Antibacterial Action of Nanoparticles by Lethal Stretching of Bacterial Cell Membranes

Destruction of virus particles via mechanical and chemical virucidal activity of nanocolumnar copper thin films

Human-generated droplets, which facilitate the transmission of viral infections, include large droplets and aerosols. The drying rates of these droplets upon adhesion to a surface vary significantly owing to the wide range of their sizes (∼nine orders of magnitude). Consequently, combating viruses requires distinct strategies under wet and dry conditions. However, studies that account for these two contrasting conditions are lacking. In the present study, we replicated these conditions and investigated the topographical properties of enveloped bacteriophages as an indicator of viral integrity via high-speed atomic force microscopy. Under wet conditions, a reduction in the virus particle volume was observed only on a nanocolumnar copper (NC-Cu) thin film and not on a chemically stable nanocolumnar cupric oxide (NC-CuO) thin film. In contrast, under dry conditions, virus particles lost their shape integrity on both NC-CuO and NC-Cu films. The deformation of virus particles on the NC-CuO film under dry conditions suggests a mechanism distinct from the chemical activity of Cu (i.e., mechanical activity). These results indicate that dry conditions trigger the mechanical activity of nanostructured surfaces. This highlights the significance of nanostructure-induced mechanical activity in virus inactivation under dry conditions, such as those involving viruses in small droplets or aerosols.

Acetazolamide-Loaded Nanoparticle Based on Modified Hyaluronic Acid as Delivery System to Target Carbonic Anhydrases in Escherichia coli

Acetazolamide (AZA) is a validated carbonic anhydrase inhibitor (CAI) that has the potential for use in various therapeutic applications. Herein, we report a novel AZA-loaded biodegradable nanodelivery system that was proven to enhance the antibacterial efficacy of the drug against Gram-negative bacteria, such as Escherichia coli. Carbonic anhydrases (CA, EC 4.2.1.1) in E. coli play a crucial role in bacterial metabolism and CO2/HCO3- balance; therefore, they represent a suitable target for antimicrobial strategies. The nanoparticles were obtained using a green synthetic protocol that allowed conjugation of a natural fatty acid to hyaluronic acid (HA) under solvent-free conditions. Full characterization of the micellar aggregates was performed (diameter of the micelles, zeta potential, and drug release study). In vitro studies demonstrated that AZA loaded in HA-based nanoparticles significantly inhibited E. coli growth at concentrations as low as 0.5 µg/mL, whereas higher concentrations of free AZA were required, as previously reported. Additionally, encapsulated AZA disrupted glucose consumption in E. coli, indicating its profound impact on bacterial metabolism. These findings suggest that the HA-palmitate nanoparticle not only enhances the delivery and efficacy of AZA but also offers a strategy to affect bacterial metabolism.

Ultrasound-Activated Selenium Nanocarrier: Bactericidal Enhancement and Osseointegration Promotion for Implant-Associated Infections

Implant-associated infections (IAIs) are common and challenging complications of orthopedic surgery. The physical barrier formed by biofilms and the antioxidant defense system of bacteria shield them from attack by antimicrobial agents and immune cells, leading to irreversible bone loss and the failure of osseointegration. To address these challenges and enhance osseointegration in the presence of biofilm infections, a sequential therapy strategy is proposed using an ultrasound-activated nanocarrier, PLGA@H/Se, designed to disrupt bacterial defenses and subsequently enhancing osteogenic differentiation. As expected, PLGA@H/Se, when activated by ultrasound, induces a cavitation effect that disrupts the outer barrier of the biofilm, while promoting the deep delivery of encapsulated SeNPs and the antimicrobial peptide HHC-36. The SeNPs target the internal H₂S-based antioxidant defense in bacteria, thereby synergistically enhancing the bactericidal effect of HHC-36. Furthermore, the sustained release of SeNPs regulates selenoprotein expression, boosts antioxidant stress responses, and activates the Wnt/β-catenin pathway, which helps restore the osteogenic differentiation potential of BMSCs impaired by oxidative damage, both in vitro and in vivo. Collectively, this ultrasound-based sequential system facilitates functional osseointegration under pathological conditions, offering a practical and comprehensive strategy for treating IAIs.

Antimicrobial and antibiofilm activity of prepared thymol@UIO-66 and thymol/ZnONPs@UIO-66 nanoparticles against Methicillin-resistant Staphylococcus aureus: A synergistic approach

This study introduces a novel approach to enhance the antibacterial properties of UIO-66 by incorporating both Thymol and ZnO nanoparticles within its framework which represents a significant advancement like exhibiting a synergistic antibacterial effect, providing a prolonged and controlled release, and mitigating cytotoxicity associated with the release of free ZnO nanoparticles by combining these two antimicrobial agents within a single, well-defined metal-organic framework. UIO-66 frameworks are investigated as carriers for the natural antimicrobial agent, Thymol, and ZnONPs offering a novel drug delivery system for antibacterial applications. Results demonstrated 132, 90, 184, and 223 nm sizes for UIO-66, ZnONPs, UIO-66 encapsulated Thymol, and UIO-66 encapsulated both Thymol and ZnONPs, respectively. Successful encapsulation of the antibacterial drug with a high entrapment efficiency of 64 % for Thymol was approved, and 49 % in-vitro release of Thymol was achieved for 72 hours. In-vitro antibacterial assays revealed promising results, with the drug-loaded nanoparticles exhibiting significantly lower MIC values and enhanced bactericidal activity against S. Aureus bacterial strains compared to the free drug, as demonstrated by agar disk diffusion and time-kill assays. MIC values reduced from a range of 31.25-250 µg/ml for free Thymol and 12.5-100 µg/ml for free ZnONPs to 3.9-62.5 µg/ml for Thymol@UIO-66 and 1.95-15.63 µg/ml for Thymol/ZnONPs@UIO-66. According to the results, the mixture of both Thymol and ZnONPs had 41 % and 16 % more antibiofilm activities in comparison with free Thymol and free ZnONPs, respectively. Furthermore, Thymol@UIO-66 had 25 % higher antibiofilm activities relative to not-encapsulated Thymol and ZnONPs, and this improvement was even 46 % more in Thymol/ZnONPs@UIO-66 in comparison with Thymol@UIO-66. Overall, this study demonstrates the potential of Thymol/ZnONPs@UIO-66 frameworks as a promising drug delivery platform for effective antibacterial therapy. This approach to overcome antibiotic resistance and improve treatment efficacy potentially.

Exploring Broad-Spectrum Antimicrobial Nanotopographies: Implications for Bactericidal, Antifungal, and Virucidal Surface Design

Inspired by the natural defense strategies of insect wings and plant leaves, nanostructured surfaces have emerged as a promising tool in various fields, including engineering, biomedical sciences, and materials science, to combat bacterial contamination and disrupt biofilm formation. However, the development of effective antimicrobial surfaces against fungal and viral pathogens presents distinct challenges, necessitating tailored approaches. Here, we aimed to review the recent advancements of the use of nanostructured surfaces to combat microbial contamination, particularly focusing on their mechano-bactericidal and antifungal properties, as well as their potential in mitigating viral transmission. We comparatively analyzed the diverse geometries and nanoarchitectures of these surfaces and discussed their application in various biomedical contexts, such as dental and orthopedic implants, drug delivery systems, and tissue engineering. Our review highlights the importance of preventing microbial attachment and biofilm formation, especially in the context of rising antimicrobial resistance and the economic impact of biofilms. We also discussed the latest progress in materials science, particularly nanostructured surface engineering, as a promising strategy for reducing viral transmission through surfaces. Overall, our findings underscore the significance of innovative strategies to mitigate microbial attachment and surface-mediated transmission, while also emphasizing the need for further interdisciplinary research in this area to optimize antimicrobial efficacy and address emerging challenges.

Nanoparticle-based antifungal therapies innovations mechanisms and future prospects

Fungal infections present an increasing global health challenge, with a substantial annual mortality rate of 1.6 million deaths each year in certain situations. The emergence of antifungal resistance has further complicated treatment strategies, underscoring the urgent need for novel therapeutic approaches. This review explores recent advances in nanoparticle-based therapies targeting fungal infections, emphasizing their unique potential to enhance drug solubility, bioavailability, and targeted delivery. Nanoparticles offer the ability to penetrate biological barriers, improve drug stability, and act as direct antifungal agents by disrupting fungal cell walls and generating reactive oxygen species. Despite their promising applications, challenges such as potential toxicity, scalability of production, and the need for controlled drug release remain. Future research should focus on optimizing nanoparticle properties, evaluating long-term safety profiles, developing environmentally sustainable synthesis methods, and exploring synergistic approaches with existing antifungal drugs. Nanotechnology offers a transformative opportunity in the management of fungal diseases, paving the way for more effective and targeted treatments.

Treatment of lung diseases via nanoparticles and nanorobots: Are these viable alternatives to overcome current treatments?

Challenges

Respiratory diseases remain challenging to treat, with current efforts primarily focused on managing symptoms rather than maintaining overall lung health. Traditional treatment methods, such as oral or parenteral administration of antiviral, antibacterial, and anti-inflammatory drugs, face limitations. These include difficulty in delivering therapeutic agents to pathogens residing deep in the airways and the risk of severe side effects due to high systemic drug concentrations. The growing threat of drug-resistant pathogens further complicates infection management.

Advancements

The lung's large surface area offers an attractive target for inhalation-based drug delivery. Nanoparticles (NP) enable uniform and sustained drug distribution across the alveolar network, overcoming challenges posed by complex lung anatomy. Recent breakthroughs in nanorobots (NR) have demonstrated precise navigation through biological environments, delivering therapies directly to affected lung areas with enhanced accuracy. Nanotechnology has also shown promise in treating lung cancer, with nanoparticles engineered to overcome biological barriers, improve drug solubility, and enable controlled drug release.

Future scope

This review explores the progress of NP and NR in addressing challenges in pulmonary drug delivery. These innovations allow targeted delivery of nucleic acids, drugs, or peptides to the pulmonary epithelium with unprecedented accuracy, offering significant potential for improving therapeutic effectiveness in respiratory disorders.

Streamlining Bacterial Gene Regulation via Nucleic Acid Delivery with Gold Nanoclusters

Delivery of exogenous nucleic acids (NAs) for gene regulation in bacteria, bypassing the barrier of the cell wall, is essential for advancing fundamental microbiology and genetic engineering, and the treatment of bacterial diseases. However, current methods that rely on electrical or chemical interventions are limited by their complexity, specialized expertise, and laboratory-specific instrumentation. This study explores the capability of gold nanoclusters (AuNCs) as carriers for delivering small-interfering RNA and antisense oligonucleotides into bacteria for targeted gene regulation while shielding them from degradation during transport. By enhancing the cytoplasmic membrane permeability, the AuNCs enable efficient internalization of NAs into both Gram-positive and Gram-negative bacteria while exerting negligible influence on bacterial activity. It is demonstrated that the rationally designed NAs can be released from the AuNCs within bacteria, enabling ~70% knockdown of mecA in Methicillin-resistant Staphylococcus aureus (MRSA). This significantly reduces MRSA's antibiotic resistance and enhances oxacillin treatment efficacy. Furthermore, the successful silencing of ligA in Escherichia coli and pilQ in Pseudomonas aeruginosa highlights the broad adaptability of the approach across diverse bacterial species. The AuNCs-based next-generation NA delivery system has the potential to transform bacterial gene regulation-previously restricted to laboratory settings-into a versatile and scalable solution for real-world application.

Large-sized and highly crystalline ceria nanorods with abundant Ce3+ species achieve efficient intracellular ROS scavenging

Intracellular reactive oxygen species (ROS) are associated with various inflammatory physiological processes and diseases, highlighting the need for their regulation to mitigate the detrimental effects of oxidative stress and to reduce cellular damage and disease progression. Here, we demonstrate cerium oxide (ceria) nanorods synthesized using a sol-gel method followed by heat treatment, called "AHT-CeNRs", as an efficient intracellular ROS scavenger. The synthesized AHT-CeNRs exhibited exceptional superoxide dismutase (SOD) and catalase (CAT)-like activities, both of which are crucial for converting ROS into harmless products. This was attributed to their high crystallinity, large surface area, numerous defects including oxygen vacancies, and abundant Ce3+ species. AHT-CeNRs exhibited higher CAT-like activities than natural CAT and conventional nanozymes, with a more than five-fold lower Km. When tested on HaCaT human keratinocyte cells, AHT-CeNRs primarily localized to the membrane but effectively scavenged intracellular ROS, potentially through their transmembrane catalytic action without disrupting the membrane. This contrasts with conventional antioxidant nanoparticles that act within the cytosol after penetrating the plasma membrane. AHT-CeNRs maintained cell viability by efficiently scavenging ROS, resulting in approximately 4-fold and 2-fold lower levels of inducible nitric oxide synthase (iNOS) and lactate dehydrogenase (LDH) compared to those in ROS-induced inflammation-stimulator lipopolysaccharide (LPS)-treated control groups, respectively. This simple yet effective method for intracellular ROS scavenging using AHT-CeNRs holds great potential for applications in cell and in vivo therapeutics to regulate intracellular ROS levels.

Injectable, Biodegradable and Photothermal Hydrogel with Quorum Sensing Inhibitory Effects for Subcutaneous Fungal Infection Treatment

Owing to the high invasion depth and easy formation of biofilms, the treatment of subcutaneous fungal infection is intractable and challenging. Herein, we report an injectable and biodegradable hydrogel with bactericidal, quorum sensing inhibition and antioxidant activities for the in situ treatment of subcutaneous fungal infection. The hydrogel (BEPE) was constructed by irradiating mixed bovine serum albumin (BSA), ε-polylysine and epigallocatechin gallate (EGCG)-loaded mesoporous polydopamine (PDA) under near-infrared (NIR) light. BEPE exerted microbicidal effects against Candida albicans (99.5%) and Streptococcus mutans (99.6%) through synergistic photothermal effects and the microbiocidal activity of slowly released ε-polylysine. Moreover, the gently released EGCG from BEPE with relatively high bioavailability, synergistically inhibited and destroyed biofilms by inhibiting quorum sensing between microbes, resulting in an antibiofilm efficiency of 80.5% against C. albicans. An in vivo subcutaneous fungal infection study revealed that BEPE accelerates tissue regeneration via targeted formation, elimination of fungal infection and alleviation of inflammation in situ, thereby promoting wound healing. This biodegradable hydrogel strategy will facilitate the design of multifunctional microbicidal agents for targeted subcutaneous fungal infection treatment.

Nanostructure-Mediated Photothermal Effect for Reinforcing Physical Killing Activity of Nanorod Arrays

The physical killing of bacteria based on surface topography has attracted much attention due to the sustainable and safe prevention of biofilm formation. However, the antibacterial efficiency of biomedical implants derived solely from nanostructures or microstructures is insufficient to combat bacteria against common infections, such as methicillin-resistant Staphylococcus aureus with thick cell walls. Herein, photothermal therapy is carried out in the presence of nanorod arrays to mitigate infection of biomedical implants. Different from traditional photothermal therapy relying on a photosensitizer, the photothermal effect is mediated by light traps rendered by the nanorod arrays, and consequently, the photosensitizer is not needed. Finite element simulations and experiments are performed to elucidate the light-to-thermal conversion mechanism. This photothermal platform, in conjunction with thermosensitive nitric oxide therapy, is applied to treat titanium implant infection. The nanostructure-mediated photothermal effect destroys bacterial cell walls by inhibiting peptidoglycan synthesis and increasing the membrane permeability by affecting fatty acid synthesis. Furthermore, the nanorods synergistically puncture the bacterial membrane easily as demonstrated by experiments and transcriptome analysis. The results provide insights into the development of efficient antibacterial treatment of implants by combining nanostructures and photothermal therapy.

Harnessing Nanoparticles to Overcome Antimicrobial Resistance: Promises and Challenges

The rise of antimicrobial resistance (AMR) has become a serious global health issue that kills millions of people each year globally. AMR developed in bacteria is difficult to treat and poses a challenge to clinicians. Bacteria develop resistance through a variety of processes, including biofilm growth, targeted area alterations, and therapeutic drug alteration, prolonging the period they remain within cells, where antibiotics are useless at therapeutic levels. This rise in resistance is linked to increased illness and death, highlighting the urgent need for effective solutions to combat this growing challenge. Nanoparticles (NPs) offer unique solutions for fighting AMR bacteria. Being smaller in size with a high surface area, enhancing interaction with bacteria makes the NPs strong antibacterial agents against various infections. In this review, we have discussed the epidemiology and mechanism of AMR development. Furthermore, the role of nanoparticles as antibacterial agents, and their role in drug delivery has been addressed. Additionally, the potential, challenges, toxicity, and future prospects of nanoparticles as antibacterial agents against AMR pathogens have been discussed. The research work discussed in this review links with Sustainable Development Goal 3 (SDG-3), which aims to ensure disease-free lives and promote well-being for all ages.

Targeting the Weak Spot: Preferential Disruption of Bacterial Poles by Janus Nanoparticles

The interaction between nanoparticles (NPs) and bacterial cell envelopes is crucial for designing effective antibacterial materials against multi-drug-resistant pathogens. However, the current understanding assumes a uniform bacterial cell wall. This study challenges that assumption by investigating how bacterial cell wall curvature impacts antibacterial NP action. Focusing on Janus NPs, which feature segregated hydrophobic and polycationic ligands and previously demonstrated high efficacy against diverse bacteria, we found that these NPs preferentially target and disrupt bacterial poles. Experimental and computational approaches reveal that curvature at E. coli poles induces conformational changes in lipopolysaccharide (LPS) polymers on the outer membrane, exposing underlying lipids for NP-mediated disruption. We establish that curvature-induced targeting by Janus NPs depends on the outer membrane composition and is most pronounced at physiologically relevant LPS densities. This work demonstrates that high-curvature regions of bacterial cell walls are "weak spots" for Janus NPs, thereby aiding the development of more effective targeted therapies.

Electrospun nanofibrous membranes meet antibacterial nanomaterials: From preparation strategies to biomedical applications

Electrospun nanofibrous membranes (eNFMs) have been extensively developed for bio-applications due to their structural and compositional similarity to the natural extracellular matrix. However, the emergence of antibiotic resistance in bacterial infections significantly impedes the further development and applications of eNFMs. The development of antibacterial nanomaterials substantially nourishes the engineering design of antibacterial eNFMs for combating bacterial infections without relying on antibiotics. Herein, a comprehensive review of diverse fabrication techniques for incorporating antibacterial nanomaterials into eNFMs is presented, encompassing an exhaustive introduction to various nanomaterials and their bactericidal mechanisms. Furthermore, the latest achievements and breakthroughs in the application of these antibacterial eNFMs in tissue regenerative therapy, mainly focusing on skin, bone, periodontal and tendon tissues regeneration and repair, are systematically summarized and discussed. In particular, for the treatment of skin infection wounds, we highlight the antibiotic-free antibacterial therapy strategies of antibacterial eNFMs, including (i) single model therapies such as metal ion therapy, chemodynamic therapy, photothermal therapy, and photodynamic therapy; and (ii) multi-model therapies involving arbitrary combinations of these single models. Additionally, the limitations, challenges and future opportunities of antibacterial eNFMs in biomedical applications are also discussed. We anticipate that this comprehensive review will provide novel insights for the design and utilization of antibacterial eNFMs in future research.

Membrane-Nanoparticle Interactions: The Impact of Membrane Lipids

The growing field of nanotechnology presents opportunity for applications across many sectors. Nanostructures, such as nanoparticles, hold distinct properties based on their size, shape, and chemical modifications that allow them to be utilized in both highly specific as well as broad capacities. As the classification of nanoparticles becomes more well-defined and the list of applications grows, it is imperative that their toxicity be investigated. One such cellular system that is of importance are cellular membranes (biomembranes). Membranes present one of the first points of contact for nanoparticles at the cellular level. This review will address current studies aimed at defining the biomolecular interactions of nanoparticles at the level of the cell membrane, with a specific focus of the interactions of nanoparticles with prominent lipid systems.

Nanoscale Multipatterning Zn,Co-ZIF@FeOOH for Eradication of Multidrug-Resistant Bacteria and Antibacterial Treatment of Wounds

The rising incidence of infections caused by multidrug-resistant bacteria highlights the urgent need for innovative bacterial eradication strategies. Metal ions, such as Zn2+ and Co2+, have bactericidal effects by disrupting bacterial cell membranes and interfering with essential cellular processes. This has led to increased attention toward metal-organic frameworks (MOFs) as potential nonantibiotic bactericidal agents. However, the uniform and enhanced localized release of bactericidal metal ions remains a challenge. Herein, we introduce a nanoscale multipatterned Zn,Co-ZIF@FeOOH, featuring a multipod-like morphology with spiky corners, and dual-bactericidal metal ions. Compared to pure Zn,Co-ZIF, the multipod-like morphology of Zn,Co-ZIF@FeOOH exhibits enhanced adhesion toward bacterial surfaces via topological and multiple interactions of electrostatic interaction, significantly increasing the local release of Zn2+ and Co2+. Additionally, the spiky corners of the spindle-shaped FeOOH nanorods physically penetrate bacterial membranes, causing damage and further enhancing adhesion to bacteria. Nine Gram-negative and one Gram-positive bacteria were selected for in vitro test. Notably, the nanoscale multipatterned Zn,Co-ZIF@FeOOH exhibited high bactericidal efficacy against various multidrug-resistant bacteria, including extended-spectrum β-lactamase-producing (ESBL+) bacteria and carbapenem-resistant bacteria, performing well in both acidic and neutral environments. The wound healing activity of Zn,Co-ZIF@FeOOH was further demonstrated using female Balb/c mouse models infected with bacteria, where the materials show robust antibacterial efficacy and commendable biocompatibility. This study showcases the assembly of metal oxide/MOF composites for nanoscale multipatterning, aims at synergistic bacterial eradication and offers insights into developing nanomaterial-based strategies against multidrug-resistant bacteria.

Unveiling the Potential of CuO and Cu2O Nanoparticles against Novel Copper-Resistant Pseudomonas Strains: An In-Depth Comparison

Four novel Pseudomonas strains with record resistance to copper (Cu2+) previously isolated from ecologically diverse samples (P. lactis UKR1, P. panacis UKR2, P. veronii UKR3, and P. veronii UKR4) were tested against sonochemically synthesised copper-oxide (I) (Cu2O) and copper-oxide (II) (CuO) nanoparticles (NPs). Nanomaterials characterisation by X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and High-Resolution Transmission Electron Microscopy (HRTEM) confirmed the synthesis of CuO and Cu2O NPs. CuO NPs exhibited better performance in inhibiting bacterial growth due to their heightened capacity to induce oxidative stress. The greater stability and geometrical shape of CuO NPs were disclosed as important features associated with bacterial cell toxicity. SEM and TEM images confirmed that both NPs caused membrane disruption, altered cell morphology, and pronounced membrane vesiculation, a distinctive feature of bacteria dealing with stressor factors. Finally, Cu2O and CuO NPs effectively decreased the biofilm-forming ability of the Cu2+-resistant UKR strains as well as degraded pre-established biofilm, matching NPs' antimicrobial performance. Despite the similarities in the mechanisms of action revealed by both NPs, distinctive behaviours were also detected for the different species of wild-type Pseudomonas analysed. In summary, these findings underscore the efficacy of nanotechnology-driven strategies for combating metal tolerance in bacteria.

Progress and challenges in bacterial infection theranostics based on functional metal nanoparticles

The rapid proliferation and infection of bacteria, especially multidrug-resistant bacteria, have become a great threat to global public health. Focusing on the emergence of "super drug-resistant bacteria" caused by the abuse of antibiotics and the insufficient and delayed early diagnosis of bacterial diseases, it is of great research significance to develop new technologies and methods for early targeted detection and treatment of bacterial infection. The exceptional effects of metal nanoparticles based on their unique physical and chemical properties make such systems ideal for the detection and treatment of bacterial infection both in vitro and in vivo. Metal nanoparticles also have admirable clinical application prospects due to their broad antibacterial spectrum, various antibacterial mechanisms and excellent biocompatibility. Herein, we summarized the research progress concerning the mechanism of metal nanoparticles in terms of antibacterial activity together with the detection of bacterial. Representative achievements are selected to illustrate the proof-of-concept in vitro and in vivo applications. Based on these observations, we also give a brief discussion on the current problems and perspective outlook of metal nanoparticles in the diagnosis and treatment of bacterial infection.

Synergistic Effects of Microplastics and Marine Pollutants on the Destabilization of Lipid Bilayers

Microplastics have been detected in diverse environments, including soil, snowcapped mountains, and even within human organs and blood. These findings have sparked extensive research into the health implications of microplastics for living organisms. Recent studies have shown that microplastics can adsorb onto lipid membranes and induce mechanical stress. In controlled laboratory conditions, the behavior and effects of microplastics can differ markedly from those in natural environments. In this study, we investigate how exposure of microplastics to pollutants affects their interactions with lipid bilayers. Our findings reveal that pollutants, such as chemical solvents, significantly enhance the mechanical stretching effects of microplastics. This suggests that microplastics can act as vectors for harmful pollutants, facilitating their penetration through lipid membranes and thus strongly affect their biophysical properties. This research underscores the complex interplay between microplastics and environmental contaminants.

Influence of Physicochemical Properties of Iron Oxide Nanoparticles on Their Antibacterial Activity

The increasing occurrence of infectious diseases caused by antimicrobial resistance organisms urged the necessity to develop more potent, selective, and safe antimicrobial agents. The unique magnetic and tunable properties of iron oxide nanoparticles (IONPs) make them a promising candidate for different theragnostic applications, including antimicrobial agents. Though IONPs act as a nonspecific antimicrobial agent, their antimicrobial activities are directly or indirectly linked with their synthesis methods, synthesizing precursors, size, shapes, concentration, and surface modifications. Alteration of these parameters could accelerate or decelerate the production of reactive oxygen species (ROS). An increase in ROS role production disrupts bacterial cell walls, cell membranes, alters major biomolecules (e.g., lipids, proteins, nucleic acids), and affects metabolic processes (e.g., Krebs cycle, fatty acid synthesis, ATP synthesis, glycolysis, and mitophagy). In this review, we will investigate the antibacterial activity of bare and surface-modified IONPs and the influence of physiochemical parameters on their antibacterial activity. Additionally, we will report the potential mechanism of IONPs' action in driving this antimicrobial activity.

Versatile Ce(III)‐Terephthalic Acid@Au Metal Organic Frameworks for ROS Elimination and Photothermal Sterilization

Nanozymes have been widely used for treating reactive oxygen species (ROS) caused diseases. However, the ROS‐dependent antibacterial property is inevitably damaged during the process of scavenging ROS, which is unfavorable for the treatment of diseases related to both ROS accumulation and bacterial infections. To address the issues, biomedical materials with both ROS‐elimination ability and ROS‐independent antibacterial capacity are fabricated via in situ depositing spherical Au nanoparticles (Au NPs) on rough surface of metal organic frameworks composed of Ce(III) and terephthalic acid (Ce‐BDC@Au MOFs). The synthesized Ce‐BDC@Au MOFs show multi‐enzymatic activities owing to the reversible conversion between Ce3+ and Ce4+, and can significantly scavenge ROS in cells. The deposition of spherical Au NPs on surface of Ce‐BDC MOFs causes Au NPs to come close proximity for forming plasmon resonance coupling, inducing the resonance wavelength of Au NPs red shifted to NIR region. Based on this, Ce‐BDC@Au MOFs show good photothermal conversion efficiency under NIR laser (808 nm) irradiation. Benefitting from rough surface and photothermal conversion ability, Ce‐BDC@Au MOFs have high antibacterial efficiency against staphylococcus aureus through both mechanically damaging and photothermal destruction. This strategy is biosafety and effectiveness for treating diseases related to both ROS accumulation and bacterial infections.

Silver incorporated SeTe nanoparticles with enhanced photothermal and photodynamic properties for synergistic effects on anti-bacterial activity and wound healing

Bacteria invade the host's immune system, thereby inducing serious infections. Current treatments for bacterial infections mostly rely on single modalities, which cannot completely inhibit bacteria. This study evaluates the therapeutic potential of SeTe-Ag NPs, designed with excellent photo responsiveness, with a particular focus on their dual-action antibacterial effect and wound healing properties. SeTe-Ag NPs exhibited promising synergistic antibacterial effects due to their superior photothermal and photodynamic properties. The investigation records substantial zones of inhibition of bacteria, demonstrating potent antibacterial effect. Furthermore, upon the irradiation of near-infrared (NIR) light, SeTe-Ag NPs exhibit remarkable antibiofilm and wound-healing capabilities. Overall, this study shows the applications of NIR-active SeTe-Ag NPs, which serve as a versatile platform for biomedical applications.

Revolutionizing Neurocare: Biomimetic Nanodelivery Via Cell Membranes

Brain disorders represent a significant challenge in medical science due to the formidable blood-brain barrier (BBB), which severely limits the penetration of conventional therapeutics, hindering effective treatment strategies. This review delves into the innovative realm of biomimetic nanodelivery systems, including stem cell-derived nanoghosts, tumor cell membrane-coated nanoparticles, and erythrocyte membrane-based carriers, highlighting their potential to circumvent the BBB's restrictions. By mimicking native cell properties, these nanocarriers emerge as a promising solution for enhancing drug delivery to the brain, offering a strategic advantage in overcoming the barrier's selective permeability. The unique benefits of leveraging cell membranes from various sources is evaluated and advanced technologies for fabricating cell membrane-encapsulated nanoparticles capable of masquerading as endogenous cells are examined. This enables the targeted delivery of a broad spectrum of therapeutic agents, ranging from small molecule drugs to proteins, thereby providing an innovative approach to neurocare. Further, the review contrasts the capabilities and limitations of these biomimetic nanocarriers with traditional delivery methods, underlining their potential to enable targeted, sustained, and minimally invasive treatment modalities. This review is concluded with a perspective on the clinical translation of these biomimetic systems, underscoring their transformative impact on the therapeutic landscape for intractable brain diseases.

Nanotechnology's frontier in combatting infectious and inflammatory diseases: prevention and treatment

Inflammation-associated diseases encompass a range of infectious diseases and non-infectious inflammatory diseases, which continuously pose one of the most serious threats to human health, attributed to factors such as the emergence of new pathogens, increasing drug resistance, changes in living environments and lifestyles, and the aging population. Despite rapid advancements in mechanistic research and drug development for these diseases, current treatments often have limited efficacy and notable side effects, necessitating the development of more effective and targeted anti-inflammatory therapies. In recent years, the rapid development of nanotechnology has provided crucial technological support for the prevention, treatment, and detection of inflammation-associated diseases. Various types of nanoparticles (NPs) play significant roles, serving as vaccine vehicles to enhance immunogenicity and as drug carriers to improve targeting and bioavailability. NPs can also directly combat pathogens and inflammation. In addition, nanotechnology has facilitated the development of biosensors for pathogen detection and imaging techniques for inflammatory diseases. This review categorizes and characterizes different types of NPs, summarizes their applications in the prevention, treatment, and detection of infectious and inflammatory diseases. It also discusses the challenges associated with clinical translation in this field and explores the latest developments and prospects. In conclusion, nanotechnology opens up new possibilities for the comprehensive management of infectious and inflammatory diseases.

Construction of antibacterial bone implants and their application in bone regeneration

Bacterial infection represents a prevalent challenge during the bone repair process, often resulting in implant failure. However, the extensive use of antibiotics has limited local antibacterial effects at the infection site and is prone to side effects. In order to address the issue of bacterial infection during the transplantation of bone implants, four types of bone scaffold implants with long-term antimicrobial functionality have been constructed, including direct contact antimicrobial scaffold, dissolution-penetration antimicrobial scaffold, photocatalytic antimicrobial scaffold, and multimodal synergistic antimicrobial scaffold. The direct contact antimicrobial scaffold involves the physical penetration or disruption of bacterial cell membranes by the scaffold surface or hindrance of bacterial adhesion through surface charge, microstructure, and other factors. The dissolution-penetration antimicrobial scaffold releases antimicrobial substances from the scaffold's interior through degradation and other means to achieve local antimicrobial effects. The photocatalytic antimicrobial scaffold utilizes the absorption of light to generate reactive oxygen species (ROS) with enhanced chemical reactivity for antimicrobial activity. ROS can cause damage to bacterial cell membranes, deoxyribonucleic acid (DNA), proteins, and other components. The multimodal synergistic antimicrobial scaffold involves the combined use of multiple antimicrobial methods to achieve synergistic effects and effectively overcome the limitations of individual antimicrobial approaches. Additionally, the biocompatibility issues of the antimicrobial bone scaffold are also discussed, including in vitro cell adhesion, proliferation, and osteogenic differentiation, as well as in vivo bone repair and vascularization. Finally, the challenges and prospects of antimicrobial bone implants are summarized. The development of antimicrobial bone implants can provide effective solutions to bacterial infection issues in bone defect repair in the foreseeable future.

Photoelectrons Sequentially Regulate Antibacterial Activity and Osseointegration of Titanium Implants

Titanium implants are widely used ; however, implantation occasionally fails due to infections during the surgery or poor osseointegration after the surgery. To solve the problem, an intelligent functional surface on titanium implant that can sequentially eradicate bacteria biofilm at the initial period and promote osseointegration at the late period of post-surgery time is designed. Such surfaces can be excited by near infrared light (NIR), with rare earth nanoparticles to upconvert the NIR light to visible range and adsorb by Au nanoparticles, supported by titanium oxide porous film on titanium implants. Under NIR irradiation, the implant converts the energy of phonon to hot electrons and lattice vibrations, while the former flows directly to the contact substance or partially reacts with the surrounding to generate reactive oxygen species, and the latter leads to the local temperature increase. The biofilm or microbes on the implant surface can be eradicated by NIR treatment in vitro and in vivo. Additionally, the surface exhibits superior biocompatibility for cell survival, adhesion, proliferation, and osteogenic differentiation, which provides the foundation for osseointegration. In vivo implantation experiments demonstrate osseointegration is also promoted. This work thus demonstrates NIR-generated electrons can sequentially eradicate biofilms and regulate the osteogenic process, providing new solutions to fabricate efficient implant surfaces.

A three-in-one nanoplatform with photo/chemodynamic activities combined with glutathione depletion for treating bacterial infections

The misuse of antibiotics leading to bacterial multidrug resistance is responsible for severe infectious diseases and a significant cause of mortality worldwide, resulting in numerous human disasters. Photodynamic antibacterial therapy (PDAT) is a promising strategy against multiantibiotic-resistant bacteria, but its antibacterial activity is greatly limited by reduced glutathione (GSH) in bacteria. In this study, we constructed a nanoplatform through the formation of metal chelating complexes (FeP) between ferric and pyrophosphate ions, with subsequent adsorption of the photosensitizer ZnPc(COOH)8 (octa-carboxyl substituted zinc phthalocyanine) mediated by polylysine (PL) on the surface. The nanocomplexes FeP@PL:ZnPc(COOH)8 exhibited the capacity of GSH depletion and chemodynamic activity, which synergistically enhanced PDAT efficacy. FeP@PL:ZnPc(COOH)8 possessed the excellent antibacterial activity in vivo and in vitro, which might be attributed to the increased production of reactive oxygen species (ROS), reduced GSH level in bacteria, improved bacterial uptake, and enhanced destruction of the bacterial outer membrane. Moreover, FeP@PL:ZnPc(COOH)8 exhibited accelerated wound healing efficacy and the ability to recognize bacteria-infected wounds, rendering it an effective theranostic nanoplatform for bacterial infections. The construction strategy of nanocomplexes in this study holds theoretical and practical significance for high-efficiency synergistic photodynamic and chemodynamic antibacterial therapy.

Post-functionalization of sulfur quantum dots and their aggregation-dependent antibacterial activity

Sulfur quantum dots (SQDs) have emerged as an intriguing class of luminescent nanomaterial due to their exceptional physiochemical and optoelectronic properties. However, their biomedical application is still in its infancy due to the limited scope of their surface functionalization. Herein, we explored the surface functionalization of SQDs through different thiol ligands with tuneable functionality and tested their antibacterial efficacy. Notably, very high antibacterial activity of functionalized SQDs (10-25 ng ml-1) was noted, which is 105 times higher compared to that of nonfunctionalized SQDs. Moreover, a rare phenomenon of the reverse trend of antibacterial activity through surface modification was observed, with increasing surface hydrophobicity of various nanomaterials as the antibacterial activity increased. However, we also noted that as the surface hydrophobicity increased, the SQDs tended to exhibit a propensity for aggregation, which consequently decreased their antibacterial efficacy. This identical pattern was also evident in in vivo assessments. Overall, this study illuminates the importance of surface modifications of SQDs and the role of surface hydrophobicity in the development of antibacterial agents.

Size-dependent magnetomechanically enhanced photothermal antibacterial effect of Fe3O4@Au/PDA nanodurian

The global health crisis of bacterial resistance to antibiotics requires innovative antibacterial strategies. One promising solution is the exploitation of multifunctional nanoplatforms based on non-resistant antibacterial mechanisms. This work reports a novel Fe3O4@Au/polydopamine (PDA) nanodurian with excellent photothermal-magnetomechanic synergistic antibacterial effects. The one-step formed Au/PDA hybrid shell provides good photothermal properties and spiky surfaces for enhanced magnetomechanic effects. Upon near-infrared (NIR) irradiation, the Fe3O4@Au/PDA nanodurian (200 μg mL-1) achieved nearly 100% antibacterial effect against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The efficiency of photothermal antimicrobial activity was further enhanced by the application of a rotating magnetic field (RMF), with the sterilization efficiency being increased by up to more than a half compared to the action alone. Interestingly, the size of the nanodurian has a significant impact on the synergistic sterilization effect, with larger particles showing a superior performance due to stronger chain-like structures in the magnetic field. Finally, the Fe3O4@Au/PDA nanodurian also demonstrates effective biofilm removal, with larger particles exhibiting the best eradication effect under the photothermal-magnetomechanic treatment. Overall, this magnetic field enhanced photothermal antibacterial strategy provides a promising broad-spectrum antimicrobial solution to combat bacterial infections. Thus, it possesses great potential in future nanomedicine and pollution treatment.

Photodynamic toluidine blue-gold nanoconjugates as a novel therapeutic for Staphylococcal biofilms

Staphylococci are among the most frequent bacteria known to cause biofilm-related infections. Pathogenic biofilms represent a global healthcare challenge due to their high tolerance to antimicrobials. In this study, water soluble polyethylene glycol (PEG)-coated gold nanospheres (28 ppm) and nanostars (15 ppm) with electrostatically adsorbed photosensitizer (PS) Toluidine Blue O (TBO) ∼4 μM were successfully synthesized and characterized as PEG-GNPs@TBO and PEG-GNSs@TBO. Both nanoconjugates and the TBO 4 μM solution showed remarkable, if similar, antimicrobial photodynamic inactivation (aPDI) effects at 638 nm, inhibiting the formation of biofilms by two Staphylococcal strains: a clinical methicillin-resistant Staphylococcus aureus (MRSA) isolate and Staphylococcus epidermidis (S. epidermidis) RP62A. Alternatively in biofilm eradication treatments, the aPDI effects of PEG-GNSs@TBO were more effective and yielded a 75% and 50% reduction in viable count of MRSA and S. epidermidis RP62A preformed biofilms, respectively and when compared with untreated samples. This reduction in viable count was even greater than that obtained through aPDI treatment using a 40 μM TBO solution. Confocal laser microscopy (CLSM) and scanning electron microscope (SEM) images of PEG-GNSs@TBO's aPDI treatments revealed significant changes in the integrity and morphology of biofilms, with fewer colony masses. The generation of reactive oxygen species (ROS) upon PEG-GNSs@TBO's aPDI treatment was detected by CLSM using a specific ROS fluorescent probe, demonstrating bright fluorescence red spots across the surfaces of the treated biofilms. Our findings shine a light on the potential synergism between gold nanoparticles (AuNPs) and photosensitizers in developing novel nanoplatforms to target Staphylococcal biofilm related infections.

Cryptotanshinone-Doped Photothermal Synergistic MXene@PDA Nanosheets with Antibacterial and Anti-Inflammatory Properties for Wound Healing

Humans are threatened by bacteria and other microorganisms, resulting in countless pathogen-related infections and illnesses. Accumulation of reactive oxygen species (ROS) in infected wounds activates strong inflammatory responses. The overuse of antibiotics has led to increasing bacterial resistance. Therefore, effective ROS scavenging and bactericidal capacity are essential and the advanced development of collaborative therapeutic techniques to combat bacterial infections is needed. Here, this work developes an MXene@polydopamine-cryptotanshinone (MXene@PDA-CPT) antibacterial nanosystem with excellent reactive oxygen and nitrogen species scavenging ability, which effectively inactivates drug-resistant bacteria and biofilms, thereby promoting wound healing. In this system, the adhesion of polydopamine nanoparticles to MXene produced a photothermal synergistic effect and free radical scavenging activity, presenting a promising antibacterial and anti-inflammatory strategy. This nanosystem causes fatal damage to bacterial membranes. The loading of cryptotanshinone further expanded the advantages of the system, causing a stronger bacterial killing effect and inflammation mitigatory effect with desired biosafety and biocompatibility. In addition, combining nanomaterials and active ingredients of traditional Chinese medicine, this work provides a new rationale for the future development of wound dressings, which contributes to eliminating bacterial resistance, delaying disease deterioration, and alleviating the pain of patients.

Simultaneous Electrophysiology and Imaging Reveal Changes in Lipid Membrane Thickness and Tension upon Uptake of Amphiphilic Gold Nanoparticles

Amphiphilic gold core nanoparticles (AmNPs) striped with hydrophilic 11-mercapto-1-undecanesulfonate (MUS) and hydrophobic 1-octanethiol (OT) ligands are promising candidates for drug carriers that passively and nondisruptively enter cells. Yet, how they interact with cellular membranes is still only partially understood. Herein, we use electrophysiology and imaging to carefully assess changes in droplet interface bilayer lipid membranes (DIBs) incurred by striped AmNPs added via microinjection. We find that AmNPs spontaneously reduce the steady-state specific capacitance and contact angle of phosphatidylcholine DIBs by amounts dependent on the final NP concentration. These reductions, which are greater for NPs with a higher % OT ligands and membranes containing unsaturated lipids but negligible for MUS-only-coated NPs, reveal that AmNPs passively embed in the interior of the bilayer where they increase membrane thickness and lateral tension through disruption of lipid packing. These results demonstrate the enhanced evaluation of nano-bio interactions possible via electrophysiology and imaging of DIBs.

Analysis of Antibacterial Efficacy and Cellular Alignment Regulation on Plasma Nanotextured Chitosan Surfaces

To address implant-related infections, antibacterial solutions specific to biomaterials are required to prevent bacterial proliferation. Traditional antibiotic usage has been found insufficient, motivating researchers to investigate alternative strategies such as surface modification and the application of antifouling or infection-resistant properties. A developing interest lies in designing surfaces that mimic natural antibacterial nanotopographies. In this study, we conducted a quantitative analysis of the outcomes from plasma nanotexturing, with particular emphasis on how the organization of topography influences antibacterial efficacy and the regulation of cell alignment. Plasma nanotexturing was applied to chitosan surfaces, which gradually transformed from nanopores to pillars and eventually into tilted pillars, as the plasma parameters (fluence and angle) increased. We used directed plasma nanosynthesis, a plasma-based technique that primarily induces topographical alterations on the surfaces. The surfaces were systematically characterized, incorporating methods such as scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). A comprehensive comparison of the nanotextures was executed by utilizing a trapezoidal method to calculate aspect ratios and assess texture orientation by examining the gaps in the nanostructures. We evaluated antibacterial properties against E. coli and S. aureus strains and assessed the survival and alignment of human bone marrow mesenchymal stem cells. Our findings reveal a significant reduction in bacterial adhesion (>80%) and growth on nanotextured surfaces, underscoring their potential for clinical applications. Moreover, we measured cell alignment, presenting the results in both a color-coded and numerical format to demonstrate the preferential alignment orientation induced specially by the tilted nanotexture. These insights highlight the profound impacts of plasma nanotexturing, indicating its potential for innovative biomedical applications such as advanced wound healing and tissue engineering.

Recent advances in nanomaterial-mediated bacterial molecular action and their applications in wound therapy

Because of the multi-pathway antibacterial mechanisms of nanomaterials, they have received widespread attention in wound therapy. However, owing to the complexities of bacterial responses toward nanomaterials, antibacterial molecular mechanisms remain unclear, making it difficult to rationally design highly efficient antibacterial nanomaterials. Fortunately, molecular dynamics simulations and omics techniques have been used as effective methods to further investigate the action targets of nanomaterials. Therefore, the review comprehensively analyzes the antibacterial mechanisms of nanomaterials from the morphology-dependent antibacterial activity and physicochemical/optical properties-dependent antibacterial activity, which provided guidance for constructing excellently efficient and broad-spectrum antibacterial nanomaterials for wound therapy. More importantly, the main molecular action targets of nanomaterials from the membranes, DNA, energy metabolism pathways, oxidative stress defense systems, ribosomes, and biofilms are elaborated in detail. Furthermore, nanomaterials used in wound therapy are reviewed and discussed. Finally, future directions of nanomaterials from mechanisms to nanomedicine are further proposed.

Hydrodynamic tearing of bacteria on nanotips for sustainable water disinfection

Water disinfection is conventionally achieved by oxidation or irradiation, which is often associated with a high carbon footprint and the formation of toxic byproducts. Here, we describe a nano-structured material that is highly effective at killing bacteria in water through a hydrodynamic mechanism. The material consists of carbon-coated, sharp Cu(OH)2 nanowires grown on a copper foam substrate. We show that mild water flow (e.g. driven from a storage tank) can efficiently tear up bacteria through a high dispersion force between the nanotip surface and the cell envelope. Bacterial cell rupture is due to tearing of the cell envelope rather than collisions. This mechanism produces rapid inactivation of bacteria in water, and achieved complete disinfection in a 30-day field test. Our approach exploits fluidic energy and does not require additional energy supply, thus offering an efficient and low-cost system that could potentially be incorporated in water treatment processes in wastewater facilities and rural communities.

Nano-Biotechnology for Bacteria Identification and Potent Anti-bacterial Properties: A Review of Current State of the Art

Sepsis is a critical disease caused by the abrupt increase of bacteria in human blood, which subsequently causes a cytokine storm. Early identification of bacteria is critical to treating a patient with proper antibiotics to avoid sepsis. However, conventional culture-based identification takes a long time. Polymerase chain reaction (PCR) is not so successful because of the complexity and similarity in the genome sequence of some bacterial species, making it difficult to design primers and thus less suitable for rapid bacterial identification. To address these issues, several new technologies have been developed. Recent advances in nanotechnology have shown great potential for fast and accurate bacterial identification. The most promising strategy in nanotechnology involves the use of nanoparticles, which has led to the advancement of highly specific and sensitive biosensors capable of detecting and identifying bacteria even at low concentrations in very little time. The primary drawback of conventional antibiotics is the potential for antimicrobial resistance, which can lead to the development of superbacteria, making them difficult to treat. The incorporation of diverse nanomaterials and designs of nanomaterials has been utilized to kill bacteria efficiently. Nanomaterials with distinct physicochemical properties, such as optical and magnetic properties, including plasmonic and magnetic nanoparticles, have been extensively studied for their potential to efficiently kill bacteria. In this review, we are emphasizing the recent advances in nano-biotechnologies for bacterial identification and anti-bacterial properties. The basic principles of new technologies, as well as their future challenges, have been discussed.

Antimicrobial Activity of Selenium Nanoparticles (SeNPs) against Potentially Pathogenic Oral Microorganisms: A Scoping Review

Biofilms are responsible for the most prevalent oral infections such as caries, periodontal disease, and pulp and periapical lesions, which affect the quality of life of people. Antibiotics have been widely used to treat these conditions as therapeutic and prophylactic compounds. However, due to the emergence of microbial resistance to antibiotics, there is an urgent need to develop and evaluate new antimicrobial agents. This scoping review offers an extensive and detailed synthesis of the potential role of selenium nanoparticles (SeNPs) in combating oral pathogens responsible for causing infectious diseases. A systematic search was conducted up until May 2022, encompassing the MEDLINE, Embase, Scopus, and Lilacs databases. We included studies focused on evaluating the antimicrobial efficacy of SeNPs on planktonic and biofilm forms and their side effects in in vitro studies. The selection process and data extraction were carried out by two researchers independently. A qualitative synthesis of the results was performed. A total of twenty-two articles were considered eligible for this scoping review. Most of the studies reported relevant antimicrobial efficacy against C. albicans, S. mutans, E. faecalis, and P. gingivalis, as well as effective antioxidant activity and limited toxicity. Further research is mandatory to critically assess the effectiveness of this alternative treatment in ex vivo and in vivo settings, with detailed information about SeNPs concentrations employed, their physicochemical properties, and the experimental conditions to provide enough evidence to address the construction and development of well-designed and safe protocols.

A review on synthesis and antibacterial potential of bio-selenium nanoparticles in the food industry

Effective control of foodborne pathogen contamination is a significant challenge to the food industry, but the development of new antibacterial nanotechnologies offers new opportunities. Notably, selenium nanoparticles have been extensively studied and successfully applied in various food fields. Selenium nanoparticles act as food antibacterial agents with a number of benefits, including selenium as an essential trace element in food, prevention of drug resistance induction in foodborne pathogens, and improvement of shelf life and food storage conditions. Compared to physical and chemical methods, biogenic selenium nanoparticles (Bio-SeNPs) are safer and more multifunctional due to the bioactive molecules in Bio-SeNPs. This review includes a summarization of (1) biosynthesized of Bio-SeNPs from different sources (plant extracts, fungi and bacteria) and their antibacterial activity against various foodborne bacteria; (2) the antibacterial mechanisms of Bio-SeNPs, including penetration of cell wall, damage to cell membrane and contents leakage, inhibition of biofilm formation, and induction of oxidative stress; (3) the potential antibacterial applications of Bio-SeNPs as food packaging materials, food additives and fertilizers/feeds for crops and animals in the food industry; and (4) the cytotoxicity and animal toxicity of Bio-SeNPs. The related knowledge contributes to enhancing our understanding of Bio-SeNP applications and makes a valuable contribution to ensuring food safety.

Interference with Bacterial Conjugation and Natural Alternatives to Antibiotics: Bridging a Gap

Horizontal gene transfer (HGT) in food matrices has been investigated under conditions that favor gene exchange. However, the major challenge lies in determining the specific conditions pertaining to the adapted microbial pairs associated with the food matrix. HGT is primarily responsible for enhancing the microbial repertoire for the evolution and spread of antimicrobial resistance and is a major target for controlling pathogens of public health concern in food ecosystems. In this study, we investigated Salmonella Heidelberg (SH) and Escherichia coli (EC) regarding gene exchange under conditions mimicking the industrial environment, with the coproducts whey (SL) and chicken juice (CJ). The S. Heidelberg strain was characterized by antibiotic susceptibility standards and PCR to detect the bla_TEM gene. A concentration of 0.39 mg/mL was determined to evaluate the anti-conjugation activity of nanostructured lipid nanocarriers (NLCs) of essential oils to mitigate β-lactam resistance gene transfer. The results showed that the addition of these coproducts promoted an increase of more than 3.5 (whey) and 2.5 (chicken juice) orders of magnitude in the conjugation process (p < 0.01), and NLCs of sage essential oil significantly reduced the conjugation frequency (CF) by 74.90, 90.6, and 124.4 times when compared to the transfers in the absence of coproducts and the presence of SL and CJ, respectively. For NLCs from olibanum essential oil, the decrease was 4.46-fold for conjugations without inhibitors and 3.12- and 11.3-fold in the presence of SL and CJ. NLCs associated with sage and olibanum essential oils effectively control the transfer of antibiotic resistance genes and are a promising alternative for use at industrial levels.

Near-Infrared Copper Sulfide Hollow Nanostructures with Enhanced Photothermal and Photocatalytic Performance for Effective Bacterial Sterilization

The development of nonantibiotic strategies to combat bacterial infection is highly needed, owing to the widespread infectious disease and bacterial resistance becoming a significant health threat to the world's population. In recent years, photoactivated antibacterial therapies including photocatalytic and photothermal therapies have attracted increasing attention due to their high efficiency and low side effect. Herein, we introduce a copper sulfide (Cu_2-xS) hollow nanostructure-based near-infrared antibacterial platform with synergy photothermal and photocatalytic properties for effective bacterial sterilization. Compared to traditional Cu_2-xS nanoparticles, this unique hollow Cu_2-xS nanostructure can generate multiple scattered light, which is conducive to light collection. Moreover, its thin shell can shorten the transmission distance of carrier, thus reducing the charge recombination that usually causes the greatest energy loss. As a result, such a Cu_2-xS hollow nanostructure enables enhanced photothermal and photocatalytic bacterial killing activities against both Escherichia coli and Staphylococcus aureus, showing promise for antibiotic-free infection treatment and other bacterial sterilization applications.

Injectable Zn2+ and Paeoniflorin Release Hydrogel for Promoting Wound Healing

As more and more superbugs emerge, wounds are struggling to heal due to the inflammation that accompanies infection. Therefore, there is an urgent need to reduce the abuse of antibiotics and find nonantibiotic antimicrobial methods to counter infections to accelerate wound healing. In addition, common wound dressings struggle to cover irregular wounds, causing bacterial invasion or poor drug release, which reduces the wound healing rate. In this study, Chinese medicinal monomer paeoniflorin which can inhibit inflammation is loaded in mesoporous zinc oxide nanoparticles (mZnO), while Zn²⁺ released from mZnO degradation can kill bacteria and facilitate wound healing. The drug-loaded mZnO was encapsulated by a hydrogel formed from oxidized konjac glucomannan and carboxymethyl chitosan via rapid Schiff base reaction to obtain an injectable drug-releasing hydrogel wound dressing. The immediate-formation hydrogel allows the dressing to cover any wound shape. In vitro and in vivo studies have demonstrated that the dressing has good biocompatibility and superior antibacterial properties, which can promote wound healing and tissue regeneration by promoting angiogenesis and collagen production, providing a promising perspective for the further development of multifunctional wound dressings.

Quantifiable Relationship Between Antibacterial Efficacy and Electro-Mechanical Intervention on Nanowire Arrays

Physical disruption is an important antibacterial means as it is lethal to bacteria without spurring antimicrobial resistance. However, it is very challenging to establish a quantifiable relationship between antibacterial efficacy and physical interactions such as mechanical and electrical forces. Herein, titanium nitride (TN) nanowires with adjustable orientations and capacitances are prepared to exert gradient electro-mechanical forces on bacteria. While vertical nanowires show the strongest mechanical force resulting in an antibacterial efficiency of 0.62 log reduction (vs 0.22 for tiled and 0.36 for inclined nanowires, respectively), the addition of electrical charges maximizes the electro-mechanical interactions and elevates the antibacterial efficacy to more than 3 log reduction. Biophysical and biochemical analyses indicate that electrostatic attraction by electrical charge narrows the interface. The electro-mechanical intervention more easily stiffens and rips the bacteria membrane, disturbing the electron balance and generating intracellular oxidative stress. The antibacterial ability is maintained in vivo and bacteria-challenged rats are protected from serious infection. The physical bacteria-killing process demonstrated here can be controlled by adjusting the electro-mechanical interactions. Overall, these results revealed important principles for rationally designing high-performance antibacterial interfaces for clinical applications.

Review of Antimicrobial Nanocoatings in Medicine and Dentistry: Mechanisms of Action, Biocompatibility Performance, Safety, and Benefits Compared to Antibiotics

This review discusses topics relevant to the development of antimicrobial nanocoatings and nanoscale surface modifications for medical and dental applications. Nanomaterials have unique properties compared to their micro- and macro-scale counterparts and can be used to reduce or inhibit bacterial growth, surface colonization and biofilm development. Generally, nanocoatings exert their antimicrobial effects through biochemical reactions, production of reactive oxygen species or ionic release, while modified nanotopographies create a physically hostile surface for bacteria, killing cells via biomechanical damage. Nanocoatings may consist of metal nanoparticles including silver, copper, gold, zinc, titanium, and aluminum, while nonmetallic compounds used in nanocoatings may be carbon-based in the form of graphene or carbon nanotubes, or composed of silica or chitosan. Surface nanotopography can be modified by the inclusion of nanoprotrusions or black silicon. Two or more nanomaterials can be combined to form nanocomposites with distinct chemical or physical characteristics, allowing combination of different properties such as antimicrobial activity, biocompatibility, strength, and durability. Despite their wide range of applications in medical engineering, questions have been raised regarding potential toxicity and hazards. Current legal frameworks do not effectively regulate antimicrobial nanocoatings in matters of safety, with open questions remaining about risk analysis and occupational exposure limits not considering coating-based approaches. Bacterial resistance to nanomaterials is also a concern, especially where it may affect wider antimicrobial resistance. Nanocoatings have excellent potential for future use, but safe development of antimicrobials requires careful consideration of the "One Health" agenda, appropriate legislation, and risk assessment.

Microwave Irradiation vs. Structural, Physicochemical, and Biological Features of Porous Environmentally Active Silver–Silica Nanocomposites

Heavy metals and other organic pollutants burden the environment, and their removal or neutralization is still inadequate. The great potential for development in this area includes porous, spherical silica nanostructures with a well-developed active surface and open porosity. In this context, we modified the surface of silica spheres using a microwave field (variable power and exposure time) to increase the metal uptake potential and build stable bioactive Ag2O/Ag2CO3 heterojunctions. The results showed that the power of the microwave field (P = 150 or 700 W) had a more negligible effect on carrier modification than time (t = 60 or 150 s). The surface-activated and silver-loaded silica carrier features like morphology, structure, and chemical composition correlate with microbial and antioxidant enzyme activity. We demonstrated that the increased sphericity of silver nanoparticles enormously increased toxicity against E. coli, B. cereus, and S. epidermidis. Furthermore, such structures negatively affected the antioxidant defense system of E. coli, B. cereus, and S. epidermidis through the induction of oxidative stress, leading to cell death. The most robust effects were found for nanocomposites in which the carrier was treated for an extended period in a microwave field.

In Situ Microscopic Studies on the Interaction of Multi-Principal Element Nanoparticles and Bacteria

Multi-principal element nanoparticles are an emerging class of materials with potential applications in medicine and biology. However, it is not known how such nanoparticles interact with bacteria at nanoscale. In the present work, we evaluated the interaction of multi-principal elemental alloy (FeNiCu) nanoparticles with Escherichia coli (E. coli) bacteria using the in situ graphene liquid cell (GLC) scanning transmission electron microscopy (STEM) approach. The imaging revealed the details of bacteria wall damage in the vicinity of nanoparticles. The chemical mappings of S, P, O, N, C, and Cl elements confirmed the cytoplasmic leakage of the bacteria. Our results show that there is selective release of metal ions from the nanoparticles. The release of copper ions was much higher than that for nickel while the iron release was the lowest. In addition, the binding affinity of bacterial cell membrane protein functional groups with Cu, Ni, and Fe cations is found to be the driving force behind the selective metal cations' release from the multi-principal element nanoparticles. The protein functional groups driven dissolution of multielement nanoparticles was evaluated using the density functional theory (DFT) computational method, which confirmed that the energy required to remove Cu atoms from the nanoparticle surface was the least in comparison with those for Ni and Fe atoms. The DFT results support the experimental data, indicating that the energy to dissolve metal atoms exposed to oxidation and/or the to presence of oxygen atoms at the surface of the nanoparticle catalyzes metal removal from the multielement nanoparticle. The study shows the potential of compositional design of multi-principal element nanoparticles for the controlled release of metal ions to develop antibacterial strategies. In addition, GLC-STEM is a promising approach for understanding the nanoscale interaction of metallic nanoparticles with biological structures.

Phospholipid-Mimetic Aggregation-Induced Emission Luminogens for Specific Elimination of Gram-Positive and Gram-Negative Bacteria

Precise elimination of both Gram-positive and Gram-negative bacteria greatly contributes to the fight against bacterial infection but remains challenging. Herein, we present a series of phospholipid-mimetic aggregation-induced emission luminogens (AIEgens) that selectively kill bacteria by capitalizing on both the different structure of two bacterial membrane and the regulated length of substituted alkyl chains of AIEgens. Because of the positive charges that they contain, these AIEgens are able to kill bacteria by anchoring onto the bacterial membrane. For AIEgens with short alkyl chains, they could combine with the membrane of Gram-positive bacteria other than Gram-negative bacteria, because of their complicated outer layers, thus exhibiting selective ablation to Gram-positive bacteria. On the other hand, AIEgens with long alkyl chains have strong hydrophobicity with bacterial membranes, as well as large sizes. This inhibits the combination with Gram-positive bacterial membrane but destroys the membranes of Gram-negative bacteria, resulting in selective ablation to Gram-negative bacteria. Moreover, the combined processes to two bacteria are clearly observed by fluorescent imaging, and in vitro and in vivo experiments show the extraordinary antibacterial selectivity toward a Gram-positive and Gram-negative bacterium. This work could facilitate the development of species-specific antibacterial agents.

Micro-structured P-N junction surfaces: large-scale preparation, antifouling properties, and a synergistic antibacterial mechanism

Constructing an antifouling surface cost-effectively is vitally important for many applications. Herein, a series of silicon substrates with micro-pyramid structures and p-n junctions were fabricated following a simple industrial processing flow, among which the p⁺n-Si substrate, fabricated through boron doping of a micro-pyramid structured n-type silicon wafer, exhibited the most pronounced antibacterial performance. Broad-spectrum bactericidal and bacteriostatic activity of p⁺n-Si under ambient light illumination was observed, with an inhibition ability of 73-100% compared to that of a bare glass against both airborne and contact-transmitted bacteria in the intensive care unit. The synergetic effect of mechanical rupture and electric injury was supposed to be responsible for the potent antibacterial activity. This work proposes a state-of-the-art concept that p-n junctions enhance the anti-infection ability of micro-structured surfaces and provide a promising strategy for fabricating practical antifouling surfaces with a large-size, a facile manufacturing procedure, and gentle working conditions, as well as broad-spectrum and physical antibacterial mechanisms.

Antibacterial Nanomaterials: Mechanisms, Impacts on Antimicrobial Resistance and Design Principles

Antimicrobial resistance (AMR) is one of the biggest threats to the environment and health. AMR rapidly invalidates conventional antibiotics, and antimicrobial nanomaterials have been increasingly explored as alternatives. Interestingly, several antimicrobial nanomaterials show AMR-independent antimicrobial effects without detectable new resistance and have therefore been suggested to prevent AMR evolution. In contrast, some are found to trigger the evolution of AMR. Given these seemingly conflicting findings, a timely discussion of the two faces of antimicrobial nanomaterials is urgently needed. This review systematically compares the killing mechanisms and structure-activity relationships of antibiotics and antimicrobial nanomaterials. We then focus on nano-microbe interactions to elucidate the impacts of molecular initiating events on AMR evolution. Finally, we provide an outlook on future antimicrobial nanomaterials and propose design principles for the prevention of AMR evolution.