to many challenges in traditional antibacterial methods. Photothermal therapies that convert light energy into localized physical heat to kill target microorganisms do not induce resistance and provide an alternative for antibacterial treatment. However, many photothermal materials cannot specifically target bacteria, which can lead to thermal damage to normal tissues, thus seriously affecting their biological applications. Here, we designed and synthesized bacteria-affinitive photothermal carbon dots (BAPTCDs) targeting MurD ligase that catalyzes the synthesis of peptidoglycan (PG) in bacteria. BAPTCDs presented specific recognition ability and excellent photothermal properties. BAPTCDs can bind to bacteria very tightly due to their chiral structure and inhibit enzyme activity by competing with D-glutamic acid to bind to MurD ligases, thus inhibiting the synthesis of bacterial walls. It also improves the accuracy of bacteria treatment by laser irradiation. Through the synergy of biochemical and physical effects, the material offers outstanding antibacterial effects and potentially contributes to tackling the spread of antibiotic resistance and facilitation of antibiotic stewardship.

Colorimetric and fluorescent probes for the rapid detection of profenofos in farmland system

Colorimetric and fluorescent sensors were developed for the detection of profenofos. The colorimetric assay relied on the aggregation of cysteine modified gold nanoparticles (Au-cys) composite caused by the hydrogen bond and Au-S bond between profenofos and Au-cys. The further addition of S, N-doped carbon quantum dots (CDs) (fluorescence quantum yield up to 98%) into the Au-cys system depended on the change of fluorescence intensity of Au-cys-CDs owing to the inner filter effect between Au-cys and CDs. Under the optimal conditions, the sensor exhibits good linearity within 0.2-1.2 mg L^-1 and 20-320 μg L^-1, and limit of detection of 21.7 μg L^-1 and 5.5 μg L^-1 in colorimetry and fluorescence mode, respectively. The developed sensor did not only possess favorable selectivity and sensitivity, but also feasibility of usage in the actual detection of profenofos in farmland system samples.

Carbon Dots Boost dsRNA Delivery in Plants and Increase Local and Systemic siRNA Production

In this work, we obtained carbon dots from glucose or saccharose as the nucleation source and passivated them with branched polyethylenimines for developing dsRNA nanocomposites. The CDs were fully characterized using hydrodynamic analyses, transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The ζ potential determined that the CDs had positive charges, good electrophoretic mobility and conductivity, and were suitable for obtaining dsRNA nanocomposites. DsRNA naked or coated with the CDs were delivered to leaves of cucumber plants by spraying. Quantitation of the dsRNA that entered the leaves showed that when coated with the CDs, 50-fold more dsRNA was detected than when naked dsRNA. Moreover, specific siRNAs derived from the sprayed dsRNAs were 13 times more abundant when the dsRNA was coated with the CDs. Systemic dsRNAs were determined in distal leaves and showed a dramatic increase in concentration when delivered as a nanocomposite. Similarly, systemic siRNAs were significantly more abundant in distal leaves when spraying with the CD-dsRNA nanocomposite. Furthermore, FITC-labeled dsRNA was shown to accumulate in the apoplast and increase its entry into the plant when coated with CDs. These results indicate that CDs obtained by hydrothermal synthesis are suitable for dsRNA foliar delivery in RNAi plant applications.

Mandelic acid appended chiral gels as efficient templates for multicolour circularly polarized luminescence

Mandelic acid is a medicinally important chiral molecule that is widely used as a vital component in antibiotics, antiseptics and cosmetics. While the medicinal properties of mandelic acid are well known, its aggregation and gelation characteristics, which are crucial to finding applications as cosmetics and ointments, are least explored. We have designed and synthesized a pair of mandelic acid derivatives and investigated their aggregation properties in binary solvent mixtures. The compounds undergo self-assembly through various noncovalent interactions, leading to the formation of robust chiral gels. Strong birefringence could be visualised from the individual structures constituting the gel. The large rod-like chiral structures are utilized as efficient templates for the assembly of ultra-small luminescent achiral carbon nanodots. The transfer of optical activity from the chiral host matrix to the fluorescent guest nanoparticles resulted in the generation of circularly polarized luminescence signals from the hybrid nanocomposites. The use of blue, green and red-emitting nanodots led to the fabrication of multicolour chiral light-emitting materials capable of covering the entire visible range. Considering the numerous medicinal benefits offered by mandelic acid and carbon nanodots, the materials constituting the nanocomposites, the distinct dimensions presented in the current work open new avenues for chiral light emitting materials to be used in biomedical research.

Chiral carbon dots: synthesis, optical properties, and emerging applications

Carbon dots are luminescent carbonaceous nanoparticles that can be endowed with chiral properties, making them particularly interesting for biomedical applications due to their low cytotoxicity and facile synthesis. In recent years, synthetic efforts leading to chiral carbon dots with other attractive optical properties such as two-photon absorption and circularly polarized light emission have flourished. We start this review by introducing examples of molecular chirality and its origins and providing a summary of chiroptical spectroscopy used for its characterization. Then approaches used to induce chirality in nanomaterials are reviewed. In the main part of this review we focus on chiral carbon dots, introducing their fabrication techniques such as bottom-up and top-down chemical syntheses, their morphology, and optical/chiroptical properties. We then consider emerging applications of chiral carbon dots in sensing, bioimaging, and catalysis, and conclude this review with a summary and future challenges.

Alleviation role of functional carbon nanodots for tomato growth and soil environment under drought stress

The biotoxicity and environmental applications of carbon nanomaterials have always been the focus of research. In this research, functional carbon nanodots (FCNs) show high promotion effects on regulating the growth, development and yield of tomato under drought stress, due to their up-regulation effects on the physiological processes of plants including photosynthesis, antioxidant system, osmotic adjustment, as well as soil amelioration in physicochemical properties and microbial environment during vegetative and reproductive growth stage. The reduction of tissue water content and water use efficiency are moderated by FCNs through improving root vigor and osmolytes (soluble sugar and proline) level, which contributes to maintain the enzyme function, photosynthesis and nutrient uptake in plant. FCNs regulate the enzymatic and non-enzymatic antioxidant system to scavenge reactive oxygen species (ROS) and inhibit the lipid peroxidation, thus protect the membrane structure and function of plant cells under stress. FCNs up-regulate soil microbial communities under drought stress by regulating the soil pH, enzyme activity, organic carbon and organic matters contents. Our results prove that FCNs are biological friendly to plant growth and soil environment under drought stress, thus exhibit potential as emendator to promote plant tolerance and improve agricultural productivity in water-deficient areas.

Multi-omics analyses revealed key factors involved in fluorescent carbon-dots-regulated secondary metabolism in Tetrastigma hemsleyanum

BACKGROUND

Luminescent nanomaterials (LNMs), especially newly-exploited fluorescent carbon-dots (CDs), have demonstrated promising candidates for sunlight harvesting and enhanced photosynthesis efficiency of crops. However, most of the studies focus on the design and synthesis of LNMs and primary metabolism in biomass acceleration, secondary metabolism that closely associated with the quality ingredients of plants is rarely mentioned.

RESULTS

UV-absorptive and water-soluble NIR-CDs were harvested via a facile microwave-assisted carbonization method. The effect and regulatory mechanism of NIR-CDs on the secondary metabolism and bioactive ingredients accumulation in Tetrastigma hemsleyanum were explored. A total of 191 differential secondary metabolites and 6874 differentially expressed genes were identified when the NIR-CDs were adopted for enhancing growth of T. hemsleyanum. The phenolic acids were generally improved, but the flavonoids were more likely to decrease. The pivotal differentially expressed genes were involved in biosynthesis of secondary metabolites, flavonoid biosynthesis, porphyrin and chlorophyll metabolism, etc. The gene-metabolite association was constructed and 44 hub genes highly related to quality ingredients accumulation and growth were identified, among which and the top 5 genes of the PPI network might be the key regulators.

CONCLUSION

This research provided key regulatory genes and differentially accumulating quality ingredients under NIR-CDs-treatment, which could provide a theoretical basis for expanding the applications of nanomaterial in industrial crop agriculture.

Fluorescence Imaging, Metabolism, and Biodistribution of Biocompatible Carbon Dots Synthesized Using Punica granatum L. Peel

In this study, a green, low-cost strategy is reported for the synthesis of carbon dots (CDs) using Punica granatum L. A systematic metabolic analysis and determination of the biodistribution of the nitrogen-doped carbon dots was conducted in vivo in mice. Fluorescence images of carbon dots in the whole body, in individual organs (kidney, gallbladder, and bladder), and in two cell lines from different tissue sources were observed. The results suggest not only that the carbon dots are fluorescent in solution, as reported previously, but also that they behave well as contrast agents in live mice. Moreover, metabolic process curves of carbon dots in blood and urine were obtained for the first time. Unlike quantum dots, which can persist in the body for more than 7 days, the carbon dots diffused and were excreted very quickly after injection into mice; within 3 min, fluorescence could be observed in blood, tissue and urine, indicating the rapid distribution of CDs. The fluorescence faded by approximately 4 h in organs and by approximately 10 h in urine, indicating that the CDs were excreted completely in half a day. Our results on the absorption, distribution, metabolism, and excretion of carbon dots may have great significance for the application of these CDs in drug delivery, as drug targets, and for biological imaging. We also demonstrated that these CDs have good biocompatibility for use in studies of mother-child barriers and in fluorescence imaging in plants.

Carbon dots: a novel platform for biomedical applications

Carbon dots (CDs) are a recently synthesised class of carbon-based nanostructures known as zero-dimensional (0D) nanomaterials, which have drawn a great deal of attention owing to their distinctive features, which encompass optical properties (e.g., photoluminescence), ease of passivation, low cost, simple synthetic route, accessibility of precursors and other properties. These newly synthesised nano-sized materials can replace traditional semiconductor quantum dots, which exhibit significant toxicity drawbacks and higher cost. It is demonstrated that their involvement in diverse areas of chemical and bio-sensing, bio-imaging, drug delivery, photocatalysis, electrocatalysis and light-emitting devices consider them as flawless and potential candidates for biomedical application. In this review, we provide a classification of CDs within their extended families, an overview of the different methods of CDs preparation, especially from natural sources, i.e., environmentally friendly and their unique photoluminescence properties, thoroughly describing the peculiar aspects of their applications in the biomedical field, where we think they will thrive as the next generation of quantum emitters. We believe that this review covers a niche that was not reviewed by other similar publications.

Orange-emissive carbon quantum dots for ligand-directed Golgi apparatus-targeting and in vivo imaging

Golgi apparatus is one of the most important organelles in cells. Targeting and monitoring the morphology and structure of Golgi apparatus are crucial and challenging. Aimed at the cysteine (Cys)...

Plant Bioelectronics and Biohybrids: The Growing Contribution of Organic Electronic and Carbon-Based Materials

Life in our planet is highly dependent on plants as they are the primary source of food, regulators of the atmosphere, and providers of a variety of materials. In this work, we review the progress on bioelectronic devices for plants and biohybrid systems based on plants, therefore discussing advancements that view plants either from a biological or a technological perspective, respectively. We give an overview on wearable and implantable bioelectronic devices for monitoring and modulating plant physiology that can be used as tools in basic plant science or find application in agriculture. Furthermore, we discuss plant-wearable devices for monitoring a plant's microenvironment that will enable optimization of growth conditions. The review then covers plant biohybrid systems where plants are an integral part of devices or are converted to devices upon functionalization with smart materials, including self-organized electronics, plant nanobionics, and energy applications. The review focuses on advancements based on organic electronic and carbon-based materials and discusses opportunities, challenges, as well as future steps.

Influence of the chirality of carbon nanodots on their interaction with proteins and cells

Carbon nanodots with opposite chirality possess the same major physicochemical properties such as optical features, hydrodynamic diameter, and colloidal stability. Here, a detailed analysis about the comparison of the concentration of both carbon nanodots is carried out, putting a threshold to when differences in biological behavior may be related to chirality and may exclude effects based merely on differences in exposure concentrations due to uncertainties in concentration determination. The present study approaches this comparative analysis evaluating two basic biological phenomena, the protein adsorption and cell internalization. We find how a meticulous concentration error estimation enables the evaluation of the differences in biological effects related to chirality.

Chiral Carbon Dots-Enzyme Nanoreactors with Enhanced Catalytic Activity for Cancer Therapy

As a class of functional proteins, enzymes possess inherent insignificant features, for instance, mediocre stability and membrane impermeability and reduced enzymatic activity after modification, which partly limit their biomedical applications. Thus, it is indispensable to exploit robust nanoreactors with high enzymatic activity and good stability and cell permeability. Here, the chiral carbon dots (CDs)-glucose oxidase (GOx) nanoreactors named LGOx and DGOx were constructed by the coassembly of GOx with L/D-CDs, respectively. L/DGOx can significantly enhance the activity of GOx and improve the efficient delivery of GOx to cancer cells. Moreover, these nanoreactors can generate hydrogen peroxide to efficaciously kill cancer cells and restrain tumor growth, and DGOx exhibits higher enzymatic activity than LGOx. According to our understanding, this is the first report about utilizing chiral CDs as vectors to construct effective CDs-enzyme nanohybrids for cancer therapy, which is envisioned to be a versatile strategy for multitudinous biomedical applications.

Chiral carbon quantum dots as fluorescent probe for rapid chiral recognition of isoleucine enantiomers

Chiral recognition is always a significant and challenging work in analytical chemistry. A fluorescent chiral recognition method based on chiral carbon quantum dots (CCQDs) towards isoleucine (Ile) enantiomers was developed in this work. CCQDs were synthesized by one-step hydrothermal method using l-cysteine as chiral source. The fluorescence intensity of CCQDs enhanced obviously in the presence of L-Ile, but had no observable change in the presence of D-Ile. The response speed of this chiral sensing system is fast, Ile enantiomers can be discriminated by CCQDs within 5 min, the enantioselectivity (I_L/I_D) can reach up to 2.2. Good linearity for detecting L-Ile was obtained over the concentration range from 0 to 30 mM with a LOD of 0.29 mM. The fluorescence intensity also increased linearly with the enantiomeric percentages of L-Ile in the mixture of Ile enantiomers. Thus, the developed method not only can achieve quantitative detection of L-Ile but also can determine the enantiomeric percentage in racemates. The chiral recognition mechanism can be explained by the difference in binding energy and interaction types between D-Ile and L-Ile with CCQDs by molecular modeling. The current method was applied in detecting L-Ile in real samples of functional drinks, the detection results were in consistent with the results obtained from high performance liquid chromatography, and the recoveries of standard addition were also satisfactory, which verified the reliability of the developed method.

The formation mechanism and chirality evolution of chiral carbon dots prepared via radical assisted synthesis at room temperature

We report on a Cu(ii) catalyzed process for the production of cysteine based chiral carbon dots; the process does not require any thermal treatment and the carbon dot formation is driven by the production of reactive radical species that are generated in the reaction media by the catalytic role played by the multivalent transition metal. The nanomaterial presents a well-defined chirality and the enantioselectivity of the synthesis is proved by the isolation of both the carbon dot enantiomers. We focused our attention on the processes that take place during the carbon dot formation and the relationship with the structure of the organic starting material. Thanks to the comparison of reactions conducted with different organic substrates whose thiyl radical chemistry is known, we recognized a non-trivial role of the radical hydrogen abstraction reactions in the carbon dot formation process. The reported process allows access to a large variety of analyses to monitor the reaction mixtures during the reaction course. Finally, we report a detailed analysis on the evolution of optical chirality during the synthesis and related this feature with the formation mechanism of the nanomaterial revealing significant evidence on the chirality origin and structure of chiral carbon dots.

Estimation of carbon dots amelioration of copper toxicity in maize studied by synchrotron radiation-FTIR

Carbon dots are biocompatible and non-toxic nanoparticles with chemical affinity to some heavy metals. Human activities increase soil pollution with copper. Cu is an essential microelement in plants, but excess can induce a harmful effects. In plant response to Cu, the cell wall plays an important role. This study aims to estimate possible amelioration effects of folic acid based CDs on Cu toxicity by studying the intracellular and cell wall compounds in maize (Zea mays L.) roots and leaves after 7 day-treatment in hydroponics. The sub-cellular compartmentalization and bio-macromolecular changes induced by 5 μM Cu applied alone or with CDs (167 and 500 mg/L) were studied using the Synchrotron-based Fourier transformmicro-spectroscopy (SR-FTIR) combined with X-Ray photoelectron spectroscopy (XPS). Cu induced changes in content of cell wall polysaccharides, proteins, and lipids. The XPS detected CDs transport throughout the plants. The Cu/167CDs treatment reduced Cu concentration in the roots, possibly by complexation/trapping between the functional groups on CDs surface and Cu²⁺. Principal component analysis of FTIR spectra confirmed that Cu/500CDs treatment increased Cu adverse effects in most tissues but alleviated adverse Cu effects on cell wall polysaccharides in the root xylem, and on polysaccharides and proteins in leaf phloem and mesophyll.

Impact of photoluminescent carbon quantum dots on photosynthesis efficiency of rice and corn crops

Photosynthesis is one of the most fundamental biochemical processes on earth such that it is vital to the existence of most lives on this planet. In fact, unravelling the potentials in enhancing photosynthetic efficiency and electron transfer process, which are thought to improve plant growth is one of the emerging approaches in tackling modern agricultural shortcomings. In light of this, zero-dimensional carbon quantum dots (CQD) have emerged and garnered much interest in recent years which can enhance photosynthesis by modulating the associated electron transfer process. In this work, CQD was extracted from empty fruit bunch (EFB) biochar using a green acid-free microwave method. The resulting CQD was characterized using HRTEM, PL, UV-Vis and XPS. Typical rice (C₃) and corn (C₄) crops were selected in the present study in order to compare the significant effect of CQD on the two different photosynthetic pathways of crops. CQD was first introduced into crop via foliar spraying application instead of localised placement of CQD before seedling development. The influence of CQD on the photosynthetic efficiency of rice (C₃) and corn (C₄) leaves was determined by measuring both carbon dioxide conversion and the stomatal conductance of the leaf. As a result, the introduction of CQD greatly enhanced the photosynthesis in CQD-exposed crops. This is the first study focusing on phylogenetically constrained differences in photosynthetic responses between C₃ and C₄ crops upon CQD exposure, which gives a better insight into the understanding of photosynthesis process and shows considerable promise in nanomaterial research for sustainable agriculture practices.

Edible and highly biocompatible nanodots from natural plants for the treatment of stress gastric ulcers

The incidence rate of stress ulcers has increased in recent years, with an increase in life pressure, unavoidable trauma and other factors. The therapy of acute stress ulcers has always been an important challenge. Carbon dots (CDs) have been reported to show excellent biological activities, but research on the stress ulcer curative effect of CDs is unprecedented. Here, we prepared a series of semi-carbonized nanodots (SCNDs) from natural plants or herbs as precursors and the as prepared SCNDs were later proved to be effective in the treatment and inhibition of stress gastric ulcers in a rat model. One kind of SCND from edible and medicinal plants, charred Atractylodes macrocephala (SCNDs-1), is demonstrated in detail for its strong anti-stress gastric ulcer effect with inhibition up to 90% and shows extremely high biocompatibility and ultra-low toxicity. These SCNDs lead to the reduction of inflammatory factors and oxidative stress, and the protection of the gastric mucosa. The SCNDs also reduce the excessive neuroendocrine response caused by stress, regulate the energy metabolism and the structure of intestinal flora, improve the damage to the body caused by the stress state, thus alleviating the occurrence of stress-induced gastric ulcers. This work provides new insights into the preparation of carbon nanomaterials from natural plants through a semi-carbonization process and opens new ways to apply bio-active and bio-safe SCNDs in the modern pharmaceutical field.

You Don't Learn That in School: An Updated Practical Guide to Carbon Quantum Dots

Carbon quantum dots (CQDs) have started to emerge as candidates for application in cell imaging, biosensing, and targeted drug delivery, amongst other research fields, due to their unique properties. Those applications are possible as the CQDs exhibit tunable fluorescence, biocompatibility, and a versatile surface. This review aims to summarize the recent development in the field of CQDs research, namely the latest synthesis progress concerning materials/methods, surface modifications, characterization methods, and purification techniques. Furthermore, this work will systematically explore the several applications CQDs have been subjected to, such as bioimaging, fluorescence sensing, and cancer/gene therapy. Finally, we will briefly discuss in the concluding section the present and future challenges, as well as future perspectives and views regarding the emerging paradigm that is the CQDs research field.

Enzyme-free and label-free detection of Staphylococcus aureus based on target-inhibited fluorescence signal recovery

In this work, a one-step fluorometric strategy based on nanometal surface energy transfer (NSET) between carbon dots (CDs) and gold nanoparticles (AuNPs) was developed for facile detection of Staphylococcus aureus (S. aureus). The fluorescence of CDs was quenched up to 63.5% by AuNPs due to nucleic acid hybridization in the presence of linker DNA, which contained the complementary sequences of S. aureus-specific aptamer, and the fluorescence signal was in the "off" state. Upon aptamer addition, the CDs was released from linker DNA through the strong competitiveness of aptamer, leading to the notable fluorescence recovered. Once S. aureus is introduced, aptamer preferentially bind to the bacterial surface and cannot hybridize with complementary sequences in the linker DNA, resulting in the fluorescence signal with "off" state. Based on these findings, the performance and reliability of the fluorescence-based assay were evaluated. Compared to direct hybridization of complementary DNA on the surface of CDs and AuNPs, our sensing strategy has enhanced detection limit (10 cfu⋅mL^-1) and improved linear range (10 to 10⁶ cfu⋅mL^-1) for S. aureus. Therefore, our proposed enzyme-free and label-free strategy may become a promising method for ease of operation, sensitive and selective S. aureus detection.