Bacteria-Targeted Combined with Photothermal/NO Nanoparticles for the Treatment and Diagnosis of MRSA Infection In Vivo

Cyclodextrin-based self-assembling hydrogel for Photothermal-controlled nitric oxide release in stage-specific treatment of MRSA-induced arthritis

MRSA-induced arthritis is a prevalent and highly debilitating orthopedic condition. The inflammatory response induced by bacterial infection hinders tissue repair and exacerbates bone loss. Traditional antibiotic therapies are limited by low bioavailability, substantial side effects, and narrow efficacy, rendering them inadequate for comprehensive treatment of arthritis. Nitric oxide (NO) has demonstrated considerable potential in overcoming bacterial resistance, modulating immune responses, and facilitating tissue repair. Therefore, a stage-specific NO release strategy, tailored to the distinct phases of bacterial arthritis, is essential for effective treatment. In this study, mesoporous polydopamine nanoparticles were utilized as NO donors (mPDA/NONOate) and encapsulated within a supramolecular hydrogel formed via the host-guest interaction between α-cyclodextrin (α-CD) and Pluronic F127. The injectable nature of the resulting NO/PDA-Gel hydrogel ensured uniform distribution within irregular bone joint infection sites, minimizing NO donor loss and enhancing local bioavailability. Notably, upon near-infrared (NIR) irradiation, the hydrogel induces a rapid increase in local temperature, facilitating rapid NO release. At the same time, the synergistic photothermal effect effectively kills bacteria and rapidly controls the infection. Without light irradiation, NO is sustainably and stably released from the NO/PDA-Gel, modulating the bone immune microenvironment, alleviating inflammation, promoting chondrocyte proliferation and differentiation, and accelerating bone tissue repair, thus significantly shortening the healing time of MRSA-induced arthritis. In conclusion, the injectable self-assembled NO/PDA-Gel offers a precise, stage-matched therapeutic approach for MRSA-induced arthritis and holds promise for the treatment of deep-seated infections caused by other multidrug-resistant pathogens.

Layer-Restacked 3D Ti3C2 Nanostructures with Efficient Photothermal Antibacterial Activities

Multidrug-resistant bacterial infections have emerged as a global public health crisis due to antibiotic misuse. In this study, we develop a layer-restacked 3D Ti3C2 nanostructure utilizing ice-templating. This nanostructure exhibits outstanding hydrophilicity, biocompatibility, and stability, as well as enhanced absorption, extinction coefficient, and photothermal conversion efficiency. Additionally, the layer-restacked 3D Ti3C2 nanostructure demonstrates excellent antibacterial activity against MDR Escherichia coli and MDR Staphylococcus aureus irradiated by 808 nm near-infrared light (NIR). Specifically, the mechanism of photothermal action against multidrug-resistant bacteria involves structural damage to the bacterial membranes, leading to the leakage of bacterial contents after layer-restacked 3D Ti3C2 nanostructures adhered under NIR irradiation. The results of transcriptome analysis show that the 3D Ti3C2 nanostructure regulates the membrane transporters and membrane transporter proteins on the bacterial cell membrane as well as the activities of enzymes associated with them, which in turn affect the metabolic processes of organic acids and other organic substances in the bacterial cell. The DNA-binding transcriptional activator EvgA is significantly downregulated, which may play a crucial role in inhibiting the emergence of drug resistance in bacteria when exposed to the layer-restacked 3D Ti3C2 nanostructure. The layer-restacked 3D Ti3C2 nanostructure is an effective photothermal antimicrobial nanostructure against multidrug-resistant bacteria.

Nanomedicines as disruptors or inhibitors of biofilms: Opportunities in addressing antimicrobial resistance

The problem of antimicrobial resistance (AMR) has caused global concern due to its great threat to human health. Evidences are emerging for a critical role of biofilms, one of the natural protective mechanisms developed by bacteria during growth, in resisting commonly used clinical antibiotics. Advances in nanomedicines with tunable physicochemical properties and unique anti-biofilm mechanisms provide opportunities for solving AMR risks more effectively. In this review, we summarize the five "A" stages (adhesion, amplification, alienation, aging and allocation) of biofilm formation and mechanisms through which they protect the internal bacteria. Aimed at the characteristics of biofilms, we emphasize the design "THAT" principles (targeting, hacking, adhering and transport) of nanomedicines in their interactions with biofilms and internal bacteria. Furthermore, recent progresses in multimodal antibacterial nanomedicines, including biofilms disruption and bactericidal activity, and the types of currently available antibiofilm nanomedicines contained organic and inorganic nanomedicines are outlined and highlighted their potential applications in the development of preclinical research. Last but not least, we offer a perspective for the effectiveness of nanomedicines designed to address AMR and challenges associated with their clinical translation.

NIR-activating glycyrrhizic acid/carbon nanozyme injectable polysaccharides-based hydrogels for promoting polymicrobial infected wound healing

The slow healing or non-healing of skin wounds caused by polymicrobial infections has become a serious problem in clinical wound treatment. Herein, we have developed a near-infrared (NIR) activating glycyrrhizic acid/carbon nanozyme injectable polysaccharides-based hydrogel (the CPCA hydrogel) for the synergistic treatment of polymicrobial infected wound. The CPCA hydrogel could undergo phase transition at a specific temperature and facilitate administration at the wound site. Additionally, under near-infrared light irradiation, the CPCA hydrogel could generate heat and promote the release of glycyrrhizic acid (GA) for achieving photothermal-drug synergistic treatment of multiple bacteria. Furthermore, the carbon nanozyme (CN) within the injectable polysaccharides-based hydrogel could mimic the activity of superoxide dismutase (SOD) and catalase (CAT) for enabling the removal of reactive oxygen species, effectively alleviating inflammation and promoting wound healing caused by polymicrobial infections. The results of in vitro antibacterial experiments demonstrated the excellent antibacterial effect of CPCA hydrogel on methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa. Furthermore, in vivo experiments confirmed that the hydrogels significantly reduced inflammatory responses and accelerated angiogenesis in polymicrobial infected wounds. Collectively, the CPCA hydrogel exhibited excellent antibacterial and anti-inflammatory properties, offering a novel strategy for developing new treatments for polymicrobial infections.

Maltodextrin-driven MOF Nano-antibacterial system for effective targeted bacteria and enhancing photodynamic therapy in bacterial keratitis

The occurrence of bacterial keratitis (BK) presents a significant threat to ocular health, often leading to visual impairment. Currently, conventional antibiotic therapies tend to promote bacterial resistance and lack biocompatibility. Therefore, it is of great significance to develop an alternative product with safe and efficient antimicrobial properties. In this study, we developed a novel smart pH-responsive nano-antibacterial system (PM/Ag-Ce6@ZIF-8) based on a metal-organic framework (MOF), enabling specific bacterial targeting and photodynamic therapy. By utilizing bacteria-specific maltodextrin transport pathway, the intelligent nano-antibacterial modified with maltotriose can accurately discriminate between bacterial infection and normal tissue, specifically target the site of infection, and efficiently accumulate at the infection site to enhance safety and efficacy. Furthermore, the incorporation of silver nanoparticles enhances the effectiveness of MOF photodynamic therapy by effectively eradicating bacteria. The nano-antibacterial system exhibits potent inhibition of biofilm formation as well as antibacterial activity while demonstrating excellent in vitro and in vivo biocompatibility. In an animal model of bacterial keratitis, PM/Ag-Ce6@ZIF-8 exhibits superior antibacterial activity compared to Levofloxacin (LVFX) eye drops, significantly improving therapeutic outcomes for bacterial keratitis in mice. Hence, this intelligent nano-antibacterial platform holds promising potential for clinical applications in treating keratitis.

Semiconducting Perylene Diimide J-aggregates Cross-linked Hydrogel Enables High-Efficiency Photothermal Controlled Release of Nitric Oxide for Antibiofilm Therapy

Antibiofilm treatment, particularly drug-containing wound healing dressings, does not typically penetrate the robust protective extracellular polymeric substance of biofilm and eradicate the bacteria. Here, a rational design of nitric oxide (NO) donor N,N'-di-sec-butyl-N,N'-dinitroso-1,4-phenylenediamine (BNN6)-based injectable hydrogel, is reported in which the NO release can be triggered by a photothermal effect owing to semiconducting perylene diimide (PDI) J-aggregation fibers. The synthetic PDI derivatives self-assembling into 0D nanoparticles and then aggregating to 1D J fiber is accompanied by absorbance red-shifting from 700 to 790 nm and then to 852 nm. After encapsulating BNN6, a "sandwich roll" (SR) like structure is evenly crosslinked into an injectable hydrogel (SRH) exhibiting a high photothermal convenience efficiency of 72%, which enables the SRH to achieve highly efficient photocontrol NO release. The SRH shows excellent injectability, shape adaptability, and effective antibacterial efficacy over 99% to the E.coli and S. aureus. and remarkable in vivo antibiofilm efficiency of 99.58% by laser irradiation. Furthermore, the synergistic treatment displays the ability to eliminate inflammation, facilitate angiogenesis, and promote collagen deposition, thereby significantly stimulating the healing process of wounds. The semiconducting J-aggregation injectable hydrogel can be a versatile strategy for the treatment of biofilm.

Targeting ClpP: Unlocking a novel therapeutic approach of isochlorogenic acid A for methicillin-resistant Staphylococcus aureus-infected osteomyelitis

A medical predicament has led to extensive drug resistance in methicillin-resistant Staphylococcus aureus (MRSA), and the complexity of treatment has increased exponentially with the induction of osteomyelitis. In view of the severe situation and the potential of bacterial antivirulence strategies, this study focused on the key virulence factor caseinolytic protease (ClpP) of S. aureus to identify new strategies against MRSA-induced osteomyelitis. As the main protein "quality control" system of S. aureus, ClpP is indispensable for coordinating drug resistance, regulating adhesion, and acting on numerous virulence targets. Through fluorescence resonance energy transfer (FRET), we successfully identified isochlorogenic acid A (I-A), a polyphenol derivative, as an efficient inhibitor of ClpP, with an IC50 value of 24.89 μg/mL. Further analysis revealed that I-A can effectively inhibit the expression of virulence factors of MRSA and significantly reduce its adhesion to fibrinogen. Molecular docking revealed the potential binding sites of ClpP and I-A, namely, ILE-81, LYS-109, GLU-156, ARG-157, and GLY-184. At the cellular level, I-A can alleviate the death and increased secretion of inflammatory factors caused by MRSA USA300 in MC3T3-E1 cells. Moreover, it downregulates the activity of ClpP and reduces the response of bacteria to environmental stress. In vivo experiments have confirmed that I-A shows significant efficacy in both rat osteomyelitis models and Galleria mellonella infection models. This study provides new insights into the field of treatment strategies targeting virulence and provides a solid foundation for further exploration of the potential of I-A in combating drug-resistant S. aureus.

Harnessing Nature's Power: Plant and Polymeric-Based Antibacterials as Potential Therapeutics for Infectious Skin Wound Healing

This comprehensive review explores the potential of plant- and biopolymeric-based antibacterials as innovative therapeutic agents for infectious skin wound healing. By researching the antibacterial properties of various plants, the review highlights their application in skin tissue engineering. Beyond reviewing antibacterial plant extracts, the article delves into the limitations these natural compounds face, such as hydrophilicity, drug release rates, cell attachment, and scaffold stability when integrated into tissue engineering constructs. The review also emphasizes the role of biopolymeric materials, hydrogel optimization, and crosslinkers to improve scaffold performance. This review provides a roadmap for future research by addressing critical factors in scaffold construction. In the end, it aims to guide the development of more effective wound dressings and tissue scaffolds, combining the natural power of plants with advanced biopolymeric materials for enhanced wound healing therapies.

Macrophage Membrane-Encapsulated Carbon Dots for Precise Targeting Diagnosis and Treatment of Bacterial Infections

How to accurately diagnose and treat bacterial infections in vivo remains a huge challenge. Therefore, we have developed a targeted delivery nanosystem by coextruding the pretreated macrophage membrane of S. aureus with carbon dots (M@CD). The M@CD nanosystem demonstrates potent antibacterial effects both in vivo and in vitro through the generation of reactive oxygen species (ROS). Furthermore, M@CD exhibits enhanced targeting ability and stable fluorescence properties, addressing issues such as poor targeting efficiency and high immunogenicity in vivo. This innovative approach enables infection site specific aggregation and elimination of bacterial infections, thereby providing a promising strategy for the integrated diagnosis, treatment, and monitoring of bacterial infections.

Self-Cascade of ROS/Glucose-Scavenging Immunomodulatory Hydrogels for Programmed Therapeutics of Infected Diabetic Ulcers via Nrf2/NF-κB Pathway

Diabetic ulcers (DUs) are characterized by a microenvironment with high oxidative stress, high blood glucose levels, and recalcitrant bacterial infections. This microenvironment is accompanied by long-term suppression of endogenous antioxidant systems, which makes their clinical management extremely challenging. To address this issue, a hybridized novel gold-palladium (AuPd) nanoshell of the injectable/injectable hydrogel system UiO/AuPdshells/BNN6/PEG@Gel (UAPsBP@Gel) is developed. The system is capable of acting as a nitric oxide (NO) reactor utilizing synergistic therapy that harnesses NIR-II light-triggered photothermal effects and controlled release of NO gas for synergistic treatment to eradicate biofilm infections at different depths. The AuPd nanoshells exhibits superoxide dismutase (SOD)-, glucose oxidase (GOx)-, and catalase (CAT)-like activities, enabling self-cascade process for scavenging both reactive oxygen species (ROS) and glucose. This activity reshapes the DUs microenvironment, switches on the endogenous antioxidant Nrf2/HO-1 pathway and inhibits the NF-κB pathway, promotes macrophage polarization toward the anti-inflammatory M2 phenotype, and reduces oxidative stress, resulting in efficient immunomodulation. In vitro/in vivo results demonstrate that the UAPsBP@Gel can multifacetedly enhance the epithelial rejuvenation process through wound hemostasis, pro-cellular migration and vascularization. These results highlight that a programmed therapeutic based on UBAPsP@Gel tailored to the different stages of infected DUs can meet complex clinical needs.

Injectable antibacterial drug-free hydrogel dressing enabled by a bioactive peptide-mimicking synthetic peptidyl polymer

The management of bacterial wounds presents a significant challenge in the field of medicine and poses a grave threat to public health. Traditional gauze materials exhibit limited efficacy in treating bacterial infection wounds, while antibiotics demonstrate cytotoxicity and resistance. Therefore, in this study, the peptide biomimetic polymer (PAL-BA) was designed and served as the antibacterial framework for constructing an antibiotic drug-free antibacterial hydrogel dressing through a Schiff base reaction with oxidized hyaluronic acid (OHA). The design of PAL-BA aims to emulate the antimicrobial properties of host defense peptides, serving as a viable alternative to antibiotics drugs. It exhibits comparable antimicrobial activity to polylysine while maintaining biosafety. In vitro experiments demonstrated that PAL-BA exhibited exceptional antibacterial activity against both Staphylococcus aureus and Escherichia coli, while the PAL-BA based antibacterial hydrogel (PBP gel) effectively eliminated 100% of pathogenic bacteria within a duration of 140 min. In vivo studies further demonstrated that PBP hydrogels effectively accelerate the healing of bacterial infected wounds by blocking the infection process. Therefore, the antimicrobial peptide biomimetic polymer hydrogel exhibits significant promise for the management of bacterial wound infections. STATEMENT OF SIGNIFICANCE: The management of bacterial infection wounds remains a challenging issue in clinical practice. In this study, we propose the utilization of a peptide biomimetic polymer (PAL-BA) as an antibacterial framework and its combination with oxidized hyaluronic acid (OHA) through Schiff base reactions to develop an antibiotic drug-free antibacterial hydrogel dressing for the treatment of bacterial infections wounds. The design of PAL-BA aims to mimic the antimicrobial properties of host defense peptides, providing a promising alternative to antibiotic drugs. It demonstrates comparable antimicrobial activity to poly-lysine while maintaining biosafety. Importantly, this antimicrobial peptide biomimetic polymer hydrogel effectively inhibits the infection process in mouse wounds and accelerates the healing of bacterially infected wounds, offering a therapeutic approach for treating infected wounds.

Spatially confined photoacoustic effects of responsive nanoassembly boosts lysosomal membrane permeabilization and immunotherapy of triple-negative breast cancer

Although immunogenic cell death (ICD) induced by lysosomal membrane permeabilization (LMP) evidently enhance the effectiveness of antitumor immunity for triple-negative breast cancer (TNBC) with poor immunogenicity, their potential is increasingly restricted by the development of other death pathways and the repair of lysosomes by endoplasmic reticulum (ER) during LMP induction. Herein, a polydopamine nanocomposite with i-motif DNA modified and BNN6 loaded is prepared toward boosting LMP and immunotherapy of TNBC by synergy of spatially confined photoacoustic (PA) effects and nitric oxide. Combining the high-frequency pulsed laser (4000 kHz) with the intra-lysosomal assembly of nanocomposites produced spatially confined and significantly boosted PA effects (4.8-fold higher than the individually dispersed particles extracellular), suppressing damage to other cellular components and selectively reducing lysosomal integrity to 19.2 %. Simultaneously, the releasing of nitric oxide inhibited the repair of lysosomes by ER stress, causing exacerbated LMP. Consequently, efficient immune activation was achieved, including the abundant releasing of CRT/HMGB1 (5.93-6.8-fold), the increasing maturation of dendritic cells (3.41-fold), and the fostered recruitment of CD4+/CD8+T cells (3.99-3.78-fold) in vivo. The study paves a new avenue for the rational design and synergy of confined energy conversion and responsive nanostructures to achieve the treatment of low immunogenicity tumors. STATEMENT OF SIGNIFICANCE: A strategy of boosting lysosomal membrane permeabilization (LMP) and concomitantly preventing the repair was developed to address the immunotherapy challenge of triple-negative breast cancer. Spatially confined and significantly enhanced photoacoustic (PA) effects were achieved through DNA-guided pH-responsive assembly of polydopamine nanocomposites in lysosomes and application of a high-frequency pulsed laser. Efficient immunogenic cell death was guaranteed by selective and powerful damage of lysosomal membranes through the significant contrast of PA intensities for dispersed/assembled particles and nitric oxide release induced endoplasmic reticulum stress. The study paves a new avenue for the rational design and synergy of confined energy conversion and responsive nanostructures to achieve the treatment of low immunogenicity tumors.

Sea Anemone-Inspired Slippery Liquid-Infused Porous Surface (SLIPS) with Bionic Cilia for Responsive 4D Antifouling

The formation process of biofouling is actually a 4D process with both spatial and temporal dimensions. However, most traditional antifouling coatings, including slippery liquid-infused porous surface (SLIPS), are limited to performing antifouling process in the 2D coating plane. Herein, inspired by the defensive behavior of sea anemones' wielding toxic tentacles, a "4D SLIPS" (FSLIPS) is constructed with biomimetic cilia via a magnetic field self-assembly method for antifouling. The bionic cilia move in 3D space driven by an external magnetic field, thereby preventing the attachment of microorganisms. The FSLIPS releases the gaseous antifoulant (nitric oxide) at 1D time in response to light, thereby achieving a controllable biocide effect on microorganisms. The FSLIPS regulates the movement of cilia via the external magnetic field, and controls the release of NO overtime via the light response, so as to adjust the antifouling modes on demand during the day or night. The light/magnetic response mechanism endow the FSLIPS with the ability to adjust the antifouling effect in the 4D dimension of 1D time and 3D space, effectively realizing the intelligence, multi-dimensionality and precision of the antifouling process.

Polydopamine Nanocarriers with Cascade-Activated Nitric Oxide Release Combined Photothermal Activity for the Therapy of Drug-Resistant Bacterial Infections

Antibiotic abuse leads to increased bacterial resistance, and the surviving planktonic bacteria aggregate and secrete extracellular polymers to form biofilms. Conventional antibacterial agents find it difficult to penetrate the biofilm, remove the bacteria wrapped in it, and produce an excellent therapeutic effect. In this study, a dual pH- and NIR-responsive nanocomposite (A-Ca@PDA) was developed to remove drug-resistant bacteria through a cascade of catalytic nitric oxide (NO) release and photothermal clearance. NO can melt in the outer package of the biofilm, facilitating the nanocomposites to have better permeability. Thermal therapy further inhibits the growth of planktonic bacteria. The locally generated high temperature and the burst release of NO together aggravate the biofilm collapse and bacterial death after NIR irradiation. The nanocomposites achieved a remarkable photothermal conversion efficiency of 47.5%, thereby exhibiting significant advancements in energy conversion. The nanocomposites exhibited remarkable efficacy in inhibiting multidrug-resistant (MDR) Escherichia coli and MDR Staphylococcus aureus, thus achieving an inhibition rate of >90%. Moreover, these nanocomposites significantly improved the wound-healing process in the MDR S. aureus-infected mice. Thus, this novel nanocomposite offers a novel strategy to combat drug-resistant bacterial infections.

Synergistic antibacterial and antifouling wound dressings: Integration of photothermal-activated no release and zwitterionic surface modification

Addressing the pervasive issue of bacteria and biofilm infections is crucial in the development of advanced antifouling wound dressings. In this study, a novel wound healing treatment using sulfobetaine (SBMA) decorated electrospun fibrous membrane based on polycaprolactone (PCL)/nitric oxide (NO) donors was developed. The fabrication involved a dual strategy, first integrating NO donors into mesoporous polydopamine (MPDA) and complexed with PCL/PEI to electrospin nanofibers. The fibrous membrane exhibited a potent antibacterial response upon irradiation at 808 nm, owing to a combination of NO and photothermal effect that effectively targets bacteria and disrupts biofilms. Surface functionalization of the membrane with PEI allowed for the attachment of SBMA via Michael addition, fabricating a zwitterionic surface, which significantly hinders protein adsorption and reduces biofilm formation on the wound dressing. In vitro and in vivo assessments confirmed the rapid bactericidal capabilities and its efficacy in biofilm eradication. Combining photothermal activity, targeted NO release and antifouling surface, this multifaceted wound dressing addresses key challenges in bacterial infection management and biofilm eradication, promoting efficient wound healing.

Applications of nitric oxide-releasing nanomaterials in dermatology: Skin infections and wound healing

Nitric oxide (NO) is produced in most cells in the skin and is an important regulator of essential cutaneous functions, including responses to UV irradiation, microbial defense, wound healing, melanogenesis and epidermal permeability barrier homeostasis. Harnessing the physiological activities of NO for therapeutic use is difficult because the molecule is highly reactive and unstable. A variety of exogenous NO delivery platforms have been developed and evaluated; however, they have limited clinical applications in dermatology due to instability and poor cutaneous penetration. NO-releasing nanomaterials overcome these limitations, providing targeted tissue delivery, and sustained and controlled NO release. This review provides a comprehensive and up-to-date evaluation of the use of NO-releasing nanomaterials in dermatology for the treatment of skin and soft tissue infections and wound healing.

Strategies to Promote the Journey of Nanoparticles Against Biofilm-Associated Infections

Biofilm-associated infections are one of the most challenging healthcare threats for humans, accounting for 80% of bacterial infections, leading to persistent and chronic infections. The conventional antibiotics still face their dilemma of poor therapeutic effects due to the high tolerance and resistance led by bacterial biofilm barriers. Nanotechnology-based antimicrobials, nanoparticles (NPs), are paid attention extensively and considered as promising alternative. This review focuses on the whole journey of NPs against biofilm-associated infections, and to clarify it clearly, the journey is divided into four processes in sequence as 1) Targeting biofilms, 2) Penetrating biofilm barrier, 3) Attaching to bacterial cells, and 4) Translocating through bacterial cell envelope. Through outlining the compositions and properties of biofilms and bacteria cells, recent advances and present the strategies of each process are comprehensively discussed to combat biofilm-associated infections, as well as the combined strategies against these infections with drug resistance, aiming to guide the rational design and facilitate wide application of NPs in biofilm-associated infections.

Regulation of the upconversion effect to promote the removal of biofilms on a titanium surface via photoelectrons

Biofilms on public devices and medical instruments are harmful. Hence, it is of great importance to fabricate antibacterial surfaces. In this work, we target the preparation of an antibacterial surface excited by near-infrared light via the coating of rare earth nanoparticles (RE NPs) on a titanium surface. The upconverted luminescence is absorbed by gold nanoparticles (Au NPs, absorber) to produce hot electrons and reactive oxygen species to eliminate the biofilms. The key parameters in tuning the upconversion effect to eliminate the biofilms are systematically investigated, which include the ratios of the sensitizer, activator, and matrix in the RE NPs, or the absorber Au NPs. The regulated RE NPs exhibit an upconversion quantum yield of 3.5%. Under illumination, photogenerated electrons flow through the surface to bacteria, such as E. coli, which disrupt the breath chain and eventually lead to the death of bacteria. The mild increase of the local temperature has an impact on the elimination of biofilms on the surface to a certain degree as well. Such a configuration on the surface of titanium exhibits a high reproducibility on the removal of biofilms and is functional after the penetration of light using soft tissue. This work thus provides a novel direction in the application of upconversion materials to be used in the fabrication of antibacterial surfaces.

A nanocomposite hydrogel for co-delivery of multiple anti-biofilm therapeutics to enhance the treatment of bacterial biofilm-related infections

The characteristics of biofilms have exacerbated the issue of clinical antibiotic resistance, rendering it a pressing challenge in need of resolution. The combination of biofilm-dispersing agents and antibiotics can eliminate biofilms and promote healing synergistically in infected wounds. In this study, we developed a novel nanocomposite hydrogel (NC gel) comprised of the poly(lactic acid)-hyperbranched polyglycerol (PLA-HPG) based bioadhesive nanoparticles (BNPs) and a hydrophilic carboxymethyl chitosan (CS) network. The NC gel was designed to co-deliver two biofilm-dispersing agents (an NO-donor SNO, and an α-amylase Am) and an antibiotic, cefepime (Cef), utilizing a synergistic anti-biofilm mechanism in which Am loosens the matrix structure and NO promotes the release of biofilm bacteria via quorum sensing, and Cef kills bacteria. The drug-loaded NC gel (SNO/BNP/CS@Am-Cef) demonstrated sustained drug release, minimal cytotoxicity, and increased drug-bacterial interactions at the site of infection. When applied to mice infected with methicillin-resistant Staphylococcus aureus (MRSA) biofilms in vivo, SNO/BNP/CS@Am-Cef enhanced biofilm elimination and promoted wound healing compared to traditional antibiotic treatments. Our work demonstrates the feasibility of the co-delivery of biofilm-dispersing agents and antibiotics using the NC gel and presents a promising approach for the polytherapy of bacterial biofilm-related infections.

Photothermal synergistic nitric oxide controlled release injectable self-healing adhesive hydrogel for biofilm eradication and wound healing

The development of injectable self-healing adhesive hydrogel dressings with excellent bactericidal activity and wound healing ability is urgently in demand for combating biofilm infections. Herein, a multifunctional hydrogel (QP/QT-MB) with near-infrared (NIR) light-activated mild photothermal/gaseous antimicrobial activity was developed based on the dynamic reversible borate bonds and hydrogen bonds crosslinking between quaternization chitosan (QCS) derivatives alternatively containing phenylboronic acid and catechol-like moieties in conjunction with the in situ encapsulation of BNN6-loaded mesoporous polydopamine (MPDA@BNN6 NPs). Given the dynamic reversible cross-linking feature, the versatile hybrid hydrogel exhibited injectability, flexibility, and rapid self-healing ability. The numerous phenylboronic acid and catechol-like moieties on the QCS backbone confer the hydrogel with specific bacterial affinity, desirable tissue adhesion, and antioxidant stress ability that enhance bactericidal activity and facilitate the regeneration of infection wounds. Under NIR irradiation, the QP/QT-MB hydrogels exhibited a desirable mild photothermal effect and NIR-activity controllable NO delivery, combined with the endogenous contact antimicrobial activity of hydrogel, contributing jointly to induce dispersal of biofilms and disruption of the bacterial plasma membranes, ultimately leading to bacteria inactivation and biofilm elimination. In vivo experiments demonstrated that the fabricated QP/QT-MB hydrogel platform was capable of inducing efficient eradication of the S. aureus biofilm in a severely infected wound model and accelerating infected wound repair by promoting collagen deposition, angiogenesis, and suppressing inflammatory responses. Additionally, the QP/QT-MB hydrogel demonstrated excellent biocompatibility in vitro and in vivo. Collectively, the hydrogel (QP/QT-MB) reveals great potential application prospects as a promising alternative in the field of biofilm-associated infection treatment.

Recent Progress of Photothermal Therapy Based on Conjugated Nanomaterials in Combating Microbial Infections

Photothermal therapy has the advantages of non-invasiveness, low toxicity, simple operation, a broad spectrum of antibacterial ability, and non-proneness to developing drug resistance, which provide it with irreplaceable superiority in fighting against microbial infection. The effect of photothermal therapy is closely related to the choice of photothermal agent. Conjugated nanomaterials are potential candidates for photothermal agents because of their easy modification, excellent photothermal conversion efficiency, good photostability, and biodegradability. In this paper, the application of photothermal agents based on conjugated nanomaterials in photothermal antimicrobial treatment is reviewed, including conjugated small molecules, conjugated oligomers, conjugated polymers, and pseudo-conjugated polymers. At the same time, the application of conjugated nanomaterials in the combination of photothermal therapy (PTT) and photodynamic therapy (PDT) is briefly introduced. Finally, the research status, limitations, and prospects of photothermal therapy using conjugated nanomaterials as photothermal agents are discussed.