L-Arg-Rich Amphiphilic Dendritic Peptide as a Versatile NO Donor for NO/Photodynamic Synergistic Treatment of Bacterial Infections and Promoting Wound Healing

Photothermal/photodynamic synergistic antibacterial study of MOF nanoplatform with SnFe2O4 as the core

Drug-resistant bacterial infections cause significant harm to public life, health, and property. Biofilm is characterized by overexpression of glutathione (GSH), hypoxia, and slight acidity, which is one of the main factors for the formation of bacterial resistance. Traditional antibiotic therapy gradually loses its efficacy against multi-drug-resistant (MDR) bacteria. Therefore, synergistic therapy, which regulates the biofilm microenvironment, is a promising strategy. A multifunctional nanoplatform, SnFe2O4-PBA/Ce6@ZIF-8 (SBC@ZIF-8), in which tin ferrite (SnFe2O4, denoted as SFO) as the core, loaded with 3-aminobenzeneboronic acid (PBA) and dihydroporphyrin e6 (Ce6), and finally coated with zeolite imidazole salt skeleton 8 (ZIF-8). The platform has a synergistic photothermal therapy (PTT)/photodynamic therapy (PDT) effect, which can effectively remove overexpressed GSH by glutathione peroxidase-like activity, reduce the antioxidant capacity of biofilm, and enhance PDT. The platform had excellent photothermal performance (photothermal conversion efficiency was 55.7 %) and photothermal stability. The inhibition rate of two MDR bacteria was more than 96 %, and the biofilm clearance rate was more than 90 % (150 μg/mL). In the animal model of MDR S. aureus infected wound, after 100 μL SBC@ZIF-8+NIR (150 μg/mL) treatment, the wound area of mice was reduced by 95 % and nearly healed. The serum biochemical indexes and H&E staining results were within the normal range, indicating that the platform could promote wound healing and had good biosafety. In this study, we designed and synthesized multifunctional nanoplatforms with good anti-drug-resistant bacteria effect and elucidated the molecular mechanism of its anti-drug-resistant bacteria. It lays a foundation for clinical application in treating wound infection and promoting wound healing.

A Zn-MOF-GOx-based cascade nanoreactor promotes diabetic infected wound healing by NO release and microenvironment regulation

Diabetic wound healing is a great clinical challenge due to the microenvironment of hyperglycemia and high pH value, bacterial infection and persistent inflammation. Here, we develop a cascade nanoreactor hydrogel (Arg@Zn-MOF-GOx Gel, AZG-Gel) with arginine (Arg) loaded Zinc metal organic framework (Zn-MOF) and glucose oxidase (GOx) based on chondroitin sulfate (CS) and Pluronic (F127) to accelerate diabetic infected wound healing. GOx in AZG-Gel was triggered by hyperglycemic environment to reduce local glucose and pH, and simultaneously produced hydrogen peroxide (H2O2) to enable Arg-to release nitric oxide (NO) for inflammation regulation, providing a suitable microenvironment for wound healing. Zinc ions (Zn2+) released from acid-responsive Zn-MOF significantly inhibited the proliferation and biofilm formation of S.aureus and E.coli. AZG-Gel significantly accelerated diabetic infected wound healing by down-regulating pro-inflammatory tumor necrosis factor (TNF)-α and interleukin (IL)-6, up-regulating anti-inflammatory factor IL-4, promoting angiogenesis and collagen deposition in vivo. Collectively, our nanoreactor cascade strategy combining "endogenous improvement (reducing glucose and pH)" with "exogenous resistance (anti-bacterial and anti-inflammatory)" provides a new idea for promoting diabetic infected wound healing by addressing both symptoms and root causes. STATEMENT OF SIGNIFICANCE: A cascade nanoreactor (AZG-Gel) is constructed to solve three key problems in diabetic wound healing, namely, hyperglycemia and high pH microenvironment, bacterial infection and persistent inflammation. Local glucose and pH levels are reduced by GOx to provide a suitable microenvironment for wound healing. The release of Zn2+ significantly inhibits bacterial proliferation and biofilm formation, and NO reduces wound inflammation and promotes angiogenesis. The pH change when AZG-Gel is applied to wounds is expected to enable the visualization of wound healing to guide the treatment of diabetic wound. Our strategy of "endogenous improvement (reducing glucose and pH)" combined with "exogenous resistance (anti-bacterial and anti-inflammatory)" provides a new way for promoting diabetic wound healing.

Functional nanomaterials as photosensitizers or delivery systems for antibacterial photodynamic therapy

Bacterial infection is a global health problem that closely related to various diseases threatening human life. Although antibiotic therapy has been the mainstream treatment method for various bacterial infectious diseases for decades, the increasing emergence of bacterial drug resistance has brought enormous challenges to the application of antibiotics. Therefore, developing novel antibacterial strategies is of great importance. By producing reactive oxygen species (ROS) with photosensitizers (PSs) under light irradiation, antibacterial photodynamic therapy (aPDT) has emerged as a non-invasive and promising approach for treating bacterial infections without causing drug resistance. However, the insufficient therapeutic penetration, poor hydrophilicity, and poor biocompatibility of traditional PSs greatly limit the efficacy of aPDT. Recently, studies have found that nanomaterials with characteristics of favorable photocatalytic activity, surface plasmonic resonance, easy modification, and high drug loading capacity can improve the therapeutic efficacy of aPDT. In this review, we aim to provide a comprehensive understanding of the mechanism of nanomaterials-mediated aPDT and summarize the representative nanomaterials in aPDT, either as PSs or carriers for PSs. In addition, the combination of advanced nanomaterials-mediated aPDT with other therapies, including targeted therapy, gas therapy, and multidrug resistance (MDR) therapy, is reviewed. Also, the concerns and possible solutions of nanomaterials-based aPDT are discussed. Overall, this review may provide theoretical basis and inspiration for the development of nanomaterials-based aPDT.

Curcumin-loaded mesoporous polydopamine nanoparticles modified by quaternized chitosan against bacterial infection through synergistic effect

Clinically, open wounds caused by accidental trauma and surgical lesion resection are easily infected by external bacteria, hindering wound healing. Antibacterial photodynamic therapy has become a promising treatment strategy for wound infection. In this study, a novel antibacterial nanocomposite material (QMC NPs) was synthesized by curcumin, quaternized chitosan and mesoporous polydopamine nanoparticles. The results showed that 150 μg/mL QMC NPs had good biocompatibility and exerted excellent antibacterial activity against Staphylococcus aureus and Escherichia coli after blue laser irradiation (450 nm, 1 W/cm2). In vivo, QMC NPs effectively treated bacterial infection and accelerated the healing of infected wounds in mice.

Photodynamic and nitric oxide therapy-based synergistic antimicrobial nanoplatform: an advanced root canal irrigation system for endodontic bacterial infections

BACKGROUND

The main issues faced during the treatment of apical periodontitis are the management of bacterial infection and the facilitation of the repair of alveolar bone defects to shorten disease duration. Conventional root canal irrigants are limited in their efficacy and are associated with several side effects. This study introduces a synergistic therapy based on nitric oxide (NO) and antimicrobial photodynamic therapy (aPDT) for the treatment of apical periodontitis.

RESULTS

This research developed a multifunctional nanoparticle, CGP, utilizing guanidinylated poly (ethylene glycol)-poly (ε-Caprolactone) polymer as a carrier, internally loaded with the photosensitizer chlorin e6. During root canal irrigation, the guanidino groups on the surface of CGP enabled effective biofilm penetration. These groups undergo oxidation by hydrogen peroxide in the aPDT process, triggering the release of NO without hindering the production of singlet oxygen. The generated NO significantly enhanced the antimicrobial capability and biofilm eradication efficacy of aPDT. Furthermore, CGP not only outperforms conventional aPDT in eradicating biofilms but also effectively promotes the repair of alveolar bone defects post-eradication. Importantly, our findings reveal that CGP exhibits significantly higher biosafety compared to sodium hypochlorite, alongside superior therapeutic efficacy in a rat model of apical periodontitis.

CONCLUSIONS

This study demonstrates that CGP, an effective root irrigation system based on aPDT and NO, has a promising application in root canal therapy.

H2S-Releasing Versatile Montmorillonite Nanoformulation Trilogically Renovates the Gut Microenvironment for Inflammatory Bowel Disease Modulation

Abnormal activation of the intestinal mucosal immune system, resulting from damage to the intestinal mucosal barrier and extensive invasion by pathogens, contributes to the pathogenesis of inflammatory bowel disease (IBD). Current first-line treatments for IBD have limited efficacy and significant side effects. An innovative H2S-releasing montmorillonite nanoformulation (DPs@MMT) capable of remodeling intestinal mucosal immune homeostasis, repairing the mucosal barrier, and modulating gut microbiota is developed by electrostatically adsorbing diallyl trisulfide-loaded peptide dendrimer nanogels (DATS@PDNs, abbreviated as DPs) onto the montmorillonite (MMT) surface. Upon rectal administration, DPs@MMT specifically binds to and covers the damaged mucosa, promoting the accumulation and subsequent internalization of DPs by activated immune cells in the IBD site. DPs release H2S intracellularly in response to glutathione, initiating multiple therapeutic effects. In vitro and in vivo studies have shown that DPs@MMT effectively alleviates colitis by eliminating reactive oxygen species (ROS), inhibiting inflammation, repairing the mucosal barrier, and eradicating pathogens. RNA sequencing revealed that DPs@MMT exerts significant immunoregulatory and mucosal barrier repair effects, by activating pathways such as Nrf2/HO-1, PI3K-AKT, and RAS/MAPK/AP-1, and inhibiting the p38/ERK MAPK, p65 NF-κB, and JAK-STAT3 pathways, as well as glycolysis. 16S rRNA sequencing demonstrated that DPs@MMT remodels the gut microbiota by eliminating pathogens and increasing probiotics. This study develops a promising nanoformulation for IBD management.

Co-release of nitric oxide and L-arginine from poly (β-amino ester)-based adhesive reprogram macrophages for accelerated wound healing and angiogenesis in vitro and in vivo

Recently, insufficient angiogenesis and prolonged inflammation are crucial challenges of chronic skin wound healing. The sustained release of L-Arginine (L-Arg) and nitric oxide (NO) production can control immune responses, improve angiogenesis, enhance re-epithelialization, and accelerate wound healing. Here, we aim to improve wound healing via the controlled release of NO and L-Arg from poly (β-amino ester) (PβAE). In this regard, PβAE is functionalized with methacrylate poly-L-Arg (PAMA), and the role of PAMA content (50, 66, and 75 wt%) on the adhesive properties, L-Arg, and NO release, as well as collagen deposition, inflammatory responses, and angiogenesis, is investigated in vitro and in vivo. Results show that the PAMA/ PβAE could provide suitable adhesive strength (~25 kPa) for wound healing application. In addition, increasing the PAMA content from 50 to 75 wt% results in an increased release of L-Arg (approximately 1.4-1.7 times) and enhanced NO production (approximately 2 times), promoting skin cell proliferation and migration. The in vitro studies also show that compared to PβAE hydrogel, incorporation of 66 wt% PAMA (PAMA 66 sample) reveals superior collagen I synthesis (~ 3-4 times) of fibroblasts, controlled pro-inflammatory and improved anti-inflammatory cytokines secretion of macrophages, and accelerated angiogenesis (~1.5-2 times). In vivo studies in a rat model with a full-thickness skin defect also demonstrate the PAMA66 sample could accelerate wound healing (~98 %) and angiogenesis, compared to control (untreated wound) and Tegaderm™ commercial wound dressing. In summary, the engineered multifunctional PAMA functionalized PβAE hydrogel with desired NO and L-Arg release, and adhesive properties can potentially reprogram macrophages and accelerate skin healing for chronic wound healing.

Bacteria-responsive programmed self-activating antibacterial hydrogel to remodel regeneration microenvironment for infected wound healing

There is still an urgent need to develop hydrogels with intelligent antibacterial ability to achieve on-demand treatment of infected wounds and accelerate wound healing by improving the regeneration microenvironment. We proposed a strategy of hydrogel wound dressing with bacteria-responsive self-activating antibacterial property and multiple nanozyme activities to remodel the regeneration microenvironment in order to significantly promote infected wound healing. Specifically, pH-responsive H2O2 self-supplying composite nanozyme (MSCO) and pH/enzyme-sensitive bacteria-responsive triblock micelles encapsulated with lactate oxidase (PPEL) were prepared and encapsulated in hydrogels composed of L-arginine-modified chitosan (CA) and phenylboronic acid-modified oxidized dextran (ODP) to form a cascade bacteria-responsive self-activating antibacterial composite hydrogel platform. The hydrogels respond to multifactorial changes of the bacterial metabolic microenvironment to achieve on-demand antibacterial and biofilm eradication through transformation of bacterial metabolites, and chemodynamic therapy enhanced by nanozyme activity in conjunction with self-driven nitric oxide (NO) release. The composite hydrogel showed 'self-diagnostic' treatment for changes in the wound microenvironment. Through self-activating antibacterial therapy in the infection stage to self-adaptive oxidative stress relief and angiogenesis in the post-infection stage, it promotes wound closure, accelerates wound collagen deposition and angiogenesis, and completely improves the microenvironment of infected wound regeneration, which provides a new method for the design of intelligent wound dressings.

Photoactive rhodamine-based photosensitizer eliminates Staphylococcus aureus via superoxide radical photosensitization

Due to the antibiotics abuse, bacterial infection has become one of the leading causes of human death worldwide. Novel selective antimicrobial agents are urgently needed, with the hope of maintaining the balance of the microbial environment. Photo-activated chemotherapeutics have shown great potential to eliminate bacteria with appealing spatiotemporal selectivity. In this work, we reported the structural modification to enhance the triplet excited state property of Rhodamine B, synthesizing a rhodamine-based photosensitizer RBPy. Upon light activation, RBPy exhibited much stronger photosensitization ability than the parent compound Rhodamine B both in solution and in bacteria. Importantly, RBPy can selectively inactivate Staphylococcus aureus and inhibit biofilm formation with high biocompatibility. This work provides a new strategy to develop rhodamine-based photoactive chemotherapeutics for antimicrobial photodynamic therapy.

Construction of antibacterial bone implants and their application in bone regeneration

Bacterial infection represents a prevalent challenge during the bone repair process, often resulting in implant failure. However, the extensive use of antibiotics has limited local antibacterial effects at the infection site and is prone to side effects. In order to address the issue of bacterial infection during the transplantation of bone implants, four types of bone scaffold implants with long-term antimicrobial functionality have been constructed, including direct contact antimicrobial scaffold, dissolution-penetration antimicrobial scaffold, photocatalytic antimicrobial scaffold, and multimodal synergistic antimicrobial scaffold. The direct contact antimicrobial scaffold involves the physical penetration or disruption of bacterial cell membranes by the scaffold surface or hindrance of bacterial adhesion through surface charge, microstructure, and other factors. The dissolution-penetration antimicrobial scaffold releases antimicrobial substances from the scaffold's interior through degradation and other means to achieve local antimicrobial effects. The photocatalytic antimicrobial scaffold utilizes the absorption of light to generate reactive oxygen species (ROS) with enhanced chemical reactivity for antimicrobial activity. ROS can cause damage to bacterial cell membranes, deoxyribonucleic acid (DNA), proteins, and other components. The multimodal synergistic antimicrobial scaffold involves the combined use of multiple antimicrobial methods to achieve synergistic effects and effectively overcome the limitations of individual antimicrobial approaches. Additionally, the biocompatibility issues of the antimicrobial bone scaffold are also discussed, including in vitro cell adhesion, proliferation, and osteogenic differentiation, as well as in vivo bone repair and vascularization. Finally, the challenges and prospects of antimicrobial bone implants are summarized. The development of antimicrobial bone implants can provide effective solutions to bacterial infection issues in bone defect repair in the foreseeable future.

Biofilm Microenvironment-Sensitive Piezoelectric Nanomotors for Enhanced Penetration and ROS/NO Synergistic Bacterial Elimination

Sonodynamic therapy offers a highly accurate treatment for bacterial infections; however, its antibacterial efficacy is hindered by bacterial biofilms that limit the penetration of sonosensitizers. Herein, a nitric oxide (NO)-driven mushroom-like Janus nanomotor (BT@PDA-La) based on the unilateral coating of polydopamine (PDA) on piezoelectric tetragonal barium titanate (BT) and further modified with l-arginine (l-Arg) on the PDA side is fabricated. In the infected microenvironment with high levels of H2O2, NO is produced unilaterally from BT@PDA-La, thus leading to its self-propelled movement and facilitating its permeability in the biofilm. Under ultrasonic vibrations, the piezoelectric effect of BT@PDA-La is triggered by the exogenous mechanical wave, and toxic reactive oxygen species (ROS) are efficiently generated via an in situ catalytic reaction. The synergistic treatment with ROS/NO achieved the destruction of biofilms and embedded drug-resistant bacteria in vitro. Importantly, BT@PDA-La exhibits excellent biofilm penetration capacity, effectively eliminating biofilm infection while accelerating the healing of infected muscles by alleviating oxidative stress, regulating inflammatory factors, and accelerating angiogenesis. Collectively, this study provides a promising strategy for enhancing the penetration of pathological environment-driven nanomaterials through biofilms and advances the application of nanomotors for the therapy of bacterial infections in clinical medicine.

Red light-triggered release of ROS and carbon monoxide for combinational antibacterial application

The abuse of antibiotics has led to the emergence of a wide range of drug-resistant bacteria. To address the challenge of drug-resistant bacterial infections and related infectious diseases, several effective antibacterial strategies have been developed. To achieve enhanced therapeutic effects, combinational treatment approaches should be employed. With this in mind, a metal-organic framework (MOF) based nanoreactor with integrated photodynamic therapy (PDT) and gas therapy which can release reactive oxygen species (ROS) and carbon monoxide (CO) under red light irradiation has been developed. The release of ROS and CO under red light irradiation exerts a preferential antibacterial effect on Gram-positive/Gram-negative bacteria. The bactericidal effects of ROS and CO on Staphylococcus aureus (S. aureus) and methicillin-resistant S. aureus (MRSA) are better than ROS only, showing a combinational antibacterial effect. Furthermore, the fluorescence emission properties of porphyrin moieties can be leveraged for real-time tracking and imaging of the nanoreactors. The simple preparation procedures of this material further enhance its potential as a versatile and effective antibacterial candidate, thereby presenting a new strategy for PDT and gas combinational treatment.

Gelatinase-responsive biodegradable targeted microneedle patch for abscess wound treatment of S. aureus infection

Abscess wound caused by bacterial infection is usually difficult to heal, thus greatly affect people's quality of life. In this study, a biodegradable drug-loaded microneedle patch (MN) is designed for targeted eradication of S. aureus infection and repair of abscess wound. Firstly, the bacterial responsive composite nanoparticle (Ce6@GNP-Van) with a size of about 182.6 nm is constructed by loading the photosensitizer Ce6 into gelatin nanoparticle (GNP) and coupling vancomycin (Van), which can specifically target S. aureus and effectively shield the phototoxicity of photosensitizer during delivery. When Ce6@GNP-Van is targeted and enriched in the infected regions, the gelatinase secreted by the bacteria can degrade GNP in situ and release Ce6, which can kill the bacteria by generating ROS under laser irradiation. In vivo experiments show that the microneedle is basically degraded in 10 min after inserting into skin, and the abscess wound is completely healed within 13 d after applying Ce6@GNP-Van-loaded MN patch to the abscess wound of the bacterial infected mice with laser irradiation, which can simultaneously achieve the eradication of biofilm and subsequent wound healing cascade activation, showing excellent synergistic antibacterial effect. In conclusion, this work establishes a synergistic treatment strategy to facilitate the repair of chronic abscess wound.

Overview of the effects and mechanisms of NO and its donors on biofilms

Microbial biofilm is undoubtedly a challenging problem in the food industry. It is closely associated with human health and life, being difficult to remove and antibiotic resistance. Therefore, an alternate method to solve these problems is needed. Nitric oxide (NO) as an antimicrobial agent, has shown great potential to disrupt biofilms. However, the extremely short half-life of NO in vivo (2 s) has facilitated the development of relatively more stable NO donors. Recent studies reported that NO could permeate biofilms, causing damage to cellular biomacromolecules, inducing biofilm dispersion by quorum sensing (QS) pathway and reducing intracellular bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) levels, and significantly improving the bactericidal effect without drug resistance. In this review, biofilm hazards and formation processes are presented, and the characteristics and inhibitory effects of NO donors are carefully discussed, with an emphasis on the possible mechanisms of NO resistance to biofilms and some advanced approaches concerning the remediation of NO donor deficiencies. Moreover, the future perspectives, challenges, and limitations of NO donors were summarized comprehensively. On the whole, this review aims to provide the application prospects of NO and its donors in the food industry and to make reliable choices based on these available research results.

Zwitterionic dendrimer self-assembled nanodrugs with high drug loading for enhanced anti-tumor ability

Zwitterionic dendrimers have been used to construct many nanomedicines due to their ability to achieve controlled drug release, but their low drug loading content limits their application in nanodrug delivery. To solve this problem, the surface of second generation polypropylimine (G2 PPI) was modified with mercapturized paclitaxel (PTX-SH) and zwitterionic groups to prepare zwitterionic prodrug molecule (PPIMPC), and then zwitterionic dendrimer self-assembled nanodrugs (PPIMPC-DOX micelles) were prepared by incorporating doxorubicin (DOX) into the micelles. The DOX loading and paclitaxel (PTX) loading in PPIMPC-DOX micelles was 6.7% and 26.2%, respectively, and the total drug loading of PPIMPC-DOX was high to 32.9%. In addition, PPIMPC-DOX micelles showed enhanced cytotoxicity due to improved cell uptake of DOX. More importantly, the inhibition rate of tumor was much higher than free DOX. The zwitterionic property and high drug loading of PPIMPC-DOX micelles enhanced anti-tumor ability of chemotherapeutic drugs. The method of preparation of zwitterionic and high drug loading of nanodrugs shows good application prospects in the future.

Novel photoactivated Indole-pyridine chemotherapeutics with strong antimicrobial and antibiofilm activity toward Staphylococcus aureus

The challenge of antibiotic resistance worldwide has brought an urgent need to explore novel drugs for bacterial infections. Antimicrobial photodynamic therapy has been proven to be a potential antimicrobial modality but is limited by biofilms. In this study, we synthesized three cationic photosensitizers with strong photoinduced antimicrobial and antibiofilm activities toward gram-positive Staphylococcus aureus. The indole-pyridine compounds illustrated multiple type I/II photosensitization and coenzyme NAD(P)H photocatalytic activity upon excitation. A mechanistic study showed that intracellular reactive oxygen generation and NAD(P)H oxidation caused membrane damage, leading to protein/nucleus acid leakage. This research provides insights into the development of novel chemotherapeutics with synergetic photodynamic and photocatalytic reactivity.

Nitric Oxide-Assisted Photodynamic Therapy for Enhanced Penetration and Hypoxic Bacterial Biofilm Elimination

The presence of a biofilm matrix barrier and hypoxic microenvironment within the biofilm significantly impedes the efficacy of photodynamic therapy for bacterial biofilm infections. Herein, a phototherapeutic nanoagent with type-I photodynamic behavior and nitric oxide (NO) release performance is reported for overcoming biofilm-associated infectious diseases. Sodium nitroprusside (SNP), a NO donor, is loaded onto amino-modified mesoporous silica nanoparticles (MSN) to form MSN@SNP NPs. The resulting nanoparticles are further modified with a porphyrin-based metal-organic framework (Ti-TCPP MOF) to obtain MSN@MOF/SNP NPs (MMS NPs) for phototherapeutic applications. In the hypoxia biofilm microenvironment, the MMS NPs release NO to enhance the biofilm permeability and induce the generation of hydroxyl radical (•OH) and superoxide anion radical (O2 •- ) via Type-I photodynamic pathway under laser irradiation. Subsequently, the biofilm-associated infections are effectively eliminated through reactive oxygen species (ROS) and NO gas synergistic therapy. In addition, NO also stimulates collagen deposition and promotes angiogenesis in vivo. Therefore, the MMS NPs efficiently treat biofilm-related infections, providing an alternative approach to combat biofilm-associated infectious diseases.

A near-infrared light-triggered nano-domino system for efficient biofilm eradication: Activation of dispersing and killing functions by generating nitric oxide and peroxynitrite via cascade reactions

One of the serious threats to global public health is the bacterial biofilm, which results in numerous persistent and recurrent infections. Herein, we proposed a near-infrared (NIR) light-triggered "nano-domino" system with "dispersing and killing" functionality for biofilm eradication. The nanoplatform was fabricated by the self-assembly of chitosan conjugated with L-arginine (L-Arg, a natural nitric oxide (NO) donor) and indocyanine green (ICG, a phototherapy agent). Using an NIR irradiation "trigger", a series of reactive oxygen species (ROS) including singlet oxygen (1O2), hydrogen peroxide (H2O2), and superoxide anions (·O2-), as well as heat were generated from ICG aggregates. Subsequently, 1O2 and H2O2 catalyzed L-Arg to produce NO, which dispersed the biofilm and reacted with ·O2- to form peroxynitrite to kill bacteria with ROS collaboratively. Meanwhile, the generated heat increased the permeability of bacterial membranes, aggravating the damage to biofilm bacteria. The experiments on biofilm eradication demonstrated that this "nano-domino" system was capable to eradicate over 99.99% of biofilms formed by Methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa under 5-min NIR irradiation. Notably, these integrated benefits allowed the system to promote the healing of MRSA biofilm-infected wounds in vivo with negligible toxicity. Overall, this reported NIR-triggered "nano-domino" system holds great promise for addressing the difficulties associated with bacterial biofilm eradication. STATEMENT OF SIGNIFICANCE: Novel agents for biofilm eradication are urgently needed due to the alarming rise in antimicrobial resistance to conventional antibiotics and the critical shortage of new drugs. In this study, we created a nano-domino system that uses near-infrared (NIR) light as a trigger to eradicate mature biofilms. In response to a short-term NIR irradiation, the proposed nanoplatform could generate nitric oxide and peroxynitrite to disperse the biofilm and kill the bacteria inside, respectively, leading to efficient eradication of Methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa biofilms with minimal cytotoxicity. The findings, therefore, indicate that this nanoplatform with enhanced antibiofilm performance might provide a reliable and promising solution to biofilm-related problems.

Dye-sensitized rare-earth-doped nanoprobe for simultaneously enhanced NIR-II imaging and precise treatment of bacterial infection

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for causing life-threatening infections that result in high morbidity and mortality rates. The development of advanced imaging and therapeutic methods for in vivo diagnosis and treatment of MRSA infections remains challenging. Here, we develop a hybrid nanoplatform based on rare-earth-doped nanoparticles (RENPs) sensitized by a moiety-engineered near-infrared (NIR) TPEO-820 dye and with a ZIF-8 layer that incorporates CysNO, a photochemically triggered nitric oxide donor. We then use the hybrid for both NIR-II bioimaging and photoactivatable treatment of MRSA-infected wounds. We show that the NIR dye sensitization leads to an 8.5-fold enhancement of the downshifting emission and facilitates deep-tissue NIR-II imaging of bacterial infections. Moreover, the sensitization strategy enhances the UV emission of RENPs by two orders of magnitude, leading to the efficiently controllable release of nitric oxide for effective disinfection of MRSA in vitro and in vivo. The hybrid nanoplatform thus offers promising opportunities for simultaneous localization and controllable treatment of MRSA. STATEMENT OF SIGNIFICANCE: Early detection and treatment of MRSA infections are crucial for reducing public health risks. It is a significant challenge that develops sensitive in vivo diagnosis and complete elimination of drug-resistant bacterial infections. Herein, a nanoplatform has been developed for photoactivatable therapy of MRSA infections and deep tissue NIR-II imaging. This platform utilizes lanthanide-doped rare earth nanoparticles (RENPs) that are sensitized by a moiety-engineered near-infrared (NIR) dye TPEO-820. The TPEO-820 sensitized RENPs exhibit 5 times increase in the release of NO concentration for MRSA treatment compared to unsensitized RENPs, enabling precise therapy of MRSA infection both in vitro and in vivo. Moreover, the platform demonstrates NIR-II luminescence in vivo, allowing for sensitive imaging in deep tissue for MRSA infection.

Environment-Responsive Therapeutic Platforms for the Treatment of Implant Infection

The application of medical implants has greatly improved the survival rate and life quality of patients. Nevertheless, in recent years, there are increasing cases of implant dysfunction or failure because of bacterial infections. Despite significant improvements in biomedicine, there are still serious challenges in the treatment of implant-related infections. With the formation of bacterial biofilms and the development of bacterial resistance, these limitations lead to a low efficacy of conventional antibiotics. To address these challenges, it is urgent to exploit innovative treatment strategies for implant-related infections. Based on these ideas, environment-responsive therapeutic platforms with high selectivity, low drug resistance, and minor dose-limiting toxicity have attracted widespread attention. By using exogenous/endogenous stimuli, the antibacterial activity of therapeutics can be activated on demand and exhibit remarkable therapeutic effects. Exogenous stimuli include photo, magnetism, microwave, and ultrasound. Endogenous stimuli mainly include the pathological characteristics of bacterial infections such as acidic pH, anomalous temperature, and abnormal enzymatic activities. In this review, the recent progress of environment-responsive therapeutic platforms with spatiotemporally controlled drug release/activation is systematically summarized. Afterward, the limitations and opportunities of these emerging platforms are highlighted. Finally, it is hoped that this review will offer novel ideas and techniques to combat implant-related infections.

Recent theranostic applications of hydrogen peroxide-responsive nanomaterials for multiple diseases

It is well established that hydrogen peroxide (H2O2) is associated with the initiation and progression of many diseases. With the rapid development of nanotechnology, the diagnosis and treatment of those diseases could be realized through a variety of H2O2-responsive nanomaterials. In order to broaden the application prospects of H2O2-responsive nanomaterials and promote their development, understanding and summarizing the design and application fields of such materials has attracted much attention. This review provides a comprehensive summary of the types of H2O2-responsive nanomaterials including organic, inorganic and organic-inorganic hybrids in recent years, and focused on their specific design and applications. Based on the type of disease, such as tumors, bacteria, dental diseases, inflammation, cardiovascular diseases, bone injury and so on, key examples for above disease imaging diagnosis and therapy strategies are introduced. In addition, current challenges and the outlook of H2O2-responsive nanomaterials are also discussed. This review aims to stimulate the potential of H2O2-responsive nanomaterials and provide new application ideas for various functional nanomaterials related to H2O2.

Biomimetic Antithrombotic Tissue-Engineered Vascular Grafts for Converting Cholesterol and Free Radicals into Nitric Oxide

Small-diameter tissue-engineered vascular grafts (sdTEVGs) are essential materials used in bypass or replacement surgery for cardiovascular diseases; however, their application efficacy is limited because of patency rates, especially under hyperlipidemia, which is also clinically observed in patients with cardiovascular diseases. In such cases, improving sdTEVG patency is challenging because cholesterol crystals easily cause thrombosis and impede endothelialization. Herein, the development of a biomimetic antithrombotic sdTEVG incorporating cholesterol oxidase and arginine into biomineralized collagen-gold hydrogels on a sdTEVG surface is described. Biomimetic antithrombotic sdTEVGs represent a multifunctional substrate for the green utilization of hazardous substances and can convert cholesterol into hydrogen peroxide, which can react with arginine to generate nitric oxide (NO). NO is a vasodilator that can simulate the antithrombotic action of endothelial cells under hyperlipidemic conditions. In vivo studies show that sdTEVGs can rapidly produce large amounts of NO via a cholesterol catalytic cascade to inhibit platelet aggregation, thereby improving the blood flow velocity and patency rates 60 days after sdTEVG transplantation. A practical and reliable strategy for transforming "harmful" substances into "beneficial" factors at early transplantation stages is presented, which can also promote vascular transplantation in patients with hyperlipidemia.

An Overview of Stimuli-Responsive Intelligent Antibacterial Nanomaterials

Drug-resistant bacteria and infectious diseases associated with biofilms pose a significant global health threat. The integration and advancement of nanotechnology in antibacterial research offer a promising avenue to combat bacterial resistance. Nanomaterials possess numerous advantages, such as customizable designs, adjustable shapes and sizes, and the ability to synergistically utilize multiple active components, allowing for precise targeting based on specific microenvironmental variations. They serve as a promising alternative to antibiotics with diverse medical applications. Here, we discuss the formation of bacterial resistance and antibacterial strategies, and focuses on utilizing the distinctive physicochemical properties of nanomaterials to achieve inherent antibacterial effects by investigating the mechanisms of bacterial resistance. Additionally, we discuss the advancements in developing intelligent nanoscale antibacterial agents that exhibit responsiveness to both endogenous and exogenous responsive stimuli. These nanomaterials hold potential for enhanced antibacterial efficacy by utilizing stimuli such as pH, temperature, light, or ultrasound. Finally, we provide a comprehensive outlook on the existing challenges and future clinical prospects, offering valuable insights for the development of safer and more effective antibacterial nanomaterials.

Advanced Nitric Oxide Generating Nanomedicine for Therapeutic Applications

Nitric oxide (NO), a gaseous transmitter extensively present in the human body, regulates vascular relaxation, immune response, inflammation, neurotransmission, and other crucial functions. Nitrite donors have been used clinically to treat angina, heart failure, pulmonary hypertension, and erectile dysfunction. Based on NO's vast biological functions, it further can treat tumors, bacteria/biofilms and other infections, wound healing, eye diseases, and osteoporosis. However, delivering NO is challenging due to uncontrolled blood circulation release and a half-life of under five seconds. With advanced biotechnology and the development of nanomedicine, NO donors packaged with multifunctional nanocarriers by physically embedding or chemically conjugating have been reported to show improved therapeutic efficacy and reduced side effects. Herein, we review and discuss recent applications of NO nanomedicines, their therapeutic mechanisms, and the challenges of NO nanomedicines for future scientific studies and clinical applications. As NO enables the inhibition of the replication of DNA and RNA in infectious microbes, including COVID-19 coronaviruses and malaria parasites, we highlight the potential of NO nanomedicines for antipandemic efforts. This review aims to provide deep insights and practical hints into design strategies and applications of NO nanomedicines.

PHMB modified photothermally triggered nitric oxide release nanoplatform for precise synergistic therapy of wound bacterial infections

Bacterial infection has been considered as a significant obstacle for wound healing. Nitric oxide (NO), as a novel alternative for antibiotics, has emerged as a promising antibacterial agent. However, the precise spatiotemporal controlled release of NO still remains a major challenge. Herein, a near-infrared (NIR) light triggered NO release nanoplatform (designated as PB-NO@PDA-PHMB) with enhanced broad-spectrum antibacterial and anti-biofilm properties was constructed. Given that PB-NO@PDA-PHMB has strong absorption in the NIR region and exhibits excellent photothermal effect, it can rapidly trigger NO release by NIR irradiation. PB-NO@PDA-PHMB can effectively contact and capture bacteria, and then exhibit synergistic effect of photothermal and gas therapy. In vitro and in vivo experiments indicated that PB-NO@PDA-PHMB exhibited excellent biocompatibility, satisfactory synergistic antibacterial efficacy and the capability of accelerating wound healing. Under NIR irradiation (808 nm, 1 W cm^-2, 7 min), PB-NO@PDA-PHMB (80 μg mL^-1) achieved 100% bactericidal activity against both Gram-negative bacteria Escherichia coli (E. coli) and Gram-positive bacteria Staphyloccocus aureus (S. aureus), removed 58.94% of S. aureus biofilm. Therefore, this all-in-one antibacterial nanoplatform with high NIR responsiveness provides a promising antibiotic-free strategy for bacterial infection treatment.

Synergistic antibacterial effect of multifunctional TiO2-X-based nanoplatform loading arginine and polydopamine for promoting infected wounds healing

The gas therapy of some endogenous signaling molecules to treat diseases has caused extensive research, among which NO gas has shown great potential in fighting infection with various pathogens, promoting wound healing, etc. Here, we propose a photothermal/photodynamic/NO synergistic antibacterial nanoplatform by loading L-arginine (LA) on mesoporous TiO₂ and then encapsulating it with polydopamine. The obtained TiO_2-x-LA@PDA nanocomposite possesses both the excellent photothermal effect and ROS generation ability of mesoporous TiO₂, and the release of nitric oxide (NO) from L-arginine under near-infrared (NIR) light irradiation, while the sealing layer of PDA could induce NIR-triggered NO controlled release. In vitro antibacterial experiments confirmed that the synergistic effect of TiO_2-x-LA@PDA nanocomposites has excellent antibacterial effects against Gram-negative and Gram-positive bacteria, while in vivo experiments showed that it has lower toxicity. It is worth noting that compared with the pure photothermal effect and ROS, the generated NO showed a better bactericidal effect, and NO had a better ability to promote wound healing. In conclusion, the developed TiO_2-x-LA@PDA nanoplatform can be used as a nanoantibacterial agent, which can be further explored in the related biomedical field of photothermal activation of multimodal combined antibacterial therapy.

Recent Advances in Functional Nanomaterials for Catalytic Generation of Nitric Oxide: A Mini Review

As a gaseous second messenger, nitric oxide (NO) plays an important role in a series of signal pathways. Research on the NO regulation for various disease treatments has aroused wide concern. However, the lack of accurate, controllable, and persistent release of NO has significantly limited the application of NO therapy. Profiting from the booming development of advanced nanotechnology, a mass of nanomaterials with the properties of controllable release have been developed to seek new and effective NO nano-delivery approaches. Nano-delivery systems that generate NO through catalytic reactions exhibit unique superiority in terms of precise and persistent release of NO. Although certain achievements have been made in the catalytically active NO delivery nanomaterials, some basic but critical issues, such as the concept of design, are of low attention. Herein, an overview of the generation of NO through catalytic reactions and the design principles of related nanomaterials are summarized. Then, the nanomaterials that generate NO through catalytic reactions are classified. Finally, the bottlenecks and perspectives are also discussed in depth for the future development of catalytical NO generation nanomaterials.

Zwitterionic Targeting Doxorubicin -Loaded Micelles Assembled by Amphiphilic Dendrimers with Enhanced Antitumor Performance

Chemotherapy is the main method of treating malignant tumors in clinical treatment. However, the commonly used chemotherapeutic drugs have the disadvantages of high biological toxicity, poor water solubility, low targeting ability, and high side effects. Zwitterionic micelles assembled by amphiphilic dendrimers modified with zwitterionic groups and targeting ligand should largely overcome these shortcomings. Herein, the zwitterionic group and targeting peptide c(RGDfC) were modified on the surface of generation 2 poly(propylene imine) dendrimers (G2 PPI), which was conjugated with hydrophobic N-(2-mercaptoethyl) oleamide to form amphiphilic dendrimers (PPIMYRC). PPIMYRC self-assembled into micelles with doxorubicin (DOX) loaded in the interior of micelles to prepare DOX-loaded micelles (PPIMYRC-DOX micelles). The PPIMYRC-DOX micelles had great stability in fibrinogen and pH-responsive drug release. Furthermore, PPIMYRC-DOX micelles had higher cellular uptake rates than free DOX, resulting in higher cytotoxicity of PPIMYRC-DOX micelles than that of free DOX. More importantly, PPIMYRC-DOX micelles inhibited tumors much better than free DOX. The tumor inhibition rate of PPIMYRC-DOX micelles was as high as 93%. Taken together, PPIMYRC-DOX micelles were assembled by amphiphilic dendrimers with the zwitterionic and targeting groups, which enhanced the therapeutic effect of DOX and reduced its side effects. The prepared targeting nanodrug has great potential for further application in antitumor therapy.

Nucleus-Targeting Nanoplatform Based on Dendritic Peptide for Precise Photothermal Therapy

Photothermal therapy directly acting on the nucleus is a potential anti-tumor treatment with higher killing efficiency. However, in practical applications, it is often difficult to achieve precise nuclear photothermal therapy because agents are difficult to accurately anchor to the nucleus. Therefore, it is urgent to develop a nanoheater that can accurately locate the nucleus. Here, we designed an amphiphilic arginine-rich dendritic peptide (RDP) with the sequence CRRK(RRCG(Fmoc))2, and prepared a nucleus-targeting nanoplatform RDP/I by encapsulating the photothermal agent IR780 in RDP for precise photothermal therapy of the tumor nucleus. The hydrophobic group Fmoc of the dendritic peptide provides strong hydrophobic force to firmly encapsulate IR780, which improves the solubility and stability of IR780. Moreover, the arginine-rich structure facilitates cellular uptake of RDP/I and endows it with the ability to quickly anchor to the nucleus. The nucleus-targeting nanoplatform RDP/I showed efficient nuclear enrichment ability and a significant tumor inhibition effect.

Photoacidolysis-Mediated Iridium(III) Complex for Photoactive Antibacterial Therapy

Photoactive antibacterial therapy is one of the novel therapeutic methods that has great application potential and prospects for curbing bacterial infections. In this work, a photoactivated iridium complex (Ir-Cl) is synthesized for photoactive antibacterial research. Ir-Cl exhibits photoacidolysis, which can generate H⁺ and be converted into a photolysis product Ir-OH under blue light irradiation. At the meantime, this process is accompanied by ¹O₂ generation. Notably, Ir-Cl can selectively permeate S. aureus and exhibit excellent photoactive antibacterial activity. Mechanism studies show that Ir-Cl can ablate bacterial membranes and biofilms under light irradiation. Metabolomics analysis proves that Ir-Cl with light exposure mainly disturbs some amino acids' degradation (e.g., valine, leucine, isoleucine, arginine) and pyrimidine metabolism, which indirectly causes the ablation of biofilms and ultimately produces irreversible damage to S. aureus. This work provides guidance for metal complexes in antibacterial application.

Nitric oxide-releasing poly(ionic liquid)-based microneedle for subcutaneous fungal infection treatment

Poor permeation of therapeutic agents and similar eukaryotic cell metabolic and physiological properties of fungi and human cells are two major challenges that lead to the failure of current therapy for fungi-induced skin and soft tissue infections. Herein, a nitric oxide (NO)-releasing poly(ionic liquid)-based microneedle (PILMN-NO) with the capacity of deep persistent NO toward subcutaneous fungal bed is presented as a synergistic antifungal treatment strategy to treat subcutaneous fungal infection. Upon the insertion of PILMN-NO into skin, the contact fungicidal activities induced by electrostatic and hydrophobic effects of poly(ionic liquid) and the released NO sterilization resulting from the peroxidation and nitrification effect of NO achieved enhanced antifungal efficacy against fungi (Candida albicans) both in vitro and in vivo. Simultaneously, PILMN-NO showed biofilm ablation ability and efficiently eliminated mature biofilms. In vivo fungal-induced subcutaneous abscess studies revealed that PILMN-NO could effectively sterilize fungi while suppressing the inflammatory reaction, facilitating collagen deposition and angiogenesis, and promoting wound healing. This work provides a new strategy to overcome the difficulties in deep skin fungal infection treatment and has potential for further exploitation of NO-releasing microbicidal therapy.

Structural optimization of BODIPY photosensitizers for enhanced photodynamic antibacterial activities

Enhancing the interactions between photosensitizers and bacteria is key to developing effective photodynamic antibacterial agents. However, the influence of different structures on the therapeutic effects has not been systematically investigated. Herein, 4 BODIPYs with distinct functional groups, including the phenylboronic acid (PBA) group and pyridine (Py) cations, were designed to explore their photodynamic antibacterial activities. The BODIPY with the PBA group (IBDPPe-PBA) exhibits potent activity against planktonic Staphylococcus aureus (S. aureus) upon illumination, while the BODIPY with Py cations (IBDPPy-Ph) or both the PBA group and Py cations (IBDPPy-PBA) can significantly minimize the growth of both S. aureus and Escherichia coli (E. coli). In particular, IBDPPy-Ph can not only eliminate the mature S. aureus biofilm and E. coli biofilm in vitro, but also promote the healing of the infected wound. Our work provides an alternative for reasonable design of photodynamic antibacterial materials.

Temporin-GHb-Derived Peptides Exhibit Potent Antibacterial and Antibiofilm Activities against Staphylococcus aureus In Vitro and Protect Mice from Acute Infectious Pneumonia

With the continuous development of drug resistance in bacteria to traditional antibiotics, the demand for novel antibacterial agents is urgent. Antimicrobial peptides (AMPs) are promising candidates because of their unique mechanism of action and low tendency to induce drug resistance. Previously, we cloned temporin-GHb (hereafter referred to simply as "GHb") from Hylarana guentheri. In this study, a series of derived peptides were designed, namely, GHbR, GHbK, GHb3K, GHb11K, and GHbK4R. The five derived peptides had stronger antibacterial activities against Staphylococcus aureus than the parent peptide GHb and could effectively inhibit the formation of biofilms and eradicate mature biofilms in vitro. GHbR, GHbK, GHb3K, and GHbK4R exerted bactericidal effects by disrupting membrane integrity. However, GHb11K exhibited bacteriostatic efficacy with toroidal pore formation on the cell membrane. In comparison to GHbK4R, GHb3K showed much lower cytotoxicity against A549 alveolar epithelial cells, with an IC₅₀ > 200 μM, which was much higher than its minimal inhibitory concentration (MIC = 3.1 μM) against S. aureus. The anti-infection potential of GHbK4R and GHb3K was investigated in vivo. Compared with vancomycin, the two peptides displayed significant efficacy in a mouse model of acute pneumonia infected with S. aureus. Both GHbK4R and GHb3K also had no obvious toxicity to normal mice after intraperitoneal administration (15 mg/kg) for 8 days. Our results indicate that GHb3K and GHbK4R might be promising candidates for the treatment of bacterial pneumonia infected with S. aureus.

Recent nanotechnology-based strategies for interfering with the life cycle of bacterial biofilms

Biofilm formation plays an important role in the resistance development in bacteria to conventional antibiotics. Different properties of the bacterial strains within biofilms compared with their planktonic states and the protective effect of extracellular polymeric substances contribute to the insusceptibility of bacterial cells to conventional antimicrobials. Although great effort has been devoted to developing novel antibiotics or synthetic antibacterial compounds, their efficiency is overshadowed by the growth of drug resistance. Developments in nanotechnology have brought various feasible strategies to combat biofilms by interfering with the biofilm life cycle. In this review, recent nanotechnology-based strategies for interfering with the biofilm life cycle according to the requirements of different stages are summarized. Additionally, the importance of strategies that modulate the bacterial biofilm microenvironment is also illustrated with specific examples. Lastly, we discussed the remaining challenges and future perspectives on nanotechnology-based strategies for the treatment of bacterial infection.

Photonics-based treatments: Mechanisms and applications in oral infectious diseases

Infectious diseases remain a serious global challenge threatening human health. Oral infectious diseases, a major neglected global problem, not only affect people's lifestyles but also have an intimate association with systemic diseases. Antibiotic therapy is a common treatment. However, the emergence of new resistance problems hindered and enhanced the complication of the treatment. Currently, antimicrobial photodynamic therapy (aPDT) has long been the topic of intense interest due to the advantage of being minimally invasive, low toxicity, and high selectivity. aPDT is also becoming increasingly popular and applied in treating oral diseases such as tooth caries, pulpitis, periodontal diseases, peri-implantitis, and oral candidiasis. Photothermal therapy (PTT), another phototherapy, also plays an important role in resisting resistant bacterial and biofilm infections. In this mini-review, we summarize the latest advances in photonics-based treatments of oral infectious diseases. The whole review is divided into three main parts. The first part focuses on photonics-based antibacterial strategies and mechanisms. The second part presents applications for photonics-based treatments of oral infectious diseases. The last part discusses present problems in current materials and future perspectives.

Recent Nanotechnologies to Overcome the Bacterial Biofilm Matrix Barriers

Bacterial biofilm-related infectious diseases severely influence human health. Under typical situations, pathogens can colonize inert or biological surfaces and form biofilms. Biofilms are functional aggregates that coat bacteria with extracellular polymeric substances (EPS). The main reason for the failure of biofilm infection treatment is the low permeability and enrichment of therapeutic agents within the biofilm, which results from the particular features of biofilm matrix barriers such as negatively charged biofilm components and highly viscous compact EPS structures. Hence, developing novel therapeutic strategies with enhanced biofilm penetrability is crucial. Herein, the current progress of nanotechnology methods to improve therapeutic agents' penetrability against biofilm matrix, such as regulating material morphology and surface properties, utilizing the physical penetration of nano/micromotors or microneedle patches, and equipping nanoparticles with EPS degradation enzymes or signal molecules, is first summarized. Finally, the challenges, perspectives, and future implementations of engineered delivery systems to manage biofilm infections are presented in detail.

Smart delivery systems for microbial biofilm therapy: Dissecting design, drug release and toxicological features

Bacterial biofilms are highly protected surface attached communities of bacteria that typically cause chronic infections. To address their recalcitrance to antibiotics and minimise side effects of current therapies, smart drug carriers are being explored as promising platforms for antimicrobials. Herein, we briefly summarize recent efforts and considerations that have been applied in the design of these smart carriers. We guide readers on a journey on how they can leverage the inherent biofilm microenvironment, external stimuli, or combine both types of stimuli in a predictable manner. The specific carrier features that are responsible for their 'on-demand' properties are detailed and their impact on antibiofilm property are further discussed. Moreover, an analysis on the impact of such features on drug release profiles is provided. Since nanotechnology represents a significant slice of the drug delivery pie, some insights on the potential toxicity are also depicted. We hope that this review inspires researchers to use their knowledge and creativity to design responsive systems that can eradicate biofilm infections.

Enzyme-regulated NO programmed to release from hydrogel-forming microneedles with endogenous/photodynamic synergistic antibacterial for diabetic wound healing

The infection-prone wound pathology microenvironment leads to ulceration and difficult healing of diabetic wounds, which seriously affects the quality of survival of patients. In this study, natural polymer materials gelatin and polylysine were used as substrates. By introducing iron/tannic acid (Fe^IIITA) composite nanoparticles with excellent photothermal properties into the system, the glutamine residues of gelatin were crosslinked with the primary ammonia of polylysine by glutamine aminotransferase. A nanocomposite hydrogel with excellent antibacterial ability and NO production was constructed it was used to improve the clinical problems of diabetes wounds that were difficult to vascularize and easy to be infected. Under the premise of maintaining its structural stability, the hydrogel can be customized to meet the needs of different mechanical strengths by adjusting the ratios to match different diabetic wounds. Meanwhile, the photothermal effect of Fe^IIITA nanoparticles can synergize with the endogenous antibacterial ability of polylysine to improve the antibacterial efficacy of hydrogels. The potential of hydrogel to promote intracellular NO production was confirmed by fluorescent staining. Microneedle patches prepared from hydrogel can be applied to diabetic wounds, which can achieve NO deep release. Its anti-inflammatory and angiogenic abilities are also useful in achieving effective healing of diabetic wounds.

Hydrogen Peroxide-Activated Nitric Oxide-Releasing Vancomycin-Loaded Electrostatic Complexation for Efficient Elimination of Methicillin-Resistant Staphylococcus aureus Abscesses

The treatment of subcutaneous abscesses has been greatly hindered due to the spread of drug-resistant strains such as methicillin-resistant Staphylococcus aureus (MRSA). Thus, alternative strategies are highly desired to complement conventional antibiotic therapies and surgical intervention. As one of such strategies, applications of nitric oxide (NO) have shown great potential in the treatment of bacteria-induced subcutaneous abscesses by improving the efficacy of many therapeutic methods. However, it is extremely challenging to achieve precise delivery and controlled release because of its gaseous nature. In the present study, an effective strategy was reported in which on demand hydrogen peroxide (H₂O₂)-activated nitric oxide-releasing vancomycin (Van)-loaded electrostatic complexation (Lipo/Van@Arg) was fabricated. In this system, Van was encapsulated into a negative-charged DSPG/Chol liposome (Lipo/Van) and electrostatically bound with the positive-charged l-arginine (l-Arg). As expected, Lipo/Van@Arg exhibited superior bacterial binding and biofilm penetration abilities. After being in the interior of the biofilms, Lipo/Van@Arg could be triggered by the endogenous H₂O₂ and effectively release NO. The released NO could exhibit combined antibacterial and biofilm eradication effects with Van. Moreover, an in vivo evaluation using a BALB/c mouse model of subcutaneous abscesses indicated that the combination treatment of NO and Van based on Lipo/Van@Arg could effectively eliminate MRSA from the abscesses, thereby preventing abscess recurrence. In summary, the Lipo/Van@Arg system developed in this study realized controlled delivery and precise release of NO, which had significant clinical implications in the efficient treatment of abscesses.

Magnetocontrollable droplet mobility on liquid crystal-infused porous surfaces

Magnetocontrollable droplet mobility on surfaces of both solids and simple fluids have been widely used in a wide range of applications. However, little is understood about the effect of the magnetic field on the wettability and mobility of droplets on structured fluids. Here, we report the manipulation of the dynamic behaviors of water droplets on a film of thermotropic liquid crystals (LCs). We find that the static wetting behavior and static friction of water droplets on a 4'-octyl-4-biphenylcarbonitrile (8CB) film strongly depend on the LC mesophases, and that a magnetic field caused no measurable change to these properties. However, we find that the droplet dynamics can be affected by a magnetic field as it slides on a nematic 8CB film, but not on isotropic 8CB, and is dependent on both the direction and strength of the magnetic field. By measuring the dynamic friction of a droplet sliding on a nematic 8CB film, we find that a magnetic field alters the internal orientational ordering of the 8CB which in turn affects its viscosity. We support this interpretation with a scaling argument using the LC magnetic coherence length that includes (i) the elastic energy from the long-range orientational ordering of 8CB and (ii) the free energy from the interaction between 8CB and a magnetic field. Overall, these results advance our understanding of droplet mobility on LC films and enable new designs for responsive surfaces that can manipulate the mobility of water droplets.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (further details of the stability of LCIPS against water-induced dewetting, the interfacial tension and contact angle measurement using a goniometer, the estimation of the thickness of LC wrapping layer at air-water interface on droplets, SEM measurements, the average sliding velocity of a water droplet on 5CB, E7, silicone oil, and mineral oil films with and without a magnetic field, representative force diagram (F _d versus time) of a 3-µL water droplet moving at a speed of 0.1 mm/s on a nematic 8CB film, F _dynamic acting on 3 µL water droplets moving at speeds of 0.1-1 mm/s on an isotropic 8CB film, the calculated magnetic coherence length as a function of the magnitude of the magnetic field applied to the nematic LCIPS, and the apparent advancing and receding contact angles of a moving water droplet on nematic LCIPS as a function of time, and polarized light micrographs (top view) of a nematic 8CB film between two DMOAP-functionalized glass slides before and after applying a horizontal magnetic field) is available in the online version of this article at 10.1007/s12274-022-5318-y.

Antibacterial and Antibiofilm Activity of Carvacrol against Oral Pathogenic Bacteria

Faced with the current situation of high rates of microbial resistance, together with the scarcity of new antibiotics, it is necessary to search for and identify new antimicrobials, preferably natural, to alleviate this situation. The aim of this work was to evaluate the antibacterial activity of carvacrol (CAR), a phenolic compound of essential oils, against pathogenic microorganisms causing oral infections, such as Streptococcus mutans and S. sanguinis, never evaluated before. The minimum inhibitory and the minimum bactericidal concentration were 93.4 μg/mL and 373.6 μg/mL, respectively, for the two strains. The growth kinetics under different concentrations of CAR, as well as the bactericidal power were determined. The subinhibitory concentrations delayed and decreased bacterial growth. Its efficacy on mature biofilms was also tested. Finally, the possible hemolytic effect of CAR, not observable at the bactericidal concentrations under study, was evaluated. Findings obtained point to CAR as an excellent alternative agent to safely prevent periodontal diseases. In addition, it is important to highlight the use of an experimental methodology that includes dual-species biofilm and subinhibitory concentration models to determine optimal CAR treatment concentrations. Thus, CAR could be used preventively in mouthwashes or biomaterials, or in treatments to avoid existing antibiotic resistance.

Biomimetic Bacteriophage-Like Particles Formed from Probiotic Extracts and NO Donors for Eradicating Multidrug-Resistant Staphylococcus aureus

Effectively clearing multidrug-resistant bacteria through nonantibiotic treatments is crucial for the recovery of infected tissues in favorable biological environments. Herein, a thermally responsive donor of cell-messenger nitric oxide (NO) is combined with extracts of food-grade Lactobacillus casei to form biomimetic phage-like microparticles with a tailspike structure. These particles can invade bacterial membranes and release NO to disrupt nitrogen and respiratory metabolisms, which initiates the programmed death of multidrug-resistant Staphylococcus aureus (MRSA) for inducing lysis, like the bacterial virus. Experiments suggest that these microparticles can also weaken bacterial toxicity and provide favorable conditions for cell proliferation because of the continuously released NO. By encapsulating these microparticles into graphene-oxide-doped polymers, a dual-mode antibacterial hydrogel (DMAH) can be constructed. In vivo results reveal that the DMAH achieves a long-time sterilization of MRSA with 99.84 ± 0.13% antibacterial rate in the dark because of the phage-like performance of the biomimetic microparticles. In its other antibacterial mode, DMAH subjected to 20 min of near-infrared irradiation release NO, which, together with the photothermal effect, synergistically damages bacterial cell membranes to achieve very fast disinfection (97.13 ± 0.41% bactericidal rate). This multifunctional hydrogel can also significantly accelerate wound healing due to the phage-like particles.

Synergistic chemo-/photothermal therapy based on supercritical technology-assisted chitosan-indocyanine green/luteolin nanocomposites for wound healing

Despite the success, it is highly challenging to battle against pathogenic biofilms-based chronic bacterial infections by conventional antibiotic therapy. Herein, we report a near-infrared (NIR)/acid-induced nanoplatform based on chitosan (CS)-coated indocyanine green (ICG, photosensitizer)/luteolin (LUT, a natural quorum sensing inhibitor) nanocomposites (ICG/LUT-CS) as antibacterial and antibiofilm agents for skin wound healing. Initially, the ICG/LUT nanoplatforms are prepared by the supercritical antisolvent technology and coated with the CS layer. The obtained ICG/LUT-CS with ultra-high encapsulation efficiency exhibited more favorable photothermal conversion effects and improved NIR laser/acid dual-induced drug release behavior than individual modalities, achieving exceptional bacteria-killing and biofilm elimination effects. Moreover, the ICG/LUT-CS realized the synergetic effects of chemotherapy and photothermal therapy outcomes for wound healing. Together, our findings provided an appealing strategy for the rapid preparation and future translational application of ICG/LUT-CS as an ideal agent for fighting against biofilm infections.

Potential Utility of Ultrasound-Enhanced Delivery of Antibiotics, Anti-Inflammatory Agents, and Nutraceuticals: A Mini Review

Ultrasound technology has therapeutic properties that can be harnessed to enhance topical drug delivery in a process known as phonophoresis. The literature on this method of drug delivery is currently sparse and scattered. In this review, we explore in vivo and in vitro controlled trials as well as studies detailing the mechanism of action in phonophoresis to gain a clearer picture of the treatment modality and explore its utility in chronic wound management. Upon review, we believe that phonophoresis has the potential to aid in chronic wound management, particularly against complicated bacterial biofilms. This would offer a minimally invasive wound management option for patients in the community.

A self-assembled bilayer polypeptide-engineered hydrogel for spatiotemporal modulation of bactericidal and anti-inflammation process in osteomyelitis treatment

Background

Drug resistance of pathogens and immunosuppression are the main causes of clinical stagnation of osteomyelitis. The ideal treatment strategy for osteomyelitis is to achieve both efficient antibacterial and bone healing through spatiotemporal modulation of immune microenvironment.

Methods

In this study, a bilayer hydrogel based on genetically engineered polypeptide AC10A and AC10ARGD was prepared by self-assembly. Ag2S QDs@DSPE-mPEG2000-Ce6/Aptamer (AD-Ce6/Apt) was loaded in the top layer AC10A hydrogel (AA) for antibacterial, and bone marrow-derived mesenchymal stem cells (BMSCs) were loaded in the lower layer AC10ARGD hydrogel (MAR) for bone healing. The AD-Ce6/Apt can be released from the AA hydrogel to target S. aureus before bacterial biofilm formation and achieved significant bactericidal effect under irradiation with a 660 nm laser. Moreover, AD-Ce6/Apt can induce M1 type polarization of macrophages to activate the immune system and eliminate residual bacteria. Subsequently, BMSCs released from the MAR hydrogel can differentiate into osteoblasts and promote the formation of an anti-inflammatory microenvironment by regulating the M2 type polarization of macrophages. The bilayer AA-MAR hydrogel possessed good biocompatibility.

Results

The in vitro and in vivo results showed that the AA-MAR hydrogel not only realized efficient photodynamic therapy of S. aureus infection, but also promoted the transformation of immune microenvironment to fulfill the different needs of each stage, which ultimately improved bone regeneration and mechanical properties post-surgery.

Conclusion

This work presents an approach for spatiotemporal modulation of immune microenvironment in the treatment of osteomyelitis.

Graphical Abstract