Interfacial regulation of BiOI@Bi2S3/MXene heterostructures for enhanced photothermal and photodynamic therapy in antibacterial applications

Defect-engineered magnetic bismuth nanomedicine for dual-modal imaging and synergistic lung tumor therapy

Bismuth sulfide (Bi2S3) nanomaterials are recognized for their potential in tumor therapy due to their narrow bandgap and low toxicity. However, limited photothermal conversion efficiency (PCE) and low carrier density restrict their broader application in photothermal cancer treatment. To address these challenges, we designed defect-engineered, magnetic-targeting Bi2S3-based photothermal nanoparticles, Fe3O4@Au@Bi2S3 nanorugbys (Fe3O4@Au@Bi2S3 NRs). These nanoparticles were developed using a layer-by-layer encapsulation strategy with sulfur vacancies (Vs) and Bi antisite defects (Bi replacing S, Bis), enhancing electron trapping and recombination to boost the near-infrared (NIR) response. The PCE of Fe3O4@Au@Bi2S3 NRs reached 44.34 %, which significantly improved their efficacy in photothermal treatment for lung tumors. Moreover, the polyvinylpyrrolidone (PVP) coating on the nanoparticles enabled efficient loading and pH-responsive release of doxorubicin hydrochloride (DOX), facilitating synergistic chemo-photothermal therapy. When exposed to an external magnetic field, the nanoparticles demonstrated strong magnetic targeting and enhanced computed tomography (CT) imaging capabilities, improving tumor treatment accuracy. Both in vitro and in vivo studies showed that this combined therapy effectively induced cancer cell apoptosis and inhibited tumor proliferation, showcasing outstanding anti-tumor performance. This study provides a promising strategy for enhancing chemo-photothermal therapy through defect-engineered, magnetic-targeted Fe3O4@Au@Bi2S3 nanoparticles, holding significant potential for clinical applications in tumor therapy.

A flexible multifunctional sensor with a conductive network based on silk nanofibers and MXene for monitoring physiological activity, capacitive pens, photothermal conversion and antibacterial

Flexible electronic sensors that can capture subtle physical, chemical and biological signals and generate real-time stimulus responses are of great importance in the fields of human-computer interaction, biomedicine, etc. Herein, a multifunctional sensing hydrogel was developed by tightly adhering two-dimensional rigid conductive MXene nanosheets to the surface of vimineous silk nanofibers (SNFs) and assembling them into an SNF@MXene network structure. Polyvinyl alcohol (PVA) was then in situ polymerized in SNF@MXene as a filling matrix. MXene nanosheets were attached to the SNF network skeleton, avoiding the settlement and aggregation of MXene and forming a PSM composite hydrogel with a uniform and dense conductive network. The designed PSM hydrogel-based sensor showed excellent mechanical properties (tensile strength = 5.07 MPa), wide operating range (700.6 %), high sensitivity (gauge factor = 8.2), high electrical conductivity (1.64 S m-1), and adhesion. The sensor could detect various physiological activities of the human body. In addition, it also showed the application potential in speech recognition, capacitive pen, etc. PSM exhibited excellent photothermal conversion efficiency. It could be rapidly heated to 82.8 °C under NIR irradiation and used for photothermal therapy. This study provides a simple conductive network design strategy for the fabrication of flexible electronic devices with multiple functions.

A multifunctional hydrogel of cellulose nanofiber/microfibrillated cellulose hierarchical network for photothermal antibacterial and all-solid supercapacitor assembly

In recent years, flexible-hydrogel wearable devices have undergone rapid development while photothermal therapy, energy storage/conversion, and other fields have been widely developed and used. However, the poor mechanical properties of hydrogels can affect their stability and reliability in practical applications, and it is often difficult to achieve both excellent mechanical properties and multifunctional characteristics. This study prepared a hierarchical cellulose network/PVA multifunctional composite hydrogel (MCPH) using cellulose nanofiber as fine fibers and microfibrillated cellulose as coarse fibers. The hierarchical cellulose network provides tensile strength as a skeleton while the PVA serves as the soft matrix to assist energy dissipation, which provides the composite hydrogel with good mechanical properties (toughness of 1.21 MJ m-3 and tensile modulus of 2.20 MPa). In addition, owing to hierarchical cellulose network preventing excessive stacking of MXene while achieving stable series connection of nano fillers, MCPH exhibits excellent photothermal conversion rate, photothermal antibacterial ability (viability of Escherichia coli and Staphylococcus aureus < 0.88 %), and energy storage capacity (6886 mF/cm2). Thus, this study not only prepared a composite hydrogel with good mechanical properties and excellent multifunctional properties but also expanded the application potential of cellulose, an important green renewable plant resource, in high-value-added wearable products.

MXene-Derived Multifunctional Biomaterials: New Opportunities for Wound Healing

The process of wound healing is frequently impeded by metabolic imbalances within the wound microenvironment. MXenes exhibit exceptional biocompatibility, biodegradability, photothermal conversion efficiency, conductivity, and adaptable surface functionalization, demonstrating marked potential in the development of multifunctional platforms for wound healing. Moreover, the integration of MXenes with other bioactive nanomaterials has been shown to enhance their therapeutic efficacy, paving the way for innovative approaches to wound healing. In this review, we provide a systematic exposition of the mechanisms through which MXenes facilitate wound healing and offer a comprehensive analysis of the current research landscape on MXene-based multifunctional bioactive composites in this field. By delving into the latest scientific discoveries, we identify the existing challenges and potential future trajectories for the advancement of MXenes. Our comprehensive evaluation aims to provide insightful guidance for the formulation of more effective wound healing strategies.

Bismuth-based photocatalysts for pollutant degradation and bacterial disinfection in sewage system: Classification, modification and mechanism

The discharge of polluted water poses a great threat to human health. Therefore, the development of effective sewage treatment technology is a key to achieve sustainable health development of society. Recent research showed that light-driven bismuth-based nanomaterials provided a promising chance for treating sewage system owing to their adjustable electronic features, excellent physical and chemical properties, abundant storage and environmental safety. However, the detailed overview and systematic understanding of the development of highly efficient bismuth-based photocatalysts is still unsatisfactory. In this review, we summarized the classification of bismuth-based photocatalysts, and the relationship between the structural design and the change of optical performance is illustrated. Importantly, the reliable modification strategies for improving photocatalytic capability are emphasized. Finally, the challenges and future development directions of light-driven bismuth-based nanoplatforms in wastewater treatment applications are discussed, hoping to provide an effective guidance for exploring the photocatalytic wastewater treatment process.

Silk fibroin aerogels with AIE-featured berberine and MXene for rapid hemostasis and efficient wound healing

Rapid hemostasis and wound healing are crucial in emergency trauma situations for saving patients' lives. Traditional hemostatic materials often have drawbacks such as slow hemostasis and susceptibility to post-hemostasis bacterial infections. Therefore, there is an urgent need for advanced wound dressing materials that can provide both rapid hemostasis and antimicrobial properties. In this study, we designed and fabricated a biocompatible hemostatic silk fibroin (SF) aerogel loaded with aggregation-induced emission (AIE)-featured berberine (BBr) and Ti3C2Tx MXene. The resulting SFMB aerogel demonstrates robust mechanical properties and a porous structure that enables quick hemostasis. This aerogel exhibits photodynamic and photothermal responses for antimicrobial activity, releases BBr upon light exposure to enhance bacterial-killing efficiency (99.33 % in vitro and 99.09 % in vivo), and effectively promotes the healing of infected wounds in vivo through combined photothermal/photodynamic antibacterial and anti-inflammatory mechanisms. Furthermore, the aerogel shows high hemocompatibility and cytocompatibility, supporting its potential biomedical applications. Overall, the synthesized SFMB aerogel holds promise for treating bacteria-infected wounds and for use in first aid applications in clinical settings.

Advancements in Nanoparticle-Based Strategies for Enhanced Antibacterial Interventions

The escalating global threat of antibiotic resistance underscores the urgent need for innovative antimicrobial strategies. This review explores the cutting-edge applications of nanotechnology in combating bacterial infections, addressing a critical healthcare challenge. We critically assess the antimicrobial properties and mechanisms of diverse nanoparticle systems, including liposomes, polymeric micelles, solid lipid nanoparticles, dendrimers, zinc oxide, silver, and gold nanoparticles, as well as nanoencapsulated essential oils. These nanomaterials offer distinct advantages, such as enhanced drug delivery, improved bioavailability, and efficacy against antibiotic-resistant strains. Recent advancements in nanoparticle synthesis, functionalization, and their synergistic interactions with conventional antibiotics are highlighted. The review emphasizes biocompatibility considerations, stressing the need for rigorous safety assessments in nanomaterial applications. By synthesizing current knowledge and identifying emerging trends, this review provides crucial insights for researchers and clinicians aiming to leverage nanotechnology for next-generation antimicrobial therapies. The integration of nanotechnology represents a promising frontier in combating infectious diseases, underscoring the timeliness and imperative of this comprehensive analysis.

Rough Ag2S@H-CeO2 photonic nanocomposites for effective eradication of drug-resistant bacteria and improved healing of infected cutaneous wounds

With the continuous increasing threat of drug-resistant bacteria induced cutaneous wound infections, there is a growing demand for novel effective antibiotics-alternative antibacterial strategies for clinical anti-infective therapy. Here, we report the fabrication and antibacterial efficacy of Ag2S@H-CeO2 photonic nanocomposites with rough surface through in-situ growth of Ag2S nanoparticles on CeO2 hollow spheres. With excellent photothermal property and peroxidase-like activity, as well as increased bacterial adhesion, the photonic nanocomposites demonstrated a broad-spectrum synergistic antibacterial effect against Gram-positive, Gram-positive bacteria and fungi as well biofilm in vitro. Significantly, the nanocomposites can effectively eradicate drug-resistant bacteria such as Gram-positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram-negative extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (ESBL E. coli). Notably, in vivo assessments validated its synergistic therapeutic potential in the treatment of MRSA-infected cutaneous wounds, all while maintaining excellent biosafety and biocompatibility. Our study offers a competitive and promising strategy for the development of a multifunctional synergistic antibacterial platform poised to effectively treat drug-resistant bacteria-infected cutaneous wounds.

Engineered MXene/Bi2S3 nanoflowers in sodium alginate hydrogel: A synergistic eradicator of disinfected byproducts in aqueous environment

In this work, Bi2S3 nanoflowers were in situ anchored on the surface of Ti3C2 via a hydrothermal process to obtain MXene-supported Ti3C2/Bi2S3 nanocomposite, then incorporated inside in sodium alginate polymer to prepared hydrogel materials (Ti3C2/Bi2S3@SA-H) which outperforms and have an excellent capability for the removal of pollutants like disinfected byproducts. The synthesized hydrogel material Ti3C2/Bi2S3@SA-H may be utilized for a variety of functional materials in environmental applications. Furthermore, the Ti3C2/Bi2S3@SA-H was characterized by SEM, EDX, XRD, BET, AFM, FTIR, Zeta potential, XPS, Raman and TGA. Remarkably, Ti3C2/Bi2S3@SA-H hydrogel 0.007 cm3 g-1, 159.5 nm and 0.0017 cm3 g-1, 160.5 nm materials exhibited the highest average pore diameter. The research focused on evaluating the adsorption capability of Ti3C2/Bi2S3@SA-H hydrogel materials for 2,6-dibromo-4-nitrophenol (DBNP), 2,4,6-triiodophenol (TIP), 2,4,6-Trichlorophenol (TCP) and 2,6-dichloro-4-nitrophenol (DCNP). The findings indicated that the material exhibited the eradication efficiency of about 662, 657, 647 and 617 mg/g from DBNP, TIP, TCP and DCNP respectively. Several adsorption isotherms were extensively examined, encompassing the Temkin, Langmuir and Freundlich models, alongside pseudo-first and second-order models. The Langmuir and pseudo-second-order models showed the highest degree of consistency with the observed data. Concerning regeneration and reusability, the materials demonstrated easy regeneration and effective recyclability over the course of 10 cycles. The notable adsorption capacity, coupled with the innovative combination of Ti3C2/Bi2S3 and polymer hydrogel, along with its recyclability, positions our material Ti3C2/Bi2S3@SA-H as a highly prospective competitors for wastewater treatment and other critical areas in water research.

Elaborated Bio-Heterojunction With Robust Sterilization Effect for Infected Tissue Regeneration via Activating Competent Cell-Like Antibacterial Tactic

Phototherapy, such as photothermal therapy (PTT) and photodynamic therapy (PDT) has been a powerful strategy to combat bacterial infection. However, the compact cell membranes of pathogenic bacteria, especially drug-resistant bacteria, significantly diminish the efficiency of heat conduction and impede the entrance of reactive oxygen species (ROS) into cells, resulting in unsatisfactory sterilization. Enlightened by the membrane feature of competent bacteria, herein a MXene/CaO2 bio-heterojunction (MC bio-HJ) is elaborated to achieve rapid disinfection and promote infected tissue regeneration through activating competent cell-like antibacterial tactics. The bio-HJ first compels pathogenic bacteria to become a competent cell-like stage through the coordination of Ca2+ and membrane phospholipid, and potentiates the membrane permeability. Assisted by near infrared (NIR) irradiation, the heat and ROS generated from PTT and PDT of bio-HJ easily pass through bacterial membrane and drastically perturb bacterial metabolism, leading to rapid disinfection. More importantly, employing two in vivo infected model of mice, it have corroborated that the MC bio-HJs not only effectively accelerate MRSA-infected cutaneous regeneration, but also considerably boost osseointegration in an infected bone defect after coating on orthopedic implants. As envisaged, this work demonstrates a novel therapeutic tactic with robust antibacterial effect to remedy infected tissue regeneration through activating competent cell-like stage.

Organic-Inorganic Interfacial Dipole Induced by Energy Level Alignment for Efficient Photocatalytic Sterilization

Photocatalytic molecules are considered to be one of the most promising substitutions of antibiotics against multidrug-resistant bacterial infections. However, the strong excitonic effect greatly restricts their efficiency in antibacterial performance. Inspired by the interfacial dipole effect, a Ti3C2 MXene modified photocatalytic molecule (MTTTPyB) is designed and synthesized to enhance the yield of photogenerated carriers under light irradiation. The alignment of the energy level between Ti3C2 and MTTTPyB results in the formation of an interfacial dipole, which can provide an impetus for the separation of carriers. Under the role of a dipole electric field, these photogenerated electrons can rapidly migrate to the side of Ti3C2 for improving the separation efficiency of photogenerated electrons and holes. Thus, more electrons can be utilized to produce reactive oxygen species (ROS) under light irradiation. As a result, over 97.04% killing efficiency can be reached for Staphylococcus aureus (S. aureus) when the concentration of MTTTPyB/Ti3C2 was 50 ppm under 660 nm irradiation for 15 min. A microneedle (MN) patch made from MTTTPyB/Ti3C2 was used to treat the subcutaneous bacterial infection. This design of an organic-inorganic interface provides an effective method to minimize the excitonic effect of molecules, further expanding the platform of inorganic/organic hybrid materials for efficient phototherapy.

Molybdenum disulfide nanosheets based non-oxygen-dependent and heat-initiated free radical nanogenerator with antimicrobial peptides for antimicrobial, biofilm ablation and wound healing

Chronic refractory wounds caused by multidrug-resistant (MDR) bacterial and biofilm infections are a substantial threat to human health, which presents a persistent challenge in managing clinical wound care. We here synthesized a composite nanosheet AIPH/AMP/MoS2, which can potentially be used for combined therapy because of the photothermal effect induced by MoS2, its ability to deliver antimicrobial peptides, and its ability to generate alkyl free radicals independent of oxygen. The synthesized nanosheets exhibited 61 % near-infrared (NIR) photothermal conversion efficiency, marked photothermal stability and free radical generating ability. The minimal inhibitory concentrations (MICs) of the composite nanosheets against MDR Escherichia coli (MDR E. coli) and MDR Staphylococcus aureus (MDR S. aureus) were approximately 38 μg/mL and 30 μg/mL, respectively. The composite nanosheets (150 μg/mL) effectively ablated >85 % of the bacterial biofilm under 808-nm NIR irradiation for 6 min. In the wound model experiment, approximately 90 % of the wound healed after the 4-day treatment with the composite nanosheets. The hemolysis experiment, mouse embryonic fibroblast (MEFs) cytotoxicity experiment, and mouse wound healing experiment all unveiled the excellent biocompatibility of the composite nanosheets. According to the transcriptome analysis, the composite nanosheets primarily exerted a synergistic therapeutic effect by disrupting the cellular membrane function of S. aureus and inhibiting quorum sensing mediated by the two-component system. Thus, the synthesized composite nanosheets exhibit remarkable antibacterial and biofilm ablation properties and therefore can be used to improve wound healing in chronic biofilm infections.

Copper selenide nanosheets with photothermal therapy-related properties and multienzyme activity for highly effective eradication of drug resistance

Bacterial infections are among the most significant causes of death in humans. Chronic misuse or uncontrolled use of antibiotics promotes the emergence of multidrug-resistant superbugs that threaten public health through the food chain and cause environmental pollution. Based on the above considerations, copper selenide nanosheets (CuSe NSs) with photothermal therapy (PTT)- and photodynamic therapy (PDT)-related properties have been fabricated. These CuSe NSs possess enhanced PDT-related properties and can convert O2 into highly toxic reactive oxygen species (ROS), which can cause significant oxidative stress and damage to bacteria. In addition, CuSe NSs can efficiently consume glutathione (GSH) at bacterial infection sites, thus further enhancing their sterilization efficacy. In vitro antibacterial experiments with near-infrared (NIR) irradiation have shown that CuSe NSs have excellent photothermal bactericidal properties. These experiments also showed that CuSe NSs exerted excellent bactericidal effects on wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) and significantly promoted the healing of infected wounds. Because of their superior biological safety, CuSe NSs are novel copper-based antimicrobial agents that are expected to enter clinical trials, serving as a modern approach to the major problem of treating bacterially infected wounds.

Tumour microenvironment-responded Fe-doped carbon dots-sensitized cubic Cu2O for Z-scheme heterojunction-enhanced sono-chemodynamic synergistic tumor therapy

The efficacy of electron-hole separation in a single sonosensitizer and the complexities of the tumor microenvironment (TME) present significant challenges to the effectiveness of sonodynamic therapy (SDT). Designing efficient sonosensitizers to enhance electron-hole separation and alleviate TME resistance is crucial yet challenging. Herein, we introduce a novel Z-scheme heterojunctions (HJs) sonosensitizer using Fe-doped carbon dots (CDs) as auxiliary semiconductors to sensitize cubic Cu2O (Fe-CDs@Cu2O) for the first time. Fe-CDs@Cu2O demonstrated enhanced SDT effects due to improved electron-hole separation. Additionally, the introduction of Fe ions in CDs synergistically enhances Fenton-like reactions with Cu ions in Cu2O, resulting in enhanced chemodynamic therapy (CDT) effects. Moreover, Fe-CDs@Cu2O exhibited rapid glutathione (GSH) depletion, effectively mitigating TME resistance. With high rates of 1O2 and OH generated by Fe-CDs@Cu2O, coupled with strong GSH depletion, single drug injection and ultrasound (US) irradiation effectively eliminate tumors. This innovative heterojunction sonosensitizer offers a promising pathway for clinical anti-tumor treatment.

Research Progress on Ti3C2Tx-Based Composite Materials in Antibacterial Field

The integration of two-dimensional Ti3C2Tx nanosheets and other materials offers broader application options in the antibacterial field. Ti3C2Tx-based composites demonstrate synergistic physical, chemical, and photodynamic antibacterial activity. In this review, we aim to explore the potential of Ti3C2Tx-based composites in the fabrication of an antibiotic-free antibacterial agent with a focus on their systematic classification, manufacturing technology, and application potential. We investigate various components of Ti3C2Tx-based composites, such as metals, metal oxides, metal sulfides, organic frameworks, photosensitizers, etc. We also summarize the fabrication techniques used for preparing Ti3C2Tx-based composites, including solution mixing, chemical synthesis, layer-by-layer self-assembly, electrostatic assembly, and three-dimensional (3D) printing. The most recent developments in antibacterial application are also thoroughly discussed, with special attention to the medical, water treatment, food preservation, flexible textile, and industrial sectors. Ultimately, the future directions and opportunities are delineated, underscoring the focus of further research, such as elucidating microscopic mechanisms, achieving a balance between biocompatibility and antibacterial efficiency, and investigating effective, eco-friendly synthesis techniques combined with intelligent technology. A survey of the literature provides a comprehensive overview of the state-of-the-art developments in Ti3C2Tx-based composites and their potential applications in various fields. This comprehensive review covers the variety, preparation methods, and applications of Ti3C2Tx-based composites, drawing upon a total of 171 English-language references. Notably, 155 of these references are from the past five years, indicating significant recent progress and interest in this research area.

Type I photodynamic antimicrobial therapy: Principles, progress, and future perspectives

The emergence of drug-resistant bacteria has significantly diminished the efficacy of existing antibiotics in the treatment of bacterial infections. Consequently, the need for finding a strategy capable of effectively combating bacterial infections has become increasingly urgent. Photodynamic therapy (PDT) is considered one of the most promising emerging antibacterial strategies due to its non-invasiveness, low adverse effect, and the fact that it does not lead to the development of drug resistance. However, bacteria at the infection sites often exist in the form of biofilm instead of the planktonic form, resulting in a hypoxic microenvironment. This phenomenon compromises the treatment outcome of oxygen-dependent type-II PDT. Compared to type-II PDT, type-I PDT is not constrained by the oxygen concentration in the infected tissues. Therefore, in the treatment of bacterial infections, type-I PDT exhibits significant advantages over type-II PDT. In this review, we first introduce the fundamental principles of type-I PDT in details, including its physicochemical properties and how it generates reactive oxygen species (ROS). Next, we explore several specific antimicrobial mechanisms utilized by type-I PDT and summarize the recent applications of type-I PDT in antimicrobial treatment. Finally, the limitations and future development directions of type-I photosensitizers are discussed. STATEMENT OF SIGNIFICANCE: The misuse and overuse of antibiotics have accelerated the development of bacterial resistance. To achieve the effective eradication of resistant bacteria, pathfinders have devised various treatment strategies. Among these strategies, type I photodynamic therapy has garnered considerable attention owing to its non-oxygen dependence. The utilization of non-oxygen-dependent photodynamic therapy not only enables the effective elimination of drug-resistant bacteria but also facilitates the successful eradication of hypoxic biofilms, which exhibits promising prospects for treating biofilm-associated infections. Based on the current research status, we anticipate that the novel type I photodynamic therapy agent can surmount the biofilm barrier, enabling efficient treatment of hypoxic biofilm infections.

3D Printed Photothermal Scaffold Sandwiching Bacteria Inside and Outside Improves The Infected Microenvironment and Repairs Bone Defects

Bone infection is one of the most devastating orthopedic outcomes, and overuse of antibiotics may cause drug-resistance problems. Photothermal therapy(PTT) is a promising antibiotic-free strategy for treating infected bone defects. Considering the damage to normal tissues and cells caused by high-temperature conditions in PTT, this study combines the antibacterial property of Cu to construct a multi-functional Cu2 O@MXene/alpha-tricalcium phosphate (α-TCP) scaffold support with internal and external sandwiching through 3D printing technology. On the "outside", the excellent photothermal property of Ti3 C2 MXene is used to carry out the programmed temperature control by the active regulation of 808 nm near-infrared (NIR) light. On the "inside", endogenous Cu ions gradually release and the release accumulates within the safe dose range. Specifically, programmed temperature control includes brief PTT to rapidly kill early bacteria and periodic low photothermal stimulation to promote bone tissue growth, which reduces damage to healthy cells and tissues. Meanwhile, Cu ions are gradually released from the scaffold over a long period of time, strengthening the antibacterial effect of early PTT, and promoting angiogenesis to improve the repair effect. PTT combined with Cu can deliver a new idea forinfected bone defects through in vitro and vivo application.