Nanocopper-loaded Black phosphorus nanocomposites for efficient synergistic antibacterial application

Current advances in black phosphorus-based antibacterial nanoplatform for infection therpy

Black phosphorus (BP) has attracted much attention due to its excellent physiochemical properties. However, due to its biodegradability and simple antibacterial mechanism, using only BP nanomaterials to combat bacterial infections caused by drug-resistant pathogens remains a significant challenge. In order to improve the antibacterial efficiency and avoid the emergence of drug resistance, BP nanomaterials have been combined with other functional materials to form black phosphorus-based antibacterial nanoplatform (BPANP), which provides unprecedented opportunities for the treatment of drug-resistant infections. This article reviews the performance of BPANP and its multiple antibacterial mechanisms while emphatically introducing its design direction and latest application progress in antibacterial fields. Moreover, this paper additionally summarizes and discusses the current challenges and inadequacies of BPANP that need to be improved in future research. We believe that this review will provide researchers with an up-to-date and multifaceted reference, and provide new ideas for designing effective strategies against drug-resistant bacteria.

Molybdenum Disulfide-Supported Cuprous Oxide Nanocomposite for Near-Infrared-I Light-Responsive Synergistic Antibacterial Therapy

Drug-resistant bacterial infections pose a serious threat to human health; thus, there is an increasingly growing demand for nonantibiotic strategies to overcome drug resistance in bacterial infections. Mild photothermal therapy (PTT), as an attractive antibacterial strategy, shows great potential application due to its good biocompatibility and ability to circumvent drug resistance. However, its efficiency is limited by the heat resistance of bacteria. Herein, Cu2O@MoS2, a nanocomposite, was constructed by the in situ growth of Cu2O nanoparticles (NPs) on the surface of MoS2 nanosheets, which provided a controllable photothermal therapeutic effect of MoS2 and the intrinsic catalytic properties of Cu2O NPs, achieving a synergistic effect to eradicate multidrug-resistant bacteria. Transcriptome sequencing (RNA-seq) results revealed that the antibacterial process was related to disrupting the membrane transport system, phosphorelay signal transduction system, oxidative stress response system, as well as the heat response system. Animal experiments indicated that Cu2O@MoS2 could effectively treat wounds infected with methicillin-resistant Staphylococcus aureus. In addition, satisfactory biocompatibility made Cu2O@MoS2 a promising antibacterial agent. Overall, our results highlight the Cu2O@MoS2 nanocomposite as a promising solution to combating resistant bacteria without inducing the evolution of antimicrobial resistance.

Polyelectrolyte modified black phosphorus/titania nanosheet heterojunction enhanced photocatalysis: Synergistic enhancement effect of interface affinity and electron transport channel

The instability and high electron-hole recombination have limited the application of black phosphorus (BP) as an excellent photocatalyst. To address these challenges, poly dimethyl diallyl ammonium chloride (PDDA), poly (allylamine hydrochloride) (PAH), and polyethyleneimine (PEI) are introduced to the functionalization of BP (F-BP), which can not only enhance its stability, but also boost the carrier transfer. Furthermore, a high-performance heterojunction photocatalyst is fabricated using F-BP and titania nanosheets (TNs) via a layer-by-layer self-assembly approach. The experimental outcomes unequivocally indicate that F-BP exhibits fast charge migration compared to BP. The density functional theory (DFT), in situ Kelvin-probe force microscopy (KPFM) and other advanced characterization techniques collectively unfold that PDDA modified BP can notably boost separation and propagation of charges, along with an enhanced carrier abundance. In summary, this novel strategy of using polyelectrolytes to enhance the electron transfer and the stability of BP permits immense potential in building next-generation BP-based high efficiency photocatalysts.

Black phosphorus, an advanced versatile nanoparticles of antitumor, antibacterial and bone regeneration for OS therapy

Osteosarcoma (OS) is the most common primary malignant bone tumor. In the clinic, usual strategies for OS treatment include surgery, chemotherapy, and radiation. However, all of these therapies have complications that cannot be ignored. Therefore, the search for better OS treatments is urgent. Black phosphorus (BP), a rising star of 2D inorganic nanoparticles, has shown excellent results in OS therapy due to its outstanding photothermal, photodynamic, biodegradable and biocompatible properties. This review aims to present current advances in the use of BP nanoparticles in OS therapy, including the synthesis of BP nanoparticles, properties of BP nanoparticles, types of BP nanoparticles, and modification strategies for BP nanoparticles. In addition, we have discussed comprehensively the application of BP in OS therapy, including single, dual, and multimodal synergistic OS therapies, as well as studies about bone regeneration and antibacterial properties. Finally, we have summarized the conclusions, limitations and perspectives of BP nanoparticles for OS therapy.

Regulation of band gap and localized surface plasmon resonance by loading Au nanorods on violet phosphene nanosheets for photodynamic/photothermal synergistic anti-infective therapy

In the face of the serious threat to human health and the economic burden caused by bacterial antibiotic resistance, 2D phosphorus nanomaterials have been widely used as antibacterial agents. Violet phosphorus nanosheets (VPNSs) are an exciting bandgap-adjustable 2D nanomaterial due to their good physicochemical properties, yet the study of VPNS-based antibiotics is still in its infancy. Here, a composite of gold nanorods (AuNRs) loaded onto VPNS platforms (VPNS/AuNR) is constructed to maximize the potential of VPNSs for antimicrobial applications. The loading with AuNRs not only enhances the photothermal performance via a localized surface plasmon resonance (LSPR) effect, but also enhances the light absorption capacity due to the narrowing of the band gap of the VPNSs, thus increasing the ROS generation capacity. The results demonstrate that VPNS/AuNR exhibits outstanding antibacterial properties and good biocompatibility. Attractively, VPNS/AuNR is then extensively tested for treating skin wound infections, suggesting promising in vivo antibacterial and wound-healing features. Our findings may open a novel direction to develop a versatile VPNS-based treatment platform, which can significantly boost the progress of VPNS exploration.

Recent progress on bismuth-based light-triggered antibacterial nanocomposites: Synthesis, characterization, optical properties and bactericidal applications

Bacterial infections pose a seriously threat to the safety of the environment and human health. In particular, the emergence of drug-resistant pathogens as a result of antibiotic abuse and high trauma risk has rendered conventional therapeutic techniques insufficient for treating infections by these so-called "superbugs". Therefore, there is an urgent need to develop highly efficient and environmentally-friendly antimicrobial agents. Bismuth-based nanomaterials with unique structures and physicochemical characteristics have attracted considerable attention as promising antimicrobial candidates, with many demonstratingoutstanding antibacterial effects upon being triggered by broad-spectrum light. These nanomaterials have also exhibited satisfactory energy band gaps and electronic density distribution with improved photonic properties for extensive and comprehensive applications after being modified through various engineering methods. This review summarizes the latest research progress made on bismuth-based nanomaterials with different morphologies, structures and compositions as well as the different methods used for their synthesis to meet their rapidly increasing demand, especially for antibacterial applications. Moreover, the future prospects and challenges regarding the application of these nanomaterials are discussed. The aim of this review is to stimulate interest in the development and experimental transformation of novel bismuth-based nanomaterials to expand the arsenal of effective antimicrobials.

In the View of Electrons Transfer and Energy Conversion: The Antimicrobial Activity and Cytotoxicity of Metal-Based Nanomaterials and Their Applications

The global pandemic and excessive use of antibiotics have raised concerns about environmental health, and efforts are being made to develop alternative bactericidal agents for disinfection. Metal-based nanomaterials and their derivatives have emerged as promising candidates for antibacterial agents due to their broad-spectrum antibacterial activity, environmental friendliness, and excellent biocompatibility. However, the reported antibacterial mechanisms of these materials are complex and lack a comprehensive understanding from a coherent perspective. To address this issue, a new perspective is proposed in this review to demonstrate the toxic mechanisms and antibacterial activities of metal-based nanomaterials in terms of energy conversion and electron transfer. First, the antimicrobial mechanisms of different metal-based nanomaterials are discussed, and advanced research progresses are summarized. Then, the biological intelligence applications of these materials, such as biomedical implants, stimuli-responsive electronic devices, and biological monitoring, are concluded based on trappable electrical signals from electron transfer. Finally, current improvement strategies, future challenges, and possible resolutions are outlined to provide new insights into understanding the antimicrobial behaviors of metal-based materials and offer valuable inspiration and instructional suggestions for building future intelligent environmental health.

Black Phosphorus - A Rising Star in the Antibacterial Materials

Antibiotics are the most commonly used means to treat bacterial infection at present, but the unreasonable use of antibiotics induces the generation of drug-resistant bacteria, which causes great problems for their clinical application. In recent years, researchers have found that nanomaterials with high specific surface area, special structure, photocatalytic activity and other properties show great potential in bacterial infection control. Among them, black phosphorus (BP), a two-dimensional (2D) nanomaterial, has been widely reported in the treatment of tumor and bone defect due to its excellent biocompatibility and degradability. However, the current theory about the antibacterial properties of BP is still insufficient, and the relevant mechanism of action needs to be further studied. In this paper, we introduced the structure and properties of BP, elaborated the mechanism of BP in bacterial infection, and systematically reviewed the application of BP composite materials in the field of antibacterial. At the same time, we also discussed the challenges faced by the current research and application of BP, which laid a solid theoretical foundation for the further study of BP in the future.

Two-dimensional TiO nanosheets with photothermal effects for wound sterilization

To combat multidrug-resistant bacteria, researchers have poured into the development and design of antimicrobial agents. Here, low-cost two-dimensional (2D) antibacterial material titanium monoxide nanosheets (TiO NSs) were prepared by an ultrasonic-assisted liquid-phase exfoliation method. When cultured with bacteria, TiO NSs showed intrinsic antimicrobial capacity, possibly due to membrane damage caused by the sharp edges of TiO NSs. Under near-infrared (NIR) laser irradiation, TiO NSs showed high photothermal conversion efficiency (PTCE) and sterilization efficiency. By combining these two antibacterial mechanisms, TiO NSs exhibited a strong killing effect on Gram-negative Escherichia coli (E. coli) and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA). Especially after treatment with TiO NSs (150 μg mL-1) +near-infrared (NIR) light irradiation, both bacteria were completely killed. In vivo experiments on wound repair of bacterial infection further confirmed its antibacterial effect. In addition, TiO NSs had no obvious toxicity or side effects, so as a kind of broad-spectrum 2D antibacterial nanoagent, TiO NSs have broad application prospects in the field of pathogen infection.

Radially Electrospun Fibrous Membrane Incorporated with Copper Peroxide Nanodots Capable of Self-Catalyzed Chemodynamic Therapy for Angiogenesis and Healing Acceleration of Diabetic Wounds

Vascular dysfunction severely hinders the healing process of diabetic wounds. Therefore, a radially structured fibrous membrane was fabricated through electrospinning by using a polycaprolactone (PCL) and polyvinylpyrrolidone (PVP) mixed solution containing copper peroxide nanoparticles (CPs) as the chemodynamic therapy (CDT) agents, aiming to simultaneously accelerate tissue regeneration and angiogenesis. The fabricated membrane allowed for the in situ H₂O₂ generation activated by the acidic diabetic microenvironment and the subsequent Fenton-type reactions to realize 99.4% elimination against Staphylococcus aureus. Besides, the released Cu²⁺ ions significantly enhanced the expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) in human umbilical vein endothelial cells (HUVECs), and they showed enhanced in vitro angiogenesis. Interestingly, the CP-embedded membrane also guided cell spreading and orientated migration of L929 fibroblasts along the fiber distribution through the radially aligned topology. The in vivo implantation indicated that the raidally structured membrane modified by CPs not only dramatically accelerated wound healing of diabetic Sprague-Dawley (SD) rats in 14 days but also promoted angiogenesis in wound sites. The combination of the in situ CDT with the radially structured morphology of the functional membrane is highly promising in applications to promote diabetic wound healing through anti-infection and revascularization.

Facile photosynthesis of novel porphyrin-derived nanocomposites containing Ag, Ag/Au, and Ag/Cu for photobactericidal study

In this research, the one-step synthesis of novel porphyrin-based nanocomposites was performed easily using a photochemical under visible light illumination strategy. As a result, the focus of this research is on synthesizing and using decorated ZnTPP (zinc(II)tetrakis(4-phenyl)porphyrin) nanoparticles with Ag, Ag/AgCl/Cu, and Au/Ag/AgCl nanostructures as antibacterial agents. Initially, ZnTPP NPs were synthesized as a result of the self-assembly of ZnTPP. In the next step, in a visible-light irradiation photochemically process, the self-assembled ZnTPP nanoparticles were used to make ZnTPP/Ag NCs, ZnTPP/Ag/AgCl/Cu NCs, and ZnTPP/Au/Ag/AgCl NCs. A study on the antibacterial activity of nanocomposites was carried out for Escherichia coli, and Staphylococcus aureus as pathogen microorganisms by the plate count method, well diffusion tests, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) values determination. Thereafter, the reactive oxygen species (ROS) were determined by the flow cytometry method. All the antibacterial tests and the flow cytometry ROS measurements were carried out under LED light and in dark. The (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was applied to investigate the cytotoxicity of the ZnTPP/Ag/AgCl/Cu NCs, against Human foreskin fibroblast (HFF-1) normal cells. Due to the specific properties such as admissible photosensitizing properties of porphyrin, mild reaction conditions, high antibacterial properties in the presence of LED light, crystal structure, and green synthesis, these nanocomposites were recognized as kinds of antibacterial materials that are activated in visible light, got the potential for use in a broad range of medical applications, photodynamic therapy, and water treatment.

Transcriptome Analysis Reveals the Growth Promotion Mechanism of Enteropathogenic Escherichia coli Induced by Black Phosphorus Nanosheets

With the extensive production and application of black phosphorus (BP) nanosheets, release to the environment is inevitable, which raises concerns about the fate and effects of this two-dimensional (2D) material on sensitive receptors such as environmental microbes. Although the bacterial toxicity of BP nanosheets has been demonstrated, whether the biological response differs in pathogenic and nonpathogenic strains of a microorganism is unknown. Here, enteropathogenic Escherichia coli (EPEC) and nonpathogenic Escherichia coli DH5α (E. coli DH5α), Escherichia coli k12 (E. coli k12), and Bacillus tropicus (B. tropicus) are used to comparatively study the microbial toxicity of BP nanosheets. Upon exposure to BP nanosheets across a range of doses from 10 to 100 μg mL^-1 for 12 h, EPEC experienced enhanced growth and E. coli DH5α and E. coli k12 were not affected, whereas B. tropicus exhibited clear toxicity. By combining transcriptome sequencing, proteome analysis, and other sensitive biological techniques, the mechanism of BP-induced growth promotion for EPEC was uncovered. Briefly, BP nanosheets activate the antioxidation system to resist oxidative stress, promote protein synthesis and secretion to attenuate membrane damage, enhance the energy supply, and activate growth-related pathways. None of these impacts were evident with nonpathogenic strains. By describing the mechanism of strain-dependent microbial effects, this study not only highlights the potential risks of BP nanosheets to the environment and to human health but also calls attention to the importance of model strain selection when evaluating the hazard and toxicity of emerging nanomaterials.

A Review on Montmorillonite-Based Nanoantimicrobials: State of the Art

One of the crucial challenges of our time is to effectively use metal and metal oxide nanoparticles (NPs) as an alternative way to combat drug-resistant infections. Metal and metal oxide NPs such as Ag, Ag2O, Cu, Cu2O, CuO, and ZnO have found their way against antimicrobial resistance. However, they also suffer from several limitations ranging from toxicity issues to resistance mechanisms by complex structures of bacterial communities, so-called biofilms. In this regard, scientists are urgently looking for convenient approaches to develop heterostructure synergistic nanocomposites which could overcome toxicity issues, enhance antimicrobial activity, improve thermal and mechanical stability, and increase shelf life. These nanocomposites provide a controlled release of bioactive substances into the surrounding medium, are cost effective, reproducible, and scalable for real life applications such as food additives, nanoantimicrobial coating in food technology, food preservation, optical limiters, the bio medical field, and wastewater treatment application. Naturally abundant and non-toxic Montmorillonite (MMT) is a novel support to accommodate NPs, due to its negative surface charge and control release of NPs and ions. At the time of this review, around 250 articles have been published focusing on the incorporation of Ag-, Cu-, and ZnO-based NPs into MMT support and thus furthering their introduction into polymer matrix composites dominantly used for antimicrobial application. Therefore, it is highly relevant to report a comprehensive review of Ag-, Cu-, and ZnO-modified MMT. This review provides a comprehensive overview of MMT-based nanoantimicrobials, particularly dealing with preparation methods, materials characterization, and mechanisms of action, antimicrobial activity on different bacterial strains, real life applications, and environmental and toxicity issues.

Silver nanoparticles modified hFGF2-linking camelina oil bodies accelerate infected wound healing

Bacterial infection wounds are common in life. At present, although various wound materials have shown antibacterial activity, there is a lack of overall strategy to promote wound healing. Therefore, it is necessary to develop multifunctional wound materials. In this study, silver nanoparticles (Ag NPs) modified camelina oil bodies (OB) which surface covalently bonded human fibroblast growth factor 2 (Ag NPs-hFGF2-OB) were designed for the treatment of bacterial infection wounds. The prepared Ag NPs-hFGF2-OB not only act as an antibacterial agent to realize sterilization, but also act as a tissue repair agent that effectively promotes wound healing. Ag⁺ was reduced in situ to Ag NPs by ascorbic acid, and the activity of hFGF2 protein was not affected after hFGF2-OB was modified by Ag NPs, which displaying broad apectrum antibacterial ability for both S. aureus and E. coli, with an antibacterial rate of more than 70 % (the concentration of Ag NPs was 20 μg/mL, the hFGF2 protein concentration was 20 µg/mL). Ag NPs-hFGF2-OB can effectively promote the migration of NIH/3T3 cells, showing good biocompatibility. The mouse bacterial infection wound model experiments proved that the wound healing rate of Ag NPs-hFGF2-OB group (the concentration of Ag NPs was 20 μg/mL, the hFGF2 protein concentration was 20 µg/mL) was much higher than other treatment groups, especially on the 7th day after treatment, the wound healing rate reached 71.71 ± 2.38 %, while the healing rate of other treatment groups were only 34.54 ± 1.10 %, 37.08 ± 2.85 % and 47.99 ± 2.01 %. Therefore, Ag NPs-hFGF2-OB, which can inhibit bacterial growth, promotes collagen deposition, granulation tissue regeneration and angiogenesis without any significant toxicity, shows good potential for application in the repair of bacterial infection wounds.

Facile synthesis of black phosphorus-zinc oxide nanohybrids for antibacterial coating of titanium surface

Bacterial infection is a major complication associated with bioimplant materials, including titanium (Ti) based orthopedic joints and dental implants. Thus, the fabrication of Ti surfaces with antibacterial activity is highly important. Black phosphorus (BP) is a recently discovered promising two-dimensional semiconductor for various biomedical applications due to its tunable bandgap and physicochemical properties. The present study aimed to synthesize zinc oxide (ZnO) laden BP nanohybrids (NH) and their coatings on a Ti bioimplant surface for improving the antibacterial activities against pathogenic bacteria with and without near-infrared (NIR) light irradiation. Nanohybrids were produced with the slightly oxidized BP NF and electrostatically laden ZnO NP. The produced BP-ZnO NH was a NIR active nanomaterial (up to ∼1000 nm), demonstrating a photothermal effect against bacterial infection and showing improved activity by damaging the cell membrane towards S. aureus in comparison to E. coli. Ti surface coated with BP-ZnO NH embedded chitosan (CS) demonstrated better antibacterial activity than BP NF, especially with NIR light treatment. Additionally, the produced BP nanoflakes and BP-ZnO NH, and their coatings over the Ti surface were found to be toxic at a negligible level. Electrochemical studies revealed the high corrosion resistance of the Ti surface coated with the synthesized antibacterial agents without altering its characteristic passive behavior. Owing to the interactions between the charged groups between chitosan and cell surfaces, a slight increase in antibacterial activities was noticed. Chitosan-based coating matrix embedded with nanoagents has adhered well over the Ti surface due to its inherent film-forming and high adhesion properties.

Design, synthesis, and characterization of novel eco-friendly chitosan-AgIO3 bionanocomposite and study its antibacterial activity

This work reports a facile and green approach to preparing AgIO₃ nanoparticles decorated with chitosan (chitosan-AgIO₃). The bionanocomposite was fully characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM) images, energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction analysis (XRD). The antibacterial effect of chitosan-AgIO₃ bionanocomposite was investigated for Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus saprophyticus, Escherichia coli, and Staphylococcus aureus as pathogen microorganisms via the plate count method, disk diffusion method, and optical density (OD) measurements. The antibacterial performance of the bionanocomposite was compared with two commercial drugs (penicillin and silver sulfadiazine) and in some cases, the synthesized bionanocomposite has a better effect in the eradication of bacteria. The bionanocomposite represented great antibacterial properties. Flow cytometry was performed to investigate the mechanism of bionanocomposite as an antibacterial agent. Reactive oxygen species (ROS) production was responsible for the bactericidal mechanisms. These results demonstrate that the chitosan-AgIO₃ bionanocomposite, as a kind of antibacterial material, got potential for application in a broad range of biomedical applications and water purification. The design and synthesis of green and biodegradable antibacterial materials with simple processes and by using readily available materials cause the final product to be economically affordable and could be scaled in different industries.

Silver-decorated black phosphorus: a synergistic antibacterial strategy

Black phosphorus (BP) exhibits great potential as antibacterial materials due to its unique photocatalytic activity. However, the unsatisfactory optical absorption and quick recombination of photoinduced electron-hole pairs restrain its photocatalytic antibacterial performance. In this work, silver nanoparticles (AgNPs) were decorated on BP to construct BP@AgNPs nanohybrids and then introduced into poly-l-lactic acid scaffold. Combining the tunable bandgap of BP and the LSPR effect of AgNPs, BP@AgNPs nanohybrids displayed the broaden visible light absorption. Furthermore, AgNPs acted as electron acceptors could accelerate charge transfer and suppress electron-hole recombination. Therefore, BP@AgNPs nanohybrids achieved synergistically enhanced photocatalytic antibacterial activity under visible light irradiation. Fluorescence probe experiment verified that BP@AgNPs promoted the generation of reactive oxygen species, which could disrupt bacteria membrane, damage DNA and oxide proteins, and finally lead to bacteria apoptosis. As a result, the scaffold possessed strong antibacterial efficiency with a bactericidal rate of 97% under light irradiation. Moreover, the scaffold also exhibited good cytocompatibility. This work highlighted a new strategy to develop photocatalytic antibacterial scaffold for bone implant application.

An outstanding role of novel virus-like heterojunction nanosphere BOCO@Ag as high performance antibacterial activity agent

The development of highly efficient photonic nanomaterials with synergistic biological effects is critical and challenging task for public hygiene health well-being and has attracted extensive interest. In this study, a type of near-infrared (NIR) driven, virus-like heterojunction was first developed for synergistic biological application. The Ag-coated Bi₂CO₅ nanomaterial (BOCO@Ag) demonstrated good biocompatibility, low cytotoxicity, high antibacterial activity and excellent light utilization stability. The synthesized BOCO@Ag performed a potential high photothermal conversion (efficiency~46.81%) to generate high temperatures when irradiated with near-infrared light illumination. As expected, compared to single Ag+ disinfection, BOCO@Ag can exhibit better antibacterial performance when combined with photothermal energy and released Ag+ . These results suggest that BOCO@Ag can be a promising photo-activate antimicrobial candidate and provide security for humans health and the environment treatment.

One-Pot Surface Modification of β-Cu2O NPs for Biocatalytic Performance against A-549 Lung Carcinoma Cell Lines through Docking Analysis

The physicochemical approaches and biological principles in bio-nanotechnology favor specially functionalized nanosized particles. Cuprous oxide nanoparticles (β-Cu₂O NPs) of cuprite phase with a little tenorite (CuO) may be very effective in the development of novel therapeutic approaches against several fatalities including A-549 lung carcinoma cell lines. Consequently, the synthesis of β-Cu₂O NPs for the improvement in the therapeutic index and drug delivery application is becoming an effective strategy in conventional anticarcinoma treatment. Hence, surface-enhanced nanosized spherical cuprous oxide nanoparticles (β-Cu₂O NPs) of cuprite phase were successfully prepared using poly(ethylene glycol) (PEG) as an amphiphilic nonionic surfactant and l-ascorbic acid (K₃[Cu(Cl₅)]@LAA-PEG) reduced to cuprites β-Cu₂O NPs via the sonochemical route. Less improved toxicity and better solubility of β-Cu₂O NPs compared with Axitinib were a major reason for producing β-Cu₂O NPs from K₃[Cu(Cl₅)]@LAA-PEG (LAA, l-ascorbic acid, PEG, poly(ethylene glycol) (PEG)). These nanoparticle syntheses have been suggested to influence their cytotoxicity, free-radical scavenging analysis, and reactive oxygen species (ROS) using poly(ethylene glycol) (PEG) and l-ascorbic acid (LAA) as coated and grafted materials due to their dose-dependent nature and IC₅₀ calculations. The surface morphology of the formed β-Cu₂O NPs has been examined via UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy with energy diffraction scattering spectroscopy (SEM@EDS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) analysis. X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) surface analysis results confirm the presence of pure cuprite with a very little amount of tenorite (CuO) phase, Dynamic light scattering (DLS) confirms the negative ζ-value with stable nature. Docking was performed using PDB of lung carcinomas and others, as rigid receptors, whereas the β-Cu₂O NP cluster was treated as a flexible ligand.

A Stable Quaternized Chitosan-Black Phosphorus Nanocomposite for Synergetic Disinfection of Antibiotic-Resistant Pathogens

Antibiotics are widely used for treatment of bacterial infections, and their overuse has contributed to microbial resistance. Currently, an alternative antibiotic-free therapy for inactivating bacteria is of great interest. Black phosphorus (BP), a biocompatible and nontoxic rising-star two-dimensional layered material, has gained remarkable interest in many bioapplications including biosensing, cancer therapy, drug delivery, and also antibacterial treatment. However, BP nanosheets suffer from instability in ambient environments due to rapid oxidation and degradation. To address this issue, BP nanosheets were modified with quaternized chitosan (QCS) by electrostatic adsorption to prepare a BP-QCS composite for photothermal/pharmaco treatment of bacterial infection. The BP-QCS has obviously enhanced solubility and chemical stability in aqueous suspensions. We have demonstrated that under near-infrared (NIR) irradiation, the BP-QCS can synergistically inactivate more than 95% methicillin-resistant Staphylococcus aureus (S. aureus) (MRSA) and Escherichia coli within 10 min with a dose of only 75 μg/mL in vitro. Meanwhile, the BP-QCS composite under NIR can synergistically inactivate 98% S. aureus in vivo. Furthermore, the BP-QCS suspensions at effective antibacterial concentrations have negligible cytotoxicity and in vivo toxicity.

Biomedical applications of 2D monoelemental materials formed by group VA and VIA: a concise review

The development of two-dimensional (2D) monoelemental nanomaterials (Xenes) for biomedical applications has generated intensive interest over these years. In this paper, the biomedical applications using Xene-based 2D nanomaterials formed by group VA (e.g., BP, As, Sb, Bi) and VIA (e.g., Se, Te) are elaborated. These 2D Xene-based theranostic nanoplatforms confer some advantages over conventional nanoparticle-based systems, including better photothermal conversion, excellent electrical conductivity, and large surface area. Their versatile and remarkable features allow their implementation for bioimaging and theranostic purposes. This concise review is focused on the current developments in 2D Xenes formed by Group VA and VIA, covering the synthetic methods and various biomedical applications. Lastly, the challenges and future perspectives of 2D Xenes are provided to help us better exploit their excellent performance and use them in practice.

Recent advances of monoelemental 2D materials for photocatalytic applications

As a sustainable environmental governance strategy and energy conversion method, photocatalysis has considered to have great potential in this field due to its excellent optical properties and has become one of the most attractive technologies today. Among 2D materials, the emerging two-dimensional (2D) monoelemental materials mainly distributed in the -IIIA, -IVA, -VA and -VIA groups and show excellent performance in solar energy conversion due to their graphene-like 2D atomic structure and unique properties, thereby drawing increasing attention. This review briefly summarizes the preparation processes and fundamental properties of 2D single-element nanomaterials, as well as various modification strategies and adjustment mechanisms to enhance their photocatalytic properties. In particular, this article comprehensively discusses the related practical applications of 2D single-element materials in the field of photocatalysis, including photocatalytic degradation for contaminants removal, photocatalytic pathogen inactivation, photocatalytic fouling control and photocatalytic energy conversion. This review will provide some new opportunities for the rational design of other excellent photocatalysts based on 2D monoelemental materials, as well as present tremendous novel ideas for 2D monoelemental materials in other environmental conservation and energy-related applications, such as supercapacitors, electrocatalysis, solar cells, and so on.

Portable wireless intelligent sensing of ultra-trace phytoregulator α-naphthalene acetic acid using self-assembled phosphorene/Ti3C2-MXene nanohybrid with high ambient stability on laser induced porous graphene as nanozyme flexible electrode

The harm of pesticide residues to human health via environmental pollution in agriculture has recently become a significant livelihood issue. Herein, a new strategy for smart ultra-trace analysis of phytoregulator α-naphthalene acetic acid (NAA) residues in farmland environments and agro-products via machine learning (ML) using a nanozyme flexible electrode fabricated by two-dimensional phosphorene (BP) nanohybrid with graphene-like titanium carbide MXene (Ti₃C₂-MXene) on the flexible substrate surface of laser-induced porous graphene (LIPG) is proposed. Highly ambient-stable BP nanohybrid with Ti₃C₂-MXene is prepared by ultrasonic-assisted liquid-phase exfoliation in organic solvent containing grinding black phosphorus, cuprous chloride and, Ti₃C₂-MXene that is obtained by selectively etching Al layers of Ti₃AlC₂. Nanozyme flexible electrode is fabricated by drop-coating Ti₃C₂-MXene/BP that is formed through electrostatic self-assembly between positively charged BP and negatively charged Ti₃C₂-MXene onto LIPG that is obtained by direct laser writing on commercial polyimide and patterned via a computer-aided design system as a flexible substrate. The ML model via artificial neural network algorithm for smart output of NAA is discussed. NAA is electrochemically detected in a wide linear range of 0.02-40 μM with a low limit of detection (LOD) of 1.6 nM using a portable mini-workstation. Large and rough surfaces, excellent electrochemical response, and satisfactory practicability demonstrated the feasibility and detectability of the proposed method. This will provide a portable wireless intelligent nanozyme flexible sensing platform for cost-effective, simple, fast and, ultra-trace detection of hazardous substances in the safety of environments, products, and food in agriculture.

Au-ZnO Conjugated Black Phosphorus as a Near-Infrared Light-Triggering and Recurrence-Suppressing Nanoantibiotic Platform against Staphylococcus aureus

Antibiotic therapy is the gold standard for bacterial infections treatment. However, the rapid increase in multidrug-resistant (MDR) bacterial infections and its recent use for secondary bacterial infections in many COVID-19 patients has considerably weakened its treatment efficacy. These shortcomings motivated researchers to develop new antibacterial materials, such as nanoparticle-based antibacterial platform with the ability to increase the chances of killing MDR strains and prevent their drug resistance. Herein, we report a new black phosphorus (BP)-based non-damaging near-infrared light-responsive platform conjugated with ZnO and Au nanoparticles as a synergistic antibacterial agent against Staphylococcus aureus species. First, BP nanosheets containing Au nanoparticles were assembled in situ with the ZnO nanoparticles prepared by a low-temperature solution synthesis method. Subsequently, the antibacterial activities of the resulting Au-ZnO-BP nanocomposite against the non-resistant, methicillin-resistant, and erythromycin-resistant S. aureus species were determined, after its photothermal efficacy was assessed. The synthesized nanocomposite exhibited excellent anti-S. aureus activity and good photothermal characteristics. The non-resistant S. aureus species did not produce drug-resistant bacteria after the treatment of multiple consecutive passages under the pressure of the proposed nanoantibiotic, but rapidly developed resistance to erythromycin. This work clearly demonstrates the excellent photothermal antibacterial properties of Au-ZnO-BP nanocomposite against the MDR S. aureus species.

Gold nanoplates with superb photothermal efficiency and peroxidase-like activity for rapid and synergistic antibacterial therapy

Gold nanoplates exhibit 68.5% photothermal conversion efficiency and peroxidase-like activity, and AuNPTs (50 μg mL⁻¹)/H₂O₂ (0.1 mM)/NIR (1 W cm⁻², 3 min) show excellent synergistic antibacterial ability and promote MRSA-infected wound healing in vivo.

Two dimensional BP@AuNP nanocomposites for photothermal/photodynamic therapy mediated wound disinfection and infected wound healing under a single light source

BP@AuNP nanocomposites can perform photothermal and photodynamic therapies simultaneously and exhibited a synergistic combination of multiple therapies for S. aureus and E. coli under a 650 nm laser.

Phototherapy-based combination strategies for bacterial infection treatment

The development of nanomedicine is expected to provide an innovative direction for addressing challenges associated with multidrug-resistant (MDR) bacteria. In the past decades, although nanotechnology-based phototherapy has been developed for antimicrobial treatment since it rarely causes bacterial resistance, the clinical application of single-mode phototherapy has been limited due to poor tissue penetration of light sources. Therefore, combinatorial strategies are being developed. In this review, we first summarized the current phototherapy agents, which were classified into two functional categories: organic phototherapy agents (e.g., small molecule photosensitizers, small molecule photosensitizer-loaded nanoparticles and polymer-based photosensitizers) and inorganic phototherapy agents (e.g., carbo-based nanomaterials, metal-based nanomaterials, composite nanomaterials and quantum dots). Then the development of emerging phototherapy-based combinatorial strategies, including combination with chemotherapy, combination with chemodynamic therapy, combination with gas therapy, and multiple combination therapy, are presented and future directions are further discussed. The purpose of this review is to highlight the potential of phototherapy to deal with bacterial infections and to propose that the combination therapy strategy is an effective way to solve the challenges of single-mode phototherapy.

Enhanced photodynamic inactivation for Gram-negative bacteria by branched polyethylenimine-containing nanoparticles under visible light irradiation

Antibiotic pollution has been a serious global public health concern in recent years, photodynamic inactivation is one of the most promising and innovative methods for antibacterial applications that avoids antibiotic abuse and minimizes risks of antibiotic resistance. However, limited by the weak interaction between the photosensitizers and Gram-negative bacteria, the effect of photodynamic inactivation cannot be fully exerted. Herein, photosensitizer chlorin e6-loaded polyethyleneimine-based micelle was constructed. The synergy of electrostatic and hydrophobic interactions between the nanoparticles and the bacterial surface promoted the anchoring of nanoparticles onto the bacteria, resulting in enhanced photoinactivation activities on Gram-negative bacteria. As expected, an eminent antibacterial effect was also observed on the Gram-positive bacteria Staphylococcus aureus. The cellular uptake results showed that photosensitizer was firmly anchored to the bacterial cell surface of Escherichia coli or Staphylococcus aureus by the introduction of branched polyethylenimine-containing nanoparticles. The light-triggered generation of reactive oxygen species, mainly singlet oxygen, from the membrane-bound nanoparticles caused irreversible damage to the bacterial outer membrane, achieving enhanced bactericidal efficiency than free photosensitizer. The study would provide an efficient and promising antimicrobial alternative to prevent overuse of antibiotics and have enormous potential for human healthcare and the environment remediation.