Molecular Mechanisms of Cationic Fusogenic Liposome Interactions with Bacterial Envelopes

Advanced biomaterials for targeting mature biofilms in periodontitis therapy

Periodontitis is a chronic inflammatory disease primarily caused by bacteria, leading to inflamed and bleeding gums, periodontal pocket formation, and bone loss. Affecting 70%-90% of adults over 65, periodontitis is a leading cause of tooth loss and significantly impacts quality of life. Standard treatments, including subgingival scraping and antibiotics, have limitations, and antibiotic resistance among periodontal pathogens is an increasing concern. Biofilms are barriers to drugs and immune responses, contributing to bacterial resistance and reducing antibiotic effectiveness. Due to their adjustable physicochemical properties, bioactive materials potentially eliminate bacterial biofilms, presenting a promising alternative for periodontitis therapy. In this review, the recent innovations in biomaterials for removing mature biofilms in periodontitis are examined, and their broader potential is discussed. Additionally, the compositions of bacterial biofilms, formation pathways, and intrinsic drug resistance mechanisms are discussed. Finally, the strategies for optimizing subgingival biofilm removal in periodontitis are highlighted, such as targeting biofilms-embedded bacteria, disrupting the extracellular polymeric substances, and utilizing combined approaches. A comprehensive understanding of the properties of biomaterials guides the rational design of highly targeted and effective therapies for periodontitis.

Nanomaterial-based drug delivery systems in overcoming bacterial resistance: Current review

Antimicrobial resistance is one of the most serious contemporary global health concerns, threatening the effectiveness of existing antibiotics and resulting in morbidity, mortality, and economic burdens. This review examines the contribution of nanomaterial-based drug delivery systems to solving the problems associated with bacterial resistance and provides a thorough overview of their mechanisms of action, efficiency, and perspectives for the future. Owing to their unique physicochemical properties, nanomaterials reveal new ways of passing through the traditional mechanisms of bacterial defence connected to the permeability barrier of membranes, efflux pumps, and biofilm formation. This review addresses the different types of nanomaterials, including metallic nanoparticles, liposomes, and polymeric nanoparticles, in terms of their antimicrobial properties and modes of action. More emphasis has been placed on the critical discussion of recent studies on such active systems. Both in vitro and in vivo models are discussed, with particular attention paid to multidrug-resistant bacteria. This review begins by reviewing the urgency for antimicrobial resistance (AMR) by citing recent statistics, which indicate that the number of deaths and reasons for financial losses continue to increase. A background is then provided on the limitations of existing antibiotic therapies and the pressing need to develop innovative approaches. Nanomaterial-based drug delivery systems have been proposed as promising solutions because of their potential to improve drug solubility, stability, and targeted delivery, although side effects can also be mitigated. In addition to established knowledge, this review also covers ongoing debates on the continuous risks associated with the use of nanomaterials, such as toxicity and environmental impact. This discussion emphasizes the optimization of nanomaterial design to target specific bacteria, and rigorous clinical trials to establish safety and efficacy in humans. It concludes with reflections on the future directions of nanomaterial-based drug delivery systems in fighting AMR, underlining the need for an interdisciplinary approach, along with continuous research efforts to translate these promising technologies into clinical practice. As the fight against bacterial resistance reaches its peak, nanomaterials may be the key to developing next-generation antimicrobial therapies.

Development of nanovehicles for co-delivery of colistin and ArnT inhibitors

Antimicrobial resistance (AMR) represents a critical global health challenge, with increasing prevalence among high-priority pathogens such as Pseudomonas aeruginosa. Colistin, a last-resort antibiotic, faces limitations in efficacy due to toxicity and bacterial resistance, primarily driven by lipid A modifications that impair colistin binding. In P. aeruginosa, resistance to colistin is mainly due to activation of the arn operon whose last enzyme is ArnT. This study explores a liposomal nanocarrier approach to co-deliver colistin with an ArnT inhibitor, isostevic acid (ISA), aiming to restore colistin's efficacy against resistant P. aeruginosa strain. We designed liposomes incorporating colistin in the aqueous core and ISA within the lipid bilayer, optimizing formulations to achieve stable, high-efficiency encapsulation by varying the cholesterol/egg phosphatidylcholine ratios. These co-loaded liposomes demonstrated enhanced antimicrobial activity, significantly lowering the minimum inhibitory concentration (MIC) of colistin against resistant strain. The dual-drug liposomes also achieved bactericidal effects at lower colistin concentrations compared to the free drug, attributed to the synergistic action of ISA as an adjuvant that locks colistin resistance mechanisms. The results suggest that liposome-mediated co-delivery of colistin and ISA offers a promising strategy to counteract colistin-resistant infections. This approach could improve the clinical management of multidrug-resistant P. aeruginosa and highlights the potential for liposomal systems to modulate drug release and target bacterial resistance mechanisms.

Selective Single-Bacterium Analysis and Motion Tracking Based on Conductive Bulk-Surface Imprinting

Conductive molecular imprinting (MI) shows great potential in enhancing the selectivity of electrochemical bacterial assays, but its efficiency is hindered due to the rigid long-conjugated structure and imprecise specific recognition sites. It is thus urgent to activate the surface MI with clear specific recognition sites toward the bacteria and to develop a single-bacterium monitoring technique for precisely verifying the MI efficiency microscopically. Herein, using lipopolysaccharides and Escherichia coli (E. coli) cells as the surface and bulk templates, respectively, an ideal monomer is successfully predicted by the density functional theory, and the MI with clear and high-precision recognition sites for bacterial matching is prepared. A deep learning-assisted single-bacteria movement trajectory tracking method is developed, and the trained model can effectively recognize and track the movement paths and velocities of both single and group bacteria. Accordingly, the surface MI capture process of the specific recognition sites for E. coli is systematically monitored and analyzed, opening the way for establishing a multidimensional system for characterizing the selective capture process of single and group bacteria by MI polymers. Moreover, the as-prepared electrochemical sensors accomplish the rapid, sensitive sensing of E. coli with a detection limit of 10 CFU/mL and a 433%-increased selectivity, which could promote the development of finer-grained bacterial imprinting techniques and smart bacterial biosensors.

Nature Inspired Delivery Vehicles for CRISPR-Based Genome Editing

The advent of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-based genome editing technologies has opened up groundbreaking possibilities for treating a wide spectrum of genetic disorders and diseases. However, the success of these technologies relies heavily on the development of efficient and safe delivery systems. Among the most promising approaches are natural and synthetic nanocarrier-mediated delivery systems, including viral vectors, extracellular vesicles (EVs), engineered cellular membrane particles, liposomes, and various nanoparticles. These carriers enhance the efficacy of the CRISPR system by providing a unique combination of efficiency, specificity, and reduced immunogenicity. Synthetic carriers such as liposomes and nanoparticles facilitate CRISPR delivery with high reproducibility and customizable functions. Viral vectors, renowned for their high transduction efficiency and broad tropism, serve as powerful vehicles for delivering CRISPR components to various cell types. EVs, as natural carriers of RNA and proteins, offer a stealth mechanism to evade immune detection, allowing for the targeted delivery of genome editors with minimal off-target effects. Engineered cellular membrane particles further improve delivery by simulating the cellular environment, enhancing uptake, and minimizing immune response. This review explores the innovative integration of CRISPR genome editors with various nanocarrier systems, focusing on recent advancements, applications, and future directions in therapeutic genome editing.

Current developments and prospects of the antibiotic delivery systems

Antibiotics have remained the cornerstone for the treatment of bacterial infections ever since their discovery in the twentieth century. The uproar over antibiotic resistance among bacteria arising from genome plasticity and biofilm development has rendered current antibiotic therapies ineffective, urging the development of innovative therapeutic approaches. The development of antibiotic resistance among bacteria has further heightened the clinical failure of antibiotic therapy, which is often linked to its low bioavailability, side effects, and poor penetration and accumulation at the site of infection. In this review, we highlight the potential use of siderophores, antibodies, cell-penetrating peptides, antimicrobial peptides, bacteriophages, and nanoparticles to smuggle antibiotics across impermeable biological membranes to achieve therapeutically relevant concentrations of antibiotics and combat antimicrobial resistance (AMR). We will discuss the general mechanisms via which each delivery system functions and how it can be tailored to deliver antibiotics against the paradigm of mechanisms underlying antibiotic resistance.

The modification of conventional liposomes for targeted antimicrobial delivery to treat infectious diseases

Some of the most crucial turning points in the treatment strategies for some major infectious diseases including AIDS, malaria, and TB, have been reached with the introduction of antimicrobials and vaccines. Drug resistance and poor effectiveness are key limitations that need to be overcome. Conventional liposomes have been explored as a delivery system for infectious diseases bioactives to treat infectious diseases to provide an efficient approach to maximize the therapeutic outcomes, drug stability, targetability, to reduce the side-effects of antimicrobials, and enhance vaccine performance where necessary. However, as the pathological understanding of infectious diseases become more known, the need for more advanced liposomal technologies was born to continue having a profound effect on targeted chemotherapy for infectious diseases. This review therefore provides a concise incursion into the most recent and vogue liposomal formulations used to treat infectious diseases. An appraisal of immunological, stimuli-responsive, biomimetic and functionalized liposomes and other novel modifications to conventional liposomes is assimilated in sync with mutations of resistant pathogens.

The impact of surface charge on the interaction of cholesterol-free fusogenic liposomes with planktonic microbial cells and biofilms

This study focused on the development of cholesterol-free fusogenic liposomes with different surface charge with the aim of improving biofilm penetration. In vitro assessments of the liposomes included physical stability, biocompatibility, fusion with microbial cells, and the ability to penetrate established biofilms. Using dynamic light scattering, cholesterol-free, fusogenic liposomes were found to be < 200 nm in size with small size distribution (PDI < 0.1) and physically stable for a year when stored at 4 °C. Transmission electron microscopy (TEM) images confirmed vesicular sizes for selected liposomal formulations. Liposomal ability to fuse with microbial cells was assessed using lipid mixing and flow cytometer assays. Fusion levels were found to be higher with Escherichia coli compared to Staphylococcus aureus and Candida albicans regardless of the liposomal charge. Neutral liposomes exhibited highest fusion, followed by cationic and anionic liposomes, respectively. Our investigations demonstrated that fusion is a multifactorial process influenced by the chemical composition of the liposomes, the liposomal surface charge, and components of the microbial cell envelope. Penetration and retention within preformed S. aureus biofilms were assessed for liposomes with various surface charges. All liposomes, regardless of surface charge, were capable of penetrating and diffusing through the biofilm matrix. However, cationic liposomes displayed greatest interaction and retention. Biocompatibility was confirmed through haemolysis and cytotoxicity studies. The cholesterol-free fusogenic liposomes developed in this study demonstrated promising potential as drug delivery systems for incorporating antimicrobial agents for biofilm treatment.

Exploring the Interfacial Dynamics of Unilamellar and Multilamellar Cationic Liposomes on SiO2 and Their Interactions with Membrane-Active Peptide

Understanding the interplay between lipid assemblies and solid supports is crucial for advancing model membrane systems and biomedical applications. This study investigates the interfacial behaviors of unilamellar and multilamellar cationic liposomes on silicon dioxide and their interactions with a membrane-active AH peptide. Using QCM-D monitoring, unilamellar liposomes were found to rapidly form SLBs through one-step adsorption kinetics, whereas multilamellar liposomes exhibited slower adsorption. Further addition of liposomes caused fusogenic interactions with SLBs, where multilamellar liposomes formed more rigid lipid membranes. Upon AH peptide exposure, unilamellar-based lipid membranes showed higher susceptibility to structural transformations, achieving complete SLB formation, while multilamellar-based lipid membranes displayed reduced sensitivity and retained residual viscoelastic components, indicative of incomplete SLB formation. These findings underscore the significant influence of liposome lamellarity on their interfacial dynamics and peptide interactions, crucial for designing effective lipid-based delivery and sensing systems.

Dual osmotic controlled release platform for antibiotics to overcome antimicrobial-resistant infections and promote wound healing

Methicillin-Resistant Staphylococcus aureus forming into biofilms can trigger chronic inflammation and disrupt skin wound healing processes. Prolonged and excessive use of antibiotics can expedite the development of resistance, primarily because of their limited ability to penetrate microbial membranes and biofilms, especially antibiotics with intracellular drug targets. Herein, we devise a strategy in which virus-inspired nanoparticles control the release of antibiotics through rapid penetration into both bacterial cells and biofilms, thereby combating antimicrobial-resistant infections and promoting skin wound healing. Lipid-based nanoparticles based on stearamine and cholesterol were designed to mimic viral highly ordered nanostructures. To mimic the arginine-rich fragments in viral protein transduction domains, the primary amines on the surface of the lipid-based nanoparticles were exchanged by guanidine segments. Levofloxacin, an antibiotic that inhibits DNA replication, was chosen as the model drug to be incorporated into nanoparticles. Hyaluronic acid was coated on the surface of nanoparticles acting as a capping agent to achieve bacterial-specific degradation and guanidine explosion in the bacterial microenvironment. Our virus-inspired nanoparticles displayed long-acting antibacterial effects and powerful biofilm elimination to overcome antimicrobial-resistant infections and promote skin wound healing. This work demonstrates the ability of virus-inspired nanoparticles to achieve a dual penetration of microbial cell membranes and biofilm structures to address antimicrobial-resistant infections and trigger skin wound healing.

Targeting the outer membrane of gram-negative foodborne pathogens for food safety: compositions, functions, and disruption strategies

Foodborne pathogens are a major threat to both food safety and public health. The current trend toward fresh and less processed foods and the misuse of antibiotics in food production have made controlling these pathogens even more challenging. The outer membrane has been employed as a practical target to combat foodborne Gram-negative pathogens due to its accessibility and importance. In this review, the compositions of the outer membrane are extensively described firstly, to offer a thorough overview of this target. Current strategies for disrupting the outer membrane are also discussed, with emphasized on their mechanism of action. The disruption of the outer membrane structure, whether caused by severe damage of the lipid bilayer or by interference with the biosynthesis pathway, has been demonstrated to represent an effective antimicrobial strategy. Interference with the outer membrane-mediated functions of barrier, efflux and adhesion also contributes to the fight against Gram-negative pathogens. Their potential for control of foodborne pathogens in the production chain are also proposed. However, it is possible that multiple components in the food matrix may act as a protective barrier against microorganisms, and it is often the case that contamination is not caused by a single microorganism. Further investigation is needed to determine the effectiveness and safety of these methods in more complex systems, and it may be advisable to consider a multi-technology combined approach. Additionally, further studies on outer membranes are necessary to discover more promising mechanisms of action.

Supramolecular interaction in the action of drug delivery systems

Complex diseases and diverse clinical needs necessitate drug delivery systems (DDSs), yet the current performance of DDSs is far from ideal. Supramolecular interactions play a pivotal role in various aspects of drug delivery, encompassing biocompatibility, drug loading, stability, crossing biological barriers, targeting, and controlled release. Nevertheless, despite having some understanding of the role of supramolecular interactions in drug delivery, their incorporation is frequently overlooked in the design and development of DDSs. This perspective provides a brief analysis of the involved supramolecular interactions in the action of drug delivery, with a primary emphasis on the DDSs employed in the clinic, mainly liposomes and polymers, and recognized phenomena in research, such as the protein corona. The supramolecular interactions implicated in various aspects of drug delivery systems, including biocompatibility, drug loading, stability, spatiotemporal distribution, and controlled release, were individually analyzed and discussed. This perspective aims to trigger a comprehensive and systematic consideration of supramolecular interactions in the further development of DDSs. Supramolecular interactions embody the true essence of the interplay between the majority of DDSs and biological systems.