Research progress of nanoparticle targeting delivery systems in bacterial infections

Juxtaposing the antibacterial activities of different ZIFs in photodynamic therapy and their oxidative stress approach

Instigating oxidative stress is a crucial aspect of antibacterial therapy. Yet, its behavior is poorly understood in the context of zeolitic imidazolate frameworks (ZIFs) - a group of highly promising antibacterial agents. To address this gap, a series of ZIF@Ce6 particles were synthesized to investigate the impact of particle shape, size, and metal ion type on oxidative stress and bactericidal activity. For the first time, the interplay between the physicochemical properties and antibacterial activities of different ZIF@Ce6 particles is demonstrated, while unearthing their oxidative stress strategy in photodynamic therapy. Notably, the incorporation of chlorin e6 (Ce6), combined with light irradiation, amplified the bactericidal effect of the ZIFs and achieved a rare minimum inhibition concentration (MIC) of 12.5 µgmL-1 for ZIF-8. We discovered that singlet oxygen (1O2) production varies with particle shape and size, while photodynamic activity reshuffles the antibacterial performance sequence from pristine to modified ZIF-8. Interestingly, reactive oxygen species (ROS) accumulation and glutathione depletion tests revealed that oxidative stress in pristine ZIF-8 is predominantly induced by ROS, whereas both ROS and glutathione contribute to the oxidative stress in ZIF@Ce6 and pristine ZIF-67. When bacteria are preincubated with the antioxidant N-acetyl cysteine, the bactericidal activity of ZIF@Ce6 increases while the activity of pristine ZIF-8 is reduced and that of ZIF-67 remains unchanged. This study deepens our understanding of the antibacterial properties of ZIFs and their oxidative stress paths, paving way for the fabrication of ZIF-based materials with enriched and targeted antibacterial properties.

Biofilm Resilience: Molecular Mechanisms Driving Antibiotic Resistance in Clinical Contexts

Healthcare-associated infections pose a significant global health challenge, negatively impacting patient outcomes and burdening healthcare systems. A major contributing factor to healthcare-associated infections is the formation of biofilms, structured microbial communities encased in a self-produced extracellular polymeric substance matrix. Biofilms are critical in disease etiology and antibiotic resistance, complicating treatment and infection control efforts. Their inherent resistance mechanisms enable them to withstand antibiotic therapies, leading to recurrent infections and increased morbidity. This review explores the development of biofilms and their dual roles in health and disease. It highlights the structural and protective functions of the EPS matrix, which shields microbial populations from immune responses and antimicrobial agents. Key molecular mechanisms of biofilm resistance, including restricted antibiotic penetration, persister cell dormancy, and genetic adaptations, are identified as significant barriers to effective management. Biofilms are implicated in various clinical contexts, including chronic wounds, medical device-associated infections, oral health complications, and surgical site infections. Their prevalence in hospital environments exacerbates infection control challenges and underscores the urgent need for innovative preventive and therapeutic strategies. This review evaluates cutting-edge approaches such as DNase-mediated biofilm disruption, RNAIII-inhibiting peptides, DNABII proteins, bacteriophage therapies, antimicrobial peptides, nanoparticle-based solutions, antimicrobial coatings, and antimicrobial lock therapies. It also examines critical challenges associated with biofilm-related healthcare-associated infections, including diagnostic difficulties, disinfectant resistance, and economic implications. This review emphasizes the need for a multidisciplinary approach and underscores the importance of understanding biofilm dynamics, their role in disease pathogenesis, and the advancements in therapeutic strategies to combat biofilm-associated infections effectively in clinical settings. These insights aim to enhance treatment outcomes and reduce the burden of biofilm-related diseases.

Synergistic NIR and ultrasound-responsive tellurium nanorods for enhanced antibacterial and osteogenic activity

Bacterial infections and deficient osteogenic activity are the primary factors contributing to the failure of orthopedic implants. In recent years, light- and sound-based external stimulus-responsive therapies have emerged as highly effective in killing drug-resistant bacteria. In this study, we successfully synthesized tellurium nanorods coated with bovine serum albumin (Te@BSA). This novel nanomaterial exhibits excellent biocompatibility and possesses near-infrared light (NIR) and ultrasound (US) synergistic response properties. At a concentration of 100 μg/mL, Te@BSA nanorods, under combined NIR and US treatment, achieved 94 % bacterial eradication against drug-resistant strains, while maintaining cell viability above 90 % in osteoblast cultures. This dual-modality approach minimizes the risk of local thermal damage associated with conventional photothermal therapy, enhancing osteogenic activity by up to 150 % upon NIR exposure. By combining photothermal therapy and sonodynamic therapy, we achieved a remarkable antibacterial effect and enhanced osteogenic capacities in a mild and controlled manner. This study successfully balances antibacterial and osteogenic capabilities. These light- and sound-based external stimulus-responsive strategies aslo offer new perspectives and valuable insights for the surface modification of orthopedic implants.

Photodynamic and photothermal bacteria targeting nanosystems for synergistically combating bacteria and biofilms

The escalating hazards posed by bacterial infections underscore the imperative for pioneering advancements in next-generation antibacterial modalities and treatments. Present therapeutic methodologies are frequently impeded by the constraints of insufficient biofilm infiltration and the absence of precision in pathogen-specific targeting. In this current study, we have used chlorin e6 (Ce6), zeolitic imidazolate framework-8 (ZIF-8), polydopamine (PDA), and UBI peptide to formulate an innovative nanosystem meticulously engineered to confront bacterial infections and effectually dismantle biofilm architectures through the concerted mechanism of photodynamic therapy (PDT)/photothermal therapy (PTT) therapies, including in-depth research, especially for oral bacteria and oral biofilm. Ce6@ZIF-8-PDA/UBI nanosystem, with effective adhesion and bacteria-targeting, affords a nuanced bacterial targeting strategy and augments penetration depth into oral biofilm matrices. The Ce6@ZIF-8-PDA/UBI nanosystem potentiated bacterial binding and aggregation. Upon exposure to red-light (RL) irradiation, Ce6@ZIF-8-PDA/UBI showed excellent antibacterial effect on S. aureus, E. coli, F. nucleatum, and P. gingivalis and exceptional light-driven antibiofilm activity to P. gingivalis biofilm, which was a result of the efficient bacterial localization mediated by PDA/UBI, as well as the PDT/PTT facilitated by Ce6/PDA interactions. Collectively, these versatile nanoplatforms augur a promising and strategic avenue for controlling infection and biofilm, thereby holding significant potential for future integration into clinical paradigms. The original application of the developed nanosystem in oral biofilms also provides a new strategy for effective oral infection treatment.

Engineering Stimuli-Responsive Materials for Precision Medicine

Over the past decade, precision medicine has garnered increasing attention, making significant strides in discovering new therapeutic drugs and mechanisms, resulting in notable achievements in symptom alleviation, pain reduction, and extended survival rates. However, the limited target specificity of primary drugs and inter-individual differences have often necessitated high-dosage strategies, leading to challenges such as restricted deep tissue penetration rates and systemic side effects. Material science advancements present a promising avenue for these issues. By leveraging the distinct internal features of diseased regions and the application of specific external stimuli, responsive materials can be tailored to achieve targeted delivery, controllable release, and specific biochemical reactions. This review aims to highlight the latest advancements in stimuli-responsive materials and their potential in precision medicine. Initially, we introduce disease-related internal stimuli and capable external stimuli, elucidating the reaction principles of responsive functional groups. Subsequently, we provide a detailed analysis of representative pre-clinical achievements of stimuli responsive materials across various clinical applications, including enhancements in the treatment of cancers, injury diseases, inflammatory diseases, infection diseases, and high-throughput microfluidic biosensors. Finally, we discuss some clinical challenges, such as off-target effects, long-term impacts of nano-materials, potential ethical concerns, and offer insights into future perspectives of stimuli-responsive materials.

Versatile self-assembled near-infrared SERS nanoprobes for multidrug-resistant bacterial infection-specific surveillance and therapy

The rise of multidrug-resistant bacteria (MDRB) has made bacterial infection one of the biggest health threats, causing numerous antibiotics to fail. Real-time monitoring of bacterial disease treatment efficacy at the infection site is required. Herein, we report a versatile Raman tag 3,3'-diethylthiatricarbocyanine iodide (DTTC)-conjugated star-shaped Au-MoS2@hyaluronic acid (AMD@HA) nanocomposite as a surface-enhanced Raman scattering (SERS) nanoprobe for quick bacterial identification and in-situ eradication. Localized surface plasmon resonance (LSPR) from the hybrid metallic nanostructure makes AMD@HA highly responsive to the near-infrared laser, enabling it to demonstrate a photothermal (PTT) effect, increased SERS activity, and peroxidase-like catalytic reaction to release reactive oxygen species. The tail vein injection of AMD@HA nanoprobes is invasive, however SERS imaging for bacterial identification is non-invasive and sensitive, making it an efficient residual bacteria monitoring method. The detection limit for methicillin-resistant Staphylococcus aureus (MRSA) is as low as 102 CFU·mL-1, and the substrates allow for taking 120 s to acquire a Raman image of 1600 (40 × 40) pixels. In mouse models of MRSA-induced wound infection and skin abscess, the combination of AMD@HA-mediated PTT and catalytic therapy demonstrates a synergistic effect in promoting wound healing through rapid sterilization. This SERS-guided therapeutic approach exhibits little toxicity and does not cause considerable collateral damage, offering a highly promising intervention for treating diseases caused by MDRB. STATEMENT OF SIGNIFICANCE: This research introduces a SERS nanoprobe, AMD@HA, for the rapid identification and eradication of multidrug-resistant bacteria (MDRB), a critical health threat. The nanoprobe leverages localized surface plasmon resonance for photothermal therapy and enhanced Raman signals, offering a sensitive, non-invasive diagnostic tool. With a low detection limit for MRSA and a synergistic therapeutic effect in mouse models, our approach holds significant promise for treating MDRB-driven infections with minimal toxicity, advancing the field of antimicrobial strategies.

Nanoscale fluconazole-constructed metal-organic frameworks with smart drug release for eradication of Candida biofilms in vulvovaginitis infection

Fungal infections associated with oral, gynecological, and skin ailments pose significant clinical challenges. The presence of biofilms often hampers the efficacy of conventional antifungal drugs owing to the complex microenvironment they create. In this study, the widely used antifungal medication fluconazole is utilized as a foundational component to be incorporated into zinc 2-methylimidazolate frameworks, resulting in the synthesis of nanoscale fluconazole-constructed metal-organic frameworks (F-ZIF). The F-ZIF is constructed through coordination interactions between zinc and fluconazole, retaining the structure and pH-responsiveness of the zinc 2-methylimidazolate framework. The pH-responsiveness F-ZIF makes sure the fluconazole can be released in acidic biofilm, which prevents the undesired release in healthy tissue, resulting in good biocompatibility both in vitro and in vivo. The in vitro studies demonstrated that F-ZIF exhibits enhanced efficacy in eradicating fungal pathogens in their biofilm growth state compared with the free fluconazole. Furthermore, in vivo experiments reveal the better effectiveness of F-ZIF in treating Candida albicans-induced vulvovaginal candidiasis, and less infection-related inflammation was observed. Hence, the one-port synthetic F-ZIF presents a promising solution for addressing fungal biofilm-related infections.

Recent advances of aggregation‐induced emission in body surface organs

The surface organs mainly comprise the superficial layers of various parts of the mammalian body, including the skin, eyes, and ears, which provide solid protection against various threats to the entire body. Damage to surface organs could lead to many serious diseases or even death. Currently, despite significant advancements in this field, there remain numerous enigmas that necessitate expeditious resolution, particularly pertaining to diagnostic and therapeutic objectives. The advancements in nanomedicine have provided a significant impetus for the development of novel approaches in the diagnosis, bioimaging, and therapy of superficial organs. The aggregation‐induced emission (AIE) phenomenon, initially observed by Prof. Ben Zhong Tang, stands out due to its contrasting behavior to the aggregation‐caused quenching effect. This discovery has significantly revolutionized the field of nanomedicine for surface organs owing to its remarkable advantages. In this review of literature, we aim to provide a comprehensive summary of recent advances of AIE lumenogen (AIEgen)‐based nanoplatforms in the fields of detection, diagnosis, imaging, and therapeutics of surface organ‐related diseases and discuss their prospects in the domain. It is hoped that this review will help attract researchers’ attention toward the utilization of this field for the exploration of a wider range of biomedical and clinical applications.

Synergistic bactericidal combinations between gentamicin and chitosan capped ZnO nanoparticles: A promising strategy for repositioning this first-line antibiotic

Gentamicin (GEN), a widely used broad-spectrum antibiotic, faces challenges amid the global emergency of antimicrobial resistance. This study aimed to explore the synergistic effects of zinc oxide nanoparticles (ZnO NPs) in combination with GEN on the bactericidal activity against various bacterial strains. Results showed ZnO NPs with MICs ranging from 0.002 to 1.5 μg/mL, while the precursor salt displayed a MIC range of 48.75-1560 μg/mL. Chitosan (CS)-capped ZnO NPs exhibited even lower MICs than their uncapped counterparts, with the CS-capped synthesized ZnO NPs demonstrating the lowest values. Minimal bactericidal concentrations (MBC) aligned with MIC trends. Combinations of CS-capped synthesized ZnO NPs and GEN proved highly effective, inhibiting bacterial growth at significantly lower concentrations than GEN or ZnO NPs alone. This phenomenon may be attributed to the conformation of CS on the ZnO NPs' surface, enhancing the positive particle surface charge. This possibly facilitates a more effective interaction between ZnO NPs and microorganisms, leading to increased accumulation of zinc and GEN within bacterial cells and an overproduction of reactive oxygen species (ROS). It's crucial to note that, while this study did not specifically involve resistant strains, its primary focus remains on enhancing the overall antimicrobial activity of gentamicin. The research aims to contribute to addressing the global challenge of antimicrobial resistance, recognizing the urgent need for effective strategies to combat this critical issue. The findings, particularly the observed synergy between ZnO NPs and GEN, hold significant implications for repositioning the first-line antibiotic GEN.