Degradable Pseudo Conjugated Polymer Nanoparticles with NIR-II Photothermal Effect and Cationic Quaternary Phosphonium Structural Bacteriostasis for Anti-Infection Therapy

A NIR-II absorbing conjugated polymer based on tetra-fused isoindigo with ultrahigh photothermal conversion efficiency for cancer therapy

A conjugated polymer, P4TTD-DPP, based on tetra-fused isoindigo-alt-diketopyrrolopyrrole, has been synthesized as a photothermal therapeutic nanotransducer within the near-infrared-II (NIR-II) window. P4TTD-DPP exhibits a notable mass extinction coefficient of 62.8 L g-1 cm-1 at 1064 nm. Additionally, P4TTD-DPP nanoparticles demonstrate remarkable photothermal conversion efficiency of 91.5% at 1064 nm and exhibit excellent anticancer efficacy under photothermal conditions.

Nanoparticles destabilizing the cell membranes triggered by NIR light for cancer imaging and photo-immunotherapy

Cationic polymers have great potential for cancer therapy due to their unique interactions with cancer cells. However, their clinical application remains limited by their high toxicity. Here we show a cell membrane-targeting cationic polymer with antineoplastic activity (Pmt) and a second near-infrared (NIR-II) fluorescent biodegradable polymer with photosensitizer Bodipy units and reactive oxygen species (ROS) responsive thioketal bonds (PBodipy). Subsequently, these two polymers can self-assemble into antineoplastic nanoparticles (denoted mt-NPBodipy) which could further accumulate at the tumor and destroy cell membranes through electrostatic interactions, resulting in cell membrane destabilization. Meanwhile, the photosensitizer Bodipy produces ROS to induce damage to cell membranes, proteins, and DNAs to kill cancer cells concertedly, finally resulting in cell membrane lysis and cancer cell death. This work highlights the use of near-infrared light to spatially and temporarily control cationic polymers for photodynamic therapy, photo-immunotherapy, and NIR-II fluorescence for bio-imaging.

Compartmentalization into Outer and Inner Shells of Hollow Nanospheres for Antibiosis Based on Chemistry and Physical Damages

There is a substantially ascending demand for nonantibiotic strategies to overcome the resistance of bacterial infections. Here, the discovery of a distinctive antibacterial structure is reported. The novel structure of nanoparticle strategy is proposed for appreciable bacteria killing by the smart design of the delayed addition of crosslinkers into the reaction mixture. [2-(methacryloyloxy)ethyl]trimethylammonium chloride solution (MTCl), a water-soluble ionic liquid (IL), has narrow-size material distribution, good whiteness, and high weather resistance. The quaternary ammonium salt is utilized to efficiently permeate cell membranes through electrostatic interaction, accordingly, boasting a beneficiary of antibacterial properties. More importantly, it allows bacteria to attach the nanomaterials easily, especially the double-shelled nanosphere. In light of the introduction of 9-amino(9-deoxy)ep-quinine (QNNH2) on its inner shell, it blocks the nucleic acid and glucose metabolism in bacteria, which is betterment of the antibacterial activity of double-shelled structure nanoparticle compared to other structure of nanomaterials. This physical/chemical/biological triple antibacterial process eliminates the need for traditional antibiotics, and the fabrication strategies and material properties described here provide insights into the design of antibacterial nanomaterials based on chemical and physical effects.

Silver incorporated SeTe nanoparticles with enhanced photothermal and photodynamic properties for synergistic effects on anti-bacterial activity and wound healing

Bacteria invade the host's immune system, thereby inducing serious infections. Current treatments for bacterial infections mostly rely on single modalities, which cannot completely inhibit bacteria. This study evaluates the therapeutic potential of SeTe-Ag NPs, designed with excellent photo responsiveness, with a particular focus on their dual-action antibacterial effect and wound healing properties. SeTe-Ag NPs exhibited promising synergistic antibacterial effects due to their superior photothermal and photodynamic properties. The investigation records substantial zones of inhibition of bacteria, demonstrating potent antibacterial effect. Furthermore, upon the irradiation of near-infrared (NIR) light, SeTe-Ag NPs exhibit remarkable antibiofilm and wound-healing capabilities. Overall, this study shows the applications of NIR-active SeTe-Ag NPs, which serve as a versatile platform for biomedical applications.

NIR light-activated nanocomposites combat biofilm formation and enhance antibacterial efficacy for improved wound healing

Nanoparticle-based therapies are emerging as a pivotal frontier in biomedical research, showing their potential in combating infections and facilitating wound recovery. Herein, selenium-tellurium dopped copper oxide nanoparticles (SeTe-CuO NPs) with dual photodynamic and photothermal properties were synthesized, presenting an efficient strategy for combating bacterial infections. In vitro evaluations revealed robust antibacterial activity of SeTe-CuO NPs, achieving up to 99% eradication of bacteria and significant biofilm inhibition upon near-infrared (NIR) irradiation. Moreover, in vivo studies demonstrated accelerated wound closure upon treatment with NIR-activated SeTe-CuO NPs, demonstrating their efficacy in promoting wound healing. Furthermore, SeTe-CuO NPs exhibited rapid bacterial clearance within wounds, offering a promising solution for wound care. Overall, this versatile platform holds great promise for combating multidrug-resistant bacteria and advancing therapeutic interventions in wound management.

Photochemical Strategies toward Precision Targeting against Multidrug-Resistant Bacterial Infections

Infectious diseases pose a serious threat and a substantial economic burden on global human and public health security, especially with the frequent emergence of multidrug-resistant (MDR) bacteria in clinical settings. In response to this urgent need, various photobased anti-infectious therapies have been reported lately. This Review explores and discusses several photochemical targeted antibacterial therapeutic strategies for addressing bacterial infections regardless of their antibiotic susceptibility. In contrast to conventional photobased therapies, these approaches facilitate precise targeting of pathogenic bacteria and/or infectious microenvironments, effectively minimizing toxicity to mammalian cells and surrounding healthy tissues. The highlighted therapies include photodynamic therapy, photocatalytic therapy, photothermal therapy, endogenous pigments-based photobleaching therapy, and polyphenols-based photo-oxidation therapy. This comprehensive exploration aims to offer updated information to facilitate the development of effective, convenient, safe, and alternative strategies to counter the growing threat of MDR bacteria in the future.

Natural blackcurrant extract contained gelatin hydrogel with photothermal and antioxidant properties for infected burn wound healing

Burns represent a prevalent global health concern and are particularly susceptible to bacterial infections. Severe infections may lead to serious complications, posing a life-threatening risk. Near-infrared (NIR)-assisted photothermal antibacterial combined with antioxidant hydrogel has shown significant potential in the healing of infected wounds. However, existing photothermal agents are typically metal-based, complicated to synthesize, or pose biosafety hazards. In this study, we utilized plant-derived blackcurrant extract (B) as a natural source for both photothermal and antioxidant properties. By incorporating B into a G-O hydrogel crosslinked through Schiff base reaction between gelatin (G) and oxidized pullulan (O), the resulting G-O-B hydrogel exhibited good injectability and biocompatibility along with robust photothermal and antioxidant activities. Upon NIR irradiation, the controlled temperature (around 45-50 °C) generated by the G-O-B hydrogel resulted in rapid (10 min) and efficient killing of Staphylococcus aureus (99 %), Escherichia coli (98 %), and Pseudomonas aeruginosa (82 %). Furthermore, the G-O-B0.5 hydrogel containing 0.5 % blackcurrant extract promoted collagen deposition, angiogenesis, and accelerated burn wound closure conclusively, demonstrating that this well-designed and extract-contained hydrogel dressing holds immense potential for enhancing the healing process of bacterial-infected burn wounds.

Sensing, Imaging, and Therapeutic Strategies Endowing by Conjugate Polymers for Precision Medicine

Conjugated polymers (CPs) have promising applications in biomedical fields, such as disease monitoring, real-time imaging diagnosis, and disease treatment. As a promising luminescent material with tunable emission, high brightness and excellent stability, CPs are widely used as fluorescent probes in biological detection and imaging. Rational molecular design and structural optimization have broadened absorption/emission range of CPs, which are more conductive for disease diagnosis and precision therapy. This review provides a comprehensive overview of recent advances in the application of CPs, aiming to elucidate their structural and functional relationships. The fluorescence properties of CPs and the mechanism of detection signal amplification are first discussed, followed by an elucidation of their emerging applications in biological detection. Subsequently, CPs-based imaging systems and therapeutic strategies are illustrated systematically. Finally, recent advancements in utilizing CPs as electroactive materials for bioelectronic devices are also investigated. Moreover, the challenges and outlooks of CPs for precision medicine are discussed. Through this systematic review, it is hoped to highlight the frontier progress of CPs and promote new breakthroughs in fundamental research and clinical transformation.

Treatment of Acute Wound Infections by Degradable Polymer Nanoparticle with a Synergistic Photothermal and Chemodynamic Strategy

Mild-heat photothermal antibacterial therapy avoids heat-induced damage to normal tissues but causes bacterial tolerance. The use of photothermal therapy in synergy with chemodynamic therapy is expected to address this issue. Herein, two pseudo-conjugated polymers PM123 with photothermal units and PFc with ferrocene (Fc) units are designed to co-assemble with DSPE-mPEG2000 into nanoparticle NPM123/Fc. NPM123/Fc under 1064 nm laser irradiation (NPM123/Fc+NIR-II) generates mild heat and additionally more toxic ∙OH from endogenous H2O2, displaying a strong synergistic photothermal and chemodynamic effect. NPM123/Fc+NIR-II gives >90% inhibition rates against MDR ESKAPE pathogens in vitro. Metabolomics analysis unveils that NPM123/Fc+NIR-II induces bacterial metabolic dysregulation including inhibited nucleic acid synthesis, disordered energy metabolism, enhanced oxidative stress, and elevated DNA damage. Further, NPM123/Fc+NIR-II possesses >90% bacteriostatic rates at infected wounds in mice, resulting in almost full recovery of infected wounds. Immunodetection and transcriptomics assays disclose that the therapeutic effect is mainly dependent on the inhibition of inflammatory reactions and the promotion of wound healing. What is more, thioketal bonds in NPM123/Fc are susceptible to ROS, making it degradable with highly favorable biosafety in vitro and in vivo. NPM123/Fc+NIR-II with a unique synergistic antibacterial strategy would be much less prone to select bacterial resistance and represent a promising antibiotics-alternative anti-infective measure.

MoOxNWs with mechanical damage - oriented synergistic photothermal / photodynamic therapy for highly effective treating wound infections

Reactive oxygen species (ROS)-based therapy has emerged as a promising antibacterial strategy. However, it faces the limitations of uncontrollable space-time release and excessive lipid peroxidation, which may lead to a series of metabolic disorders and decreased immune function. In this study, mechanical damage by molybdenum oxide nanowires (MoOxNWs) is introduced as a synergistic factor to enhance the photothermal and photodynamic effects for controllable and efficient antibacterial therapy. Through their sharp ends, the nanowires can effectively pierce and damage the bacterial cells, thus facilitating the entry of externally generated ROS into the cells. The ROS are generated via photodynamic effect of the nanowires under a mere 5 min of near-infrared light irradiation. This approach enhances the photothermal (by 27.3 %) and photodynamic properties of ROS generation. MoOxNWs (100 μg·mL-1) achieve sterilisation rates of 97.67 % for extended-spectrum β-lactamase-producing E. coli and 96.34 % for methicillin-resistant Staphylococcus aureus, which are comparable or even exceeding the efficacy of most MoOx-based antibacterial agents. Moreover, they exhibit good biocompatibility and low in vivo toxicity.

Progress of NIR-II fluorescence imaging technology applied to disease diagnosis and treatment

Near-infrared two-region (NIR-II, 1000-1700 nm) fluorescence imaging has received widespread attention because of its high in vivo penetration depth, high imaging resolution, fast imaging speed and high efficiency, dynamic imaging, and high clinical translatability. This paper reviews the application of NIR-II imaging technology in disease diagnosis and treatment. The paper highlights the latest research progress of commonly used NIR-II imaging materials and the latest progress of multifunctional diagnostic platforms based on NIR-II imaging technology, and discusses the challenges and directions for the development and utilization of novel NIR-II imaging probes.

Reprogramming Macrophage Polarization, Depleting ROS by Astaxanthin and Thioketal-Containing Polymers Delivering Rapamycin for Osteoarthritis Treatment

Osteoarthritis (OA) is a chronic joint disease characterized by synovitis and joint cartilage destruction. The severity of OA is highly associated with the imbalance between M1 and M2 synovial macrophages. In this study, a novel strategy is designed to modulate macrophage polarization by reducing intracellular reactive oxygen species (ROS) levels and regulating mitochondrial function. A ROS-responsive polymer is synthesized to self-assemble with astaxanthin and autophagy activator rapamycin to form nanoparticles (NP@PolyRHAPM ). In vitro experiments show that NP@PolyRHAPM significantly reduced intracellular ROS levels. Furthermore, NP@PolyRHAPM restored mitochondrial membrane potential, increased glutathione (GSH) levels, and promoted intracellular autophagy, hence successfully repolarizing M1 macrophages into the M2 phenotype. This repolarization enhanced chondrocyte proliferation and vitality while inhibiting apoptosis. In vivo experiments utilizing an anterior cruciate ligament transection (ACLT)-induced OA mouse model revealed the anti-inflammatory and cartilage-protective effects of NP@PolyRHAPM , effectively mitigating OA progression. Consequently, the findings suggest that intra-articular delivery of ROS-responsive nanocarrier systems holds significant promise as a potential and effective therapeutic strategy for OA treatment.

Multifunctional hydrogel bioscaffolds based on polysaccharide to promote wound healing: A review

Various types of skin wounds pose challenges in terms of healing and susceptibility to infection, which can have a significant impact on physical and mental well-being, and in severe cases, may result in amputation. Conventional wound dressings often fail to provide optimal support for these wounds, thereby impeding the healing process. As a result, there has been considerable interest in the development of multifunctional polymer matrix hydrogel scaffolds for wound healing. This review offers a comprehensive review of the characteristics of polysaccharide-based hydrogel scaffolds, as well as their applications in different types of wounds. Additionally, it evaluates the advantages and disadvantages associated with various types of multifunctional polymer and polysaccharide-based hydrogel scaffolds. The objective is to provide a theoretical foundation for the utilization of multifunctional hydrogel scaffolds in promoting wound healing.

Simultaneous Activation of Pyroptosis and cGAS-STING Pathway with Epigenetic/ Photodynamic Nanotheranostic for Enhanced Tumor Photoimmunotherapy

Promoting innate immunity through pyroptosis induction or the cyclic GMP-AMP synthase-stimulator of interferon gene (cGAS-STING) pathway activation has emerged as a potent approach to counteract the immunosuppressive tumor microenvironment and elicit systemic antitumor immunity. However, current pyroptosis inducers and STING agonists often suffer from limitations including instability, unpredictable side effects, or inadequate intracellular expression of gasdermin and STING. Here, a tumor-specific nanotheranostic platform that combines photodynamic therapy (PDT) with epigenetic therapy to simultaneously activate pyroptosis and the cGAS-STING pathway in a light-controlled manner is constructed. This approach involves the development of oxidation-sensitive nanoparticles (NP1) loaded with the photosensitizer TBE, along with decitabine nanomicelles (NP2). NP2 enables the restoration of STING and gasdermin E (GSDME) expression, while NP1-mediated PDT facilitates the release of DNA fragments from damaged mitochondria to potentiate the cGAS-STING pathway, and promotes the activation of caspase-3 to cleave the upregulated GSDME into pore-forming GSDME-N terminal. Subsequently, the released inflammatory cytokines facilitate the maturation of antigen-presentation cells, triggering T cell-mediated antitumor immunity. Overall, this study presents an elaborate strategy for simultaneous photoactivation of pyroptosis and the cGAS-STING pathway, enabling targeted photoimmunotherapy in immunotolerant tumors. This innovative approach holds significant promise in overcoming the limitations associated with existing therapeutic modalities and represents a valuable avenue for future clinical applications.

Phosphonium-Substituted Conjugated Polyelectrolytes Display Efficient Visible-Light-Induced Antibacterial Activity

We report the light-activated antibacterial activity of a new class of phosphonium (R-PMe3+)-substituted conjugated polyelectrolytes (CPEs). These polyelectrolytes feature a poly(phenylene ethynylene) (PPE) conjugated backbone substituted with side groups with the structure -O-(CH2)nPMe3+, where n = 3 or 6. The length of the side groups has an effect on the hydrophobic character of the CPEs and their propensity to interact with bacterial membranes. In a separate study, these phosphonium-substituted PPE CPEs were demonstrated to photosensitize singlet oxygen (1O2) and reactive oxygen species, a key factor for the photoinduced inactivation of bacteria. In this study, in vitro antibacterial assays against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus were performed by employing the series of polyelectrolytes under both dark and illumination conditions. In general, the phosphonium-substituted CPEs displayed profound light-activated biocidal activity, with >99% colony forming unit (CFU) reduction after 15 min of light exposure (16 mW cm-2) at a ≤20 μM CPE concentration. Strong biocidal activity was also observed in the dark for a CPE concentration of 20 μM against S. aureus; however, higher concentrations (200 μM) were needed to enable dark inactivation of E. coli. The dark activity is ascribed to bacterial membrane disruption by the CPEs, supported by a correlation of dark biocidal activity with the chain length of the side groups. The light-activated biocidal activity is associated with the ability of the CPEs to sensitize ROS, which is cytotoxic to the microorganisms. Serial dilution bacterial plating experiments revealed that the series of CPEs was able to induce a >5-log kill versus E. coli with 15 min of exposure to a blue LED source (16 mW cm-2).

Photoelectrons Sequentially Regulate Antibacterial Activity and Osseointegration of Titanium Implants

Titanium implants are widely used ; however, implantation occasionally fails due to infections during the surgery or poor osseointegration after the surgery. To solve the problem, an intelligent functional surface on titanium implant that can sequentially eradicate bacteria biofilm at the initial period and promote osseointegration at the late period of post-surgery time is designed. Such surfaces can be excited by near infrared light (NIR), with rare earth nanoparticles to upconvert the NIR light to visible range and adsorb by Au nanoparticles, supported by titanium oxide porous film on titanium implants. Under NIR irradiation, the implant converts the energy of phonon to hot electrons and lattice vibrations, while the former flows directly to the contact substance or partially reacts with the surrounding to generate reactive oxygen species, and the latter leads to the local temperature increase. The biofilm or microbes on the implant surface can be eradicated by NIR treatment in vitro and in vivo. Additionally, the surface exhibits superior biocompatibility for cell survival, adhesion, proliferation, and osteogenic differentiation, which provides the foundation for osseointegration. In vivo implantation experiments demonstrate osseointegration is also promoted. This work thus demonstrates NIR-generated electrons can sequentially eradicate biofilms and regulate the osteogenic process, providing new solutions to fabricate efficient implant surfaces.

Design of biodegradable polyurethanes and post-modification with long alkyl chains via inhibiting biofilm formation and killing drug-resistant bacteria for the treatment of wound bacterial infection

The development of cationic polymers that simulate antimicrobial peptides to treat bacterial infections has received much research interest. In order to obtain polymers that can not only eradicate bacteria but also inhibit biofilm formation, without inducing bacterial drug resistance, a series of cationic polymers have been developed. Despite recent progress, the chemical structures of these polymers are stable, making them recalcitrant to biodegradation and metabolism within organisms, potentially inducing long-term toxicity. To overcome this limitation, herein, a novel strategy of designing biodegradable polyurethanes with tertiary amines and quaternary ammonium salts via condensation polymerization and post-functionalizing them is reported. These polymers were found to exhibit potent antibacterial activity against Staphylococcus aureus and Escherichia coli, effectively prevent the formation of Staphylococcus aureus biofilms, act quickly and effectively against bacteria and display no resistance after repeated use. In addition, the potent in vivo antibacterial effects of these antimicrobial polyurethanes in a mouse model with methicillin-resistant Staphylococcus aureus skin infection are demonstrated.

Near infrared II excitation nanoplatform for photothermal/chemodynamic/antibiotic synergistic therapy combating bacterial biofilm infections

Drug-resistant bacterial biofilm infections (BBIs) are refractory to elimination. Near-infrared-II photothermal therapy (NIR-II PTT) and chemodynamic therapy (CDT) are emerging antibiofilm approaches because of the heavy damage they inflict upon bacterial membrane structures and minimal drug-resistance. Hence, synergistic NIR-II PTT and CDT hold great promise for enhancing the therapeutic efficacy of BBIs. Herein, we propose a biofilm microenvironment (BME)-responsive nanoplatform, BTFB@Fe@Van, for use in the synergistic NIR-II PTT/CDT/antibiotic treatment of BBIs. BTFB@Fe@Van was prepared through the self-assembly of phenylboronic acid (PBA)-modified small-molecule BTFB, vancomycin, and the CDT catalyst Fe2+ ions in DSPE-PEG2000. Vancomycin was conjugated with BTFB through a pH-sensitive PBA-diol interaction, while the Fe2+ ions were bonded to the sulfur and nitrogen atoms of BTFB. The PBA-diol bonds decomposed in the acidic BME, simultaneously freeing the vancomycin and Fe2+ irons. Subsequently, the catalytic product hydroxyl radical was generated by the Fe2+ ions in the oxidative BME overexpressed with H2O2. Moreover, under 1064 nm laser, BTFB@Fe@Van exhibited outstanding hyperthermia and accelerated the release rate of vancomycin and the efficacy of CDT. Furthermore, the BTFB@Fe@Van nanoplatform enabled the precise NIR-II imaging of the infected sites. Both in-vitro and in-vivo experiments demonstrated that BTFB@Fe@Van possesses a synergistic NIR-II PTT/CDT/antibiotic mechanism against BBIs.

A Stable Open-Shell Conjugated Diradical Polymer with Ultra-High Photothermal Conversion Efficiency for NIR-II Photo-Immunotherapy of Metastatic Tumor

Massive efforts have been concentrated on the advance of eminent near-infrared (NIR) photothermal materials (PTMs) in the NIR-II window (1000-1700 nm), especially organic PTMs because of their intrinsic biological safety compared with inorganic PTMs. However, so far, only a few NIR-II-responsive organic PTMs was explored, and their photothermal conversion efficiencies (PCEs) still remain relatively low. Herein, donor-acceptor conjugated diradical polymers with open-shell characteristics are explored for synergistically photothermal immunotherapy of metastatic tumors in the NIR-II window. By employing side-chain regulation, the conjugated diradical polymer TTB-2 with obvious NIR-II absorption was developed, and its nanoparticles realize a record-breaking PCE of 87.7% upon NIR-II light illustration. In vitro and in vivo experiments demonstrate that TTB-2 nanoparticles show good tumor photoablation with navigation of photoacoustic imaging in the NIR-II window, without any side-effect. Moreover, by combining with PD-1 antibody, the pulmonary metastasis of breast cancer is high-effectively prevented by the efficient photo-immunity effect. Thus, this study explores superior PTMs for cancer metastasis theranostics in the NIR-II window, offering a new horizon in developing radical-characteristic NIR-II photothermal materials.

Theranostic imaging and multimodal photodynamic therapy and immunotherapy using the mTOR signaling pathway

Tumor metastases are considered the leading cause of cancer-associated deaths. While clinically applied drugs have demonstrated to efficiently remove the primary tumor, metastases remain poorly accessible. To overcome this limitation, herein, the development of a theranostic nanomaterial by incorporating a chromophore for imaging and a photosensitizer for treatment of metastatic tumor sites is presented. The mechanism of action reveals that the nanoparticles are able to intervene by local generation of cellular damage through photodynamic therapy as well as by systemic induction of an immune response by immunotherapy upon inhibition of the mTOR signaling pathway which is of crucial importance for tumor onset, progression and metastatic spreading. The nanomaterial is able to strongly reduce the volume of the primary tumor as well as eradicates tumor metastases in a metastatic breast cancer and a multi-drug resistant patient-derived hepatocellular carcinoma models in female mice.

Recent Strategies to Develop Conjugated Polymers for Detection and Therapeutics

The infectious diseases resulting from pathogenic microbes are highly contagious and the source of infection is difficult to control, which seriously endangers life and public health safety. Although the emergence of antibiotics has a good therapeutic effect in the early stage, the massive abuse of antibiotics has brought about the evolution of pathogens with drug resistance, which has gradually weakened the lethality and availability of antibiotics. Cancer is a more serious disease than pathogenic bacteria infection, which also threatens human life and health. Traditional treatment methods have limitations such as easy recurrence, poor prognosis, many side effects, and high toxicity. These two issues have led to the exploration and development of novel therapeutic agents (such as conjugated polymers) and therapeutic strategies (such as phototherapy) to avoid the increase of drug resistance and toxic side effects. As a class of organic polymer biological functional materials with excellent photoelectric properties, Conjugated polymers (CPs) have been extensively investigated in biomedical fields, such as the detection and treatment of pathogens and tumors due to their advantages of easy modification and functionalization, good biocompatibility and low cost. A rare comprehensive overview of CPs-based detection and treatment applications has been reported. This paper reviews the design strategies and research status of CPs used in biomedicine in recent years, introduces and discusses the latest progress of their application in the detection and treatment of pathogenic microorganisms and tumors according to different detection or treatment methods, as well as the limitations and potential challenges in prospective exploration.

Novel Application of NIR-I-Absorbing Quinoidal Conjugated Polymer as a Photothermal Therapeutic Agent

Conjugated polymer nanoparticles (CP NPs) that could absorb the first near-infrared (NIR-I) window have emerged as highly desirable therapeutic nanomaterials. Here, a quinoidal-conjugated polymer (QCP), termed PQ, was developed as a novel class of therapeutic agents for photothermal therapy (PTT). Owing to its intrinsic quinoid structure, PQ exhibits molecular planarity and π-electron overlap along the conjugated backbone, endowing it with a narrow band gap, NIR-I absorption, and diradical features. The obtained PQ was coated with a poly(ethylene glycol) (PEG) moiety, affording nanosized and water-dispersed PQ nanoparticles (PQ NPs), which consequently show a high photothermal conversion efficiency (PCE) of 63.2%, good photostability, and apparent therapeutic efficacy for both in vitro and in vivo PTTs under an 808 nm laser irradiation. This study demonstrates that QCPs are promising active agents for noninvasive anticancer therapy using NIR-I light.

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.

Recent Progress in NIR-II Fluorescence Imaging-guided Drug Delivery for Cancer Theranostics

Fluorescence imaging in the second near-infrared window (NIR-II) has become a prevalent choice owing to its appealing advantages like deep penetration depth, low autofluorescence, decent spatiotemporal resolution, and a high signal-to-background ratio. This would expedite the innovation of NIR-II imaging-guided drug delivery (IGDD) paradigms for the improvement of the prognosis of patients with tumors. This work systematically reviews the recent progress of such NIR-II IGDD-mediated cancer therapeutics and collectively brings its essence to the readers. Special care has been taken to assess their performances based on their design approach, such as enhancing their drug loading and triggering release, designing intrinsic and extrinsic fluorophores, and/ or overcoming biological barriers. Besides, the state-of-the-art NIR-II IGDD platforms for different therapies like chemo-, photodynamic, photothermal, chemodynamic, immuno-, ion channel, gas-therapies, and multiple functions such as stimulus-responsive imaging and therapy, and monitoring of drug release and therapeutic response, have been updated. In addition, for boosting theranostic outcomes and clinical translation, the innovation directions of NIR-II IGDD platforms are summarized, including renal-clearable, biodegradable, sub-cellular targeting, and/or afterglow, chemiluminescence, X-ray excitable NIR-IGDD, and even cell therapy. This review will propel new directions for safe and efficient NIR-II fluorescence-mediated anticancer drug delivery.

Ultralow Charge Voltage Triggering Exceptional Post-Charging Antibacterial Capability of Co3 O4 /MnOOH Nanoneedles for Skin Infection Treatment

The post-charging antibacterial therapy is highly promising for treatment of Gram-negative bacterial wound infections. However, the therapeutic efficacy of the current electrode materials is yet unsatisfactory due to their low charge storage capacity and limited reactive oxygen species (ROS) yields. Herein, the design of MnOOH decorated Co₃ O₄ nanoneedles (MCO) with exceptional post-charging antibacterial effect against Gram-negative bacteria at a low charge voltage and their implementation as a robust antibacterial electrode for skin wound treatment are reported. Taking advantaging of the increased active sites and enhanced OH^- adsorption capability, the charge storage capacity and ROS production of the MCO electrode are remarkably boosted. As a result, the MCO electrode after charging at an ultralow voltage of 1.4 V gives a 5.49 log and 5.82 log bacterial reduction in Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) within an incubation time of only 5 min, respectively. More importantly, the antibacterial efficiency of the MCO electrode against multi-drug resistant (MDR) bacteria including Klebsiella pneumoniae (K. pneumoniae) and Acinetobacter baumannii (A. baumannii) also reaches 99.999%. In addition, the MCO electrode exhibits excellent reusability, and the role of extracellular ROS in enhancing post-charging antibacterial activity is also unraveled.

A novel donor-acceptor structured diketopyrrolopyrrole-based conjugated polymer synthesized by direct arylation polycondensation (DArP) for highly efficient antimicrobial photothermal therapy

A novel donor (D)-acceptor (A) structured conjugated polymer (PDPP-TP), which contains two alternating D-A pairs, namely thiophene (T)-diketopyrrolopyrrole (DPP) and thiophenen (T)-thieno[3,4-b]pyrazine (TP) along the main chain of the polymer, was synthesized by direct arylation polycondensation (DArP) for a highly efficient photothermal antibacterial treatment. The hydrophilic PDPP-TP-based nanoparticles (PTNPs) with a hydration diameter of about 120 nm were obtained by self-assembly using DSPE-mPEG₂₀₀₀ as the polymer matrix. PTNPs show strong near-infrared (NIR) absorbance with a λ_max at 910 nm (ε = 2.25 × 10⁴ L mol^-1 cm^-1) and NIR light-triggered photoactivity with a high photothermal conversion efficiency (PTCE) of 52.8% under 880 nm laser irradiation. Keeping the merits of excellent biocompatibility and photostability, PTNPs exhibited remarkable bacterial inhibition efficiency of almost 100% against Gram-negative E. coli and Gram-positive S. aureus with the help of an 880 nm laser (0.7 W cm^-2, 6 min), demonstrating its great potential as photothermal materials with a broad spectrum of activity for the effective treatment of microbial infections.

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.

Effective design of organic luminogens for near-infrared-II fluorescence imaging and photo-mediated therapy

Due to their electron coupling capability, organic luminescent materials exhibit powerful optoelectronic features that are responsible for their light-harvesting and light-amplification properties. The extensive modification of conjugated systems has shown significant improvement in their photonic properties thus broadening their applicability in photo-mediated imaging and photo-based treatment. Organic luminogens with emission in the near-infrared second region are found attractive not only for their deeper penetrating power but also for accurate visual imaging superiority with higher temporal resolution and spatial resolution suitable for tumor precision treatment. In this review, we underscore the latest development in organic luminogens (conjugated polymers and small molecules), focusing on chemical design, molecular engineering, and their applications in the scope of bioimaging followed by photo-assisted treatment, including photodynamic therapy (PDT), photothermal therapy (PTT), and immunotherapy ablation. Organic luminogens integrated with an aggregation-induced emission feature significantly optimize their physicochemical properties to act as quintessential nanoplatforms for controllable image-guided therapy. In conclusion, we clarify the limitations and challenges and provide insights into how to design organic dyes with improved safety for potential clinical applications.

Nano-assemblies of phosphonium-functionalized diblock copolymers with fabulous antibacterial properties and relationships of structure-activity

As a novel antimicrobial material, quaternary phosphonium salts (QPSs) have been drawing close attention because of their excellent antimicrobial capacity with high activity and low bacterial survivability. Polymeric QPSs (PQPSs) also exhibit selectivity and long-term stability, however the polymerization of QPSs is severely challenged by low controllability and narrow selectivity of cation type. In this study, high-conversion RAFT polymerization is employed to prepare innovative phosphonium-functionalized diblock copolymers (PFDCs) with desired molecular weights and particle sizes. The excellent antibacterial activity of the PFDCs achieves lowest MIC values of 40 and 60 μg mL^-1 (i.e., 1.4 and 2.2 μmol L^-1) against E. coli and S. aureus, respectively. Mixing with an ink, dye, and latex coating does not weaken the antibacterial activity of the PFDCs, which inhibited 99.9% E. coli, showing broad applicability in different media. The effects of the cation type, synthesis medium, crosslinking content, and particle size on the morphology and antibacterial activity are studied. In summary, the RAFT polymerization of QPSs through the versatile design of ionic liquid monomers and the polymerization-induced self-assembly (PISA) method for constructing nano-assemblies with various micromorphology and particle size provides an exceedingly efficient way to build up multifunctional and multi-morphological polymeric nano-objects that open up vast possibilities in the fields of antibiotics, drug delivery, templated synthesis, and catalysis.

Clearance pathways of near-infrared-II contrast agents

Near-infrared-II (NIR-II) bioimaging gradually becomes a vital visualization modality in the real-time investigation for fundamental biological research and clinical applications. The favorable NIR-II contrast agents are vital in NIR-II imaging technology for clinical translation, which demands good optical properties and biocompatibility. Nevertheless, most NIR-II contrast agents cannot be applied to clinical translation due to the acute or chronic toxicity caused by organ retention in vivo imaging. Therefore, it is critical to understand the pharmacokinetic properties and optimize the clearance pathways of NIR-II contrast agents in vivo to minimize toxicity by decreasing organ retention. In this review, the clearance mechanisms of biomaterials, including renal clearance, hepatobiliary clearance, and mononuclear phagocytic system (MPS) clearance, are synthetically discussed. The clearance pathways of NIR-II contrast agents (classified as inorganic, organic, and other complex materials) are highlighted. Successively analyzing each contrast agent barrier, this review guides further development of the clearable and biocompatible NIR-II contrast agents.

Near-Infrared-II Light Induced Mild Hyperthermia Activate Cisplatin-Artemisinin Nanoparticle for Enhanced Chemo/Chemodynamic Therapy and Immunotherapy

Chemodynamic therapy (CDT) is an effective cancer treatment that uses Fenton reaction to induce cancer cell death. Current clinical applications of CDT are limited by the dependency of external supply of metal ions as well as low catalytic efficiency. Here, a highly efficient metal-free CDT by using endoperoxide bridge-containing artesunate as free radical-generating substance is developed. A Pt(IV) prodrug (A-Pt) containing two artesunate molecules in the axial direction is synthesized, which can be decomposed into cisplatin and artesunate under reducing intracellular environment in tumor cells. To improve the catalytic efficiency for Fenton reaction, a near-infrared-II (NIR-II) photothermal agent IR1048 is incorporated to achieve a mild hyperthermia effect. By encapsulating the A-Pt and IR1048 with human serum albumin, A-Pt-IR NP are formulated for efficient drug delivery in 4T1 tumor-bearing mice. NIR-II light irradiation of A-Pt-IR NP treated mice show accelerated Fenton reaction. In addition, A-Pt-IR NP could also induce strong immunogenic cell death, which effectively reverses the immunosuppressive tumor microenvironment, and augments antitumor immunity. This study demonstrates that A-Pt-IR NP are potent biodegradable NIR-II active chemotherapy/CDT nanomedicine for clinical translation.

Self-Sacrificially Degradable Pseudo-Semiconducting Polymer Nanoparticles that Integrate NIR-II Fluorescence Bioimaging, Photodynamic Immunotherapy, and Photo-Activated Chemotherapy

Semiconducting polymers (SP) hold great promise for cancer phototherapy due to their excellent optical properties; however, their clinical application is still hampered by their poor biodegradability. Herein, a self-sacrificially biodegradable pseudo-semiconducting polymer (PSP) for NIR-II fluorescence bioimaging, photodynamic immunotherapy, and photoactivated chemotherapy (PACT) is reported. The PSP can further co-assemble with an amphiphilic polyester with pendant doxorubicin (DOX) in its side chains via reactive oxygen species (ROS)-responsive thioketal linkages (PE^DOX ), which are denoted as NP@PE^DOX /PSP. The NP@PE^DOX /PSP can accumulate at tumor sites and generate ROS for photodynamic immunotherapy as well as near-infrared-II fluorescence (NIR-II) for bioimaging upon irradition at 808 nm. The ROS could break up thioketal linkages in PE^DOX , resulting in rapid doxorubicin (DOX) release for PACT. Finally, both PE^DOX and PSP are degraded sacrificially by intracellular glutathione (GSH), resulting in the dissociation of NP@PE^DOX /PSP. This work highlights the application of self-sacrificially degradable PSP for NIR-II fluorescence bioimaging, photodynamic immunotherapy, and PACT in cancer therapy.

Bio-Inspired Hollow Carbon Microtubes for Multifunctional Photothermal Protective Coatings

Solar energy-facilitated materials are promising to solve energy problems by converting clean solar energy to thermal energy. However, heat loss of photothermal materials still limits the photothermal conversion phenomenon. Herein, we designed bio-inspired hollow carbon microtubes (HCMTs) by one-step carbonization of renewable cotton fibers, which can avoid the complex preparation procedures of the template method. Similar to polar bears, the hollow construction can efficiently reduce heat loss, which improves the utilization of light and photothermal property. The HCMTs can be applied on a variety of substrates to obtain multifunctional photothermal protective coatings. The temperature of the coating can rapidly warm up to 97.7 °C under 1 kW/m² sun irradiation. In addition, the coatings show excellent superhydrophobic property (CA of 161.5 ± 0.9°), which can prevent the adhesion of the contaminant and maintain the long-time photothermal property of the surface. Also, the coating is able to withstand sandpaper abrasion, repeat tape-peeling, and tribological friction without losing superhydrophobic properties, indicating remarkable mechanical stability. Furthermore, the coating can withstand high-temperature calcination (400 °C), long-time UV radiation, and corrosive liquid erosion, which exhibits prominent chemical stability. More importantly, the combination of active deicing and passive anti-icing of the coating can effectively prevent the formation and accumulation of ice on the surface. The outstanding environmental adaptability can greatly extend its lifespan and meet the long-term service conditions.