Antibacterial fluorescent nano-sized lanthanum-doped carbon quantum dot embedded polyvinyl alcohol for accelerated wound healing

Supramolecular Assembly of Hydrogen-Bonded Organic Frameworks with Carbon Dots: Realizing Ultralong Aqueous Room-Temperature Phosphorescence for Anticounterfeiting

Room-temperature phosphorescent carbon dots (RTP-CDs) have received increasing attention due to their excellent optical properties and potential applications. Nevertheless, the realization of RTP-CDs in aqueous solutions remains a considerable challenge due to the water-molecule- and oxygen-induced deactivation of the triplet excitons, which leads to phosphorescence quenching. In this study, ultralong phosphorescence in water was achieved by in situ self-assembly of CDs encapsulated in a rigid hydrogen-bonded organic framework (HOF). The phosphorescence lifetime reaches an impressive 956.96 ms and exhibits long-lasting optical and structural stability in water for more than 90 days. The composite material not only has ultralong luminescence life and excellent luminescence stability but also has two-color phosphorescence emission, as well as excellent antiphotobleaching and phosphorescence stability in aqueous solution, which can solve the current problem that RTP is easily burst out by water and moisture. In addition, this study introduced a fluorescent dye based on the triplet-singlet Förster resonance energy transfer system (TS-FRET) to fine-tune the afterglow properties. This work will inspire the design of RTP systems with dual phosphor light sources and provide new strategies for the development of smart RTP materials in water.

Construction of a one-stop N-doped negatively charged carbon dot nanoplatform with antibacterial and anti-inflammatory dual activities for wound infection based on biocompatibility

The development of bacterial resistance significantly contributes to the persistence of infections. Although previous studies have highlighted the benefits of metal-doped positive carbon nanodots in managing bacterial wound infections, their mechanism of action is relatively simple and they may pose potential hazards to human cells. Therefore, it is essential to develop a one-stop carbon dot nanoplatform that offers high biocompatibility, antibacterial properties, and anti-inflammatory activities for wound infection management. This study explores the antibacterial efficacy, without detectable resistance, and wound-healing potential of nitrogen-doped (N-doped) negatively charged carbon dots (TPP-CDs). These carbon dots are synthesized using tannic acid (TA), polyethylene polyamine, and polyethylene glycol (PEG) as precursors, with a focus on their biocompatibility. Numerous systematic studies have shown that TPP-CDs can effectively destroy bacterial biofilms and deoxyribonucleic acid (DNA), while also inducing oxidative stress, leading to a potent antimicrobial effect. TPP-CDs also demonstrate the ability to scavenge excess free radicals, promote cellular proliferation, and inhibit inflammatory factors, all of which contribute to improved wound healing. TPP-CDs also demonstrate favorable cell imaging capabilities. These findings suggest that N-doped negatively charged TPP-CDs hold significant potential for treating bacterial infections and offer practical insights for their application in the medical field.

A Comprehensive Review of Nanoparticles: From Classification to Application and Toxicity

Nanoparticles are structures that possess unique properties with high surface area-to-volume ratio. Their small size, up to 100 nm, and potential for surface modifications have enabled their use in a wide range of applications. Various factors influence the properties and applications of NPs, including the synthesis method and physical attributes such as size and shape. Additionally, the materials used in the synthesis of NPs are primary determinants of their application. Based on the chosen material, NPs are generally classified into three categories: organic, inorganic, and carbon-based. These categories include a variety of materials, such as proteins, polymers, metal ions, lipids and derivatives, magnetic minerals, and so on. Each material possesses unique attributes that influence the activity and application of the NPs. Consequently, certain NPs are typically used in particular areas because they possess higher efficiency along with tenable toxicity. Therefore, the classification and the base material in the NP synthesis hold significant importance in both NP research and application. In this paper, we discuss these classifications, exemplify most of the major materials, and categorize them according to their preferred area of application. This review provides an overall review of the materials, including their application, and toxicity.

Emerging trends in CDs@hydrogels composites: from materials to applications

Carbon dots (CDs) are nanoscale carbon materials with unique optical properties and biocompatibility. Their applications are limited by their tendency to aggregate or oxidize in aqueous environments. Turning weakness to strengths, CDs can be incorporated with hydrogels, which are three-dimensional networks of crosslinked polymers that can retain large amounts of water. Hydrogels can provide a stable and tunable matrix for CDs, enhancing their fluorescence, stability, and functionality. CDs@hydrogels, known for their ease of synthesis, strong binding capabilities, and rich surface functional groups, have emerged as promising composite materials. In this review, recent advances in the synthesis and characterization of CDs@hydrogels, composite materials composed of CDs and various types of natural or synthetic hydrogels, are summarized. The potential applications of CDs@hydrogels in fluorescence sensing, adsorption, drug delivery, antibacterial activity, flexible electronics, and energy storage are also highlighted. The current challenges and future prospects of CDs@hydrogels systems for the novel functional materials are discussed.

Systematic review of the osteogenic effect of rare earth nanomaterials and the underlying mechanisms

Rare earth nanomaterials (RE NMs), which are based on rare earth elements, have emerged as remarkable biomaterials for use in bone regeneration. The effects of RE NMs on osteogenesis, such as promoting the osteogenic differentiation of mesenchymal stem cells, have been investigated. However, the contributions of the properties of RE NMs to bone regeneration and their interactions with various cell types during osteogenesis have not been reviewed. Here, we review the crucial roles of the physicochemical and biological properties of RE NMs and focus on their osteogenic mechanisms. RE NMs directly promote the proliferation, adhesion, migration, and osteogenic differentiation of mesenchymal stem cells. They also increase collagen secretion and mineralization to accelerate osteogenesis. Furthermore, RE NMs inhibit osteoclast formation and regulate the immune environment by modulating macrophages and promote angiogenesis by inducing hypoxia in endothelial cells. These effects create a microenvironment that is conducive to bone formation. This review will help researchers overcome current limitations to take full advantage of the osteogenic benefits of RE NMs and will suggest a potential approach for further osteogenesis research.

Advancements and applications of upconversion nanoparticles in wound dressings

Wound healing is a complex process that requires effective management to prevent infections and promote efficient tissue regeneration. In recent years, upconversion nanoparticles (UCNPs) have emerged as promising materials for wound dressing applications due to their unique optical properties and potential therapeutic functionalities. These nanoparticles possess enhanced antibacterial properties when functionalized with antibacterial agents, helping to prevent infections, a common complication in wound healing. They can serve as carriers for controlled drug delivery, enabling targeted release of therapeutic agents to the wound site, allowing for tailored treatment and optimal healing conditions. These nanoparticles possess the ability to convert near-infrared (NIR) light into the visible and/or ultraviolet (UV) regions, making them suitable for therapeutic (photothermal therapy and photodynamic therapy) and diagnostic applications. In the context of wound healing, these nanoparticles can be combined with other materials such as hydrogels, fibers, metal-organic frameworks (MOFs), graphene oxide, etc., to enhance the healing process and prevent the growth of microbial infections. Notably, UCNPs can act as sensors for real-time monitoring of the wound healing progress, providing valuable feedback to healthcare professionals. Despite their potential, the use of UCNPs in wound dressing applications faces several challenges. Ensuring the stability and biocompatibility of UCNPs under physiological conditions is crucial for their effective integration into dressings. Comprehensive safety and efficacy evaluations are necessary to understand potential risks and optimize UCNP-based dressings. Scalability and cost-effectiveness of UCNP synthesis and manufacturing processes are important considerations for practical applications. In addition, efficient incorporation of UCNPs into dressings, achieving uniform distribution, poses an important challenge that needs to be addressed. Future research should prioritize addressing concerns regarding stability and biocompatibility, efficient integration into dressings, rigorous safety evaluation, scalability, and cost-effectiveness. The purpose of this review is to critically evaluate the advantages, challenges, and key properties of UCNPs in wound dressing applications to provide insights into their potential as innovative solutions for enhancing wound healing outcomes. We have provided a detailed description of various types of smart wound dressings, focusing on the synthesis and biomedical applications of UCNPs, specifically their utilization in different types of wound dressings.

Preparation of polyvinyl alcohol/chitosan nanofibrous films incorporating graphene oxide and lanthanum chloride by electrospinning method for potential photothermal and chemical synergistic antibacterial applications in wound dressings

Electrospun fibres have been widely used as skin dressings due to their unique structur. However, due to the lack of intrinsic antimicrobial activity, it is easy for the wound to become infected. Bacterial infection, which leads to chronic inflammation, severely hinders the normal process of skin regeneration. In this study, a polyvinyl alcohol/chitosan (PVA/CS) composite films with chemical sterilization and near-infrared (NIR) photothermal antibacterial activity was fabricated by electrospinning. Graphene oxide (GO), a photosensitiser, was incorporated into the films, and lanthanum chloride (Lacl3) as a chemical antibacterial agent was also doped in the electrospun films. The structure, morphology, mechanical properties, wettability, and antimicrobial and photothermal antibacterial activity of the PVA/CS-based fibre films were investigated. The results showed that the addition of Lacl3 to the PVA/CS/GO nanofibres (PVA/CS/GO-La) improved the hydrophilicity, tensile strength and resistance to elastic deformation of the nanofibres. The PVA/CS/GO-La12.5 mM sample exhibited the best antibacterial performance, showing high inhibition against Staphylococcus aureus (82% antibacterial efficacy) and Escherichia coli (99.7% antibacterial efficacy). Furthermore, the antibacterial efficacy of the films surface was further enhanced after exposure to NIR light (808 nm, 0.01 W) for 20 min. In addition, the nanofibre films showed no cytotoxicity against human skin fibroblasts (HSFs), indicating its potential application in the field of broad-spectrum antibacterial materials.

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.

Animal tissue-derived biomaterials for promoting wound healing

The skin serves as the primary barrier between the human body and external environment, and is therefore susceptible to damage from various factors. In response to this challenge, animal tissue-derived biomaterials have emerged as promising candidates for wound healing due to their abundant sources, low side-effect profiles, exceptional bioactivity, biocompatibility, and unique extracellular matrix (ECM) mimicry. The evolution of modern engineering technology and therapies has allowed these animal tissue-derived biomaterials to be transformed into various forms and modified to possess the necessary properties for wound repair. This review provides an overview of the wound healing process and the factors that influence it. We then describe the extraction methods, important properties, and recent practical applications of various animal tissue-derived biomaterials. Our focus then shifts to the critical properties of these biomaterials in skin wound healing and their latest research developments. Finally, we critically examine the limitations and future prospects of biomaterials generated from animal tissues in this field.

Influence of Lanthanum Doping on the Photocatalytic and Antibacterial Capacities of Mg0.33Ni0.33Co0.33Fe2O4 Nanoparticles

The increase in environmental pollution, especially water pollution, has intensified the requirement for new strategies for the treatment of water sources. Furthermore, the improved properties of nano-ferrites permit their usage in wastewater treatment. In this regard, novel Mg0.33Ni0.33Co0.33LaxFe2−xO4 nanoparticles (NPs), where 0.00≤x≤0.08, were synthesized to test their photocatalytic, antibacterial and antibiofilm activities. The structural and optical properties of the prepared NPs were investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), UV-Vis spectroscopy and photoluminescence (PL) analysis. As La content increases, the bandgap energy increases, whereas the particle size decreases. The photocatalytic activity of the prepared NPs is evaluated by the degradation of methylene blue (MB) dye under sunlight irradiation. Superior activity is exhibited by Mg0.33Ni0.33Co0.33La0.01Fe1.99O4 NPs. The influence of catalyst dosage, pH, temperature and addition of graphene (Gr) on the photodegradation reaction was studied. Increasing the pH and temperature improved the rate of the photodegradation reaction. The antibacterial and antibiofilm activities of the NPs were assessed against Escherichia coli, Leclercia adecarboxylata, Staphylococcus aureus and Enterococcus faecium. Mg0.33Ni0.33Co0.33Fe2O4 NPs inhibited bacterial growth. They had bacteriostatic activity on all isolates, with a greater effect on Gram-positive bacteria. All tested nano-ferrites had significant antibiofilm activities against some biofilms.

A novel antibacterial and fluorescent coating composed of polydopamine and carbon dots on the surface of orthodontic brackets

Many kinds of antibacterial coatings have been designed to prevent the adherence of bacteria onto the surface of a fixed orthodontic device of brackets. However, the problems such as weak binding force, undetectable, drug resistance, cytotoxicity and short duration needed to be solved. Thus, it has great value in developing novel coating methods with long-term antibacterial and fluorescence properties according to the clinical application of brackets. In this study, we synthesized blue fluorescent carbon dots (HCDs) using the traditional Chinese medicinal honokiol, which could cause irreversible killing effects on both gram-positive and gram-negative bacteria through positive charges on the surface and inducing reactive oxygen species (ROS) production. Based on this, the surface of brackets was serially modified with polydopamine and HCDs, taking advantage of the strong adhesive properties as well as the negative surface charge of polydopamine particles. It is found that this coating exhibits stable antibacterial properties in 14 days with good biocompatibility, which can provide a new solution and strategy to solve the series of hazards caused by bacterial adhesion on the surface of orthodontic brackets.

Emerging and Versatile Platforms of Metal-Ion-Doped Carbon Dots for Biosensing, Bioimaging, and Disease Therapy

Metal ions possess abundant electrons and unoccupied orbitals, as well as large atomic radii, whose doping into carbon dots (CDs) is a facile strategy to endow CDs with additional physicochemical characteristics. After being doped with metal ions, CDs reveal obvious changes in their optical, electronic, and magnetic properties by adjustments to their electron density distribution and the energy gaps, leading them to be promising and competitive candidates as labeling probes, imaging agents, catalysts, nanodrugs, and so on. In this review, we summarize the fabrication methods of metal-ion-doped CDs (M-CDs), and highlight their biological applications including biosensing, bioimaging, tumor therapy, and anti-microbial treatment. Finally, the challenging future perspectives of M-CDs are analyzed. We hope this review will provide inspiration for further development of M-CDs in various biological aspects, and help readers who are interested in M-CDs and their biological applications.

A comprehensive review on the applications of carbon-based nanostructures in wound healing: from antibacterial aspects to cell growth stimulation

A wound is defined as damage to the integrity of biological tissue, including skin, mucous membranes, and organ tissues. The treatment of these injuries is an important challenge for medical researchers. Various materials have been used for wound healing and dressing applications among which carbon nanomaterials have attracted significant attention due to their remarkable properties. In the present review, the latest studies on the application of carbon nanomaterials including graphene oxide (GO), reduced graphene oxide (rGO), carbon dots (CDs), carbon quantum dots (CQDs), carbon nanotubes (CNTs), carbon nanofibers (CNFs), and nanodiamonds (NDs) in wound dressing applications are evaluated. Also, a variety of carbon-based nanocomposites with advantages such as biocompatibility, hemocompatibility, reduced wound healing time, antibacterial properties, cell-adhesion, enhanced mechanical properties, and enhanced permeability to oxygen has been reported for the treatment of various wounds.

Enhanced antibacterial activity with increasing P doping ratio in CQDs

It is an urgent challenge to develop efficient antibacterial agents against resistant bacteria in the treatment of infectious diseases. Carbon quantum dots (CQDs) have attracted much attention owing to their good stability, low toxicity and excellent biocompatibility. In this work, CQDs doped with different contents of the element phosphorus (P) were prepared by a simple hydrothermal method using valine as a carbon source, triethylamine as a nitrogen source and different volumes of phosphoric acid as a phosphorus source. The average diameter and the surface charge could be regulated from 2.89 nm to 1.56 nm and +2.58 mV to +5.47 mV by increasing the content of the element P in these CQDs. Importantly, these CQDs showed effective bacterial inhibition against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The minimal inhibitory concentration (MIC) decreased from 0.71, to 0.51 to 0.18 mg mL-1 on E. coli and S. aureus with the increase of P element content. Furthermore, the morphologies of E. coli cells and S. aureus were damaged and became irregular upon treatment with these CQDs. The results of singlet oxygen (1O2) detection demonstrated that intracellular 1O2 was generated during the antibacterial process. We speculated that bacterial inhibition induced by these CQDs was accompanied by disruption of permeability and structural integrity, owing to strong electrostatic interactions between negatively charged bacteria and positively charged CQDs and production of singlet oxygen of CQDs. Together, this study indicates that the CQDs can be a candidate to treat resistant bacterial infections and may improve the understanding of killing pathogens by antibacterial CQD drugs.

Antibacterial Theranostic Agents with Negligible Living Cell Invasiveness: AIE-Active Cationic Amphiphiles Regulated by Alkyl Chain Engineering

To address the threat of bacterial infection in the following post-antibiotic era, developing effective antibacterial approaches is of utmost urgency. Theranostic medicine integrating diagnosis and therapy is a promising protocol to fight against pathogenic bacteria. But numerous reported antibacterial theranostic materials are disclosed to be trapped in the excessive invasiveness to living mammal cells, leading to false positives and possible biosafety risks. Herein, a series of cationic pyridinium-substituted phosphindole oxide derivatives featuring aggregation-induced emission are designed, and alkyl chain engineering is conducted to finely tune their hydrophobicity and investigate their bioaffinity preference for living mammal cells and pathogenic bacteria. Most importantly, an efficient theranostic agent (PyBu-PIO) is acquired that is free from living cell invasiveness with negligible cytotoxicity and yet holds a good affinity for Gram-positive bacteria, including drug-resistant strains, with a superior inactivating effect. Externally applying PyBu-PIO onto Gram-positive bacteria-infected skin wounds can achieve creditable imaging effects and successfully accelerate the healing processes with reliable biosafety. This work proposes living cell invasiveness as a criterion for antibacterial theranostic materials and provides important enlightenment for the design of antibacterial theranostic materials.

Polymeric biomaterials for wound healing applications: a comprehensive review

Chronic wounds have been a global health threat over the past few decades, requiring urgent medical and research attention. The factors delaying the wound-healing process include obesity, stress, microbial infection, aging, edema, inadequate nutrition, poor oxygenation, diabetes, and implant complications. Biomaterials are being developed and fabricated to accelerate the healing of chronic wounds, including hydrogels, nanofibrous, composite, foam, spongy, bilayered, and trilayered scaffolds. Some recent advances in biomaterials development for healing both chronic and acute wounds are extensively compiled here. In addition, various properties of biomaterials for wound-healing applications and how they affect their performance are reviewed. Based on the recent literature, trilayered constructs appear to be a convincing candidate for the healing of chronic wounds and complete skin regeneration because they mimic the full thickness of skin: epidermis, dermis, and the hypodermis. This type of scaffold provides a dense superficial layer, a bioactive middle layer, and a porous lower layer to aid the wound-healing process. The hydrophilicity of scaffolds aids cell attachment, cell proliferation, and protein adhesion. Other scaffold characteristics such as porosity, biodegradability, mechanical properties, and gas permeability help with cell accommodation, proliferation, migration, differentiation, and the release of bioactive factors.

Synthesis of Doped/Hybrid Carbon Dots and Their Biomedical Application

Carbon dots (CDs) are a novel type of carbon-based nanomaterial that has gained considerable attention for their unique optical properties, including tunable fluorescence, stability against photobleaching and photoblinking, and strong fluorescence, which is attributed to a large number of organic functional groups (amino groups, hydroxyl, ketonic, ester, and carboxyl groups, etc.). In addition, they also demonstrate high stability and electron mobility. This article reviews the topic of doped CDs with organic and inorganic atoms and molecules. Such doping leads to their functionalization to obtain desired physical and chemical properties for biomedical applications. We have mainly highlighted modification techniques, including doping, polymer capping, surface functionalization, nanocomposite and core-shell structures, which are aimed at their applications to the biomedical field, such as bioimaging, bio-sensor applications, neuron tissue engineering, drug delivery and cancer therapy. Finally, we discuss the key challenges to be addressed, the future directions of research, and the possibilities of a complete hybrid format of CD-based materials.

A bacteria-triggered wearable colorimetric band-aid for real-time monitoring and treating of wound healing

Early diagnosis of bacterial infection and tracking of treatment effect are of great importance for developing a "sense-and-treat" integrated system. Herein, we developed a bacteria-triggered, portable, wearable and colorimetric film-based band-aid (FBA) for closed-loop monitoring and light-controlled therapy of wound infection. FBA with high photothermal conversion efficiency of 52.56% was prepared by wrapping Bi₂S₃ nanoflowers (BS NFs) loaded with rhodium nanoparticles (Rh NPs) and bromothymol blue (BTB) into LB agar film, integrating bacteria-triggered color change, photothermal/photodynamic therapy (PTT/PDT) synergistic bactericidal therapy and agar-based band aid in one intelligent system. Initially, FBA effectively simulates the pH sensing mechanism, and monitors the occurrence of bacterial infections within 5 min through color changes of Staphylococcus aureus (S. aureus) from blue to yellow and Escherichia coli (E. coli) from yellow to blue. Additionally, the short-term and controlled antibacterial strategy of "one light dual-mode responses" (photothermal and photodynamic responses) was implemented with the introduce of near-infrared (NIR). Ultimately, the effectiveness of FBA was fully validated in the monitoring and treating of S. aureus-infected mouse wounds. Notably, the designed FBA decisively abandoned off-target side effects maximizing the treatment effect and nakedly tracking therapeutic situation in real time, contributing an effective antibacterial alternative strategy for reducing the use of antibiotics. To the best of our knowledge, such integrated system is still unreported on film-fixed model. In view of the advantages of the low cost and convenience of the simple device, the integrated design is expected to provide a solution for the development of a closed-loop biomedical system combining diagnosis and treatment.