BODIPY-Functionalized Natural Polymer Coatings for Multimodal Therapy of Drug-Resistant Bacterial Infection

An effective approach to obtain functional poly-β-peptides for combating drug-resistant bacterial infections

The high mortality of drug-resistant bacterial infections, especially those caused by multidrug-resistant Gram-negative pathogens, highlights an urgent demand for promising antimicrobial strategies. Host defense peptide (HDP)-mimicking poly-β-peptides have demonstrated significant potential in combating drug-resistant bacterial infections, with their antimicrobial activity closely dependent on their side-chain structures. However, the restricted structural diversity of poly-β-peptides necessitates efficient synthetic methods to expand their diversity, particularly positively charged side-chain structures. This study presents a water-tolerant approach that facilitates the controllable synthesis of poly-β-peptides with different chain lengths and structurally diverse side chains, including primary amines, tertiary amines, as well as alkyl, aryl, and methoxy groups. This approach serves as an HDP-mimicking discovery platform to obtain the optimal poly-β-peptide, AOc0.8HNL0.2, which exhibits broad-spectrum antibacterial activity and high selectivity against drug-resistant bacteria. The antibacterial mechanism studies reveal that AOc0.8HNL0.2 disrupts the membrane of Gram-negative bacteria. In vivo evaluations substantiate the therapeutic potential of AOc0.8HNL0.2 in treating drug-resistant bacterial infections with no observable toxicity. This study underscores the potential of this convenient synthetic strategy as a promising platform for developing antimicrobial poly-β-peptides to combat the growing threat of drug-resistant bacterial infections.

Recent Progress in Antibacterial Surfaces for Implant Catheters

Catheter-related infections (CRIs) caused by hospital-acquired microbial infections lead to the failure of treatment and the increase of mortality and morbidity. Surface modifications of the implant catheters have been demonstrated to be effective approaches to improve and largely reduce the bacterial colonization and related complications. In this work, we focus on the last 5-year progress in the surface modifications of biomedical catheters to prevent CRIs. Their antibacterial strategies used for surface modifications are further divided into 5 classifications through the antimicrobial mechanisms, including active surfaces, passive surfaces, active and passive combination surfaces, stimulus-type response surfaces, and other types. Each feature and the latest advances in these abovementioned antibacterial surfaces of implant catheters are highlighted. Finally, these confronting challenges and future prospects are discussed for the antibacterial modifications of implant catheters.

Natural Macromolecule-Based Lubricative Catheter Coatings with Sustained Adaptive Antibacterial Property for Encrustation and Infection Prevention

Catheter-associated urinary tract infection (CAUTI) are a global health burden. Moreover, the friction during urinary catheter placement also induces pain in patients. Therefore, there is a pressing need to develop effective antibacterial and lubricative coatings on the surface of urinary catheter. In this work, a facile volatilization film-forming method is used to construct coatings on catheter surfaces. Xanthan gum (SR), which has good lubricative and antifouling properties, is oxidized to cross-link with multi-amino compounds, gentamicin (GS), and gelatin, to fabricate uniform coatings on silicone catheters (SR-GXGs). The structures of SR-GXGs are regulated by the components of the film formation solutions. The bacterial metabolism can produce an acidic micro-environment that can regulate GS release to achieve on-demand administration. SR-GXG2 can eliminate 99.99% of common pathogenic bacteria and reduce the dynamic friction coefficient by 98.73%, and showed high stability in a 7-day flowing experiment. In addition, the universality of this method is demonstrated on various kinds of matrices with different shapes, including commercial urethral catheters. In vivo, SR-GXG2 can effectively avoid urinary tract injury and encrustation phenomenon because of its good anti-infection, antifouling, and lubricative properties. This work provides a promising strategy for developing multifunctional antibacterial coatings on medical catheters.

Multifunctional Ru(III)/Fe3O4/DNA nanoplatform for photothermal-enhanced photodynamic and chemodynamic cancer therapy

Among the many cancer treatment methods, there have been many reports on the use of nanoplatforms with single treatment methods such as photothermal, photodynamic or chemodynamic for cancer treatment. In this study, Ru(III) with photodynamic effect and Fe3O4 nanoparticles with photothermal and chemodynamic effects are connected through long DNA chains with efficient active targeting rolling circle amplification to construct Ru(III)/Fe3O4/DNA nano-platform realizes the combination of photothermal, photodynamic and chemodynamic treatment, which significantly improves the therapeutic effect of the nano-platform. Its multiple active targeting capabilities reduce the damage to normal cells. Ru(III) has excellent photodynamic effect and can catalyze the respiration product NADH (Nicotinamide adenine dinucleotide)to produce highly oxidizing H2O2. Fe3O4 NPs has weak absorption at 808 nm indicates that it can perform mild photothermal treatment, and the Fe2+ in it can react with H2O2 to produce ·OH and participate in chemodynamic treatment. Each repeating unit on the rolling circle amplified DNA long chain is connected to the AS1411 aptamer that can actively target cancer cells. Unlike the passive targeting of other nanomedicines, active and efficient targeting is achieved, and a small amount of drugs can achieve high efficacy. The therapeutic effect also reduces the damage to normal cells. The comprehensive killing effect of Ru(III)/Fe3O4/DNA can reach 85.1 %. Its high targeting of cancer cells can also be used for imaging detection of cancer cells. This new nanoplatform provides an idea for the synergy of multiple cancer treatments.

Charge Engineering of Star-Shaped Organic Photosensitizers Enables Efficient Type-I Radicals for Photodynamic Therapy of Multidrug-Resistant Bacterial Infection

Infection induced by multidrug-resistant bacteria is now the second most common cause of accidental death worldwide. However, identifying a high-performance strategy with good efficiency and low toxicity is still urgently needed. Antibacterial photodynamic therapy (PDT) is considered a non-invasive and efficient approach with minimal drug resistance. Whereas, the precise molecular design for highly efficient oxygen-independent type-I photosensitizers is still undefined. In this work, the regulation of the positive charge of star-shaped NIR-emissive organic photosensitizers can boost radical generation for the efficient treatment of wounds infected with multidrug-resistant bacteria. With positive charge engineering, TPAT-DNN, which has six positive charges, mainly produces hydroxyl radicals via the type-I pathway, while TPAT-DN, which has three positive charges, tends to generate singlet oxygen and superoxide radicals. For multidrug-resistant bacteria, TPAT-DNN exhibited specific killing effects on multidrug-resistant gram-positive bacteria at low concentrations, while TPAT-DN is similar antibacterial effects on both multidrug-resistant gram-negative and gram-positive bacteria. Furthermore, the efficiency and safety of TPAT-DNN for eradicating multidrug-resistant bacteria methicillin-resistant S. aureus (MRSA) infection and accelerating wound healing in an MRSA-infected mouse model are demonstrated. This work offers a new approach toward manipulating efficient type-I photosensitizers for MRSA treatment.

Antimicrobial materials based on photothermal action and their application in wound treatment

Considering the increasing abundance of antibiotic-resistant bacteria, novel antimicrobial approaches need to be investigated. Photothermal therapy (PTT), an innovative noninvasive therapeutic technique, has demonstrated significant potential in addressing drug-resistant bacteria and bacterial biofilms. However, when used in isolation, PTT requires higher-temperature conditions to effectively eradicate bacteria, thereby potentially harming healthy tissues and inducing new inflammation. This study aims to present a comprehensive review of nanomaterials with intrinsic antimicrobial properties, antimicrobial materials relying on photothermal action, and nanomaterials using drug delivery antimicrobial action, along with their applications in antimicrobials. Additionally, the synergistic mechanisms of these antimicrobial approaches are elucidated. The review provides a reference for developing multifunctional photothermal nanoplatforms for treating bacterially infected wounds.

Nanomaterials at the forefront of antimicrobial therapy by photodynamic and photothermal strategies

In the face of the increasing resistance of microorganisms to traditional antibiotics, the development of innovative treatment methods is becoming increasingly urgent. Nanophototherapy technology can precisely target the infected area and achieve synergistic antibacterial effects in multiple modes. This phototherapy method has shown significant efficacy in treating diseases caused by drug-resistant bacteria, especially in the elimination of biofilms, where it has demonstrated strong dissolution capabilities. PTT utilizes photothermal agents to convert near-infrared light into heat, effectively killing bacteria and promoting tissue regeneration. Similarly, PDT utilizes photosensitizers, which produce reactive oxygen species (ROS) when activated by light, destroying the structure and function of bacterial cells. This review summarizes photothermal agents and photosensitizers used for antibacterial purposes. In conducting our literature review, we employed a systematic approach to ensure a comprehensive and representative selection of studies. Additionally, this article explores the potential of phototherapy in regulating wound microenvironments, promoting wound healing, and activating the immune system. Nanophototherapeutic materials show great potential for application in antibacterial treatment and are expected to provide innovative solutions for drug-resistant bacterial infections that traditional antibiotics are struggling to address.

Harnessing Dual Phototherapy and Immune Activation for Cancer Treatment: The Development and Application of BODIPY@F127 Nanoparticles

Conventional phototherapeutic agents are typically used in either photodynamic therapy (PDT) or photothermal therapy (PTT). However, efficacy is often hindered by hypoxia and elevated levels of heat shock proteins in the tumor microenvironment (TME). To address these limitations, a formylated, near-infrared (NIR)-absorbing and heavy-atom-free Aza-BODIPY dye is presented that exhibits both type-I and type-II PDT actions with a high yield of reactive oxygen species (ROS) and manifests efficient photothermal conversion by precise adjustments to the conjugate structure and electron distribution, leading to a large amount of ROS production even under severe hypoxia. To improve biosafety and water solubility, the dye with an amphiphilic triblock copolymer (Pluronic F-127), yielding BDP-6@F127 nanoparticles (NPs) is coated. Furthermore, inspired by the fact that phototherapy triggers the release of tumor-associated antigens, a strategy that leverages potential immune activation by combining PDT/PTT with immune checkpoint blockade (ICB) therapy to amplify the systemic immune response and achieve the much-desired abscopal effect is developed. In conclusion, this study presents a promising molecular design strategy that integrates multimodal therapeutics for a precise and effective approach to cancer therapy.

A chitosan-based hydrogel with ultrasound-driven immuno-sonodynamic therapeutic effect for accelerated bacterial infected wound healing

Sonodynamic therapy has attracted much attention as a noninvasive treatment for deep infections. However, it is challenging to achieve high antibacterial activity for hydrogels under ultrasonic irradiation due to the relatively weak sono-catalysis capability of sonosensitizers. Herein, an ultrasound-responsive antibacterial hydrogel (Fe3O4/HA/Ber-LA) composed of Fe3O4-grafted-Berberine, chitosan molecules modified with L-arginine and poly (vinyl alcohol) is prepared for enhanced sonodynamic therapy and immunoregulation. The formation of heterojunction between berberine and Fe3O4 with different work function promotes the charge separation and electron flow and disrupts the conjugated structure of berberine, causing a significant decrease in the band gap, eventually enhancing the sonocatalytic activity. The combination of berberine with Fe3O4 also significantly improves the oxygen adsorption energy, enabling more O2 molecules to react with the electron-rich regions on the surface of Fe3O4 to generate more reactive oxygen species (ROS). L-arginine grafted in the hydrogel is catalyzed by the ROS to release nitric oxide, which not only possesses antibacterial activity, but also positively affects macrophage M1 polarization to display potent phagocytosis to Staphylococcus aureus, thus achieving immuno-sonodynamic therapy. Hence, Fe3O4/HA/Ber-LA hydrogel under ultrasound irradiation shows excellent antibacterial activity. Furthermore, the antioxidative activity and anti-inflammatory effect of berberine released from the hybrid hydrogel induces macrophages to polarize towards the anti-inflammatory M2 status as infection comes under control, thus accelerating the wound healing. The hybrid hydrogel based on the immuno-sonodynamic therapy may be an extraordinary candidate for the treatment of deep infections.

GSH-responsive bithiophene Aza-BODIPY@HMON nanoplatform for achieving triple-synergistic photoimmunotherapy

Photoimmunotherapy represents an innovative approach to enhancing the efficiency of immunotherapy in cancer treatment. This approach involves the fusion of immunotherapy and phototherapy (encompassing techniques like photodynamic therapy (PDT) and photothermal therapy (PTT)). Boron-dipyrromethene (BODIPY) has the potential to trigger immunotherapy owing to its excellent PD and PT efficiency. However, the improvements in water solubility, bioavailability, PD/PT combined efficiency, and tumor tissue targeting of BODIPY require introduction of suitable carriers for potential practical application. Herein, a disulfide bond-based hollow mesoporous organosilica (HMON) with excellent biocompatibility and GSH-responsive degradation properties was used as a carrier to load a bithiophene Aza-BODIPY dye (B5), constructing a sample chemotherapy reagent-free B5@HMON nanoplatform achieving triple-synergistic photoimmunotherapy. HMON, involving disulfide bond, is utilized to improve water solubility, tumor tissue targeting, and PD efficiency by depleting GSH and enhancing host-guest interaction between B5 and HMO. The study reveals that HMON's large specific surface area and porous properties significantly enhance the light collection and oxygen adsorption capacity. The HMON's rich mesoporous structure and internal cavity achieved a loading rate of B5 at 11 %. It was found that the triple-synergistic nanoplatform triggered a stronger anti-tumor immune response, including tumor invasion, cytokine production, calreticulin translocation, and dendritic cell maturation, eliciting specific tumor-specific immunological responses in vivo and in vitro. The BALB/c mouse model with 4T1 tumors was used to assess tumor suppression efficiency in vivo, showing that almost all tumors in the B5@HMON group disappeared after 14 days. Such a simple chemotherapy reagent-free B5@HMON nanoplatform achieved triple-synergistic photoimmunotherapy.

Facile Surface Modification with Croconaine-Functionalized Polymer on Polypropylene for Antifouling and NIR-Light-Mediated Photothermal Sterilization

Biomedical-device-associated infection (BAI) is undoubtedly a major concern and a serious challenge in modern medicine. Therefore, the development of biomedical materials that are capable of resisting or killing bacteria is of great importance. In this work, a croconaine-functionalized polymer with antifouling and near-infrared (NIR) photothermal bactericidal properties was prepared and facilely modified on polypropylene (PP) to combat medical device infections. Croconaine dye is elaborately modified as a "living" initiator, termed CR-4EBiB, for preparing amphiphilic block polymers by atom transfer radical polymerization (ATRP). In the formed polymer coating, the hydrophobic block can strongly adhere to the surface of the PP substrate, whereas the hydrophilic block is located on the outer layer by solvent-induced resistance to bacterial adhesion. Under the irradiation of an NIR laser (808 nm), the croconaine dye in the coating achieved maximum conversion of light to heat to effectively kill E. coli, S. aureus, and methicillin-resistant Staphylococcus aureus (MRSA). This work provides a facile and promising strategy for the development of implantable antibacterial biomedical materials.

Tailored Phototherapy Agent by Infection Site In Situ Activated Against Methicillin-Resistant S. aureus

Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), is a promising treatment approach for multidrug resistant infections. PDT/PTT combination therapy can more efficiently eliminate pathogens without drug resistance. The key to improve the efficacy of photochemotherapy is the utilization efficiency of non-radiation energy of phototherapy agents. Herein, a facile phototherapy molecule (SCy-Le) with the enhancement of non-radiative energy transfer is designed by an acid stimulation under a single laser. Introduction of the protonated receptor into SCy-Le results in a distorted intramolecular charge in the infected acidic microenvironment, pH ≈ 5.5, which in turn, enhances light capture, reduces the singlet-triplet transition energies (ΔES1-T1), promotes electron system crossing, enhances capacity of reactive oxygen species generation, and causes a significant increase in temperature by improving vibrational relaxation. SCy-Le shows more than 99% bacterial killing rate against both methicillin-resistant Staphylococcus aureus and its biofilms in vitro and causes bacteria-induced wound healing in mice. This work will provide a new perspective for the design of phototherapy agents, and the emerging photochemotherapy will be a promising approach to combat the problem of antibiotic resistance.

A Stimulus-Responsive Ternary Heterojunction Boosting Oxidative Stress, Cuproptosis for Melanoma Therapy

Cuproptosis, a recently discovered copper-dependent cell death, presents significant potential for the development of copper-based nanoparticles to induce cuproptosis in cancer therapy. Herein, a unique ternary heterojunction, denoted as HACT, composed of core-shell Au@Cu2O nanocubes with surface-deposited Titanium Dioxide quantum dots and modified with hyaluronic acid is introduced. Compared to core-shell AC NCs, the TiO2/Au@Cu2O exhibits improved energy structure optimization, successfully separating electron-hole pairs for redox use. This optimization results in a more rapid generation of singlet oxygen and hydroxyl radicals triggering oxidative stress under ultrasound radiation. Furthermore, the HACT NCs initiate cuproptosis by Fenton-like reaction and acidic environment, leading to the sequential release of cupric and cuprous ions. This accumulation of copper induces the aggregation of lipoylated proteins and reduces iron-sulfur proteins, ultimately initiating cuproptosis. More importantly, HACT NCs show a tendency to selectively target cancer cells, thereby granting them a degree of biosecurity. This report introduces a ternary heterojunction capable of triggering both cuproptosis and oxidative stress-related combination therapy in a stimulus-responsive manner. It can energize efforts to develop effective melanoma treatment strategies using Cu-based nanoparticles through rational design.

Dual pH- and ATP-Responsive Antibacterial Nanospray: On-Demand Release of Antibacterial Factors, Imaging Monitoring, and Accelerated Healing of Bacteria-Infected Wounds under NIR Activation

The prevalence of pathogenic bacterial infections with high morbidity and mortality poses a widespread challenge to the healthcare system. Therefore, it is imperative to develop nanoformulations capable of adaptively releasing antimicrobial factors and demonstrating multimodal synergistic antimicrobial activity. Herein, an NIR-activated multifunctional synergistic antimicrobial nanospray MXene/ZIF-90@ICG was prepared by incorporating ZIF-90@ICG nanoparticles onto MXene-NH2 nanosheets. MXene/ZIF-90@ICG can on-demand release the antimicrobial factors MXenes, ICG, and Zn2+ in response to variations in pH and ATP levels within the bacterial infection microenvironment. Under NIR radiation, the combination of MXenes, Zn2+, and ICG generated a significant amount of ROS and elevated heat, thereby enhancing the antimicrobial efficacy of PDT and PTT. Meanwhile, NIR excitation could accelerate the further release of ICG and Zn2+, realizing the multimodal synergistic antibacterial effect of PDT/PTT/Zn2+. Notably, introducing MXenes improved the dispersion of the synthesized antimicrobial nanoparticles in aqueous solution, rendering MXene/ZIF-90@ICG a candidate for application as a nanospray. Importantly, MXene/ZIF-90@ICG demonstrated antimicrobial activity and accelerated wound healing in the constructed in vivo subcutaneous Staphylococcus aureus infection model with NIR activation, maintaining a favorable biosafety level. Therefore, MXene/ZIF-90@ICG holds promise as an innovative nanospray for adaptive multimodal synergistic and efficient antibacterial applications with NIR activation.

A universal strategy to enhance photothermal conversion efficiency by regulating the molecular aggregation states for safe photothermal therapy of bacterial infections

Photothermal therapy (PTT) has emerged as a promising approach for treating bacterial infections. However, achieving a high photothermal conversion efficiency (PCE) of photothermal agents (PTAs) remains a challenge. Such a problem is usually compensated by the use of a high-intensity laser, which inevitably causes tissue damage. Here, we present a universal strategy to enhance PCE by regulating the molecular aggregation states of PTAs within thermoresponsive nanogels. We demonstrate the effectiveness of this approach using aggregation-induced emission (AIE) and aggregation-caused quenching (ACQ) PTAs, showing significant enhancements in PCE without the need for intricate molecular modifications. Notably, the highest PCEs reach up to 80.9% and 64.4% for AIE-NG and ACQ-NG, respectively, which are nearly 2-fold of their self-aggregate counterparts. Moreover, we elucidate the mechanism underlying PCE enhancement, highlighting the role of strong intermolecular π-π interactions facilitated by nanogel-induced volume contraction. Furthermore, we validate the safety and efficacy of this strategy in in vitro and in vivo models of bacterial infections at safe laser power densities, demonstrating its potential for clinical translation. Our findings offer a straightforward, universal, and versatile method to improve PTT outcomes while minimizing cytotoxicity, paving the way for enhanced treatment of bacterial infections with safe PTT protocols.

Ternary heterostructure-driven photoinduced electron-hole separation enhanced oxidative stress for triple-negative breast cancer therapy

Zinc oxide nanoparticles (ZnO NPs) stand as among the most significant metal oxide nanoparticles in trigger the formation of reactive oxygen species (ROS) and induce apoptosis. Nevertheless, the utilization of ZnO NPs has been limited by the shallowness of short-wavelength light and the constrained production of ROS. To overcome these limitations, a strategy involves achieving a red shift towards the near-infrared (NIR) light spectrum, promoting the separation and restraining the recombination of electron-hole (e--h+) pairs. Herein, the hybrid plasmonic system Au@ZnO (AZ) with graphene quantum dots (GQDs) doping (AZG) nano heterostructures is rationally designed for optimal NIR-driven cancer treatment. Significantly, a multifold increase in ROS generation can be achieved through the following creative initiatives: (i) plasmonic Au nanorods expands the photocatalytic capabilities of AZG into the NIR domain, offering a foundation for NIR-induced ROS generation for clinical utilization; (ii) elaborate design of mesoporous core-shell AZ structures facilitates the redistribution of electron-hole pairs; (iii) the incorporation GQDs in mesoporous structure could efficiently restrain the recombination of the e--h+ pairs; (iv) Modification of hyaluronic acid (HA) can enhance CD44 receptor mediated targeted triple-negative breast cancer (TNBC). In addition, the introduced Au NRs present as catalysts for enhancing photothermal therapy (PTT), effectively inducing apoptosis in tumor cells. The resulting HA-modified AZG (AZGH) exhibits efficient hot electron injection and e--h+ separation, affording unparalleled convenience for ROS production and enabling NIR-induced PDT for the cancer treanment. As a result, our well-designed mesoporous core-shell AZGH hybrid as photosensitizers can exhibit excellent PDT efficacy.

Study on synergistic mechanism of molybdenum disulfide/sodium carboxymethyl cellulose composite nanofiber mats for photothermal/photodynamic antibacterial treatment

Innovative antibacterial therapies using nanomaterials, such as photothermal (PTT) and photodynamic (PDT) treatments, have been developed for treating wound infections. However, creating secure wound dressings with these therapies faces challenges. The primary focus of this study is to prepare an antibacterial nanofiber dressing that effectively incorporates stable loads of functional nanoparticles and demonstrates an efficient synergistic effect between PTT and PDT. Herein, a composite nanofiber mat was fabricated, integrating spherical molybdenum disulfide (MoS2) nanoparticles. MoS2 was deposited onto polylactic acid (PLA) nanofiber mats using vacuum filtration, which was further stabilized by sodium carboxymethyl cellulose (CMC) adhesion and glutaraldehyde (GA) cross-linking. The composite nanofibers demonstrated synergistic antibacterial effects under NIR light irradiation, and the underlying mechanism was explored. They induce bacterial membrane permeability, protein leakage, and intracellular reactive oxygen species (ROS) elevation, ultimately leading to >95 % antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), which is higher than that of single thermotherapy (almost no antibacterial activity) or ROS therapy (about 80 %). In addition, the composite nanofiber mats exhibited promotion effects on infected wound healing in vivo. This study demonstrates the great prospects of composite nanofiber dressings in clinical treatment of bacterial-infected wounds.

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

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

Copper(II)-infused porphyrin MOF: maximum scavenging GSH for enhanced photodynamic disruption of bacterial biofilm

Bacterial biofilm infection is a serious obstacle to clinical therapeutics. Photodynamic therapy (PDT) plays a dynamic role in combating biofilm infection by utilizing reactive oxygen species (ROS)-induced bacterial oxidation injury, showing advantages of mild side effects, spatiotemporal controllability and little drug resistance. However, superfluous glutathione (GSH) present in biofilm and bacteria corporately reduces ROS levels and seriously affects PDT efficiency. Herein, we have constructed a Cu2+-infused porphyrin metal-organic framework (MOF@Cu2+) for the enhanced photodynamic combating of biofilm infection by the maximum depletion of GSH. Our results show that the released Cu2+ from porphyrin MOF@Cu2+ could not only oxidize GSH in biofilm but also consume GSH leaked from ROS-destroyed bacteria, thus greatly weakening the antioxidant system in biofilm and bacteria and dramatically improving the ROS levels. As expected, our dual-enhanced PDT nanoplatform exhibits a strong biofilm eradication ability both in vitro and in an in vivo biofilm-infected mouse model. In addition, Cu2+ can promote biofilm-infected wound closing by provoking cell immigration, collagen sediment and angiogenesis. Besides, no apparent toxicity was detected after treatment with MOF@Cu2+. Overall, our design offers a new paradigm for photodynamic combating biofilm infection.

Electrospun fibers based anisotropic silk fibroin film with photodynamic antibacterial therapy for S. aureus infected wound healing

Bacterial infection has been regarded as a life-threatening problem in clinic. In addition to screening of new antibiotics, it is important to develop highly effective antibacterial materials against antibiotic resistance with capacities on modulating chronic inflammation. Herein, aligned Chlorin e6 (Ce6) conjugated silk fibroin electrospun fibers were successfully fabricated on silk fibroin based film via electrospining to achieve effective photodynamic antibacterial activities under near infrared (NIR) irradiation. The aligned electrospun fiber based film composite (SFCF@Film) exhibited good mechanical properties and desirable hemocompatibility. SFCF@Film provided a promising guidance cue for directing cell orientation and promoting cell growth. Significantly, SFCF@Film effectively generated ROS under NIR irradiation to kill S. aureus for treating wound infections within 10 min and promoted M2 polarization of macrophages for wound healing at later stage. Therefore, we believed that this engineered bioscaffold can be a powerful strategy for handling wound infection.

Bletilla Striata polysaccharides thermosensitive gel for photothermal treatment of bacterial infection

Skin is the most important defense shield which touched external environment directly. Effectively clearing microbes in infected wound via non-antibiotic therapy is crucial for the promotion of recovery in complex biological environments, and the wound healing is a crucial process after sterilization to avoid superinfection. Herein, a kind of Prussian blue-based photothermal responsive gel, Bletilla striata polysaccharide-mingled, isatin-functionalized Prussian blue gel (PB-ISA/BSP gel) was reported for effective treatment of bacterial infection and wound healing. The introduction of effective components of traditional Chinese medicine (TCM), isatin (ISA), enhanced the efficiency of sterilization synergistically. Furthermore, the process of wound healing was promoted by Bletilla striata polysaccharides (BSP). PB-ISA@BSP had a considerable antibacterial rate with 98.5 % under an 808 nm laser for 10 min in vitro. Besides, PB-ISA/BSP gel showed an effective antibacterial efficacy in vivo and a fast wound healing rate as well. The as-prepared functional particles can invade and destroy bacteria membrane to kill microbes. This work highlights that PB-ISA/BSP gel is a promising antibacterial agent based on synergistically enhanced photothermal effect and wound healing promotion ability and provides inspiration for future therapy based on the synergy between photothermal agent and active components in TCM.

Stimuli-Actuated Turn-On Theranostic Nanoplatforms for Imaging-Guided Antibacterial Treatment

Antibacterial theranostic nanoplatforms, which integrate diagnostic and therapeutic properties, exhibit gigantic application prospects in precision medicine. However, traditional theranostic nanoplatforms usually present an always-on signal output, which leads to poor specificity or selectivity in the treatment of bacterial infections. To address this challenge, stimuli-actuated turn-on nanoplatforms are developed for simultaneous activation of diagnostic signals (e.g., fluorescent, photoacoustic, magnetic signals) and initiation of antibacterial treatment. Specifically, by combining the infection microenvironment-responsive activation of visual signals and antibacterial activity, these theranostic nanoplatforms exert both higher accurate diagnosis rates and more effective treatment effects. In this review, the imaging and treatment strategies that are commonly used in the clinic are first briefly introduced. Next, the recent progress of stimuli-actuated turn-on theranostic nanoplatforms for treating bacterial infectious diseases is summarized in detail. Finally, current bottlenecks and future opportunities of antibacterial theranostic nanoplatforms are also outlined and discussed.

In Situ Growth of Functional Hydrogel Coatings by a Reactive Polyurethane for Biomedical Devices

Surface modification of thermoplastic polyurethane (TPU) could significantly enhance its suitability for biomedical devices and public health products. Nevertheless, customized modification of polyurethane surfaces with robust interfacial bonding and diverse functions via a simple method remains an enormous challenge. Herein, a novel thermoplastic polyurethane with a photoinitiated benzophenone unit (BPTPU) is designed and synthesized, which can directly grow functional hydrogel coating on polyurethane (PU) in situ by initiating polymerization of diverse monomers under ultraviolet irradiation, without the involvement of organic solvent. The resulting coating not only exhibits tissue-like softness, controllable thickness, lubrication, and robust adhesion strength but also provides customized functions (i.e., antifouling, stimuli-responsive, antibacterial, and fluorescence emission) to the original passive polymer substrates. Importantly, BPTPU can be blended with commercial TPU to produce the BPTPU-based tube by an extruder. Only a trace amount of BPTPU can endow the tube with good photoinitiated capacity. As a proof of concept, the hydrophilic hydrogel-coated BPTPU is shown to mitigate foreign body response in vivo and prevent thrombus formation in rat blood circulation without anticoagulants in vitro. This work offers a new strategy to guide the design of functional polyurethane, an elastomer-hydrogel composite, and holds great prospects for clinical translation.