Antibacterial Chemodynamic Therapy: Materials and Strategies

A Self-Assembled Nanoreactor for Realizing Antibacterial Photodynamic/Gas Therapy and Promoting Wound Healing

Among various treatments employed to solve the global problem of bacterial infection, photodynamic therapy (PDT) is recognized as a method with great potential to inactivate a wide range of bacteria without the development of drug resistance. However, many commonly used photosensitizers (PSs) have the disadvantages of poor water-solubility and potential toxicity, which limits their clinical application. Additionally, nitric oxide (NO) has unique advantages in antibacterial treatments due to its small molecular weight. Herein, protoporphyrin IX (PpIX), L-arginine (L-Arg), and glycol chitosan (GC) are used to construct a self-assembled cationic Arg-GC-PpIX nanoreactor for efficient bacterial inactivation under white light illumination. The Arg-GC-PpIX nanoreactor with excellent water dispersity and stability can rapidly bind to bacteria through electrostatic interaction and produce local singlet oxygen (1O2)/NO under light irradiation, leading to a high antibacterial efficiency toward both Gram-negative and Gram-positive bacteria. Besides, these NPs also possess a desirable antibiofilm ability. Finally, Arg-GC-PpIX@Gel which is obtained through loading Arg-GC-PpIX into the sodium alginate (SA)/Ca2+ hydrogel shows a satisfactory ability to promote infected wound healing when combined with white light irradiation. Therefore, the rationally designed Arg-GC-PpIX nanoreactor with light-triggered 1O2/NO release is a promising antibacterial agent for achieving effective PDT/NO gas therapy.

Cationic Polymer Brushes Functionalized with Carbon Dots and Boronic Acids for Bacterial Detection and Inactivation

Drug-resistant bacterial infections are among the most severe physiological challenges facing human health. Therefore, the detection and inactivation of pathogenic bacteria remains a crucial therapeutic goal in modern society. In this study, we design multifunctional nanocomposites aimed at bacterial binding, fluorescence labeling, and synergistic antibacterial treatment. These nanocomposites are prepared by introducing cationic polymers with quaternary ammonium compounds onto silica nanoparticles using surface-initiated atom transfer radical polymerization, followed by incorporation of copper-doped carbon dots and modification of boronic acid. The cationic polymer units and boronic acid end groups enhance the bacterial binding capacity and synergistic bactericidal effects in cooperation with the carbon dots. Due to the stable fluorescent properties of carbon dots, the nanocomposites can generate fluorescence signals around bacteria, enabling bacterial fluorescence imaging. Overall, this study demonstrates a multifunctional nanocomposite-assisted strategy for bacterial labeling, imaging, and deactivation, providing a novel approach for bacterial detection and synergistic treatment.

Integrating synthetic polypeptides with innovative material forming techniques for advanced biomedical applications

Polypeptides are highly valued in biomedical science for their biocompatibility and biodegradability, making them valuable in drug delivery, tissue engineering, and antibacterial dressing. The diverse design of polymer chains and self-assembly techniques allow different side chains and secondary structures, enhancing their biomedical potential. However, the traditional solid powder form of polypeptides presents challenges in skin applications, shipping, and recycling, limiting their practical utility. Recent advancements in material forming methods and polypeptide synthesis have produced biomaterials with uniform, distinct shapes, improving usability. This review outlines the progress in polypeptide synthesis and material-forming methods over the past decade. The main synthesis techniques include solid-phase synthesis and ring-opening polymerization of N-carboxyanhydrides while forming methods like electrospinning, 3D printing, and coating are explored. Integrating structural design with these methods is emphasized, leading to diverse polypeptide materials with unique shapes. The review also identifies research hotspots using VOSviewer software, which are visually presented in circular packing images. It further discusses emerging applications such as drug delivery, wound healing, and tissue engineering, emphasizing the crucial role of material shape in enhancing performance. The review concludes by exploring future trends in developing distinct polypeptide shapes for advanced biomedical applications, encouraging further research.

Advanced Palladium Nanosheet-Enhanced Phototherapy for Treating Wound Infection Caused by Multidrug-Resistant Bacteria

With the increasing spread of multidrug-resistant (MDR) bacteria worldwide, it is needed to develop antibiotics-alternative strategies for the treatment of bacterial infections. This work develops a multifunctional single-component palladium nanosheet (PdNS) with broad-spectrum and highly effective bactericidal activity against MDR bacteria. PdNS exerts its endogenous nanoknife (mechanical cutting) effect and peroxidase-like activity independent of light. Under near-infrared region (NIR) light irradiation, PdNS exhibits photothermal effect to produce local heat and meanwhile possesses photodynamic effect to generate 1O2; notably, PdNS has catalase-like activity-dependent extra photodynamic effect upon H2O2 addition. PdNS+H2O2+NIR employs a collectively synergistic mechanism of nanoknife effect, peroxidase/catalase-like catalytic activity, photothermal effect, and photodynamic effect for bacterial killing. PdNS+H2O2+NIR causes compensatory elevated phospholipid biosynthesis, disordered energy metabolism, increased cellular ROS levels and excessive oxidative stress, and inhibited nucleic acid synthesis in bacteria. In mice, PdNS+H2O2+NIR gives >92.7% bactericidal rates at infected wounds and almost the full recovery of infected wounds, and it leads to extensive down-regulation of proinflammatory pathways and comprehensive up-regulation of wound healing pathways, conferring elevated inflammation resolution and meanwhile accelerated wound repair. PdNS+H2O2+NIR represents a highly efficient nanoplatform for photoenhanced treatment of superficial infections.

2-D transition metal trichalcophosphogenide FePS3 against multi-drug resistant microbial infections

Antimicrobial resistance (AMR) is a significant concern to society as it threatens the effectiveness of antibiotics and leads to increased morbidity and mortality rates. Innovative approaches are urgently required to address this challenge. Among promising solutions, two dimensional (2-D) nanomaterials with layered crystal structures have emerged as potent antimicrobial agents owing to their unique physicochemical properties. This antimicrobial activity is largely attributed to their high surface area, which allows for efficient interaction with microbial cell membranes, leading to physical disruption or oxidative stress through the generation of reactive oxygen species (ROS). The latter mechanism is particularly noteworthy as it involves the degradation of these nanomaterials under specific conditions, releasing ROS that can effectively kill bacteria and other pathogens without harming human cells. This study explores the antimicrobial properties of a novel biodegradable nanomaterial based on 2-D transition metal trichalcogenides, FePS3, as a potential solution to drug-resistant microbes. Our findings indicate that FePS3 is an exceptionally effective antimicrobial agent with over 99.9% elimination of various bacterial strains. Crucially, it exhibits no cytotoxic effects on mammalian cells, underscoring the potential for safe biomedical application. The primary mechanism driving the antimicrobial efficacy of FePS3 is the release of ROS during biodegradation. ROS has a crucial role in neutralizing bacterial cells, conferring significant antipathogenic properties to this compound. The unique combination of high antimicrobial activity, biocompatibility, and biodegradability makes FePS3 a promising candidate for developing new antimicrobial strategies. This research contributes to the increasing body of evidence supporting the use of 2-D nanomaterials in addressing the global challenge of AMR, offering a potential pathway for the development of advanced, effective, and safe antimicrobial agents.

Harnessing the Power of Saussurea obvallata Zinc Oxide Nanoparticles for Accelerated Wound Healing and Antimicrobial Action

Introduction

Zinc oxide nanoparticles (ZnONPs) have been the subject of substantial research by virtue of their utility across extensive downstream applications. Moreover, the ZnONPs are inexpensive, reliable, and easy to produce. Green synthesis employing biological systems, particularly plant extracts, has arisen as a subject of study in nanotechnology and is gaining importance due to its multiple applications in biology, chemistry, physics, and medicine.

Methods

Aqueous extract of S. obvallata was prepared and ZnONPs were synthesised using zinc acetate as a substrate. UV-Vis spectrophotometric measurement confirmed the production of ZnONPs. The ZnONPs were characterized by employing SEM, EDS, XRD, and FTIR. The ZnONPs were screened for its antimicrobial and wound healing potential.

Results

The peak of absorbance for UV-Vis was observed at 370 nm. The average dimension of the particles was found to be 22.58 nm. The antibacterial activity of ZnONPs was efficient in countering a broad spectrum of bacteria and the fungi C. albicans. The results of in vitro and in vivo wound healing assays indicate that the ZnONPs possess potent wound healing potential. In the cell migration assay, the percentage of wound closure was observed to be 84.70% (p < 0.001) for ZnONPs compared to the untreated group (8.12%). In the excision wound healing rat model, the animals treated with ZnONPs and Povidone-Iodine showed a significant (p < 0.01) wound contraction in comparison to the untreated animals.

Discussion

The ZnONPs promoted wound healing processes and showed promise as a therapeutic agent. However, further research is needed to understand the mechanisms of action and evaluate the long-term safety and effectiveness of ZnONPs in wound healing applications. By using renewable biological materials, the green synthesis of ZnONPs minimizes the need for synthetic reagents and lowers the total carbon footprint related to the production of nanoparticles.

A Soothing Lavender-Scented Electrospun Fibrous Eye Mask

Electrospinning technology has demonstrated extensive applications in biomedical engineering, energy storage, and environmental remediation. However, its utilization in the cosmetic industry remains relatively underexplored. To address the challenges associated with skin damage caused by preservatives and thickeners used for extending the shelf life of conventional products, a soothing lavender-scented electrospun fibrous eye mask with coaxial layers was developed using the electrospinning technique. Polyvinyl alcohol (PVA) served as the hydrophilic outer sheath, while polycaprolactone (PCL) constituted the hydrophobic core, with lavender oil (LO) encapsulated within. The structural and physicochemical properties of the samples were characterized using a scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FT-IR), and contact angle measurements. Upon hydration, the fibrous membrane exhibited strong adhesion properties, notable antioxidant activity, and a degree of antibacterial efficacy, demonstrating its potential for safe and effective use in skincare and eye mask applications. These findings suggest that the developed electrospun material offers promising functional properties and functional properties for integration into cosmetic formulations.

Copper peroxide-decorated Prussian blue for effective bacterial elimination via photothermal-enhanced and H2O2-releasing chemodynamic therapy

Bacterial infection is a major impediment towards wound healing and threaten human health worldwide. Traditional antibiotic therapy poses a high risk of inducing bacterial resistance, thus nanomaterial-based synergistic bactericidal strategy as effective alternatives have received tremendous attention. Herein, a NIR/pH-dual responsive nanoplatform was fabricated for synergistic photothermal and chemodynamic therapy (PTT/CDT). Prussian blue (PB) were employed as supporting material, while copper peroxide (CP) were growth in situ on PB surface, resulting in a core-shell structured nanoplatform (designated as PC). PB core served as photothermal/Fenton catalyst dual agents, and CP shell could co-release Cu2+ and H2O2 under acidic bacterial infection environment, realizing synergistic PTT and H2O2-releasing CDT. Under NIR irradiation, PC exhibited photothermal-enhanced Fenton-like reaction feature and the hyperthermia facilitated Cu2+ release, leading to the rapid conversion of H2O2 into toxic •OH to effectively kill Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), eradicating S. aureus biofilm. Moreover, the released Cu2+ could improve the bactericidal effect of CDT via the depletion of GSH and significantly promote cell migration. Furthermore, in vivo experiments demonstrated PC with good biocompatibility exhibited robust bactericidal effect and promoted wound healing. Overall, this versatile nanoplatform offered an efficacious and safe antibiotic-free strategy for bacterial infection treatments.

Robust Chiral Metal-Organic Framework Coatings for Self-Activating and Sustainable Biofouling Mitigation

Surface coatings are designed to mitigate pervasive biofouling herald, a new era of surface protection in complex biological environments. However, existing strategies are plagued by persistent and recurrent biofilm attachment, despite the use of bactericidal agents. Herein, a chiral metal-organic framework (MOF)-based coating with conformal microstructures to enable a new anti-biofouling mode that involves spontaneous biofilm disassembly followed by bacterial eradication is developed. A facile and universal metal-polyphenol network (MPN) is designed to robustly anchor the MOF nanoarmor of biocidal Cu2+ ions and anti-biofilm d-amino acid ligands to a variety of substrates across different material categories and surface topologies. Incorporating a diverse array of chiral amino acids endows the resultant coatings with widespread signals for biofilm dispersal, facilitating copper-catalyzed chemodynamic reactions and inherent mechano-bactericidal activities. This synergistic mechanism yields unprecedented anti-biofouling efficacy elucidated by RNA-sequencing transcriptomics analysis, enhancing broad-spectrum antibacterial activities, preventing biofilm formation, and destroying mature biofilms. Additionally, the chelation-directed amorphous/crystalline coatings can activate photoluminescent properties to inhibit the settlement of microalgae biofilms. This study provides a distinctive perspective on chirality-enhanced antimicrobial behaviors and pioneers a rational pathway toward developing next-generation anti-biofouling coatings for diverse applications.

Cationized Decalcified Bone Matrix for Infected Bone Defect Treatment

Objective: We aim to develop a dual-functional bone regeneration scaffold (Qx-D) with antibacterial and osteogenic properties for infected bone defect treatment. Impact Statement: This study provides insights into antibacterial components that could be combined with naturally derived materials through a facile Schiff base reaction, offering a potential strategy to enhance antibacterial properties. Introduction: Naturally derived decalcified bone matrix (DBM) has been reported to be porous and biodegradable. DBM can induce various cell differentiations and participate in immune regulation, making it an ideal bone regeneration scaffold for bone defects. However, DBM does not exhibit antimicrobial properties. Therefore, it is essential to develop antibacterial functionalization method for DBM. Methods: DBM was modified with a macromolecular quaternary ammonium salt (QPEI). A series of Qx-D with tunable feeding ratios were synthesized through Schiff base reaction. The morphology, chemical property, in vitro antibacterial efficiency, in vitro biocompatibility, osteogenic property, and in vivo anti-infection performances were characterized. Results: All Qx-D exhibited marked antibacterial properties. Small adjustments in feed concentration could not induce changes in antibacterial properties. However, cell viability slightly decreased with increasing feed concentration. Q10-D demonstrated significant antibacterial properties and could promote recovery of infected bone defect in an animal model. Conclusion: Qx-D shows marked antibacterial properties and good biocompatibility. Moreover, Q10-D could be a potential choice for infected bone defects.

A Janus Adhesive Hydrogel with Integrated Attack and Defense for Bacteria Killing and Antifouling

Objective: Skin wound exposed to complex external environment for a long time is highly susceptible to bacterial infection. Impact Statement: This work designs a Janus adhesive dual-layer hydrogel containing in situ silver nanoparticles (named PSAP/DXP@AgNPs) with integrated attack and defense to simultaneously kill the existing bacteria and prevent foreign bacterial contamination. Introduction: The current gauze dressing fixed by tape fails to well fit at skin wound and lacks intrinsic antibacterial property, making it highly prone to causing secondary infection. Moreover, foreign bacteria may contaminate the wound dressing during use, further increasing the risk of secondary infection. Methods: In this work, a Janus adhesive dual-layer PSAP/DXP@AgNPs hydrogel is prepared by sequentially building the PSAP gel layer containing zwitterionic poly(sulfobetaine methacrylamide) (PSBMA) on the DXP@AgNPs gel layer containing in situ catechol-reduced AgNPs. Results: The flexible PSAP/DXP@AgNPs can adapt shape change of skin and adhere to skin tissue with interfacial toughness of 153.38 J m-2 relying on its DXP@AgNPs layer, which is beneficial to build favorable fit. The in situ reduced AgNPs released from the DXP@AgNPs layer of PSAP/DXP@AgNPs exhibit obvious antibacterial effects against Escherichia coli and Staphylococcus aureus, with antibacterial rates of 99% and 88%, respectively. Meanwhile, the hydrated PSAP layer of PSAP/DXP@AgNPs containing PSBMA is able to prevent the bacterial contamination, decreasing the risk of secondary infection. Besides, cell experiments demonstrate that PSAP/DXP@AgNPs is biocompatible. Conclusion: The PSAP/DXP@AgNPs hydrogel with integrated attack and defense simultaneously possessing bacteria-killing and bacteria-antifouling properties is a potential alternative in treating infected skin wound.

Emerging Trends in Dissolving-Microneedle Technology for Antimicrobial Skin-Infection Therapies

Skin and soft-tissue infections require significant consideration because of their prolonged treatment duration and propensity to rapidly progress, resulting in severe complications. The primary challenge in their treatment stems from the involvement of drug-resistant microorganisms that can form impermeable biofilms, as well as the possibility of infection extending deep into tissues, thereby complicating drug delivery. Dissolving microneedle patches are an innovative transdermal drug-delivery system that effectively enhances drug penetration through the stratum corneum barrier, thereby increasing drug concentration at the site of infection. They offer highly efficient, safe, and patient-friendly alternatives to conventional topical formulations. This comprehensive review focuses on recent advances and emerging trends in dissolving-microneedle technology for antimicrobial skin-infection therapy. Conventional antibiotic microneedles are compared with those based on emerging antimicrobial agents, such as quorum-sensing inhibitors, antimicrobial peptides, and antimicrobial-matrix materials. The review also highlights the potential of innovative microneedles incorporating chemodynamic, nanoenzyme antimicrobial, photodynamic, and photothermal antibacterial therapies. This review explores the advantages of various antimicrobial therapies and emphasizes the potential of their combined application to improve the efficacy of microneedles. Finally, this review analyzes the druggability of different antimicrobial microneedles and discusses possible future developments.

Micro-flow cell washing technique combined with single-cell Raman spectroscopy for rapid and automatic antimicrobial susceptibility test of pathogen in urine

Facing the rapid spread of antimicrobial resistance, methods based on single-cell Raman spectroscopy have proven their advances in reducing the turn-around time (TAT) of antimicrobial susceptibility tests (AST). However, the Raman-based methods are still hindered by the prolonged centrifugal cell washing procedure, which may require complex labor operation and induce high mechanical stress, resulting in a pretreatment time of over 1 h as well as a high cell-loss probability. In this study, we developed a micro-flow cell washing device and corresponding Raman-compatible washing chips, which were able to automatically remove the impurities in the samples, retain the bacterial cell and perform Raman spectra acquisition in situ. Results of washing the 5- and 10-μm polymethyl methacrylate (PMMA) microspheres showed that the novel technique achieved a successful removal of 99 % impurity and an 80 % particle retention rate after 6 to 10 cycles of washing. The micro-flow cell washing technique could complete the pretreatment for urine samples in a 96-well plate within 10 min, only taking 15 % of the handling time required by centrifugation. The AST profiles of urine sample spiked with E. coli 25922, E. faecalis 29212, and S. aureus 29213 obtained by the proposed Raman-based approach were found to be 100 % consistent with the results from broth micro-dilution while reducing the TAT to 3 h from several days which is required by the latter. Our study has demonstrated the micro-flow cell washing technique is a reliable, fast and compatible approach to replace centrifuge washing for sample pretreatment of Raman-AST and could be readily applied in clinical scenarios.

Recent advances in nanostructured delivery systems for vancomycin

Despite the development of new generations of antibiotics, vancomycin remained as a high-efficacy antibiotic for treating the infections caused by MRSA. Researchers have explored various nanoformulations, aiming to enhance the therapeutic efficacy of vancomycin. Such novel formulations improve the effectiveness of drug cargoes in treating bacterial infections and minimizing the risk of adverse effects. The vast of researches have focuses on enhancing the permeation ability of vancomycin through different biological barriers especially those of gastrointestinal tract. Increasing the drug loading and tuning the drug release from nanocarrier are other important goal for many conducted studies. This study reviews the newest nano-based formulations for vancomycin as a key antibiotic in treating hospitalized bacterial infections.

Upregulation of HAS2 promotes glioma cell proliferation and chemoresistance via c-myc

Glioblastoma multiforme (GBM) is the most common and aggressive primary malignant human brain tumor. Although comprehensive therapies, including chemotherapy and radiotherapy following surgery, have shown promise in prolonging survival, the prognosis for GBM patients remains poor, with an overall survival rate of only 14.6 months. Chemoresistance is a major obstacle to successful treatment and contributes to relapse and poor survival rates in glioma patients. Therefore, there is an urgent need for novel strategies to overcome chemoresistance and improve treatment outcomes for human glioma patients. Recent studies have shown that the tumor microenvironment plays a key role in chemoresistance. Our study demonstrates that upregulation of HAS2 and subsequent hyaluronan secretion promotes glioma cell proliferation, invasion, and chemoresistance in vitro and in vivo through the c-myc pathway. Targeting HAS2 sensitizes glioma cells to chemotherapeutic agents. Additionally, we found that hypoxia-inducible factor HIF1α regulates HAS2 expression. Together, our findings provide insights into the dysregulation of HAS2 and its role in chemoresistance and suggest potential therapeutic strategies for GBM.

Fluorescent carbon dots for discriminating cell types: a review

Carbon dots (CDs) are quasi-spherical carbon nanoparticles with excellent photoluminescence, good biocompatibility, favorable photostability, and easily modifiable surfaces. CDs, serving as fluorescent probes, have emerged as an ideal tool for cellular differentiation owing to their outstanding luminescence performance and tunable surface properties. In this review, we summarize the recent research progress with CDs in the differentiation of cancer/normal cells, Gram-positive/Gram-negative bacteria, and live/dead cells, as well as the cellular differences used for differentiation. Additionally, we summarize the preparation methods, raw materials, and properties of the CDs used for cell discrimination. The differentiation mechanisms and the advantages or limitations of the differentiation methods are also introduced. Finally, we propose several research challenges in this field and future research directions that require extensive investigation. It is hoped that this review will help researchers in the design of new CDs as ideal fluorescent probes for realizing diverse cell differentiation applications.

Bioinspired multifunctional cellulose film: In situ bacterial capturing and killing for managing infected wounds

Bacterial infection of cutaneous wounds can easily lead to occurrence of chronic wounds and even more serious diseases. Therefore, multifunctional, biodegradable, and reusable wound dressings that can quickly manage wound infection and promote wound healing are urgently desired. Herein, inspired by the "capturing and killing" action of Drosera peltata Thunb., a biomimetic cellulose film was constructed to capture the bacteria (via the rough structure of the film) and kill them (via the combination of photodynamic therapy and chemotherapy) to promote wound tissue remodeling. The film (termed OBC-PR) was simply prepared by chemically crosslinking the oxidized bacterial cellulose (OBC) with polyhexamethylene guanidine hydrochloride (PHGH) and rose bengal (RB). Notably, it could effectively capture Escherichia coli and Staphylococcus aureus bacterial cells with capture efficiencies of ∼99 % and ∼96 %, respectively, within 10 min. Furthermore, the in vivo experiments showed that OBC-PR could effectively promote the macrophage polarization toward the M2 phenotype and adequately induce the reconstruction of blood vessels and nerves, thus promoting wound healing. This study provides a potential direction for designing multifunctional wound dressings for managing infected skin wounds in the future.

Copper peroxide nanodot-decorated gold nanostar/silica nanorod Janus nanostructure with NIR-II photothermal and acid-triggered hydroxyl radical generation properties for the effective treatment of wound infections

Recently, bacterial infections have become a global crisis, greatly threatening the health of human beings. The development of a non-antibiotic biomaterial is recognized as an alternative way for the effective treatment of bacterial infections. In the present work, a multifunctional copper peroxide (CP) nanodot-decorated gold nanostar (GNS)/silica nanorod (SiNR) Janus nanostructure (GNS@CP/SiNR) with excellent antibacterial activity was reported. Due to the formation of the Janus nanostructure, GNS@CP/SiNR displayed strong plasmonic resonance absorbance in the near infrared (NIR)-II region that enabled the nanosystem to achieve mild photothermal therapy (MPTT). In acidic conditions, CP decorated on GNS@CP/SiNR dissociated rapidly by releasing Cu2+ and H2O2, which subsequently transformed to ˙OH via the Fenton-like reaction for chemodynamic therapy (CDT). As a result, GNS@CP/SiNR could effectively inhibit both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus), and eradicate the associated bacterial biofilms by exerting the synergistic MPTT/CDT antibacterial effect. Moreover, GNS@CP/SiNR was also demonstrated to be effective in treating wound infections, as verified on the S. aureus-infected full thickness excision wound rat model. Our mechanism study revealed that the synergistic MPTT/CDT effect of GNS@CP/SiNR firstly caused bacterial membrane damage, followed by boosting intracellular ROS via the severe oxidative stress effect, which subsequently caused the depletion of intracellular GSH and DNA damage, finally leading to the death of bacteria.

Tumor-Microenvironment-Responsive Cerium-Enriched Copper Nanozyme with O2 Supply and Oxidative Stress Amplification for In Situ Disulfiram Chemotherapy and Chemodynamic Therapy Intensification

Traditional chemotherapy has faced tough challenges of systemic toxicity, hypoxia resistance, and inadequacy of monotherapy. Developing the tumor-specific O2-supply-enhanced chemotherapy without toxic drugs while combing other precise treatments can substantially improve therapeutic efficacy. Herein, a CeO2-enriched CuO nanozyme with O2 supply and oxidative stress amplification for tumor-specific disulfiram (DSF) chemotherapy and intensified chemodynamic therapy by synergistic in situ "nontoxicity-toxicity" activation is developed. Notably, CeO2 can not only act as a morphological "regulator," but also serve as a cascaded enzyme-mimetic catalyst via tumor-microenvironment-responsive cascaded-logical programmable valence conversion. Once internalized inside tumor cells, the nanozyme can be degraded by lysosomal acidity to release nontoxic DSF and Cu2+, which can trigger in situ "Cu2+-DSF" chelation, generating a highly toxic Cu(DTC)2 for in situ chemotherapy. Moreover, the enriched CeO2 with catalase-mimetic activity can decompose the endogenous H2O2 into O2, which can relieve the hypoxia to enhance the chemotherapeutic efficacy. Furthermore, the simultaneously generated Ce3+ can exert peroxidase-mimetic activity to catalyze H2O2 into hydroxyl radicals (•OH) for chemodynamic therapy. This Fenton-like chemistry is accompanied by the regeneration of Ce4+, which can deplete the intracellular overproduced GSH to amplify the oxidative stress. Therefore, this nanozyme can provide an alternative to precise cancer treatment.

Recent design strategies for boosting chemodynamic therapy of bacterial infections

The emergence of drug-resistant bacteria poses a significant threat to people's lives and health as bacterial infections continue to persist. Currently, antibiotic therapy remains the primary approach for tackling bacterial infections. However, the escalating rates of drug resistance coupled with the lag in the development of novel drugs have led to diminishing effectiveness of conventional treatments. Therefore, the development of nonantibiotic-dependent therapeutic strategies has become imperative to impede the rise of bacterial resistance. The emergence of chemodynamic therapy (CDT) has opened up a new possibility due to the CDT can convert H2O2 into •OH via Fenton/Fenton-like reaction for drug-resistant bacterial treatment. However, the efficacy of CDT is limited by a variety of practical factors. To overcome this limitation, the sterilization efficiency of CDT can be enhanced by introducing the therapeutics with inherent antimicrobial capability. In addition, researchers have explored CDT-based combined therapies to augment its antimicrobial effects and mitigate its potential toxic side effects toward normal tissues. This review examines the research progress of CDT in the antimicrobial field, explores various strategies to enhance CDT efficacy and presents the synergistic effects of CDT in combination with other modalities. And last, the current challenges faced by CDT and the future research directions are discussed.

Type I photodynamic antimicrobial therapy: Principles, progress, and future perspectives

The emergence of drug-resistant bacteria has significantly diminished the efficacy of existing antibiotics in the treatment of bacterial infections. Consequently, the need for finding a strategy capable of effectively combating bacterial infections has become increasingly urgent. Photodynamic therapy (PDT) is considered one of the most promising emerging antibacterial strategies due to its non-invasiveness, low adverse effect, and the fact that it does not lead to the development of drug resistance. However, bacteria at the infection sites often exist in the form of biofilm instead of the planktonic form, resulting in a hypoxic microenvironment. This phenomenon compromises the treatment outcome of oxygen-dependent type-II PDT. Compared to type-II PDT, type-I PDT is not constrained by the oxygen concentration in the infected tissues. Therefore, in the treatment of bacterial infections, type-I PDT exhibits significant advantages over type-II PDT. In this review, we first introduce the fundamental principles of type-I PDT in details, including its physicochemical properties and how it generates reactive oxygen species (ROS). Next, we explore several specific antimicrobial mechanisms utilized by type-I PDT and summarize the recent applications of type-I PDT in antimicrobial treatment. Finally, the limitations and future development directions of type-I photosensitizers are discussed. STATEMENT OF SIGNIFICANCE: The misuse and overuse of antibiotics have accelerated the development of bacterial resistance. To achieve the effective eradication of resistant bacteria, pathfinders have devised various treatment strategies. Among these strategies, type I photodynamic therapy has garnered considerable attention owing to its non-oxygen dependence. The utilization of non-oxygen-dependent photodynamic therapy not only enables the effective elimination of drug-resistant bacteria but also facilitates the successful eradication of hypoxic biofilms, which exhibits promising prospects for treating biofilm-associated infections. Based on the current research status, we anticipate that the novel type I photodynamic therapy agent can surmount the biofilm barrier, enabling efficient treatment of hypoxic biofilm infections.

Antibacterial micro/nanomotors: current research progress, challenges, and opportunities

Bacterial infections remain a formidable threat to human health, a situation exacerbated by the escalating problem of antibiotic resistance. While alternative antibacterial strategies such as oxidants, heat treatments, and metal nanoparticles (NPs) have shown potential, they come with significant drawbacks, ranging from non-specificity to potential environmental concerns. In the face of these challenges, the rapid evolution of micro/nanomotors (MNMs) stands out as a revolutionary development in the antimicrobial arena. MNMs harness various forms of energy and convert it into a substantial driving force, offering bright prospects for combating microbial threats. MNMs' mobility allows for swift and targeted interaction with bacteria, which not only improves the carrying potential of therapeutic agents but also narrows the required activation range for non-drug antimicrobial interventions like photothermal and photodynamic therapies, substantially improving their bacterial clearance rates. In this review, we summarized the diverse propulsion mechanisms of MNMs employed in antimicrobial applications and articulated their multiple functions, which include direct bactericidal action, capture and removal of microorganisms, detoxification processes, and the innovative detection of bacteria and associated toxins. Despite MNMs' potential to revolutionize antibacterial research, the translation from laboratory to clinical use remains challenging. Based on the current research status, we summarized the potential challenges and possible solutions and also prospected several key directions for future studies of MNMs for antimicrobial purposes. Collectively, by highlighting the important knowns and unknowns of antimicrobial MNMs, our present review would help to light the way forward for the field of antimicrobial MNMs and prevent unnecessary blindness and detours.