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Red tides not only destroy marine ecosystems but also pose a great threat to human health. The traditional anti-red tide materials are difficult to degrade effectively in the natural environment and there may be risks of environmental leakage and secondary pollution. Furthermore, they cannot reduce the toxicity of toxins released by algae. It is very important to prepare degradable materials that can effectively control red tide and reduce their toxins in the future. Herein, degradable CDs (De-CDs) with biocompatibility and non-toxicity is successfully prepared using the one-step electrolytic method. De-CDs can effectively inhibit P. globosa (algae associated with red tide) growth. More importantly, the De-CDs not only can attenuate the toxicity of toxins released by P. globosa, but also can be degraded under visible-light irradiation in the seawater and avoids environmental leakage. The successful preparation of De-CDs provides a new idea for degradable materials with anti-red tide algae in the future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Gram-positive bacteria are one of the most common pathogens causing severe and acute infection, and hospital infection caused by Gram-positive bacteria have increased significantly. Also, as antibiotics have been widely used, abusing of antibiotics is becoming an increasingly serious problem which is followed by dangerous drug resistance. Here, we developed a series of cationic carbon dots (CDs) with high-performance as antibacterial agents by using tartaric acid and m-aminophenol as precursors. The surface charge of these CDs can be regulated from +4.5 ± 0.42 mV to +33.2 ± 0.99 mV by increasing the contents of pyridine N and pyrrolic N in CDs. Further antibacterial experiments show that 250 μg mL -1 of CDs with +33.2 ± 0.99 mV can selectively kill Gram-positive bacteria and the antibacterial efficiency can reach approximately >99%. These CDs with positive surface charge can be selectively absorbed on the cell walls of Staphylococcus aureus (S. aureus) via electrostatic interaction and then disturb their physiological metabolism, eventually leading to bacterial death. The present work provides a novel method to adjust the surface charge of CDs and apply these CDs as alternative antibacterial agents.

Infections caused by Gram-negative bacteria have been an increasing problem worldwide. Meanwhile, the overuse of traditional antibiotics has caused an emergence of drug resistance. The development of new antibacterial agents, which can cope with the threat from drug-resistant bacteria, is urgently needed. Herein, carbon dots (ACDs) derived from Artemisia argyi leaves were obtained via a smoking simulation method and exhibited selective antibacterial ability of targeting Gram-negative bacteria. The bactericidal efficiency of ACDs (150 μg mL-1) for Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, and Proteusbacillus vulgaris) can reach 100%, while for Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), ACDs have no significant antibacterial function, indicating that the particles can selectively target specific bacteria. The antibacterial mechanism for ACDs confirmed that ACDs could only damage the cell walls of Gram-negative bacteria but not that of Gram-positive bacteria. Moreover, ACDs can inhibit the activity of cell wall-related enzymes in Gram-negative bacteria by changing the enzymatic secondary structure. This work is of great significance for the development of new antibacterial nanomaterials derived from natural biomass as well as the treatment of infections caused by Gram-negative bacteria.

Carbon dots (CDs) have attracted increasing attention in disease therapy owing to their low toxicity and good biocompatibility. Their therapeutic effect strongly depends on the CDs structure (e.g., size or functional groups). However, the impact of CDs chirality on maltase and blood glucose level has not yet been fully emphasized and studied. Moreover, in previous reports, chiral CDs with targeted optical activity have to be synthesized from precursors of corresponding optical rotation, severely limiting chiral CDs design. Here, chiral CDs with optical rotation opposite to that of the precursor are facilely prepared through electrochemical polymerization. Interestingly, their chirality can be regulated by simply adjusting reaction time. At last, the resultant (+)-DCDs (700 µg mL -1 ) are employed to modify maltase in an effort to regulate the hydrolytic rate of maltose, showing an excellent inhibition ratio to maltase of 54.7%, significantly higher than that of (-)-LCDs (15.5%) in the same reaction conditions. The superior performance may be attributed to the preferable combination of DCDs with maltase. This study provides an electrochemical method to facilely regulate CDs chirality, and explore new applications of chiral CDs as antihyperglycemic therapy for controlling blood glucose levels., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Multifunctional coatings, especially those with simultaneous antibiofilm formation and anticorrosion properties are of great significance for the marine industry. Inspired by the function of fish mucus of blackhead fish, a biological epidermal secretion with negative surface potential that protects blackhead fish from colonization of microorganisms, a concept is introduced to use negatively charged carbon nanodots (CDs) as a secure and economical dual-functional additive to prepare protective coatings. The prepared CDs with strong negative surface potential initiate robust antibiofilm formation (antiadhesion and antibacteria) and anticorrosion properties (about 60 days' durability in seawater) of polymeric coatings. The incorporated CDs with negative surface potential take effect in the following ways: 1) suppressing bacterial adhesion by virtue of strong electrostatic repulsion; 2) sterilizing anchored bacteria via destroying bacterial cell walls; 3) impeding electron ejection from the metallic surface; and 4) blocking aggressive species (H 2 O and O 2 ) by narrowing the microchannels. This work provides a new train of thought propelling the development of potential materials for industrial and engineering applications., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The infection of bacteria and fungus is one of the most challenging global threats to human health. With the recent advancement in nanoscience and nanotechnology, much progress has been achieved in the development of antimicrobial nanomedicine; however, these nanomaterial-based antibacterial agents still suffer from potential biological toxicity, poor degradation, and various secondary pollution. Here, we demonstrate the fabrication of low-toxic and degradable carbon dots (CDs) from vitamin C by one-step electrochemical method. These newly generated CDs display a strong broad-spectrum antibacterial activity and antifungal activity even at low concentrations, as they destroy the bacterial walls during the diffusive entrance, perturb secondary structures of DNA/RNAs of bacteria and fungus, and inhibit important gene expressions to finally kill the bacteria and fungus. We also show that these well-characterized CDs can be completely degraded into CO 2 , CO and H 2 O under visible light in air (or at very mild temperature, about 37 °C).

Chiral compounds/materials have important effects on the growth of plants. Chiral carbon dots (CDs), as an emerging chiral carbon nanomaterial, have great potential in bio-application and bio-nanotechnology. Herein, we report a hydrothermal method to synthesize chiral CDs from cysteine (cys) and citric acid. These chiral CDs were further demonstrated to have systemic effects on the growth of mung bean plants, in which case both l- and d-CDs can promote the growth of the root in mung bean plants, stem length of mung bean sprouts and water absorption of bean seeds. The elongation of mung bean sprouts presented an increasing trend with the treatment of chiral CDs of increasing concentration (below 500 μg mL-1). Furthermore, in the optimal concentration (100 μg mL-1), the l-CDs can improve root vigor and the activity of the Rubisco enzyme of bean sprouts by 8.4% and 20.5%, while the d-CDs increased by 28.9% and 67.5%. Due to more superior properties in improving root vigor and the activity of the Rubisco enzyme of mung bean sprouts, d-CDs are able to enhance photosynthesis better and accumulate more carbohydrate in mung bean plants.

Biological nitrogen fixation is critical for the nitrogen cycle on the earth. Nitrogen-fixing bacteria, as an environmentally friendly microorganism, convert atmospheric nitrogen to available nitrogen source for plants. In this study, we found that carbon dots (CDs) could significantly enhance the nitrogen-fixing activity of azotobacter chroococcum, in which the activity of azotobacter treated with CDs (4 μg/mL) was increased by 158% compared to that of the control one. A series of experiments suggest that CDs can combine with the nitrogenase, affect the secondary structure of nitrogenase, improve the electron transfer in the biocatalytic process, and finally improve nitrogenase activity for nitrogen fixation. Our findings may offer an economical and environmentally friendly means of improving the biological nitrogen fixation as well as solving the insufficiency of nitrogen fertilizer.

Carbon dots (CDs) with enzyme-like activities play crucial roles in nanobiotechnology. However, it is difficult to establish a relationship between their structure and biocatalytic properties. In this work, a series of nitrogen-doped carbon dots (TA-NCDs) were synthesized by a hydrothermal method. Their oxidase-like activity could be triggered by visible light irradiation (420 nm≤λ ≤ 700 nm). As a nanozyme, TA-NCDs show the value of maximum reaction rates (V max) is 121.95 × 10−8 M/s and the Michaelis–Menten constants (K m) is 0.61 mM. In situ transient photovoltage (TPV) tests prove that the pyrrolic nitrogen in TA-NCDs is the catalytic active sites and substrate binding sites. Under visible light irradiation, TA-NCDs, with oxidase-like activity, increased the cellular ROS level significantly, leading to their visible light induced bioactivity to kill nearly 60% of HeLa cells. Pyrrolic nitrogen dominated the mimic oxidase activity of CDs. [Display omitted] • TA-NCDs exhibit oxidase-like activity under visible light irradiation. • The maximum velocity of TA-NCDs is 121.95 × 10−8 M/s, implying TA-NCDs show higher catalytic activity than natural enzyme. • In situ TPV test was used to explore the active sites of TA-NCDs. • The application of TA-NCDs in physiological environments was confirmed. [ABSTRACT FROM AUTHOR]

Hydrogen production from water splitting using photocatalysts and solar energy is an ideal pathway to obtain future energy sources which are cheap and easy to industrialize. In the water splitting process, the reduction of H2O gives H2, while H2O oxidation produces O2 with hydrogen peroxide (H2O2) in tiny amounts as a by‐product (poisoning the catalyst). It remains challenging to simultaneously produce H2O2 and H2 within one photocatalytic system. Inspired by a biological H2O2 generator, chlorella, the authors firstly realize the simultaneous photocatalytic water splitting and biological H2O2 generation by a living Chlorella vulgaris and carbon micro particle (needle coke) comodified g‐C3N4 (C‐N‐g‐C3N4) photocatalyst. The C‐N‐g‐C3N4 exhibits the optimal H2O2 (H2) evolution rate of 0.98 µmol h−1 (0.84 µmol h−1), giving an apparent quantum efficiency of 0.86% for H2 evolution at 420 nm. In this system, the needle coke serves as cocatalyst to work as reduction sites for H2 evolution, while the living C. vulgaris plays the key role in the production of H2O2 under the protection of g‐C3N4. Living chlorella vulgaris and carbon micro particles (needle coke) co‐modified g‐C3N4 (C‐N‐g‐C3N4) exhibit H2O2 (H2) evolution with 0.98 μmol h–1 (0.84 μmol h–1). The needle coke serves as co‐catalyst and plays the role of the reduction site for hydrogen evolution, g‐C3N4 provides oxidation sites for partial H2O2 evolution, and the living C. vulgaris take responsibility for improvement of H2O2 evolution yield. [ABSTRACT FROM AUTHOR]

Carbon dots modified WO 2 -Na x WO 3 composite was designed as UV-Vis-NIR broad spectrum-driven photocatalyst for overall water splitting. • Broad spectrum-driven WO 2 -Na x WO 3 -CDs photocatalyst can achieve overall water splitting. • The WO 2 -Na x WO 3 -CDs with 0.008 g CDs show the highest photocatalytic activity. • The H 2 /O 2 evolutions by WO 2 -Na x WO 3 -CDs show the stoichiometric ratio. • The WO 2 -Na x WO 3 -CDs shows excellent stability for about 6 cycles of repetitive experiments. • The photocataytic activity should ascribe to the synergistic effect of WO 2 -Na x WO 3 and CDs. The utilization of solar energy and valid photocatalyst is one of the most effective strategies to achieve water splitting into hydrogen (H 2) and oxygen (O 2). Although enormous effort has been devoted to photocatalysts, the sunlight still cannot be fully utilized by the developed photocatalysts. It is important but remains challenging to develop a broad spectrum-driven photocatalyst for overall water splitting. Here, we design a UV-Vis-NIR broad spectrum-driven carbon dots modified WO 2 -Na x WO 3 (WO 2 -Na x WO 3 -CDs) composite as photocatalyst for overall water splitting without requirement of any sacrificial agents or cocatalysts. When the concentration of CDs in the sample is 0.008 g CDs /g catalyst , the WO 2 -Na x WO 3 -CDs shows the highest photocatalytic activity with stoichiometric ratio of H 2 /O 2 evolutions and their rates are 0.05/0.02, 2.58/1.24, 4.74/2.28 μmol/h under UV (λ < 420 nm), visible (420 nm≤λ ≤ 760 nm) and near-infrared (λ > 760 nm) light irradiation, respectively. It is also impressive that the photocatalyst shows excellent stability for about 6 cycles of repetitive experiments. The WO 2 -Na x WO 3 -CDs composites functioned as broad spectrum-driven photocatalyst for overall water splitting should attribute to the synergistic effect of WO 2 -Na x WO 3 and CDs, in which the WO 2 -Na x WO 3 provides the suitable bandgap, while the CDs can enhance light absorption and accelerate separation efficiencies of photo-generated charge carriers. [ABSTRACT FROM AUTHOR]

Z-scheme photocatalytic system is an efficient way to achieve high efficiency photocatalytic overall water splitting. However, the acquisition of efficient Z-scheme visible-light photocatalysts is still a huge challenge at present due to the inactive visible light-active component and various low-band-gap for semiconductors. Herein, we constructed the BiVO 4 /CDs/CdS Z-scheme photocatalyst with carbon dots (CDs) as solid-state electron mediator, which exhibits excellent photocatalytic activity and stability for photocatalytic overall water splitting under visible light. The BCC50 (BiVO 4 /CDs/CdS with the mass ratio of BiVO 4 /CdS = 50%) as photocatalyst shows the best photocatalytic activity with stoichiometric ratio of H 2 evolution rate of 1.24 μmol/h and O 2 evolution rate of about 0.61 μmol/h. The enhanced photocatalytic activity of the Z-scheme photocatalyst can be attributed to high efficiencies for separation and transport of photogenerated charge carriers and extended the lifetime of electrons and holes. [ABSTRACT FROM AUTHOR]

Hydrogen production from water splitting using photocatalysts and solar energy is an ideal pathway to obtain future energy sources which are cheap and easy to industrialize. In the water splitting process, the reduction of H2O gives H2, while H2O oxidation produces O2 with hydrogen peroxide (H2O2) in tiny amounts as a by‐product (poisoning the catalyst). It remains challenging to simultaneously produce H2O2 and H2 within one photocatalytic system. Inspired by a biological H2O2 generator, chlorella, the authors firstly realize the simultaneous photocatalytic water splitting and biological H2O2 generation by a living Chlorella vulgaris and carbon micro particle (needle coke) comodified g‐C3N4 (C‐N‐g‐C3N4) photocatalyst. The C‐N‐g‐C3N4 exhibits the optimal H2O2 (H2) evolution rate of 0.98 µmol h−1 (0.84 µmol h−1), giving an apparent quantum efficiency of 0.86% for H2 evolution at 420 nm. In this system, the needle coke serves as cocatalyst to work as reduction sites for H2 evolution, while the living C. vulgaris plays the key role in the production of H2O2 under the protection of g‐C3N4. Living chlorella vulgaris and carbon micro particles (needle coke) co‐modified g‐C3N4 (C‐N‐g‐C3N4) exhibit H2O2 (H2) evolution with 0.98 μmol h–1 (0.84 μmol h–1). The needle coke serves as co‐catalyst and plays the role of the reduction site for hydrogen evolution, g‐C3N4 provides oxidation sites for partial H2O2 evolution, and the living C. vulgaris take responsibility for improvement of H2O2 evolution yield. [ABSTRACT FROM AUTHOR]