Carbon Quantum Dots Derived from Different Carbon Sources for Antibacterial Applications

Silver peroxide-incorporated carbon dots with high photothermal performance for combating bacteria

The widespread use of antibiotics often increases bacterial resistance. Herein, we reported a silver peroxide-incorporated carbon dots (defined as Ag2O2-CDs) with high photothermal conversion efficiency viain situoxidation process. The prepared Ag2O2-CDs exhibited ultra-small size of 2.0 nm and hybrid phase structure. Meanwhile, the Ag2O2-CDs were of a similar optical performance comparing with traditional carbon dots (CDs). Importantly, the incorporation of Ag2O2into CDs significantly enhanced photothermal conversion efficiency from 3.8% to 28.5%. By combining silver ion toxicity and photothermal ablation, the Ag2O2-CDs were capable of destroying gram-positive and gram-negative bacterium effectively. These findings demonstrated that the Ag2O2-CDs could be served as a potential antibacterial agent for clinical applications.

Nanoparticles in Periodontitis Therapy: A Review of the Current Situation

Periodontitis is a disease of inflammation that affects the tissues supporting the periodontium. It is triggered by an immunological reaction of the gums to plaque, which leads to the destruction of periodontal attachment structures. Periodontitis is one of the most commonly recognized dental disorders in the world and a major factor in the loss of adult teeth. Scaling and root planing remain crucial for managing patients with persistent periodontitis. Nevertheless, exclusive reliance on mechanical interventions like periodontal surgery, extractions, and root planning is insufficient to halt the progression of periodontitis. In response to the problem of bacterial resistance, some researchers are committed to finding alternative therapies to antibiotics. In addition, some scholars focus on finding new materials to provide a powerful microenvironment for periodontal tissue regeneration and promote osteogenic repair. Nanoparticles possess distinct therapeutic qualities, including exceptional antibacterial, anti-inflammatory, and antioxidant properties, immunomodulatory capacities, and the promotion of bone regeneration ability, which made them can be used for the treatment of periodontitis. However, there are many problems that limit the clinical translation of nanoparticles, such as toxic accumulation in cells, poor correlation between in vitro and in vivo, and poor animal-to-human transmissibility. In this paper, we review the present researches on nanoparticles in periodontitis treatment from the perspective of three main categories: inorganic nanoparticles, organic nanoparticles, and nanocomposites (including nanofibers, hydrogels, and membranes). The aim of this review is to provide a comprehensive and recent update on nanoparticles-based therapies for periodontitis. The conclusion section summarizes the opportunities and challenges in the design and clinical translation of nanoparticles for the treatment of periodontitis.

Abatement of microbes and organic pollutants using heterostructural nanocomposites of rice straw CQDs with substituted strontium ferrite

Sustainable use of agricultural waste still remains a challenging task. Herein, we used rice straw as a carbon precursor to prepare carbon quantum dots (CQDs) for photocatalytic applications. Nanocomposites of CQDs with Ti4+ and Mg2+ substituted strontium ferrite (Sr0·4Ti0·4Mg0·2Fe2O4.4) nanoparticles (NPs) in varying w:w ratio was synthesized by ultrasonication method. The successful formation of nanocomposites was confirmed by various microscopic and spectroscopic techniques. The photocatalytic and antibacterial activity of NPs, CQDs and nanocomposites was comparatively evaluated using tetracycline hydrochloride, azure B, Staphylococcus aureus and Escherichia coli as model pollutants. The CQDs-Sr0.4Ti0·4Mg0·2Fe2O4.4 nanocomposite with a w:w ratio of 2:1 showed excellent photocatalytic and antibacterial activity, with the degradation and inactivation efficiency ranging from 97.1% to 99.0% in presence of visible light. The increased specific surface area (117.2 m2/g), and reduction in band gap (2.48 eV-2.09 eV) and decreased photoluminescence intensity of nanocomposites all corroborated these results. The impacting experimental parameters such as catalyst dose, pH and contact time were also examined. Quenching experiments confirmed that hydroxyl radicals (HO∙) radicals and holes (h+) played a vital role in the degradation of pollutants. The kinetics of photodegradation was explained by using the Langmuir-Hinshelwood model. Box-Behnken statistical modelling was used to optimize photocatalytic parameters. Results indicated that the nanocomposite of CQDs with Sr0·4Ti0·4Mg0·2Fe2O4.4 can serve as a promising photocatalyst for the removal of pollutants and microbes.

Green synthesis of yeast cell wall-derived carbon quantum dots with multiple biological activities

Hypothesis

Yeast cell walls are a sustainable biomass source containing carbon and other elements like phosphorus. Converting cell walls into valuable nanomaterials like carbon quantum dots (CQDs) is of interest.

Experiments

Cell walls from Saccharomyces cerevisiae were hydrothermally treated in 0.5 M H2SO4 to produce CQDs. Multiple analytical techniques were utilized to confirm phosphorus-doping (P-CQDs), characterize the fluorescence properties, determine quantum yield, and evaluate the sensing, antimicrobial, photocatalytic, and antioxidant capacities.

Findings

A successful synthesis of P-CQDs was achieved with strong blue fluorescence under UV excitation, 19 % quantum yield, and excellent stability. The P-CQDs showed sensitive fluorescence quenching in response to ferric ions with a 201 nM detection limit. Antibacterial effects against Escherichia coli and Staphylococcus aureus were demonstrated. P-CQDs also exhibited dye degradation under sunlight and antioxidant activity. So, the prepared P-CQDs displayed promising multifunctional capabilities for metal ion detection, disinfection, and environmental remediation. Further research is required to fully realize and implement the multifunctional potential of P-CQDs in real-world applications.

Simultaneous Detection of Carbon Quantum Dots as Tracers for Interwell Connectivity Evaluation in a Pattern with Two Injection Wells

This study aimed to develop and implement a nanotechnology-based alternative to traditional tracers used in the oil and gas industry for assessing interwell connectivity. A simple and rapid hydrothermal protocol for synthesizing carbon quantum dots (CQDs) using agroindustry waste was implemented. Three commercial CQDs were employed (CQDblue, CQDgreen, and CQDred); the fourth was synthesized from orange peel (CQDop). The CQDs from waste and other commercials with spherical morphology, nanometric sizes less than 11 nm in diameter, and surface roughness less than 3.1 nm were used. These tracers demonstrated high colloidal stability with a negative zeta potential, containing carbonyl-type chemical groups and unsaturations in aromatic structures that influenced their optical behavior. All materials presented high colloidal stability with negative values of charge z potential between -17.8 and -49.1. Additionally, individual quantification of these tracers is feasible even in scenarios where multiple CQDs are present in the effluent with a maximum percentage of interference of 15.5% for CQDop in the presence of the other three nanotracers. The CQDs were injected into the field once the technology was insured under laboratory conditions. Monitoring the effluents allowed the determination of connectivity for five first-line producer wells. This study enables the application of CQDs in the industry, particularly in fields where the arrangement of injector and producer wells is intricate, requiring the use of multiple tracers for a comprehensive description of the system.

Antimicrobial carbon dots/pectin-based hydrogel for promoting healing processes in multidrug-resistant bacteria-infected wounds

Multidrug-resistant (MDR) bacterial infections have become a significant threat to global healthcare systems. Here, we developed a highly efficient antimicrobial hydrogel using environmentally friendly garlic carbon dots, pectin, and acrylic acid. The hydrogel had a porous three-dimensional network structure, which endowed it with good mechanical properties and compression recovery performance. The hydrogel could adhere closely to skin tissues and had an equilibrium swelling ratio of 6.21, indicating its potential as a wound dressing. In particular, the bactericidal efficacy following 24-h contact against two MDR bacteria could exceed 99.99 %. When the hydrogel was applied to epidermal wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) on mice, a remarkable healing rate of 93.29 % was observed after 10 days. This was better than the effectiveness of the traditionally used antibiotic kanamycin, which resulted in a healing rate of 70.36 %. In vitro cytotoxicity testing and hemolysis assay demonstrated a high biocompatibility. This was further proved by the in vivo assay where no toxic side effects were observed on the heart, liver, spleen, lung, or kidney of mice. This eco-friendly and easy-to-prepare food-inspired hydrogel provides an idea for the rational use of food and food by-products as a wound dressing to control MDR bacterial infections.

Quantum dots: a next generation approach for pathogenic microbial biofilm inhibition; mechanistic insights, existing challenges, and future potential

Quantum Dots (QDs) have emerged as versatile nanomaterials with origins spanning organic, inorganic, and natural sources, revolutionizing various biomedical applications, particularly in combating pathogenic biofilm formation. Biofilms, complex structures formed by microbial communities enveloped in exopolysaccharide matrices, pose formidable challenges to traditional antibiotics due to their high tolerance and resistance, exacerbating inefficacy issues in antibiotic treatments. QDs offer a promising solution, employing physical mechanisms like photothermal or photodynamic therapy to disrupt biofilms. Their efficacy is noteworthy, with lower susceptibility to resistance development and broad-spectrum action as compared to conventional antibiotic methods. The stability and durability of QDs ensure sustained biofilm activity, even in challenging environmental conditions. This comprehensive review delves into the synthesis, properties, and applications of Carbon Quantum Dots (CQDs), most widely used QDs, showcasing groundbreaking developments that position these nanomaterials at the forefront of cutting-edge research and innovation. These nanomaterials exhibit multifaceted mechanisms, disrupting cell walls and membranes, generating reactive oxygen species (ROS), and binding to nucleic materials, effectively inhibiting microbial proliferation. This opens transformative possibilities for healthcare interventions by providing insights into biofilm dynamics. However, challenges in size control necessitate ongoing research to refine fabrication techniques, ensure defect-free surfaces, and optimize biological activity. QDs emerge as microscopic yet potent tools, promising to contribute to a brighter future where quantum wonders shape innovative solutions to persistently challenging issues posed by pathogenic biofilms. Henceforth, this review aims to explore QDs as potential agents for inhibiting pathogenic microbial biofilms, elucidating the underlying mechanisms, addressing the current challenges, and highlighting their promising future potential.

Bacterially synthesized superfine tellurium nanoneedles as an antibacterial and solar-thermal still for efficient purification of polluted water

Bacterial biosynthesis of nanomaterials has several advantages (e.g., reduced energy inputs, lower cost, negligible environmental pollution) compared with traditional approaches. Various nanomaterials have been produced by bacteria. However, reports on using the bacterial biosynthesis of nanomaterials for applications with solar-thermal agents are scarce due to their narrow optical absorption. Herein, for the first time, we proposed a bacterial biosynthesis of broad-absorbing tellurium nanoneedles and demonstrated their effectiveness for solar-thermal evaporation and antibacterial applications. By simple biosynthesis within bacteria (Shewanella oneidensis MR-1), tellurium nanoneedles achieved a superfine configuration with a length-to-diameter ratio of nearly 20 and broad-spectrum absorbance. After integrating tellurium nanoneedles into a porous polyvinyl-alcohol scaffold, a solar-thermal still named TSAS-3 realized a high evaporation rate of 2.25 kg m-2 h-1 and solar-thermal conversion efficiency of 81% upon 1-Sun illumination. Based on these unique properties, the scaffold displayed good performances in seawater desalination, multiple wastewater treatment, and antibacterial applications. This work provides a simple and feasible strategy for the use of microbial-synthesized nanomaterials in solar-driven water purification and antibacterial applications.

Antibacterial potentials of carbon dots immobilized on chitosan and glass surfaces

Due to their antibacterial activity, chitosan‑carbon dot composites possess great potential for pharmaceuticals, medicine, and food preservation. Conducting a comprehensive study of the interactions between chitosan, carbon dots, and bacteria is crucial to understanding the processes behind applying these composites. This study aimed to immobilize carbon dots (C-dots) synthesized from Elaeagnus angustifolia fruits on chitosan and glass microbeads' surfaces, to characterize the test materials obtained after synthesis and immobilization, and to investigate their antibacterial potentials. C-dot synthesis was carried out from water extract in an acidic medium with the help of microwave irradiation, and their structural and optical properties were characterized by TEM, XRD, FT-IR, UV-vis, Zeta potential, and fluorescence methods. The surface of the glass microbeads was first activated and functionalized with surface amine groups with a silaning agent. C-dots were immobilized on both glass and chitosan microbeads using a crosslinking agent. Antibacterial potentials of nine different test materials, obtained before or after immobilization, were evaluated both qualitatively (MIC and MBC) and quantitatively (GI50) on E. coli, S. typhimurium, B. subtilis, and S. aureus, with the standard broth microdilution method. FT-IR and SEM-EDX analyses showed that C-dots were immobilized on chitosan (˂1 mm) and glass (˂100 μm) microbead surfaces. C-dots reduced the cell viability by ~25 % on S. typhimurium and B. subtilis (MIC = 25 mg/mL). It was also found that the highest antibacterial effect was recorded for C-dots-glass microbeads, which had a toxic effect of 43 % on S. aureus. In addition, binding C-dots to glass microbeads increased the antibacterial effect selectively in Gram-positive bacteria, while binding to chitosan microbeads was effective in all bacteria. The study showed that the antibacterial potential of C-dots-chitosan microbeads is more effective than C-dots-glass microbeads. C-dots could be used as carbon-based nanomaterials in antibacterial surface preparation once immobilized.

Bibliometric analysis of Traditional Chinese Medicine nanoparticles research from 2005 to 2023

To gain a deeper understanding of the current status of research on Traditional Chinese Medicine (TCM) and nanoparticles, we conducted a bibliometric study. We conducted a literature search in the Web of Science (WOS) for publications related to TCM and nanoparticles from 1992 to 2023. The data, including countries of publication, research institutions, journals, citations, and keywords, were analyzed using the Bibliometrix R-4.0 software package. We performed an analysis to identify the co-occurrence of keywords in the documents including their titles and abstracts. From 2005 to 2023, a total of 309 publications were included, with an average annual growth rate of 4.25%. The majority of these publications were published in Q1 journals (72, 47.06%) and Q2 journals (45, 29.41%). Among the 309 publications, 22 articles (7.12%) had an impact factor greater than 10, while 78 articles (25.24%) had an impact factor greater than 5. The analysis of international collaboration networks revealed limited international cooperation, with most collaborations occurring between institutions in China, the United States, and Australia. These 309 publications involved a total of 438 research institutions, with Chinese research institutions being the most prolific contributors. In this study, a total of 309 publications were included, comprising 1142 author keywords and 1175 keywords plus. Factor analysis of the 1175 keywords plus revealed that they could be grouped into five categories: one category included terms such as "oxide" and "zinc," another category included terms like "lipid" and "acid," a third category included terms such as "improve" and "enhance," a fourth category included terms like "silica" and "mesoporous," and the fifth category included terms like "PLGA" and "immune." Research on nanoparticles in TCM has been gradually gaining popularity. Currently, most of the research in this field is conducted in China, with limited international collaboration. The majority of TCM nanoparticle research focuses on individual herbal compounds, while research on nanoparticle formulations of traditional herbal prescriptions is relatively scarce.

Multifunctional natural derived carbon quantum dots from Withania somnifera (L.) - Antiviral activities against SARS-CoV-2 pseudoviron

Natural carbon dots (NCQDs) are expediently significant in the photo-, nano- and biomedical spheres owing to their facile synthesis, optical and physicochemical attributes. In the present study, three NCQDs are prepared and optimized from Withania somnifera (ASH) by one-step hydrothermal (bottom-up) method: HASHP (without dopant), nitrogen doped HASHNH3 (surface passivation using ammonia) and HASHEDA (surface passivation with ethylenediamine). The HR-TEM images reveal that HASHP, HASNH3, HASHEDA are spherically shaped with 2.5 ± 0.5 nm, 4 ± 1 nm and 5 ± 2 nm particle size, respectively, whereas FTIR confirms the aqueous solubility and nitrogen doping. The XRD patterns ensure that the NCQDs are amorphous and graphitic in nature. Comparatively, HASHNH3 (32.5%) and HASHEDA (27.6%) portray better fluorescence quantum yield than HASHP (5.6%). The increase in quantum yield for the doped NCQDs can be attributed to the surface passivation using ammonia and ethylenediamine. Surface passivation plays a crucial role in enhancing the fluorescence properties of quantum dots. The introduction of nitrogen through ammonia and ethylenediamine provides additional electronic states, possibly reducing non-radiative recombination sites and hence boosting the QY. In addition, an antiviral study unveils the striking potential of surface passivated NCQDs to curb Covid-19 crises with around 85% inhibition of SARS-CoV pseudoviron cells, which is better in comparison to the non-doped NCQDs. Hence, to understand the paramount efficacy of these NCQDs, a hypothesis on their possible mechanism of action against Covid-19 is discussed.

Recent advances in nanoantibiotics against multidrug-resistant bacteria

Multidrug-resistant (MDR) bacteria-caused infections have been a major threat to human health. The abuse of conventional antibiotics accelerates the generation of MDR bacteria and makes the situation worse. The emergence of nanomaterials holds great promise for solving this tricky problem due to their multiple antibacterial mechanisms, tunable antibacterial spectra, and low probabilities of inducing drug resistance. In this review, we summarize the mechanism of the generation of drug resistance, and introduce the recently developed nanomaterials for dealing with MDR bacteria via various antibacterial mechanisms. Considering that biosafety and mass production are the major bottlenecks hurdling the commercialization of nanoantibiotics, we introduce the related development in these two aspects. We discuss urgent challenges in this field and future perspectives to promote the development and translation of nanoantibiotics as alternatives against MDR pathogens to traditional antibiotics-based approaches.

Origin of Antibiotics and Antibiotic Resistance, and Their Impacts on Drug Development: A Narrative Review

Antibiotics have revolutionized medicine, saving countless lives since their discovery in the early 20th century. However, the origin of antibiotics is now overshadowed by the alarming rise in antibiotic resistance. This global crisis stems from the relentless adaptability of microorganisms, driven by misuse and overuse of antibiotics. This article explores the origin of antibiotics and the subsequent emergence of antibiotic resistance. It delves into the mechanisms employed by bacteria to develop resistance, highlighting the dire consequences of drug resistance, including compromised patient care, increased mortality rates, and escalating healthcare costs. The article elucidates the latest strategies against drug-resistant microorganisms, encompassing innovative approaches such as phage therapy, CRISPR-Cas9 technology, and the exploration of natural compounds. Moreover, it examines the profound impact of antibiotic resistance on drug development, rendering the pursuit of new antibiotics economically challenging. The limitations and challenges in developing novel antibiotics are discussed, along with hurdles in the regulatory process that hinder progress in this critical field. Proposals for modifying the regulatory process to facilitate antibiotic development are presented. The withdrawal of major pharmaceutical firms from antibiotic research is examined, along with potential strategies to re-engage their interest. The article also outlines initiatives to overcome economic challenges and incentivize antibiotic development, emphasizing international collaborations and partnerships. Finally, the article sheds light on government-led initiatives against antibiotic resistance, with a specific focus on the Middle East. It discusses the proactive measures taken by governments in the region, such as Saudi Arabia and the United Arab Emirates, to combat this global threat. In the face of antibiotic resistance, a multifaceted approach is imperative. This article provides valuable insights into the complex landscape of antibiotic development, regulatory challenges, and collaborative efforts required to ensure a future where antibiotics remain effective tools in safeguarding public health.

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

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

Antibacterial Carbon Dots: Mechanisms, Design, and Applications

The increase in antibiotic resistance promotes the situation of developing new antibiotics at the forefront, while the development of non-antibiotic pharmaceuticals is equally significant. In the post-antibiotic era, nanomaterials with high antibacterial efficiency and no drug resistance make them attractive candidates for antibacterial materials. Carbon dots (CDs), as a kind of carbon-based zero-dimensional nanomaterial, are attracting much attention for their multifunctional properties. The abundant surface states, tunable photoexcited states, and excellent photo-electron transfer properties make sterilization of CDs feasible and are gradually emerging in the antibacterial field. This review provides comprehensive insights into the recent development of CDs in the antibacterial field. The topics include mechanisms, design, and optimization processes, and their potential practical applications are also highlighted, such as treatment of bacterial infections, against bacterial biofilms, antibacterial surfaces, food preservation, and bacteria imaging and detection. Meanwhile, the challenges and outlook of CDs in the antibacterial field are discussed and proposed.

Synergistic and Long-Lasting Wound Dressings Promote Multidrug-Resistant Staphylococcus Aureus-Infected Wound Healing

Background

Multidrug-resistant staphylococcus aureus infected wounds can lead to nonhealing, systemic infections, and even death. Although advanced dressings are effective in protecting, disinfecting, and maintaining moist microenvironments, they often have limitations such as single functionality, inadequate drug release, poor biosafety, or high rates of drug resistance.

Methods

Here, a novel wound dressing comprising glycyrrhizic acid (GA) and tryptophan-sorbitol carbon quantum dots (WS-CQDs) was developed, which exhibit synergistic and long-lasting antibacterial and anti-inflammatory effects. We investigated the characterization, mechanical properties, synergistic antibacterial effects, sustained-release properties, and cytotoxicity of GA/WS-CQDs hydrogels in vitro. Additionally, we performed transcriptome sequence analysis to elucidate the antibacterial mechanism. Furthermore, we evaluated the biosafety, anti-inflammatory effects, and wound healing ability of GA/WS-CQDs dressings using an in vivo mouse model of methicillin-resistant staphylococcus aureus (MRSA)-infected wounds.

Results

The prepared GA/WS-CQDs hydrogels demonstrated superior anti-MRSA effects compared to common antibiotics in vitro. Furthermore, the sustained release of WS-CQDs from GA/WS-CQDs hydrogels lasted for up to 60 h, with a cumulative release of exceeding 90%. The sustained-released WS-CQDs exhibited excellent anti-MRSA effects, with low drug resistance attributed to DNA damage and inhibition of bacterial biofilm formation. Notably, in vivo experiments showed that GA/WS-CQDs dressings reduced the expression of inflammatory factors (TNF-α, IL-1β, and IL-6) and significantly promoted the healing of MRSA-infected wounds with almost no systemic toxicity. Importantly, the dressings did not require replacement during the treatment process.

Conclusion

These findings emphasize the high suitability of GA/WS-CQDs dressings for MRSA-infected wound healing and their potential for clinical translation.

Recent Advancements in Metal and Non-Metal Mixed-Doped Carbon Quantum Dots: Synthesis and Emerging Potential Applications

In nanotechnology, the synthesis of carbon quantum dots (CQDs) by mixed doping with metals and non-metals has emerged as an appealing path of investigation. This review offers comprehensive insights into the synthesis, properties, and emerging applications of mixed-doped CQDs, underlining their potential for revolutionary advancements in chemical sensing, biosensing, bioimaging, and, thereby, contributing to advancements in diagnostics, therapeutics, and the under standing of complex biological processes. This synergistic combination enhances their sensitivity and selectivity towards specific chemical analytes. The resulting CQDs exhibit remarkable fluorescence properties that can be involved in precise chemical sensing applications. These metal-modified CQDs show their ability in the selective and sensitive detection from Hg to Fe and Mn ions. By influencing their exceptional fluorescence properties, they enable precise detection and monitoring of biomolecules, such as uric acid, cholesterol, and many antibiotics. Moreover, when it comes to bioimaging, these doped CQDs show unique behavior towards detecting cell lines. Their ability to emit light across a wide spectrum enables high-resolution imaging with minimal background noise. We uncover their potential in visualizing different cancer cell lines, offering valuable insights into cancer research and diagnostics. In conclusion, the synthesis of mixed-doped CQDs opens the way for revolutionary advancements in chemical sensing, biosensing, and bioimaging. As we investigate deeper into this field, we unlock new possibilities for diagnostics, therapeutics, and understanding complex biological processes.

Biofabrication of carbon quantum dots and their food packaging applications: a review

Carbon quantum dots (CQDs) are an emerging class of novel carbon nanomaterials (< 10 nm). These zero-dimensional CQDs have recently invoked significant interest due to their high fluorescence ability, strong electronic conductivity, biocompatibility, excellent chemical stability, non-toxicity, and environmental safety. Bio-fabrication of CQDs from organic resources remains attractive owing to their excellent functional properties. An emerging class of CQDs is fabricated by various conventional methods. However, these methods need many chemical agents and instrument facilities. Bio-fabrication of CQDs has a lot of benefits because of its simple fabrication and eco-friendly. Therefore, the green synthesized CQDs are considered optimistic candidates for developing novel functional materials for food packaging applications. Thus, it is important to investigate the latest update on green-based CQDs for food packaging applications. This current review paper discusses the physicochemical properties of CQDs, the bio-fabrication of CQDs, and the fluorescent properties of CQDs along with their food packaging applications.

Biogenic Carbon Quantum Dots as a Neoteric Inducer in the Game of Directing Chondrogenesis

The journey into the field of stem cell biology has been an endeavor of paramount advancement in biomedicine, establishing new horizons in the avenue of materiobiology. The creative drive of the scientific community focuses on ameliorating the utilization of stem cells, which is currently untapped on a large scale. With similar motivation, we present a nascent strategy of maneuvering biogenic carbon quantum dots (CQDs) to eclipse the toxic hurdles of chemical synthesis of carbon allotropes to serve as a biocompatible trident in stem cell biology employing a three-prong action of stem cell differentiation, imaging, and migration. The derivation of CQDs from garlic peels as a biogenic precursor abets in realizing the optophysical features of CQDs to image mesenchymal stem cells without hampering the biological systems with cytotoxicity. We report the versatility of biogenic CQDs to generate reactive oxygen species (ROS) to robustly influence stem cell migration and concomitantly chondrocyte differentiation from human Wharton's jelly mesenchymal stem cells (hWJ-MSCs). This was orchestrated without the use of chondrogenic induction factors, which was confirmed from the expression of chondrogenic markers (Col II, Col X, ACAN). Even the collagen content of cells incubated with CQDs was quite comparable with that of chondrocyte-induced cells. Thus, we empirically propose garlic peel-derived CQDs as a tangible advancement in stem cell biology from a materiobiological frame of reference to hone significant development in this arena.

Natural and biocompatible dressing unit based on tea carbon dots modified core-shell electrospun fiber for diabetic wound disinfection and healing

Wound infection and healing in patients with diabetes is one of the complex problems in trauma treatment. Therefore, designing and preparing an advanced dressing membrane for treating the wounds of such patients is essential. In this study, a zein film with biological tea carbon dots (TCDs) and calcium peroxide (CaO₂) as the main components for promoting diabetic wound healing was prepared by an electrospinning technique, which combines the advantages of natural degradability and biosafety. CaO₂ is a biocompatible material with a microsphere structure that reacts with water to release hydrogen peroxide and calcium ions. TCDs with a small diameter were doped in the membrane to mitigate its properties while improving the antibacterial and healing effects of the membrane. TCDs/CaO₂ was mixed with ethyl cellulose-modified zein (ZE) to prepare the dressing membrane. The antibacterial properties, biocompatibility and wound-healing properties of the composite membrane were investigated by antibacterial experiment, cell experiment and a full-thickness skin defect. TCDs/CaO₂ @ZE exhibited significant anti-inflammatory and wound healing-promoting properties in diabetic rats, without any cytotoxicity. This study is meaningful in developing a natural and biocompatible dressing membrane for diabetic wound healing, which shows a promising application in wound disinfection and recovery in patients with chronic diseases.

Preparation of Ciprofloxacin-Based Carbon Dots with High Antibacterial Activity

Nowadays, bacterial infections are attracting great attention for the research and development of new antimicrobial agents. As one of the quinolones, ciprofloxacin (CI) has a broad-spectrum, strong antibacterial effect. However, the clinical use of ciprofloxacin is limited by drug resistance. Ciprofloxacin carbon dots (CCDs) with enhanced antibacterial activity and copper-doped ciprofloxacin carbon dots (Cu-CCDs) were synthesized by a simple hydrothermal method. The results of structural analysis and antibacterial experiments show that CCDs and Cu-CCDs have effective antibacterial properties by retaining the active groups of ciprofloxacin (-COOH, C-N, and C-F), and Cu-CCDs doped with copper have a better antibacterial effect. In addition, experiments have shown that Cu-CCDs show excellent antibacterial activity against E. coli and S. aureus and have good biocompatibility, which indicates that they have great prospects in clinical applications. Therefore, novel modified copper CCDs with broad-spectrum antibacterial activity, which can be used as antibacterial nanomaterials for potential applications in the field of antibacterial drugs, were synthesized in this study.

Colloidal Behavior and Biodegradation of Engineered Carbon-Based Nanomaterials in Aquatic Environment

Carbon-based nanomaterials (CNMs) have attracted a growing interest over the last decades. They have become a material commonly used in industry, consumer products, water purification, and medicine. Despite this, the safety and toxic properties of different types of CNMs are still debatable. Multiple studies in recent years highlight the toxicity of CNMs in relation to aquatic organisms, including bacteria, microalgae, bivalves, sea urchins, and other species. However, the aspects that have significant influence on the toxic properties of CNMs in the aquatic environment are often not considered in research works and require further study. In this work, we summarized the current knowledge of colloidal behavior, transformation, and biodegradation of different types of CNMs, including graphene and graphene-related materials, carbon nanotubes, fullerenes, and carbon quantum dots. The other part of this work represents an overview of the known mechanisms of CNMs' biodegradation and discusses current research works relating to the biodegradation of CNMs in aquatic species. The knowledge about the biodegradation of nanomaterials will facilitate the development of the principals of "biodegradable-by-design" nanoparticles which have promising application in medicine as nano-carriers and represent lower toxicity and risks for living species and the environment.

Quantum Dots and Their Interaction with Biological Systems

Quantum dots are nanocrystals with bright and tunable fluorescence. Due to their unique property, quantum dots are sought after for their potential in several applications in biomedical sciences as well as industrial use. However, concerns regarding QDs’ toxicity toward the environment and other biological systems have been rising rapidly in the past decade. In this mini-review, we summarize the most up-to-date details regarding quantum dots’ impacts, as well as QDs’ interaction with mammalian organisms, fungal organisms, and plants at the cellular, tissue, and organismal level. We also provide details about QDs’ cellular uptake and trafficking, and QDs’ general interactions with biological structures. In this mini-review, we aim to provide a better understanding of our current standing in the research of quantum dots, point out some knowledge gaps in the field, and provide hints for potential future research.

Paper mill sludge-based carbon quantum dots as a specifically ratiometric fluorescent probe for the sensitive and selective detection of coptisine

Coptisine (COP), one of the bioactive components in Rhizoma Coptidis, has many pharmacological effects. Meanwhile, the determination of COP is essential in pharmacological and clinical applications. Herein, we prepared carbon quantum dots (CQDs) by one-step oil-thermal method using paper mill sludge (PMS) as precursor, and developed a ratiometric fluorescence method for the determination of COP. The structural and optical properties of PMS-CQDs were evaluated through HRTEM, FT-IR, XPS, XRD, UV-vis, fluorescence, zeta potential and fluorescence lifetime experiments. Fluorescence intensity ratio at 550 nm and 425 nm (I₅₅₀ /I₄₂₅ ) was recorded as an index for quantitative detection of COP. The detection concentration of COP ranges from 0.1 to 50 μM in good linear correlation (R² = 0.9974) with a limit of detection of 0.028 μM (3σ/k). The quenching mechanism was deduced to be inner filter effect and static quenching. The ratiometric fluorescent probe showed impressive selectivity and sensitivity towards COP, and was successfully applied to the detection of COP in human urine with expected recoveries (95.22-111.00%) and relative standard deviation (0.46-2.95%), indicating that our developed method has a great application prospect in actual sample detection.

Photodynamic Anti-Bacteria by Carbon Dots and Their Nano-Composites

The misuse of many types of broad-spectrum antibiotics leads to increased antimicrobial resistance. As a result, the development of a novel antibacterial agent is essential. Photodynamic antimicrobial chemotherapy (PACT) is becoming more popular due to its advantages in eliminating drug-resistant strains and providing broad-spectrum antibacterial resistance. Carbon dots (CDs), zero-dimensional nanomaterials with diameters smaller than 10 nm, offer a green and cost-effective alternative to PACT photosensitizers. This article reviewed the synthesis methods of antibacterial CDs as well as the recent progress of CDs and their nanocomposites in photodynamic sterilization, focusing on maximizing the bactericidal impact of CDs photosensitizers. This review establishes the base for future CDs development in the PACT field.

Carbon nanogels exert multipronged attack on resistant bacteria and strongly constrain resistance evolution

Developing antimicrobial agents that can eradicate drug-resistant (DR) bacteria and provide sustained protection from DR bacteria is a major challenge. Herein, we report a mild pyrolysis approach to prepare carbon nanogels (CNGs) through polymerization and the partial carbonization of l-lysine hydrochloride at 270 °C as a potential broad-spectrum antimicrobial agent that can inhibit biopolymer-producing bacteria and clinical drug-resistant isolates and tackle drug resistance issues. We thoroughly studied the structures of the CNGs, their antibacterial mechanism, and biocompatibility. CNGs possess superior bacteriostatic effects against drug-resistant bacteria compared to some commonly explored antibacterial nanomaterials (silver, copper oxide, and zinc oxide nanoparticles, and graphene oxide) through multiple antimicrobial mechanisms, including reactive oxygen species generation, membrane potential dissipation, and membrane function disruption, due to the positive charge and flexible colloidal structures resulting strong interaction with bacterial membrane. The minimum inhibitory concentration (MIC) values of the CNGs (0.6 µg mL^-1 against E. coli and S. aureus) remained almost the same against the bacteria after 20 passages; however, the MIC values increased significantly after treatment with silver nanoparticles, antibiotics, the bacteriostatic chlorhexidine, and especially gentamicin (approximately 140-fold). Additionally, the CNGs showed a negligible MIC value difference against the obtained resistant bacteria after acclimation to the abovementioned antimicrobial agents. The findings of this study unveil the development of antimicrobial CNGs as a sustainable solution to combat multidrug-resistant bacteria.