Space-Confined Synthesis of Thin Polypyrrole Nanosheets in Layered Bismuth Oxychloride for a Photoresponse Antibacterial within the Near-Infrared Window and Accelerated Wound Healing

BSA-ICG-Cu(ii) complex as an NIR-responsive multifunctional platform for wound healing: deciphering therapeutic action in vitro

Therapeutic platforms suitable for NIR-responsive antimicrobial treatments through photothermal and photodynamic modalities are gaining attention in treating chronic wounds. The efficiency of such platforms can be further enhanced by making them angiogenic and a promoter of fibroblast activities. Herein, we report a novel molecular platform composed of bovine serum albumin (BSA), indocyanine green (ICG) and bivalent copper (Cu(ii)) using green chemistry by exploiting the affinity of ICG and Cu(ii) ions towards BSA. We hypothesized that in the BSA-ICG-Cu(ii) complex, ICG will help in producing heat and reactive oxygen species under NIR (808 nm) exposure, which can kill bacteria; Cu(ii) will induce angiogenesis and BSA will activate dermal fibroblasts. The SEM images of the BSA-ICG-Cu(ii) complex revealed a bead and fibril structure at the microscale. Biophysical studies (UV-vis-NIR, fluorescence and CD spectroscopy) indicated stable complex formation through the involvement of the hydrophobic BSA core. A study on NIR-mediated (808 nm LASER) killing of bacteria (S. aureus and E. coli) confirmed the photothermal and photodynamic efficiencies of the BSA-ICG-Cu(ii) complex. At the cellular level, dermal fibroblasts, when treated with the BSA-ICG-Cu(ii) complex, showed significant enhancement in cell migration and cellular VEGF expression (∼2.8 fold). The in vitro angiogenesis study using HUVEC cells demonstrated that the complex can promote tube formation. In conclusion, the BSA-ICG-Cu(ii) complex can serve as a multifunctional NIR-responsive therapeutic platform capable of exerting antibacterial, angiogenic and fibroblast-activating properties, which are beneficial for chronic wound therapy.

Potassium-Doped MnO2 Nanoparticles Reprogram Neutrophil Calcium Signaling to Accelerate Healing of Methicillin-Resistant Staphylococcus aureus-Infected Diabetic Wounds

Neutrophils, as first-line immune cells, typically lose their edge within the diabetic wounds accompanied by methicillin-resistant Staphylococcus aureus (MRSA) infections (the D/M setting), playing the role of "more foe than friend" during the healing process. Specifically, reduced influx of calcium ions (Ca2+) and impaired calcium homeostasis yield the dysfunction of neutrophil sequential behaviors in pathogen killing and wound healing, manifesting as suppressed chemotaxis, decreased intracellular reactive oxygen species (ROS) generation, prolonged apoptosis, and retention of neutrophil extracellular traps (NETs). To address this challenge, this study fabricated potassium (K)-doped manganese dioxide nanoparticles (MnO2 NPs), which activated transmembrane Ca2+ channels by inducing neutrophil depolarization via electron transfer. Subsequently, this contributed to the initial Ca2+ influx and reprogrammed Ca2+-dependent behaviors of impaired neutrophils. Also, the potential antimicrobial capacity of K-MnO2 NPs created a favorable extracellular environment that restored calcium homeostasis, enabling apoptotic neutrophils to be removed timely. Therefore, the wounds treated with K-MnO2 NPs in the D/M setting exhibited potent resistance to MRSA and rapid healing, which could be attributed to the synergistic effects of K-MnO2 NPs in leveraging Ca2+ influx and maintaining calcium homeostasis. In brief, K-MnO2 NPs constitute an effective strategy to resist MRSA and rapid wound healing in the D/M setting.

High-throughput Design of Single-atom Catalysts with Nonplanar and Triple Pyrrole-N Coordination for Highly Efficient H2O2 Electrosynthesis

Single-atom catalysts (SACs) with nonplanar configurations possess unique capabilities for tailoring the oxygen reduction reaction (ORR) catalytic performance compared with the ones with planar configurations, owing to the additional orbital rearrangement arising from the asymmetric coordination atoms. However, the systematic investigation of these nonplanar SACs has long been hindered by the difficulty in screening feasible nonplanar configurations and precisely controlling the coordination structures. Herein, we demonstrate a combined high-throughput screening and experimental verification of nonplanar SACs (ppy-MN3) with metal atoms triple-coordinated by pyrrole-N, for highly active and selective 2e- ORR electrocatalysis. With the additional p-orbital rearrangement of N-ligands for ppy-MN3 during catalysis, a new descriptor on the energy difference between d-band center of metal sites and p-band centers of N-ligands (Δϵd-p) is proposed to accurately identify the relationship between their catalytic activities and electronic structures, on top of the conventional d-band center theory. Consequently, ppy-ZnN3 is identified with excellent 2e- ORR activity (η=0.08 eV) and selectivity, as well as a low 2e- ORR kinetic barrier under alkaline condition owing to a strong hydrogen bonding between OOH* intermediate and interfacial water, which is then experimentally verified by its high electrocatalytic H2O2 yield (43 mol g-1 h-1) and selectivity (92 %) under alkaline condition. This study thus presents a proof-of-concept demonstration of the performance-oriented and precise coordination design of nonplanar SACs for efficient H2O2 electrosynthesis, and, more importantly, provides an essential complement to the d-band theory for more accurately predicting the catalytic activities of catalysts with nonplanar configurations for series potential electrochemical processes.

Multi-Functional Responsive Microcapsules with Sequential Release Capacity for Wound Healing

The development of biomaterials capable of on-demand delivery holds significant promise for wound therapy. Current research is centered on refining design precision and enhancing structural functionality to achieve effective controlled release of active agents, thereby facilitating wound healing. In this study, a coaxial microfluidic electrospray technique is employed to fabricate microcapsules comprising a black phosphorus (BP)-laden alginate shell and a gelatin methacrylate (GelMA) core. Curcumin nanoparticles (CNPs) and vascular endothelial growth factor (VEGF) are respectively incorporated into the shell and core of the microcapsules. The photothermal performance of the microcapsules contributed to superior sterilization efficacy in the early stages of wound healing, while the growth factors in the core provided robust angiogenic effects during the later stages. These attributes enabled the microcapsules to significantly accelerate wound healing, enhance collagen deposition, and modulate inflammatory responses in a rat wound model, underscoring their potential for clinical application.

A comprehensive review on nanoparticle-based photo acoustic: current application and future prospective

In vivo, molecular imaging is prevalent for biology research and therapeutic practice. Among advanced imaging technologies, photoacoustic (PA) imaging and sensing is gaining interest around the globe due its exciting features like high resolution and good (~ few cm) penetration depth. PA imaging is a recent development in ultrasonic technology that generates acoustic waves by absorbing optical energy. However, poor light penetration through tissue continues to be the key obstacle in the field. The NPs as contrast agents can assist in overcoming tissue penetration depth as NPs can produce high signal to noise (SNR) PA signal which aids reconstruction of high resolution of the PA images in deep tissue sights. Subsequently, NPs are very effective in PA based targeted and precise theranostic applications. This article detail about various NPs (organic, inorganic and hybrid) used in PA imaging and spectroscopy applications including various disease diagnosis, therapy and theranostic. It also features optical property, advantages and limitations of various NPs utilised in PA techniques which would comprehend readers about the potential of NPs in evolving PA technique from laboratory to clinical modality in future.

Localized Surface Plasmon Resonance-Enhanced Photocatalytic Antibacterial of In Situ Sprayed 0D/2D Heterojunction Composite Hydrogel for Treating Diabetic Wound

Chronic diabetic wounds pose significant challenges due to uncontrolled bacterial infections, prolonged inflammation, and impaired angiogenesis. The rapid advancement of photo-responsive antibacterial therapy shows promise in addressing these complex issues, particularly utilizing 2D heterojunction materials, which offer unique properties. Herein, an in situ sprayed Bi/BiOCl 0D/2D heterojunction composite fibrin gel with the characteristics of rapid formation and effective near-infrared activation is designed for the treatment of non-healing diabetes-infected wounds. The sprayed composite gel can provide protective shielding for skin tissues and promote endothelial cell proliferation, vascularization, and angiogenesis. The Bi/BiOCl 0D/2D heterojunction, with its localized surface plasmon resonance (LSPR), can overcome the wide bandgap limitation of BiOCl, enhancing the generation of local heat and reactive oxygen species under near-infrared irradiation. This facilitates bacterial elimination and reduced inflammation, supporting the accelerated healing of diabetes-infected wounds. This study underscores the potential of LSPR-enhanced heterojunctions as advanced wound therapies for chronic diabetic wounds.

Modification of traditional composite nonwovens with stable storage of light absorption transients and photodynamic antibacterial effect

Combining photodynamic antimicrobials with nonwovens is prospective. However, common photosensitizers still have drawbacks such as poor photoactivity and the inability to charge. In this study, a photodynamic and high-efficiency antimicrobial protective material was prepared by grafting bis benzophenone-structured 4,4-terephthaloyl diphthalic anhydride (TDPA) photosensitizer, and antimicrobial agent chlorogenic acid (CA) onto spunbond-meltblown-spunbond (SMS) membranes. The charging rates for ·OH and H2O2 were 6377.89 and 913.52 μg/g/h. The light absorption transients structural storage remained above 69% for 1 month. High electrical capacity remained after seven cycles indicating its rechargeability and recyclability. The SMS/TDPA/CA membrane has excellent bactericidal performance when under illumination or lightless conditions, and the bactericidal efficiency of Escherichia coli and Staphylococcus aureus reached over 99%. The construction of self-disinfection textiles based on the photodynamic strategies proposed in this paper is constructive for expanding and promoting the application of textile materials in the medical field.

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.

Adhesive Composite Microspheres with Dual Antibacterial Strategies for Infected Wound Healing

Skin damage and infection pose a severe challenge to human health. Construction of a novel versatile dressing with good anti-infection and healing-promoting abilities is greatly expected. In this paper, nature-source-based composite microspheres with dual antibacterial mechanisms and bioadhesive features by microfluidics electrospray for infected wound healing is developed. The microspheres enable sustained release of copper ions, which not only show long-term antibacterial properties, but also play important role in wound-healing-related angiogenesis. Additionally, the microspheres are coated with polydopamine via self-polymerization, which renders the microspheres adhesive to the wound surface, and further enhance the antibacterial ability through photothermal energy conversion. Based on the dual antibacterial strategies provided by copper ions and polydopamine as well as the bioadhesive property, the composite microspheres exhibit excellent anti-infection and wound healing performances in a rat wound model. These results, along with the nature-source-based composition and biocompatibility, indicate the great potential of the microspheres in clinical wound repair.

Research on the Antibacterial Properties of MXene-Based 2D-2D Composite Materials Membrane

Novel MXene-based two-dimensional (2D) membranes are widely used for water purification due to their highly controllable structure and antibacterial properties. However, in the process of membrane separation, the problems of membrane fouling, especially biological fouling, limits the further application of MXene-based membranes. In this study, in order to improve the antibacterial and separation properties of membranes, three kinds of MXene-based 2D-2D composite membranes (M2~M4) were prepared using polyethersulfone (PES) as the substrate, which were GO@MXene, O-g-C₃N₄@MXene and BiOCl@MXene composite membranes respectively. The results showed that the antibacterial activity of M2~M4 against Escherichia coli and Staphylococcus aureus was further improved, especially the antibacterial ratio of M4 against Escherichia coli and Staphylococcus aureus was up to 50% and 82.4%, respectively. By comparing the surface morphology of MXene membrane and modified membrane treated bacteria through scanning electron microscopy (SEM), it was found that the cell density on modified membrane was significantly lower than that of pure MXene membrane.

Efficient Near-Infrared Response Antibacterial Ceramics Based on the Method of Facile In Situ Etching Upconversion Glass-Ceramics

As the world is faced with the coronavirus disease 2019 (COVID-19) pandemic, photocatalytic antibacterial ceramics can reduce the consumption of disinfectants and improve the safety of the public health environment. However, these antibacterial ceramics are often limited by poor stability and low light utilization efficiency. Herein, an antibacterial ceramic was developed via the method of facile in situ etching of upconversion glass-ceramics (UGC) (FIEG) with HCl, in which the BiOCl nanosheets were in situ grown on the surface of GC to improve its stability and antibacterial activity. The results suggest that the upconversion antibacterial ceramics can harvest and utilize near-infrared (NIR) photons efficiently, which display notable antibacterial activity for Escherichia coli (E. coli) under NIR (≥780 nm) and visible light (420-780 nm) irradiation, with a maximum inactivation rate of 7.5 log in 30 min. Meanwhile, in the cycle experiment, more than 6 log inactivation of E. coli was achieved using an antibacterial ceramic sheet after 2-h NIR light irradiation, and the stability of the antibacterial ceramic was discussed. Furthermore, the reactive species, fluorescence-based live/dead cells, and cell structure of bacteria were analyzed to verify the antibacterial mechanism. This study provides a promising strategy for the construction of efficient and stable antibacterial ceramics.

Targeted Wolfram-Doped Polypyrrole for Photonic Hyperthermia-Synergized Radiotherapy

Single ionizing radiation at a tolerable dose is ineffectual in eliminating malignancies but readily generates harmful effects on surrounding normal tissues. Herein, we intelligently fabricated novel wolfram-doped polypyrrole (WPPy) through a simple oxidative polymerization method with WCl₆ as an oxidizing catalyst, which possessed good biocompatibility, high photothermal conversion, and intensive radiosensitivity capacities to concurrently serve as a photothermal reagent and a radiosensitizer for hyperthermia-synergized radiotherapy (RT) against a malignant tumor. In comparison with traditional polypyrrole without noble metal doping, the innovative introduction of WCl₆ not only successfully launched the polymerization of a pyrrole monomer but also endowed WPPy with additional radiosensitization. More importantly, after further decoration with an active targeted component (SP94 polypeptide), the obtained WPPy@SP94 significantly increased tumor internalization and accumulation in vitro and in vivo and induced obvious DNA damage as well as robust ROS generation under X-ray irradiation, which meanwhile synergized with strong photonic hyperthermia to effectively inhibit tumor growth by single drug injection. Moreover, such biocompatible WPPy@SP94 showed negligible adverse effects on normal cells and tissues. WPPy@SP94 developed in this study not only expands the category of polypyrrole chemical syntheses but also sheds light on WPPy@SP94-based radiosensitizers for cancer RT.

A metal–organic framework nanocomposite with oxidation and near-infrared light cascade response for bacterial photothermal inactivation

Photothermal treatment is an effective and precise bacterial disinfection method that can reduce the occurrence of bacterial drug resistance. However, most conventional photothermal treatment strategies have the problem that the photothermal response range does not match the infection area. Herein, a metal–organic framework (MOF) nanocomposite responding to the oxidation state of the bacterial infection microenvironment was constructed for near-infrared (NIR) photothermal bacterial inactivation. In this strategy, the MOF was used as a nanocarrier to load tetramethylbenzidine (TMB) and horseradish peroxidase (HPR). The high oxidation state of the bacterial infection microenvironment can trigger the enzyme-catalyzed reaction of the nanocomposite, thereby generating oxidation products with the NIR photothermal effect for bacterial disinfection. The synthesis and characterization of the nanocomposite, oxidation state (H₂O₂) response effect, photothermal properties, and antibacterial activities were systematically studied. This study provides a new idea for building a precision treatment system for bacterial infection.