A Targeting Singlet Oxygen Battery for Multidrug-Resistant Bacterial Deep-Tissue Infections

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

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

Exciting Bacteria to a Hypersensitive State for Enhanced Aminoglycoside Therapy by a Rationally Constructed AIE Luminogen

The diminishing effectiveness of existing aminoglycoside antibiotics (AGs) compels scientists to seek new approaches to enhance the sensitivity of current AGs. Despite ongoing efforts, currently available approaches remain restricted. Herein, a novel strategy involving the rational construction of an aggregation-induced-emission luminogen (AIEgen) is introduced to significantly enhance Gram-positive bacteria's susceptibility to AGs. The application of this approach involves the simple addition of AIEgens to bacteria followed by a 5 min light irradiation. Under light exposure, AIEgens efficiently generate reactive oxygen species (ROS), elevating intrabacterial ROS levels to a nonlethal threshold. Post treatment, the bacteria swiftly enter a hypersensitive state, resulting in a 21.9-fold, 15.5-fold, or 7.2-fold increase in susceptibility to three AGs: kanamycin, gentamycin, and neomycin, respectively. Remarkably, this approach is specific to AGs, and the induced hypersensitivity displays unparalleled longevity and heritability. Further in vivo studies confirm a 7.0-fold enhanced bactericidal ability of AGs against Gram-positive bacteria through this novel approach. This research not only broadens the potential applications of AIEgens but also introduces a novel avenue to bolster the effectiveness of AGs in combating bacterial infections.

Inhalable Polymeric Microparticles for Phage and Photothermal Synergistic Therapy of Methicillin-Resistant Staphylococcus aureus Pneumonia

Acute methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is a common and serious lung infection with high morbidity and mortality rates. Due to the increasing antibiotic resistance, toxicity, and pathogenicity of MRSA, there is an urgent need to explore effective antibacterial strategies. In this study, we developed a dry powder inhalable formulation which is composed of porous microspheres prepared from poly(lactic-co-glycolic acid) (PLGA), internally loaded with indocyanine green (ICG)-modified, heat-resistant phages that we screened for their high efficacy against MRSA. This formulation can deliver therapeutic doses of ICG-modified active phages to the deep lung tissue infection sites, avoiding rapid clearance by alveolar macrophages. Combined with the synergistic treatment of phage therapy and photothermal therapy, the formulation demonstrates potent bactericidal effects in acute MRSA pneumonia. With its long-term stability at room temperature and inhalable characteristics, this formulation has the potential to be a promising drug for the clinical treatment of MRSA pneumonia.

Cobalt doped Prussian blue modified hollow polydopamine for enhanced antibacterial therapy

Give the emergence of drug resistance in bacteria resulting from antibiotic misuse, there is an urgent need for research and application of novel antibacterial approaches. In recent years, nanoparticles (NPs) have garnered significant attention due to their potential to disrupt bacteria cellular structure through loading drugs and special mechanisms, thus rendering them inactive. In this study, the surface of hollow polydopamine (HPDA) NPs was utilized for the growth of Prussian blue (PB), resulting in the formation of HPDA-PB NPs. Incorporation of Co element during the preparation process led to partial doping of PB with Co2+ions. The performance test results demonstrated that the HPDA-PB NPs exhibited superior photothermal conversion efficiency and peroxidase-like activity compared to PB NPs. HPDA-PB NPs have the ability to catalyze the formation of hydroxyl radicals from H2O2in a weakly acidic environment. Due to the tiny PB particles on the surface and the presence of Co2+doping, they have strong broad-spectrum antibacterial properties. Bothin vitroandin vivoevaluations confirm their efficacy against various bacterial strains, particularlyStaphylococcus aureus, and their potential to promote wound healing, making them a promising candidate for advanced wound care and antimicrobial applications.

Programmable Singlet Oxygen Battery for Automated Photodynamic Therapy Enabled by Pyridone-Pyridine Tautomer Engineering

The efficacy of photodynamic therapy is hindered by the hypoxic environment in tumors and limited light penetration depth. The singlet oxygen battery (SOB) has emerged as a promising solution, enabling oxygen- and light-independent 1O2 release. However, conventional SOB systems typically exhibit an "always-ON" 1O2 release, leading to potential 1O2 leakage before and after treatment. This not only compromises therapeutic outcomes but also raises substantial biosafety concerns. In this work, we introduce a programmable singlet oxygen battery, engineered to address all the issues discussed above. The concept is illustrated through the development of a tumor-microenvironment-responsive pyridone-pyridine switch, PyAce, which exists in two tautomeric forms: PyAce-0 (pyridine) and PyAce (pyridone) with different 1O2 storage half-lives. In its native state, PyAce remains in the pyridone form, capable of storing 1O2 (t1/2 = 18.5 h). Upon reaching the tumor microenvironment, PyAce is switched to the pyridine form, facilitating rapid and thorough 1O2 release (t1/2 = 16 min), followed by quenched 1O2 release post-therapy. This mechanism ensures suppressed 1O2 production pre- and post-therapy with selective and rapid 1O2 release at the tumor site, maximizing therapeutic efficacy while minimizing side effects. The achieved "OFF-ON-OFF" 1O2 therapy showed high spatiotemporal selectivity and was independent of the oxygen supply and light illumination.

Targeted pH-Activated Peptide-Based Nanomaterials for Combined Photodynamic Therapy with Immunotherapy

Photodynamic therapy (PDT) has demonstrated efficacy in eliminating local tumors, yet its effectiveness against metastasis is constrained. While immunotherapy has exhibited promise in a clinical context, its capacity to elicit significant systemic antitumor responses across diverse cancers is often limited by the insufficient activation of the host immune system. Consequently, the combination of PDT and immunotherapy has garnered considerable attention. In this study, we developed pH-responsive porphyrin-peptide nanosheets with tumor-targeting capabilities (PRGD) that were loaded with the IDO inhibitor NLG919 for a dual application involving PDT and immunotherapy (PRGD/NLG919). In vitro experiments revealed the heightened cellular uptake of PRGD/NLG919 nanosheets in tumor cells overexpressing αvβ3 integrins. The pH-responsive PRGD/NLG919 nanosheets demonstrated remarkable singlet oxygen generation and photocytotoxicity in HeLa cells in an acidic tumor microenvironment. When treating HeLa cells with PRGD/NLG919 nanosheets followed by laser irradiation, a more robust adaptive immune response occurred, leading to a substantial proliferation of CD3+CD8+ T cells and CD3+CD4+ T cells compared to control groups. Our pH-responsive targeted PRGD/NLG919 nanosheets therefore represent a promising nanosystem for combination therapy, offering effective PDT and an enhanced host immune response.

Chaotropic Effect-Induced Sol-Gel Transition and Radical Stabilization for Bacterially Sensitive Near-Infrared Photothermal Therapy

Deep-seated bacterial infections (DBIs) are stubborn and deeply penetrate tissues. Eliminating deep-seated bacteria and promoting tissue regeneration remain great challenges. Here, a novel radical-containing hydrogel (SFT-B Gel) cross-linked by a chaotropic effect was designed for the sensing of DBIs and near-infrared photothermal therapy (NIR-II PTT). A silk fibroin solution stained with 4,4',4″-(1,3,5-triazine-2,4,6-triyl)tris(1-methylpyridin-1-ium) (TPT3+) was employed as the backbone, which could be cross-linked by a closo-dodecaborate cluster (B12H122-) through a chaotropic effect to form the SFT-B Gel. More interestingly, the SFT-B Gel exhibited the ability to sense DBIs, which could generate a TPT2+• radical with obvious color changes in the presence of bacteria. The radical-containing SFT-B Gel (SFT-B★ Gel) possessed strong NIR-II absorption and a remarkable photothermal effect, thus demonstrating excellent NIR-II PTT antibacterial activity for the treatment of DBIs. This work provides a new approach for the construction of intelligent hydrogels with unique properties using a chaotropic effect.

Spin-state Conversion by Asymmetrical Orbital Hybridization in Ni-doped Co3 O4 to Boost Singlet Oxygen Generation for Microbial Disinfection

Singlet oxygen (1 O2 ) plays a significant role in environmental and biomedical disinfection fields. Electrocatalytic processes hold great potential for 1 O2 generation, but remain challenging. Herein, a facile Ni doping converted spin-state transition approach is reported for boosting 1 O2 production. Magnetic analysis and theoretical calculations reveal that Ni occupied at the octahedral site of Co3 O4 can effectively induce a low-to-high spin-state transition. The high-spin Ni-Co3 O4 generate appropriate binding strength and enhance electron transfer between the Co centers with oxygen intermediates, thereby improving the catalytic activity of Ni-Co3 O4 for effective generating 1 O2 . In neutral conditions, 1×106  CFU mL-1 Gram-negative ESBL-producing Escherichia coli (E. coli) could be inactivated by Ni-Co3 O4 system within 5 min. Further antibacterial mechanisms indicate that 1 O2 can lead to cell membrane damage and DNA degradation so as to irreversible cell death. Additionally, the developed Ni-Co3 O4 system can effectively inactivate bacteria from wastewater and bioaerosols. This work provides an effective strategy for designing high-spin electrocatalysis to boost 1 O2 generation for disinfection process.

Targeted Light-Induced Immunomodulatory Strategy for Implant-Associated Infections via Reversing Biofilm-Mediated Immunosuppression

The clinical treatment efficacy for implant-associated infections (IAIs), particularly those caused by Methicillin-resistant Staphylococcus aureus (MRSA), remains unsatisfactory, primarily due to the formation of biofilm barriers and the resulting immunosuppressive microenvironment, leading to the chronicity and recurrence of IAIs. To address this challenge, we propose a light-induced immune enhancement strategy, synthesizing BSA@MnO2@Ce6@Van (BMCV). The BMCV exhibits precise targeting and adhesion to the S. aureus biofilm-infected region, coupled with its capacity to catalyze oxygen generation from H2O2 in the hypoxic and acidic biofilm microenvironment (BME), promoting oxygen-dependent photodynamic therapy efficacy while ensuring continuous release of manganese ions. Notably, targeted BMCV can penetrate biofilms, producing ROS that degrade extracellular DNA, disrupting the biofilm structure and impairing its barrier function, making it vulnerable to infiltration and elimination by the immune system. Furthermore, light-induced reactive oxygen species (ROS) around the biofilm can lyse S. aureus, triggering bacterium-like immunogenic cell death (ICD), releasing abundant immune costimulatory factors, facilitating the recognition and maturation of antigen-presenting cells (APCs), and activating adaptive immunity. Additionally, manganese ions in the BME act as immunoadjuvants, further amplifying macrophage-mediated innate and adaptive immune responses and reversing the immunologically cold BME to an immunologically hot BME. We prove that our synthesized BMCV elicits a robust adaptive immune response in vivo, effectively clearing primary IAIs and inducing long-term immune memory to prevent recurrence. Our study introduces a potent light-induced immunomodulatory nanoplatform capable of reversing the biofilm-induced immunosuppressive microenvironment and disrupting biofilm-mediated protective barriers, offering a promising immunotherapeutic strategy for addressing challenging S. aureus IAIs.

Porphyrin-anthracene covalent organic frameworks for sustainable photosterilization

Covalent organic frameworks (COFs) have promising applications in enhanced phototherapy. However, COFs that can sustainably play a role in phototherapy without continuous irradiation are extremely scarce. Herein, we report the fabrication of porphyrin-anthracene multifunctional COFs (Por-DPA) for sustainable photosterilization and bacterial-infected wound healing. A porphyrin photosensitizer, as one of the monomers, was used to provide photothermal and photodynamic activities under irradiation. An anthracene derivative, a good chemical source of singlet oxygen (1O2), was selected as another monomer to capture 1O2 and release it continuously via cycloreversion in the dark. The prepared Por-DPA COF prevents the self-aggregation quenching of the photosensitizer and thermal damage caused by continuous exposure to external light sources. Besides, Por-DPA exhibits good photothermal conversion performance and efficient 1O2 production capacity through dual pathways of photosensitization and cycloreversion. The developed sustainable photosterilization platform not only has good bactericidal effects on Escherichia coli and Staphylococcus aureus, but also promotes wound healing without obvious side effects, and is expected to be a novel efficient bactericide.