Transparent Copper-Based Antibacterial Coatings with Enhanced Efficacy against Pseudomonas aeruginosa

Computational and Experimental Study of Metal-Organic Frameworks (MOFs) as Antimicrobial Agents against Neisseria gonorrhoeae

The emergence of drug-resistant superbugs poses a critical global health threat, necessitating innovative treatment strategies. Neisseria gonorrhoeae (Ng) causes a sexually transmitted disease called gonorrhea, and the bacterium has shown alarming resistance to conventional antibiotics, underscoring the urgent need for novel therapeutic approaches. In the current study, we interfaced computational biology and materials science to investigate the interactions between in-house synthesized metal-organic frameworks (MOFs) and the penicillin-binding protein 2 (PBP2) of Ng, a key target for β-lactam antibiotics. Using molecular docking and interaction analyses, we identified three promising MOFs, namely, Fe-BDC-258445, Cu-BDC-687690, and Ni-BDC-638866, with optimum binding scores and stable interactions. These scores indicated strong interactions with PBP2, suggesting their potential as therapeutic agents. Antimicrobial screening using a standard disk diffusion assay demonstrated that the Cu-BDC MOFs were bactericidal for multiple strains of Ng, whereas the Ni-BDC and Fe-BDC MOFs were nonbactericidal. The Cu-BDC MOF did not kill other Gram-negative bacteria, thus demonstrating specificity for Ng, and showed low toxicity for human Chang conjunctival epithelial cells in vitro. No significant leaching with biological activity was observed for the Cu-BDC MOF, and microscopy demonstrated the loss of gonococcal piliation and damage to the cell membrane. These findings underscore the potential of Cu-BDC MOFs as antimicrobial agents for further development.

Photothermal Antibacterial and Osteoinductive Polypyrrole@Cu Implants for Biological Tissue Replacement

The treatment of bone defects caused by disease or accidents through the use of implants presents significant clinical challenges. After clinical implantation, these materials attract and accumulate bacteria and hinder the integration of the implant with bone tissue due to the lack of osteoinductive properties, both of which can cause postoperative infection and even lead to the eventual failure of the operation. This work successfully prepared a novel biomaterial coating with multiple antibacterial mechanisms for potent and durable and osteoinductive biological tissue replacement by pulsed PED (electrochemical deposition). By effectively regulating PPy (polypyrrole), the uniform composite coating achieved sound physiological stability. Furthermore, the photothermal analysis showcased exceptional potent photothermal antibacterial activity. The antibacterial assessments revealed a bacterial eradication rate of 100% for the PPy@Cu/PD composite coating following a 24 h incubation. Upon the introduction of NIR (near-infrared) irradiation, the combined effects of multiple antibacterial mechanisms led to bacterial reduction rates of 99% for E. coli and 98% for S. aureus after a 6 h incubation. Additionally, the successful promotion of osteoblast proliferation was confirmed through the application of the osteoinductive drug PD (pamidronate disodium) on the composite coating's surface. Therefore, the antimicrobial Ti-based coatings with osteoinductive properties and potent and durable antibacterial properties could serve as ideal bone implants.

Mussel-Inspired Antimicrobial and Antifouling Coating Constructed by the Combination of Zwitterionic Copolymers and Silver Nanoparticles

Biofouling and bacterial infections are significant challenges in biomedical devices. In this study, a biocompatible dual-functional coating with antimicrobial and antifouling properties is developed by co-depositing the zwitterionic copolymer and silver nanoparticles via a dopamine-assisted strategy. Inspired by mussel adhesion, the coating exhibits substrate-independent adhesion as a result of the formation of irreversible covalent bonds. The zwitterionic copolymer in the dual coating plays a crucial role in improving surface wettability and reducing protein adsorption and platelet and bacterial adhesion, thereby improving its antifouling property significantly. The silver nanoparticles reduced by self-polymerized polydopamine without the addition of any chemical reductants can effectively improve the antimicrobial activity. Furthermore, as the zwitterion content in the zwitterion polymer increases, the antibacterial and antifouling properties of the coating can be further advanced. The simple and effective approach presented here provides a promising pathway for constructing potent antibacterial and antifouling surfaces, demonstrating great potential for clinical applications in implanted materials.

Effect of Low Copper Doping on the Optical, Cytocompatible, Antibacterial, and SARS-CoV-2 Trapping Properties of Calcium Phosphate Glasses

Calcium phosphate glasses (CPGs) are acquiring great importance in the biomedical field because of their thermomechanical and bioresorbable properties. In this study, optically transparent copper (1 mol %)-doped calcium phosphate glasses (CPGs_Cu) were prepared through the melt-quenching method, and their biocompatibility and antibacterial and antiviral properties were evaluated and compared with undoped CPGs. Biocompatibility was evaluated on murine fibroblast NIH-3T3 cells as a preliminary study of cytocompatibility. The in vitro tests were performed through indirect and direct cytotoxicity analyses by MTT and Alamar Blue assays and supported by electron microscopy observations. Microbiological analyses were performed against the most common Gram-negative and Gram-positive pathogens that cause nosocomial infections: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and the methicillin-resistant Staphylococcus aureus strain. In addition, the bioglass samples were exposed to SARS-CoV-2 to assess their effects on viral survival. The obtained results assessed the biocompatibility of both bioglass types and their ability to reduce the viral load and trap the virus. In addition, Cu2+-doped bioglass was found to be antibacterial despite its low content (1 mol %) of copper, making this a promising candidate material for biomedical applications, e.g., surgery probes, drug delivery, and photodynamic therapy.

Differential Analysis of Three Copper-Based Nanomaterials with Different Morphologies to Suppress Alternaria alternata and Safety Evaluation

The overuse of copper-based fertilizers and pesticides over the last few decades has resulted in detrimental risks to our environment. Nano-enabled agrichemicals with a high effective utilization ratio have shown great potential for maintaining or minimizing environmental issues in agriculture. Copper-based nanomaterials (Cu-based NMs) serve as a promising alternative to fungicides. Three types of Cu-based NMs with different morphologies were analyzed for their different antifungal effects on Alternaria alternata in this current study. Compared to commercial copper hydroxide water power (Cu(OH)₂ WP), all tested Cu-based NMs, including cuprous oxide nanoparticles (Cu₂O NPs), copper nanorods (Cu NRs) and copper nanowires (Cu NWs), especially Cu₂O NPs and Cu NWs, showed higher antifungal activity against Alternaria alternata. Its EC₅₀ were 104.24 and 89.40 mg L^-1, respectively, achieving comparable activity using a dose approximately 1.6 and 1.9-fold lower. Cu-based NMs could introduce the downregulation of melanin production and soluble protein content. In contrast to trends in antifungal activity, Cu₂O NPs showed the strongest power in regulating melanin production and protein content and similarly exhibited the highest acute toxicity to adult zebrafish compared to other Cu-based NMs. These results demonstrate that Cu-based NMs could offer great potential in plant disease management strategies.

Highly Durable Antimicrobial Tantalum Nitride/Copper Coatings on Stainless Steel Deposited by Pulsed Magnetron Sputtering

Highly durable and antimicrobial tantalum nitride/copper (TaN/Cu) nanocomposite coatings were deposited on D-9 stainless steel substrates by pulsed magnetron sputtering. The Cu content in the coating was varied in the range of 1.42-35.42 atomic % (at.%). The coatings were characterized by electron probe microanalyzer, X-ray diffraction, scanning electron microscope and atomic force microscope. The antibacterial properties of the TaN/Cu coatings against gram-negative Pseudomonas aeruginosa were evaluated using a cell culture test. The peak hardness and Young's modulus of TaN/Cu with 10.46 at.% Cu were 24 and 295 GPa, respectively, which amounted to 15 and 41.67% higher than Cu-free TaN. Among all, TaN/Cu with 10.46 at.% exhibited the lowest friction coefficient. The TaN/Cu coatings exhibited significantly higher antibacterial activity than Cu-free TaN against Pseudomonas aeruginosa. On TaN, the bacterial count was about 4 × 10⁶ CFU, whereas it was dropped to 1.2 × 10² CFU in case of TaN/Cu with 10.46 at.% Cu. The bacterial count was decreased from 9 to 6 when the Cu content increased from 25.54 to 30.04 at.%. Live bacterial cells were observed in the SEM images of TaN, and dead cells were found on TaN/Cu. Overall, TaN/Cu with 10.46 at.% Cu was found to be a potential coating composition in terms of higher antimicrobial activity and mechanical durability.

Recent Progress on Bioinspired Antibacterial Surfaces for Biomedical Application

Surface bacterial fouling has become an urgent global challenge that calls for resilient solutions. Despite the effectiveness in combating bacterial invasion, antibiotics are susceptible to causing microbial antibiotic resistance that threatens human health and compromises the medication efficacy. In nature, many organisms have evolved a myriad of surfaces with specific physicochemical properties to combat bacteria in diverse environments, providing important inspirations for implementing bioinspired approaches. This review highlights representative natural antibacterial surfaces and discusses their corresponding mechanisms, including repelling adherent bacteria through tailoring surface wettability and mechanically killing bacteria via engineering surface textures. Following this, we present the recent progress in bioinspired active and passive antibacterial strategies. Finally, the biomedical applications and the prospects of these antibacterial surfaces are discussed.

Inorganic Nanoparticles in Bone Healing Applications

Modern biomedicine aims to develop integrated solutions that use medical, biotechnological, materials science, and engineering concepts to create functional alternatives for the specific, selective, and accurate management of medical conditions. In the particular case of tissue engineering, designing a model that simulates all tissue qualities and fulfills all tissue requirements is a continuous challenge in the field of bone regeneration. The therapeutic protocols used for bone healing applications are limited by the hierarchical nature and extensive vascularization of osseous tissue, especially in large bone lesions. In this regard, nanotechnology paves the way for a new era in bone treatment, repair and regeneration, by enabling the fabrication of complex nanostructures that are similar to those found in the natural bone and which exhibit multifunctional bioactivity. This review aims to lay out the tremendous outcomes of using inorganic nanoparticles in bone healing applications, including bone repair and regeneration, and modern therapeutic strategies for bone-related pathologies.

Gallium-Curcumin Nanoparticle Conjugates as an Antibacterial Agent against Pseudomonas aeruginosa: Synthesis and Characterization

Combating antibiotic resistance has found great interest in the current clinical scenario. Pseudomonas aeruginosa, an opportunistic multidrug-resistant pathogen, is well known for its deadly role in hospital-acquired infections. Infections by P. aeruginosa are among the toughest to treat because of its intrinsic and acquired resistance to antibiotics. In this study, we project gallium-curcumin nanoparticle (GaCurNP) conjugates as a prospective candidate to fight against P. aeruginosa. The synthesized GaCurNPs were spherical with an average size ranging from 25-35 nm. Analysis by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy deduced the nature of interaction between gallium and curcumin. Conjugate formation with gallium was found to improve the stability of curcumin at the physiological pH. When tested after 24 h of contact, at the physiological pH and 37 °C, the degradation of curcumin bound in the GaCurNPs was 26%, while that of native curcumin was 95%. The minimum inhibitory concentration (MIC) of GaCurNPs was found to be 82.75 μg/mL for P. aeruginosa (ATCC 27853). GaCurNPs also showed excellent biofilm inhibition at 4MIC concentration. Raman spectroscopic analysis showed that GaCurNPs are capable of disrupting the cells of P. aeruginosa within 3 h of contact. Live/dead imaging also confirmed the compromised membrane integrity in cells treated with GaCurNPs. Scanning electron microscopy analysis showed membrane lysis and cell structure damage. The AlamarBlue assay showed that when L929 cell lines were treated with GaCurNPs with concentrations as high as 350 μg/mL, the cell viability elicited by the nanoparticles was 70.89%, indicating its noncytotoxic nature. In short, GaCurNPs appear to be a promising antibacterial agent capable of fighting a clinically significant pathogen, P. aeruginosa.

High-efficiency synthesis of Cu superfine particles via reducing cuprous and cupric oxides with monoethanolamine and their antimicrobial potentials

Cuprous oxide (Cu₂O) and cupric oxide (CuO) are widely available and low cost raw materials. Their applications as precursors for wet chemical synthesis of metallic Cu materials are greatly limited due to their insoluble in water and most organic solvents. In this work, copper superfine particles (Cu SPs) are synthesized using Cu₂O and CuO as precursors via a heating process in monoethanoamine (MEA). Due to the strong coordinating character, Cu₂O and CuO can be partially dissolved in MEA. The dissolved copper source is reduced by MEA at elevated temperature with the drastically releasing of NH₃. As the dissolved copper source is reduced, more oxide will be dissolved and finally leads to the full reduction of Cu₂O and CuO to produce the Cu SPs. The advantage of this synthesis method is that MEA acts as both the solvent and the reducing agent. The antimicrobial properties are investigated to find that the obtained Cu SPs depress the growth of Escherichia coli (E. coli) and Staphylococcus aureus (St. aureus) efficiently. More interesting, the composites produced via curing Cu₂O and CuO with a small amount of MEA also exhibit excellent antimicrobial activity, indicating the MEA curing method is high-efficiency. The synthesis is low cost, high-efficiency, high atom-economy and up-scale synthesizing easily, which will benefit the wide applications of Cu SPs.

A low-swelling and toughened adhesive hydrogel with anti-microbial and hemostatic capacities for wound healing

Hydrogel-based wound dressings with tissue adhesion abilities are widely used for wound closure. However, currently developed hydrogel adhesives are still poor at continuing to seal wounds while bleeding is ongoing. Herein, we demonstrate an antibacterial and hemostatic hydrogel adhesive with low-swelling properties and toughness for wound healing. The hydrogel was composed of Pluronic F127 diacrylate, quaternized chitosan diacrylate, silk fibroin, and tannic acid, and it was not only able to maintain good tissue adhesion abilities in a moist environment but it also showed guaranteed tissue adhesion and mechanical strength after absorbing water due to its low-swelling and toughness properties. Furthermore, in vitro and in vivo tests demonstrated that the hydrogel also had antibacterial, antioxidant, and hemostatic properties, which could promote tissue regeneration. All these findings demonstrate that this hydrogel with multifunctional properties is a promising material for clinical wound healing applications.

Adhesive Antimicrobial Peptides Containing 3,4-Dihydroxy-L-Phenylalanine Residues for Direct One-Step Surface Coating

Bacterial colonization and transmission via surfaces increase the risk of infection. In this study, we design and employ novel adhesive antimicrobial peptides to prevent bacterial contamination of surfaces. Repeats of 3,4-dihydroxy-L-phenylalanine (DOPA) were added to the C-terminus of NKC, a potent synthetic antimicrobial peptide, and the adhesiveness and antibacterial properties of the resulting peptides are evaluated. The peptide is successfully immobilized on polystyrene, titanium, and polydimethylsiloxane surfaces within 10 min in a one-step coating process with no prior surface functionalization. The antibacterial effectiveness of the NKC-DOPA₅-coated polystyrene, titanium, and polydimethylsiloxane surfaces is confirmed by complete inhibition of the growth of Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus within 2 h. The stability of the peptide coated on the substrate surface is maintained for 84 days, as confirmed by its bactericidal activity. Additionally, the NKC-DOPA₅-coated polystyrene, titanium, and polydimethylsiloxane surfaces show no cytotoxicity toward the human keratinocyte cell line HaCaT. The antimicrobial properties of the peptide-coated surfaces are confirmed in a subcutaneous implantation animal model. The adhesive antimicrobial peptide developed in this study exhibits potential as an antimicrobial surface-coating agent for efficiently killing a broad spectrum of bacteria on contact.

Copper-based biomaterials for bone and cartilage tissue engineering

BACKGROUD

Tissue engineering using cells, scaffolds, and bioactive molecules can promote the repair and regeneration of injured tissues. Copper is an essential element for the human body that is involved in many physiological activities and in recent years, copper has been used increasingly in tissue engineering.

METHODS

The current advances of copper-based biomaterial for bone and cartilage tissue engineering were searched on PubMed and Web of Science.

RESULTS

Various forms of copper-based biomaterials, including pure copper, copper ions, copper nanoparticles, copper oxides, and copper alloy are introduced. The incorporation of copper into base materials provides unique properties, resulting in tuneable porosity, mechanical strength, degradation, and crosslinking of scaffolds. Copper also shows promising biological performance in cell migration, cell adhesion, osteogenesis, chondrogenesis, angiogenesis, and antibacterial activities. In vivo applications of copper for bone and cartilage tissue engineering are discussed.

CONCLUSION

This review focuses on copper's physiochemical and biological effects, and its applications in bone and cartilage tissue engineering. The potential limitations and future perspectives are also discussed.

TRANSLATIONAL POTENTIAL OF THIS ARTICLE

This review introduces the recent advances in copper-based biomaterial for bone and cartilage tissue engineering. This revie could guide researchers to apply copper in biomaterials, improving the generation of bone and cartilages, decrease the possibility of infection and shorten the recovery time so as to decrease medical costs.

Microbial corrosion of metals: The corrosion microbiome

Microbially catalyzed corrosion of metals is a substantial economic concern. Aerobic microbes primarily enhance Fe⁰ oxidation through indirect mechanisms and their impact appears to be limited compared to anaerobic microbes. Several anaerobic mechanisms are known to accelerate Fe⁰ oxidation. Microbes can consume H₂ abiotically generated from the oxidation of Fe⁰. Microbial H₂ removal makes continued Fe⁰ oxidation more thermodynamically favorable. Extracellular hydrogenases further accelerate Fe⁰ oxidation. Organic electron shuttles such as flavins, phenazines, and possibly humic substances may replace H₂ as the electron carrier between Fe⁰ and cells. Direct Fe⁰-to-microbe electron transfer is also possible. Which of these anaerobic mechanisms predominates in model pure culture isolates is typically poorly documented because of a lack of functional genetic studies. Microbial mechanisms for Fe⁰ oxidation may also apply to some other metals. An ultimate goal of microbial metal corrosion research is to develop molecular tools to diagnose the occurrence, mechanisms, and rates of metal corrosion to guide the implementation of the most effective mitigation strategies. A systems biology approach that includes innovative isolation and characterization methods, as well as functional genomic investigations, will be required in order to identify the diagnostic features to be gleaned from meta-omic analysis of corroding materials. A better understanding of microbial metal corrosion mechanisms is expected to lead to new corrosion mitigation strategies. The understanding of the corrosion microbiome is clearly in its infancy, but interdisciplinary electrochemical, microbiological, and molecular tools are available to make rapid progress in this field.

Antifouling and Antibacterial Polymer-Coated Surfaces Based on the Combined Effect of Zwitterions and the Natural Borneol

The development and application of natural antibacterial materials have always been the focus of biomedical research. Borneol as a natural antibacterial compound has received extensive attention. However, the hydrophobicity caused by its unique structure limits its application range to a certain extent. In this study, we combine zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) with a complex bicyclic monoterpene structure borneol compound and prepare an excellent antifouling and antibacterial surface via the Schiff-base bond. The prepared coating has excellent hydrophilicity verified by the contact angle (CA), and its polymer layer is confirmed by X-ray photoelectron spectroscopy (XPS). The zwitterion MPC and borneol moieties in the copolymer play a coordinating role, relying on super hydration and the special stereochemical structure to prevent protein adsorption and inhibit bacterial adhesion, respectively, which are demonstrated by bovine serum albumin (BSA) adsorption and antibacterial activity test. Moreover, the water-soluble borneol derivative as the antibacterial surfaces we designed here was biocompatible toward MRC-5 (lung fibroblasts), as showed by in vitro cytotoxicity assays. Such results indicate the potential application of the as-prepared hydrophilic surfaces in the biomedical materials.

Robust anti-infective multilayer coatings with rapid self-healing property

Surface coatings are extensively applied on biomedical devices to provide protection against biofouling and infections. However, most surface coatings prevent both bacteria and cells interactions with the biomaterials, limiting their uses as implants. Furthermore, damage to the surface such as scratches and abrasions can happen during transport and clinical usage, resulting in the loss of antibacterial property. In this work, we introduce an efficient method to fabricate stable anti-infective and self-healable multilayer coatings on stainless steel surface via a three-step procedue. Firstly, modified polyethyleneimine (PEI) and poly(acrylic acid) (PAA), both contain pendant furan groups, were deposited on the surface using Layer-by-Layer (LbL) self-assembly technique. Secondly, the polymer layers were cross-linked, via Diels-Alder cycloaddition, using a bismaleimide poly(ethylene glycol) linker, to enhance the stability of the coatings. Thirdly, the Diels-Alder adduct was utilised in the thiol-ene click reaction for post-modification of the coatings, which allowed for the grafting of antimicrobial poly(hexamethylene biguanide) (PHMB) and ε-poly(lysine) (EPL). The resultant multilayer coatings not only exhibited rapid self-healing property, with complete scratch closure within 30 min, but also demonstrated effective antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In addition, biofouling of bovine serum albumin was found to be inhibited on the coated surfaces. Furthermore, these coatings showed no toxicity effect towards seeded osteoblastic cells (MC3T3-E1) and evidence of anti-inflamatory activity when tested against macrophage cell line U-937. Our coating method thus represents an effective strategy for the anti-infective protection of biomedical-devices having direct contact with tissues.

Antibacterial and Antiviral Functional Materials: Chemistry and Biological Activity toward Tackling COVID-19-like Pandemics

The ongoing worldwide pandemic due to COVID-19 has created awareness toward ensuring best practices to avoid the spread of microorganisms. In this regard, the research on creating a surface which destroys or inhibits the adherence of microbial/viral entities has gained renewed interest. Although many research reports are available on the antibacterial materials or coatings, there is a relatively small amount of data available on the use of antiviral materials. However, with more research geared toward this area, new information is being added to the literature every day. The combination of antibacterial and antiviral chemical entities represents a potentially path-breaking intervention to mitigate the spread of disease-causing agents. In this review, we have surveyed antibacterial and antiviral materials of various classes such as small-molecule organics, synthetic and biodegradable polymers, silver, TiO2, and copper-derived chemicals. The surface protection mechanisms of the materials against the pathogen colonies are discussed in detail, which highlights the key differences that could determine the parameters that would govern the future development of advanced antibacterial and antiviral materials and surfaces.

Highly efficient and durable antibacterial cotton fabrics finished with zwitterionic polysulfobetaine by one-step eco-friendly strategy

In this work, a novel formulation of polysulfobetaine, poly (sulfobetaine-acrylamide-allyl glycidyl ether) (PSPB-AM-AGE), was synthesized and grafted onto cotton. The synthesis of PSPB-AM-AGE and its grafting on the cotton fabrics were confirmed by FTIR, XPS and SEM. The PSPB-AM-AGE treated cotton fabrics exhibited a high level of antibacterial rate against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), which are 95.18% and 98.74%, separately, as well as a good laundry durability. The mechanical tests showed that the essential cotton properties can be largely preserved in the treatment process. Moreover, the hydrophilicity, air and water permeability of the cotton were improved after treated with PSPB-AM-AGE, indicating a better wearing comfort performance. The whiteness of the cotton fabrics did not decrease significantly. The safety evaluation demonstrated that PSPB-AM-AGE had no cytotoxicity. The developed antibacterial finishing introduced a new method to apply polysulfobetaine interfaced on cellulose, providing great potential for biomedical fabric application.

Antimicrobial Copper-Based Materials and Coatings: Potential Multifaceted Biomedical Applications

Surface contamination by microbes leads to several detrimental consequences like hospital- and device-associated infections. One measure to inhibit surface contamination is to confer the surfaces with antimicrobial properties. Copper's antimicrobial properties have been known since ancient times, and the recent resurgence in exploiting copper for application as antimicrobial materials or coatings is motivated by the growing concern about antibiotic resistance and the pressure to reduce antibiotic use. Copper, unlike silver, demonstrates rapid and high microbicidal efficacy against pathogens that are in close contact under ambient indoor conditions, which enhances its range of applicability. This review highlights the mechanisms behind copper's potent antimicrobial property, the design and fabrication of different copper-based antimicrobial materials and coatings comprising metallic copper/copper alloys, copper nanoparticles or ions, and their potential for practical applications. Finally, as the antimicrobial coatings market is expected to grow, we offer our perspectives on the implications of increased copper release into the environment and the potential ecotoxicity effects and possibility of development of resistant genes in pathogens.

Poly(γ-glutamic acid)-based electrospun nanofibrous mats with photodynamic therapy for effectively combating wound infection

Pathogenic bacterial infections associated with wound healing progress usually result in serious complications. Herein, biocompatible and antimicrobial electrospun nanofibrous mats with photodynamic therapy (PDT) effect were fabricated to accelerate the infected wound healing. The nanofibrous mats were fabricated by co-electrospining of polyanionic poly(γ-glutamic acid) (γ-PGA) and cationic photosensitizer 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin tetra (p-toluenesulfonate) (TMPyP) in aqueous solution and stabilized by the chemical crosslinking. The as-prepared nanofibrous mats can not only confer the moist microenvironment to the wound bed, but also provide potent bactericidal activity upon visible light irradiation by releasing the cytotoxic reactive oxygen species (ROS). The antibacterial assay in vitro showed that they can effectively eradicate the board-spectrum bacteria at a relatively low loading dose of TMPyP (e.g., 0.1 wt%). Meanwhile, those nanofibrous mats showed good biocompatibility with no obvious adverse effects on mammalian cells and red blood cells (RBCs). The animal test in vivo suggested that the restrained inflammatory reaction and better wound healing could be achieved upon timely and effective antibacterial treatment with negligible local toxicities. This biocompatible and antibacterial γ-PGA-TMPyP nanofibrous mat may show great potential in practical infection-resistant applications, particularly for wound dressing applications.

Copper(ii)-based coordination polymer nanofibers as a highly effective antibacterial material with a synergistic mechanism

Nanofibers of a copper(ii)-based coordination polymer [Cu(HBTC)(H₂O)₃] were synthesized via a microwave-assisted hydrothermal process, while macroparticles and bulk crystals were prepared via a hydrothermal method. X-ray analysis revealed that this compound possesses one-dimensional zig-zag chains, in which the coordination polyhedron of the copper(ii) center is a five-coordinate distorted square-pyramid. The width of the as-prepared nanofibers was about 150 nm, while the size of the macroparticles was about 200 μm. The antibacterial activities of the nanofibers and macroparticles against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were evaluated by determining the minimal inhibitory concentration (MIC), the growth curve of the bacteria and the bacterial reduction assay. The nanofibers showed higher antibacterial performance as compared with macroparticles, commercial copper nanoparticles, and pure ligands alone. The bacteriostatic rates of nanofibers and macroparticles were up to 99.9% and 96.7% against E. coli, while 99.1% and 96.2% against S. aureus, respectively, when the concentration was 250 μg mL^-1. The synergistic antibacterial mechanism was also proposed based on the generation of reactive oxygen species (ROS) and the release of Cu²⁺ ions.

A maltoheptaose-decorated BODIPY photosensitizer for photodynamic inactivation of Gram-positive bacteria

A maltoheptaose-decorated BODIPY with high singlet oxygen generation efficacy was synthesized for photodynamic inactivation of Gram-positive bacteria in planktonic forms and biofilms.