Bacterial Toxin-Responsive Biomimetic Nanobubbles for Precision Photodynamic Therapy against Bacterial Infections

Treating and Protecting against Recurrent Vulvovaginal Candidiasis Using the Vaginal Epithelial Cell Membrane-Based Photoimmunotherapeutic Nanoplatform

Recurrent vulvovaginal candidiasis (RVVC) is an opportunistic infection predominantly caused by Candida albicans (C. albicans) and is particularly prevalent among individuals on immunosuppressants. Currently, there are no FDA-approved therapies for specifically controlling RVVC, mainly due to the need for therapeutics against RVVC that require both antifungal treatments to resolve active infections and strategies to prevent recurrence. This study introduces a biomimetic photoimmunotherapeutic nanoplatform consisting of an adjuvant-encapsulated polymeric core stabilized by a photosensitizer-loaded vaginal epithelial cell membrane coating to treat and protect against RVVC. With its cell membrane camouflaging, the nanoplatforms target and enhance adherence to the intravaginal site of C. albicans infection, allowing the nanoplatform to resist being flushed away by vaginal fluids. Upon subsequent near-infrared irradiation, the nanoplatform's targeted photothermal power effectively eliminates C. albicans while minimizing thermal damage to surrounding healthy tissue. Postphotothermal treatment, the generated C. albicans-based debris and candidalysin-captured nanoplatform (serving as a nanotoxoid), along with adjuvant, are processed by resident antigen-presenting cells to promote multiantigenic immunity. This response provides protection against secondary intravaginal C. albicans infection (RVVC model) and C. albicans-induced systemic infection even under immunosuppressive conditions (septicemia model). Notably, anti-C. albicans antibodies produced in the pretreated mice exhibit comparable affinity to clinically isolated C. albicans strains, indicating potential for clinical application. Overall, this study underscores the potential of the proposed photoimmunotherapeutic nanoplatform for the effective treatment and prevention of RVVC.

Impact of low-dose UV-A in Caenorhabditis elegans during candidate bacterial infections

Ultraviolet radiation is a non-ionizing radiation produced by longer wavelength energy sources with lower frequency and is categorized into UV-A, UV-B, and UV-C. Minimal exposure to this radiation has several health benefits, which include treating microbial contaminations and skin therapies. However, the antimicrobial action of low-dose UV-A during pathogenic bacterial infections is still unrevealed. In this study, the impact of low-dose UV-A as pre- or post-treatment using the model organism, Caenorhabditis elegans with candidate pathogens (Acinetobacter baumannii and Staphylococcus aureus) mediated infections was investigated. The results indicated enrichment of metabolites, reduced level of antioxidants, increased expression of dopamine biosynthesis and transportation, and decrease in serotonin biosynthesis when the organism was exposed to low-dose UV-A for 5 min. This, in turn, elevated the expression of candidate regulatory proteins involved in lifespan determination, innate immunity, and cAMP-response element binding protein (CREB), which appear to increase the lifespan and brood size of C. elegans during A. baumannii and S. aureus infections. The findings suggested that the low-dose UV-A treatment during A. baumannii and S. aureus infections prolonged the lifespan and increased the egg-laying capacity of C. elegans.

Highly effective treatment of bacterial infection-accompanied wounds by fat extract-embedded phototherapeutic hydrogel

Phototherapy presents an effective approach for treating localized methicillin-resistant Staphylococcus aureus (MRSA) infections; however, the tradeoff between therapeutic efficacy and negative off-target effect persists. To address these issues, we have developed a nanoparticle-hydrogel superstructure comprising phototherapeutic liposomal nanobubbles (NB) and fat extract (FE) encapsulated by F-127 hydrogel. After local administration to sites of MRSA infection, the superstructure effectively neutralizes high levels of MRSA toxins to protect against toxin-mediated cytotoxicity through loaded, which can also be leveraged to enhance anti-MRSA efficacy via toxin-regulated on-demand phototherapy upon near-infrared irradiation. Meanwhile, the oxidative stress-induced injury to healthy cells can be mitigated by the FE. In a murine model of skin MRSA infection, treatment with the nanoparticle-hydrogel superstructure significantly reduces MRSA load, especially when combined with MRSA toxin for enhanced bacterial inhibition. Concurrently, this superstructure accelerates wound healing by enhancing angiogenesis and collagen deposition while reducing inflammation. Overall, the nanoparticle-hydrogel superstructure shows promise for treating local pathogen-infected wounds.

CsxWO3@NBs as a Multi-Image Guided Photothermal/Photodynamic Combination Therapy Platform for the Treatment of Hepatocellular Carcinoma

Purpose

Effective cancer treatment relies on the precise deployment of clinical imaging techniques to accurately treat tumors. One highly representative technology among these is multi-imaging guided phototherapy. This work introduces a new and innovative theranostic drug that combines near-infrared (NIR) irradiation-induced photodynamic therapy (PDT) and photothermal therapy (PTT) to treat malignancies. Moreover, it can be utilized as a contrasting substance for X-ray computed tomography (CT) imaging and contrast-enhanced ultrasound (CEUS) to aid in the administration of therapy.

Methods

Cesium tungsten bronze nanobubbles (CsxWO3@NBs) were constructed via a water-controlled solvothermal synthesis and thin film hydration of phospholipid. Various methods, including dynamic light scattering, transmission electron microscopy, and X-ray photoelectron spectroscopy, were used to analyze and describe the size, shape, and chemical characteristics of the nanoparticles. In this study, hepatoma cell lines HepG2 and HUH7 were employed in vitro, and xenotransplantation mouse models were used to assess their antitumor effects. A series of in vitro and in vivo trials were conducted to assess the effectiveness of combining photodynamic and photothermal therapies, as well as using CEUS and CT imaging.

Results

The CsxWO3@NBs exhibit photothermal effects and the generation of reactive oxygen species (ROS) under laser irradiation, thereby enabling effective photothermal and photodynamic combinatorial therapy. Following combined treatment, the activity and invasive capacity of hepatocellular carcinoma cells were markedly diminished, the development rate of the tumor was noticeably reduced, and the level of biological toxicity was low. Additionally, CsxWO3@NBs possess the capacity to serve as both a CT imaging agent and a contrast-enhanced ultrasound agent.

Conclusion

CsxWO3@NBs represent a promising theranostic agent for image-guided cancer therapy.

Enhancing Root Canal Therapy with NIR-II Semiconducting Polymer AIEgen and Low-Concentration Sodium Hypochlorite Synergy

Despite significant efforts to eliminate bacterial biofilm within root canals, achieving effective disinfection remains challenging due to the complex anatomy and limitations of disinfectants. In this study, a second near-infrared (NIR-II) semiconducting polymer with aggregation-induced emission (AIE) properties, named PIDT-TBT, is deliberately designed and synthesized. This proposes an AIE luminogen-based sterilization strategy in synergy with a low concentration of sodium hypochlorite (NaClO). Water-dispersible PIDT-TBT nanoparticles (NPs) are prepared, demonstrating good biocompatibility, as well as photothermal and photodynamic properties. Subsequent antibacterial tests show that PIDT-TBT NPs exhibit excellent bactericidal effects against three bacterial strains: Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis, upon 808 nm laser irradiation. In synergy with a low concentration of NaClO (0.5%) solution, PIDT-TBT NPs significantly improves the outcome of root canal treatment under 808 nm laser irradiation in a human extracted tooth root canal infection model. Additionally, it is found that PIDT-TBT NPs combine with a low concentration of NaClO solution could safely dissolve dentin debris and further increase the efficiency of root canal preparation by altering the elemental composition of the inner root canal wall.

Red Blood Cell Membrane-Coated Nanoparticles Enable Incompatible Blood Transfusions

Blood transfusions save lives and improve health every day. Despite the matching of blood types being stricter than it ever has been, emergency transfusions among incompatible blood types are still inevitable in the clinic when there is a lack of acceptable blood types for recipients. Here to overcome this, a counter measure nanoplatform consisting of a polymeric core coated by a red blood cell (RBC) membrane is developed. With A-type or B-type RBC membrane camouflaging, the nanoplatform is capable of specifically capturing anti-A or anti-B IgM antibodies within B-type or A-type whole blood, thereby decreasing the corresponding IgM antibody levels and then allowing the incompatible blood transfusions. In addition to IgM, the anti-RBC IgG antibody in a passive immunization murine model can likewise be neutralized by this nanoplatform, leading to prolonged circulation time of incompatible donor RBCs. Noteworthily, nanoplatform made by expired RBCs (>42 days stored hypothermically) and then subjected to lyophilization does not impair their effect on antibody neutralization. Most importantly, antibody-captured RBC-NP do not exacerbate the risk of inflammation, complement activation, and coagulopathy in an acute hemorrhagic shock murine model. Overall, this biomimetic nanoplatform can safely neutralize the antibody to enable incompatible blood transfusion.

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.

Oxygen Self-Supplied Nanoplatform for Enhanced Photodynamic Therapy against Enterococcus Faecalis within Root Canals

The successful treatment of persistent and recurrent endodontic infections hinges upon the eradication of residual microorganisms within the root canal system, which urgently needs novel drugs to deliver potent yet gentle antimicrobial effects. Antibacterial photodynamic therapy (aPDT) is a promising tool for root canal infection management. Nevertheless, the hypoxic microenvironment within the root canal system significantly limits the efficacy of this treatment. Herein, a nanohybrid drug, Ce6/CaO2/ZIF-8@polyethylenimine (PEI), is developed using a bottom-up strategy to self-supply oxygen for enhanced aPDT. PEI provides a positively charged surface, which enables precise targeting of bacteria. CaO2 reacts with H2O to generate O2, which alleviates the hypoxia in the root canal and serves as a substrate for Ce6 under 660 nm laser irradiation, leading to the successful eradication of planktonic Enterococcus faecalis (E. faecalis) and biofilm in vitro and, moreover, the effective elimination of mature E. faecalis biofilm in situ within the root canal system. This smart design offers a viable alternative for mitigating hypoxia within the root canal system to overcome the restricted efficacy of photosensitizers, providing an exciting prospect for the clinical management of persistent endodontic infection.

Effects of Nanobubbles on Photochemical Processes of Levofloxacin Photosensitizer

Photodynamic therapy (PDT) stands as an efficacious modality for the treatment of cancer and various diseases, in which optimization of the electron transfer and augmentation of the production of lethal reactive oxygen species (ROS) represent pivotal challenges to enhance its therapeutic efficacy. Empirical investigations have established that the spontaneous initiation of redox reactions associated with electron transfer is feasible and is located in the gas-liquid interfaces. Meanwhile, nanobubbles (NBs) are emerging as entities capable of furnishing a plethora of such interfaces, attributed to their stability and large surface/volume ratio in bulk water. Thus, NBs provide a chance to expedite the electron-transfer kinetics within the context of PDT in an ambient environment. In this paper, we present a pioneering exploration into the impact of nitrogen nanobubbles (N2-NBs) on the electron transfer of the photosensitizer levofloxacin (LEV). Transient absorption spectra and time-resolved decay spectra, as determined through laser flash photolysis, unequivocally reveal that N2-NBs exhibit a mitigating effect on the decay of the LEV excitation triplet state, thereby facilitating subsequent processes. Of paramount significance is the observation that the presence of N2-NBs markedly accelerates the electron transfer of LEV, albeit with a marginal inhibitory influence on its energy-transfer reaction. This observation is corroborated through absorbance measurements and offers compelling evidence substantiating the role of NBs in expediting electron transfer within the ambit of PDT. The mechanism elucidated herein sheds light on how N2-NBs intricately influence both electron-transfer and energy-transfer reactions in the photosensitizer LEV. These findings not only contribute to a nuanced understanding of the underlying processes but also furnish novel insights that may inform the application of NBs in the realm of photodynamic therapy.

Nanoscale contrast agents: A promising tool for ultrasound imaging and therapy

Nanoscale contrast agents have emerged as a versatile platform in the field of biomedical research, offering great potential for ultrasound imaging and therapy. Various kinds of nanoscale contrast agents have been extensively investigated in preclinical experiments to satisfy diverse biomedical applications. This paper provides a comprehensive review of the structure and composition of various nanoscale contrast agents, as well as their preparation and functionalization, encompassing both chemosynthetic and biosynthetic strategies. Subsequently, we delve into recent advances in the utilization of nanoscale contrast agents in various biomedical applications, including ultrasound molecular imaging, ultrasound-mediated drug delivery, and cell acoustic manipulation. Finally, the challenges and prospects of nanoscale contrast agents are also discussed to promote the development of this innovative nanoplatform in the field of biomedicine.

Cell membrane-coated biomimetic nanomedicines: productive cancer theranostic tools

As the second-leading cause of human death, cancer has drawn attention in the area of biomedical research and therapy from all around the world. Certainly, the development of nanotechnology has made it possible for nanoparticles (NPs) to be used as a carrier for delivery systems in the treatment of tumors. This is a biomimetic approach established to craft remedial strategies comprising NPs cloaked with membrane obtained from various natural cells like blood cells, bacterial cells, cancer cells, etc. Here we conduct an in-depth exploration of cell membrane-coated NPs (CMNPs) and their extensive array of applications including drug delivery, vaccination, phototherapy, immunotherapy, MRI imaging, PET imaging, multimodal imaging, gene therapy and a combination of photothermal and chemotherapy. This review article provides a thorough summary of the most recent developments in the use of CMNPs for the diagnosis and treatment of cancer. It critically assesses the state of research while recognizing significant accomplishments and innovations. Additionally, it indicates ongoing problems in clinical translation and associated queries that warrant deeper research. By doing so, this study encourages creative thinking for future projects in the field of tumor therapy using CMNPs while also educating academics on the present status of CMNP research.

Precise antibacterial therapeutics based on stimuli-responsive nanomaterials

Bacterial infection refers to the process in which bacteria invade, grow, reproduce, and interact with the body, ultimately causing a series of pathological changes. Nowadays, bacterial infection remains a significant public health issue, posing a huge threat to human health and a serious financial burden. In the post-antibiotic era, traditional antibiotics are prone to inducing bacterial resistance and difficulty in removing bacterial biofilm. In recent years, antibacterial therapy based on nanomaterials has developed rapidly. Compared with traditional antibiotics, nanomaterials effectively remove bacterial biofilms and rarely result in bacterial resistance. However, due to nanomaterials' strong permeability and effectiveness, they will easily cause cytotoxicity when they are not controlled. In addition, the antibacterial effect of non-responsive nanomaterials cannot be perfectly exerted since the drug release property or other antibacterial effects of these nano-materials are not be positively correlated with the intensity of bacterial infection. Stimuli-responsive antibacterial nanomaterials are a more advanced and intelligent class of nano drugs, which are controlled by exogenous stimuli and microenvironmental stimuli to change the dosage and intensity of treatment. The excellent spatiotemporal controllability enables stimuli-responsive nanomaterials to treat bacterial infections precisely. In this review, we first elaborate on the design principles of various stimuli-responsive antibacterial nanomaterials. Then, we analyze and summarizes the antibacterial properties, advantages and shortcomings of different applied anti-bacterial strategies based on stimuli-responsive nanomaterials. Finally, we propose the challenges of employing stimuli-responsive nanomaterials and corresponding potential solutions.

Vaginal Epithelial Cell Membrane-Based Phototherapeutic Decoy Confers a "Three-in-One" Strategy to Treat against Intravaginal Infection of Candida albicans

Phototherapy is an effective strategy to control Candida albicans (C. albicans) infection without raising the concern of drug resistance. Despite its effectiveness, a higher dose of phototherapeutic power is required for C. albicans elimination compared to bacteria that have to be used, which is readily accompanied by off-target heat and toxic singlet oxygen to damage normal cells, thus limiting its usefulness for antifungal applications. Here to overcome this, we develop a "three-in-one" biomimetic nanoplatform consisting of an oxygen-dissolved perfluorocarbon camouflaged by a photosensitizer-loaded vaginal epithelial cell membrane. With a cell membrane coating, the nanoplatform is capable of specifically binding with C. albicans at the superficial or deep vaginal epithelium, thereby centering the phototherapeutic agents on C. albicans. Meanwhile, the cell membrane coating endows the nanoplatform to competitively protect healthy cells from candidalysin-medicated cytotoxicity. Upon candidalysin sequestration, pore-forming on the surface of the nanoplatform accelerates release of the preloaded photosensitizer and oxygen, resulting in enhanced phototherapeutic power for improved anti-C. albicans efficacy under near-infrared irradiation. In an intravaginal C. albicans-infected murine model, treatment with the nanoplatform leads to a significantly decreased C. albicans burden, particularly when leveraging candidalysin for further elevated phototherapy and C. albicans inhibition. Also, the same trends hold true when using the nanoplatform to treat the clinical C. albicans isolates. Overall, this biomimetic nanoplatform can target and bind with C. albicans and simultaneously neutralize the candidalysin and then transform such toxins that are always considered a positive part in driving C. albicans infection with the power of enhancing phototherapy for improved anti-C. albicans efficacy.

A dual-modal ROS generator based on multifunctional PDA-MnO2@Ce6 nanozymes for synergistic chemo-photodynamic antibacterial therapy

The rapid emergence of drug-resistant bacteria has attracted great attention to exploring advanced antibacterial methods. However, single-modal antibacterial therapy cannot easily eliminate drug-resistant bacteria completely due to its low efficacy. Therefore, it is essential to achieve multi-modal antibacterial therapy effectively. Herein, a dual-modal ROS generator was designed based on photosensitive PDA-MnO₂@Ce6/liposome (PMCL) nanozymes for synergistic chemo-photodynamic therapy. PMCL nanozymes adhere to bacteria through liposome-membrane fusion. Meanwhile, PMCL catalyzes endogenous hydrogen peroxide (H₂O₂) to generate hydroxyl radicals (˙OH) and singlet oxygen (¹O₂) under laser irradiation. Furthermore, the photothermal effect can accelerate the generation of ROS. Based on dual-enzyme activities (mimicking peroxidase and catalase) and photodynamic properties, PMCL achieves powerful antibacterial efficacy and mature bacterial biofilm eradication. With the synergistic chemo-photodynamic effects, bacterial populations decrease by >99.76% against Gram-positive S. aureus and Gram-negative E. coli. Notably, the synergistic antibacterial properties of PMCL nanozymes are further explored using a mouse wound model of S. aureus infection. This work fabricated an efficient dual-modal ROS generator to kill bacteria, further providing a new strategy for treating wound infection.

Nanobubble technologies: Applications in therapy from molecular to cellular level

Nanobubbles are gaseous entities suspended in bulk liquids that have widespread beneficial usage in many industries. Nanobubbles are already proving to be versatile in furthering the effectiveness of disease treatment on cellular and molecular levels. They are functionalized with biocompatible and stealth surfaces to aid in the delivery of drugs. At the same time, nanobubbles serve as imaging agents due to the echogenic properties of the gas core, which can also be utilized for controlled and targeted delivery. This review provides an overview of the biomedical applications of nanobubbles, covering their preparation and characterization methods, discussing where the research is currently focused, and how they will help shape the future of biomedicine.

Recent advances of cell membrane-coated nanoparticles for therapy of bacterial infection

The rapid evolution of antibiotic resistance and the complicated bacterial infection microenvironments are serious obstacles to traditional antibiotic therapy. Developing novel antibacterial agents or strategy to prevent the occurrence of antibiotic resistance and enhance antibacterial efficiency is of the utmost importance. Cell membrane-coated nanoparticles (CM-NPs) combine the characteristics of the naturally occurring membranes with those of the synthetic core materials. CM-NPs have shown considerable promise in neutralizing toxins, evading clearance by the immune system, targeting specific bacteria, delivering antibiotics, achieving responsive antibiotic released to the microenvironments, and eradicating biofilms. Additionally, CM-NPs can be utilized in conjunction with photodynamic, sonodynamic, and photothermal therapies. In this review, the process for preparing CM-NPs is briefly described. We focus on the functions and the recent advances in applications of several types of CM-NPs in bacterial infection, including CM-NPs derived from red blood cells, white blood cells, platelet, bacteria. CM-NPs derived from other cells, such as dendritic cells, genetically engineered cells, gastric epithelial cells and plant-derived extracellular vesicles are introduced as well. Finally, we place a novel perspective on CM-NPs' applications in bacterial infection, and list the challenges encountered in this field from the preparation and application standpoint. We believe that advances in this technology will reduce threats posed by bacteria resistance and save lives from infectious diseases in the future.