Peptidomimetic Polyurethanes Inhibit Bacterial Biofilm Formation and Disrupt Surface Established Biofilms

A comprehensive review of emerging 3D-printing materials against bacterial biofilm growth on the surface of healthcare settings

A significant burden on the healthcare system, microbial contamination of biomedical surfaces can result in hospital-acquired illnesses. Bacteria, viruses, and fungi may live on surfaces for days or months and spread to patients and medical personnel. This article describes the 3D printing technologies, such as fused deposition modeling, bioprinting, binder jetting/inkjet, poly-jet, electron beam manufacturing, stereolithography, selective laser sintering, and laminated object manufacturing used for manufacturing the healthcare setting's surface to reduce bacterial contamination with exploring anti-biofilm activity against different bacterial species responsible for infections, based on the critical evaluation of published reports. This strategy has immense potential to become an upcoming approach for advancing the coating concept on the material's surface in healthcare settings. Our literature evaluation identifies beneficial 3D printing materials and associated technologies against microorganisms' growth, mainly bacteria involved in implant-based infection, emphasizing the development of anti-biofilm 3D-printed surfaces. Additionally, the authors have identified a few key areas where research and development are critically required to advance 3D-printing technology in healthcare settings.

Novel strategies for vancomycin-resistant Enterococcus faecalis biofilm control: bacteriophage (vB_EfaS_ZC1), propolis, and their combined effects in an ex vivo endodontic model

BACKGROUND

Endodontic treatment failures are predominantly attributed to Enterococcus faecalis (E. faecalis) infection, a Gram-positive coccus. E. faecalis forms biofilms, resist multiple antibiotics, and can withstand endodontic disinfection protocols. Vancomycin-resistant strains, in particular, are challenging to treat and are associated with serious medical complications.

METHODS

A novel phage, vB_EfaS_ZC1, was isolated and characterized. Its lytic activity against E. faecalis was assessed in vitro through time-killing and biofilm assays. The phage's stability under various conditions was determined. Genomic analysis was conducted to characterize the phage and its virulence. The phage, propolis, and their combination were evaluated as an intracanal irrigation solution against a 4-week E. faecalis mature biofilm, using an ex vivo infected human dentin model. The antibiofilm activity was analyzed using a colony-forming unit assay, field emission scanning electron microscopy, and confocal laser scanning microscopy.

RESULTS

The isolated phage, vB_EfaS_ZC1, a siphovirus with prolate capsid, exhibited strong lytic activity against Vancomycin-resistant strains. In vitro assays indicated its effectiveness in inhibiting planktonic growth and disrupting mature biofilms. The phage remained stable under wide range of temperatures (- 80 to 60 °C), tolerated pH levels from 4 to 11; however the phage viability significantly reduced after UV exposure. Genomic analysis strongly suggests the phage's virulence and suitability for therapeutic applications; neither lysogeny markers nor antibiotic resistance markers were identified. Phylogenetic analysis clustered vB_EfaS_ZC1 within the genus Saphexavirus. The phage, both alone and in combination with propolis, demonstrated potent antibiofilm effects compared to conventional root canal irrigation.

CONCLUSION

Phage vB_EfaS_ZC1 demonstrates a promising therapy, either individually or in combination with propolis, for addressing challenging endodontic infections caused by E. faecalis.

Comprehensive LC-MS Profiling and Evaluation of Antimicrobial, Antibiofilm, Antioxidant, and Anti-inflammatory Properties of Alcoholic Extracts of Brassica fruticulosa subsp. numidica (Coss.) Maire

Brassica fruticulosa subsp. numidica, an underutilized species in the Brassicaceae family, offers significant potential for discovering bioactive compounds. This study analyzed its ethanolic (EE) and methanolic (ME) extracts for phytochemical composition and bioactivity, identifying key compounds via liquid chromatography-mass spectrometry (LC-MS). EE was rich in phenolic acids, notably cinnamic acid (59.33%) and coumaric acid (24.39%), while ME contained a high concentration of riboflavin (99.25%). EE exhibited potent antimicrobial activity, particularly against Pseudomonas aeruginosa (IZD: 17.5 mm; MIC: 62.5 µg/mL), and reduced biofilm formation by up to 72%, whereas ME demonstrated superior antioxidant (IC50: 67.46 ± 0.03 µg/mL) and anti-inflammatory effects (maximum inhibition: 78.10% at 2500 µg/mL). Neither extract showed efficacy against Staphylococcus aureus or fungal strains. These results underscore the therapeutic potential of B. fruticulosa subsp. numidica and highlight its promise for natural product-based drug discovery, warranting further research on compound isolation, mechanistic studies, and in vivo validation.

Facially amphiphilic skeleton-derived antibacterial crown ether/silver ion complexes

Silver and its derivatives have been widely explored for their antibacterial properties in the treatment of bacterial infections. However, the biological toxicity of silver limits its further development and application. In this study, we designed a facially amphiphilic skeleton incorporating crown ether moieties based on the dendrimer D-CA6-CE. The high-density crown ether units within this structure enable the chelation of silver ions, forming facially amphiphilic skeleton-derived D-CA6-CE/Ag+ complexes. These results indicate that D-CA6-CE/Ag+ can self-assemble into nano-micelles in aqueous solution. D-CA6-CE/Ag+ exhibited high antibacterial activity against Escherichia coli and Staphylococcus aureus, significantly reducing the minimum inhibitory concentrations (MICs) of Ag+ to 6.13 ± 0.19 and 7.33 ± 0.13 μg mL-1, respectively. This antibacterial efficacy surpassed that of silver sulfadiazine, primarily attributed to the enhanced ability to disturb and destroy bacterial membranes by introducing the amphiphilic structure of the cholic acid units. In addition, D-CA6-CE/Ag+ also exhibited lower hemolysis (approximately four times lower) and reduced cytotoxicity compared to silver sulfadiazine. This was likely due to the micellar structure formed by D-CA6-CE/Ag+, which further decreases the direct contact between Ag+ and cells. In summary, the D-CA6-CE/Ag+ complex, with its facially amphiphilic skeletons, exhibited superior antibacterial performance and lower biological toxicity than silver sulfadiazine does. These properties highlight its potential as a promising candidate for the treatment of bacterial infections.

Phenylboronic acid-modified carbon dot-proteinase K nanohybrids for enhanced photodynamic therapy against bacterial biofilm infections

Nanohybrids combining phenylboronic acid-modified carbon dots (PCDs) and proteinase K have been engineered for addressing the formidable challenges of antimicrobial photodynamic therapy (aPDT) against bacterial biofilm infections, overcoming biofilm barrier obstruction, the limited diffusion of reactive oxygen species (ROS), and the inadequate ROS generation of traditional photosensitizers. PCDs are formulated for superior water solubility and robust singlet oxygen (1O2) production, mitigating issues related to dispersion and aggregation-induced quenching typical of conventional photosensitizers. The conjugation of phenylboronic acid to CDs not only enhanced 1O2 generation through increased electron-hole separation but also imparted strong bacterial binding capabilities to the PCDs, enabling broad-spectrum sterilization by maximizing the ROS-mediated bacterial destruction. Proteinase K, serving as a structural "glue", actively breaks down biofilms and facilitates the deep penetration of functional PCDs, aiding effective treatment of biofilm infections. In vivo studies confirm that PCDs-proteinase K nanohybrids dramatically accelerate healing in biofilm-infected wounds by synergizing enhanced photosensitization, potent bacterial adherence, and efficient biofilm elimination and penetration. This approach highlights a straightforward strategy to significantly advance aPDT, promoting the clinical adoption of non-antibiotic methods for combating bacterial biofilm infections. STATEMENT OF SIGNIFICANCE: 1) Phenylboronic acid-modified carbon dots (PCDs) were designed for enhanced water solubility and efficient singlet oxygen generation through surface modulation, also suggesting that surface modification can improve the inherent photosensitizing activity of CDs by promoting electron-hole separation; 2) The conjugation of phenylboronic acid endowed PCDs with strong bacterial binding capabilities, enabling highly efficient and broad-spectrum sterilization by maximizing reactive oxygen species-mediated bacterial destruction; 3) Incorporation of proteinase K (PK) leveraged its specific extracellular polymeric substance degrading capability, along with the stimuli-responsive release of PCDs from the PCDs-PK nanohybrids, facilitating biofilm breakdown and enabling deeper penetration of PCDs, thereby improving the treatment of biofilm infections.

Discovery of triazole derivatives for biofilm disruption, anti-inflammation and metal ion chelation

In the face of bacterial hazards to human health and resistance to multiple antibiotics, there is an urgent need to develop new antibiotics to meet the challenge. In this paper, the triazolyl heterocyclic (3-amino-1,2,4-triazole, D) was synthesised efficiently using thiourea as starting material. Finally, the end product E was obtained by aldehyde-amine condensation reaction and the structures of all compounds were determined by spectral analysis. In vitro antimicrobial activity showed that E10 had a MIC of 32 μg/mL against the tested Escherichia coli and 16 μg/mL against the tested Staphylococcus aureus strain. Meanwhile, E10 has a good anti-biofilm effect. Antibacterial mechanism studies have shown that E10 has a good membrane targeting ability, thus disrupting cell membranes, leading to leakage of intracellular proteins and DNA and accelerating bacterial death. In terms of anti-inflammation, E10 dose-dependently inhibits the levels of inflammatory factors NO and IL-6, which deserves further exploration in the treatment of asthma. The study of metal ion removal capacity showed that the synthesised triazole derivatives have high capacity to remove heavy metals Pb2+, Cd2+, Ca2+, Mg2+, Fe3+,Cr3+ and Al3+ in the range of 42%-60%.

Multienzyme-Activity Sulfur Quantum Dot Nanozyme-Mediated Cascade Reactions in Whole-Stage Symptomatic Therapy of Infected Bone Defects

Integrating the therapeutic efficacy of early bacterial clearance, midstage inflammatory remission, and late-stage effective tissue healing is considered a pivotal challenge in symptomatic treatment of infected bone defects (IBDs). Herein, a microenvironment-adaptive nanoplatform based on a sulfur quantum dot (SQD) nanozyme was proposed for whole-stage symptomatic therapy of IBDs by mediating the sequence of enzyme cascade reactions. The SQD nanozyme prepared by a size-engineering modification strategy exhibits enhanced multienzyme activity compared to conventional micrometer- and nanometer-sized sulfur particles. In the early stages of bacterial infection, the SQD nanozyme self-activates superoxide dismutase-peroxidase activity, resulting in the production of reactive oxygen species (ROS) that effectively eliminate bacteria. After disinfection, the SQD nanozyme self-switched to superoxide dismutase-catalase mimetic behavior and eliminated excess ROS, efficiently promoting macrophage polarization to an anti-inflammatory phenotype in the midinflammatory microenvironment. Importantly, SQD nanozyme-mediated M2 macrophage polarization significantly improved the damaged bone immune microenvironment, accelerating bone repair at late-stage tissue healing. Therefore, this strategy offers a promising and viable approach for the treatment of infectious tissue healing by developing multienzyme-activity nanozymes that respond intelligently to the microenvironment at different stages, effectively fighting bacteria, reducing inflammation, and promoting tissue regeneration for whole-stage symptomatic therapy.

Injectable antibacterial drug-free hydrogel dressing enabled by a bioactive peptide-mimicking synthetic peptidyl polymer

The management of bacterial wounds presents a significant challenge in the field of medicine and poses a grave threat to public health. Traditional gauze materials exhibit limited efficacy in treating bacterial infection wounds, while antibiotics demonstrate cytotoxicity and resistance. Therefore, in this study, the peptide biomimetic polymer (PAL-BA) was designed and served as the antibacterial framework for constructing an antibiotic drug-free antibacterial hydrogel dressing through a Schiff base reaction with oxidized hyaluronic acid (OHA). The design of PAL-BA aims to emulate the antimicrobial properties of host defense peptides, serving as a viable alternative to antibiotics drugs. It exhibits comparable antimicrobial activity to polylysine while maintaining biosafety. In vitro experiments demonstrated that PAL-BA exhibited exceptional antibacterial activity against both Staphylococcus aureus and Escherichia coli, while the PAL-BA based antibacterial hydrogel (PBP gel) effectively eliminated 100% of pathogenic bacteria within a duration of 140 min. In vivo studies further demonstrated that PBP hydrogels effectively accelerate the healing of bacterial infected wounds by blocking the infection process. Therefore, the antimicrobial peptide biomimetic polymer hydrogel exhibits significant promise for the management of bacterial wound infections. STATEMENT OF SIGNIFICANCE: The management of bacterial infection wounds remains a challenging issue in clinical practice. In this study, we propose the utilization of a peptide biomimetic polymer (PAL-BA) as an antibacterial framework and its combination with oxidized hyaluronic acid (OHA) through Schiff base reactions to develop an antibiotic drug-free antibacterial hydrogel dressing for the treatment of bacterial infections wounds. The design of PAL-BA aims to mimic the antimicrobial properties of host defense peptides, providing a promising alternative to antibiotic drugs. It demonstrates comparable antimicrobial activity to poly-lysine while maintaining biosafety. Importantly, this antimicrobial peptide biomimetic polymer hydrogel effectively inhibits the infection process in mouse wounds and accelerates the healing of bacterially infected wounds, offering a therapeutic approach for treating infected wounds.

Unlocking the Antibacterial Potential of Naphthalimide-Coumarins to Overcome Drug Resistance with Antibiofilm and Membrane Disruption Ability against Escherichia coli

Resistance by bacteria to available antibiotics is a threat to human health, which demands the development of new antibacterial agents. Considering the prevailing conditions, we have developed a library of new naphthalimide-coumarin moieties as broad-spectrum antibacterial agents to fight against awful drug resistance. Preliminary studies indicate that compounds 8e and 8h display excellent antibacterial activity against Escherichia coli, exceeding the performance of marketed drug amoxicillin. These drug candidates effectively inhibit biofilm formation and disrupt the biofilm virulence factor, which is accountable for the formation of strong biofilm. In addition to this, both compounds exhibit fast bactericidal properties, thus shortening the time of treatment and resisting the emergence of drug resistance for up to 20 passages. Further, biofunctional evaluation reveals that both compounds effectively disrupt the membrane, causing the leakage of cytoplasmic contents and loss in metabolic activity. Both compounds 8e and 8h efficiently induce the ROS, leading to the oxidation of GSH to GSSG, decreasing the GSH activity of the cell, and causing oxidative damage to the cells. Additionally, both compounds effectively bind with DNA to block DNA replication and form supramolecular complexes, thus exhibiting antibacterial activity. Moreover, these compounds readily bind human serum albumin with high binding constants and can be transported to the target site easily. These findings reveal that newly synthesized naphthalimide-coumarin conjugates have the potential to build as potent antibacterial agents and can be used further for clinical trials.

Enhanced Antibacterial Activity of Hydrophobic Modified Lysozyme Against Gram-Negative Bacteria Without Accumulated Resistance

Macromolecule bactericides present challenges such as low biocompatibility and not being biodegradable, so broad-spectrum bactericides without accumulated bacteria resistance are now in urgent demand all over the world. Lysozyme, a kind of wide-spread natural enzyme easily extracted from nature, has become attractive for agriculture and medicine use. However, Gram-negative bacterial strains are highly resistant to natural lysozymes, which limits their practical application. In this study, rather than directly modifying antibacterial-active substance with lysozyme, we show an effective way to improve antibacterial performance by altering the hydrophobic functional groups of natural lysozymes and synthesize a type of hydrophobic modified lysozyme (HML). Compared with other modification methods, the antibacterial performance has been increased by over 50%. We investigated its antibacterial mechanism against Gram-negative bacteria and showed that HML could be used to treat pathogenic bacteria without obvious accumulated resistance appearance, which is a great advantage over commercial antibiotics. Overall, it is anticipated that HML could be potentially applied to food safety, infection therapy, and enzyme-medicine applications.

Interface-Engineered CuxO@Bi2MoO6 Heterojunctions to Inhibit Piezoelectric Screening Effect and Promote Double-Nanozyme Catalysis for Antibacterial Treatment

Sonodynamic therapy is confronted with the low acoustic efficiency of sonosensitizers, and nanozymes are accompanied by intrinsic low catalytic activity. Herein, to increase the piezopotential of N-type piezoelectric semiconductors, the P-N heterojunction is designed to inhibit the piezoelectric screening effect (PSE) and increase electron utilization efficiency to enhance nanozyme activity. P-type CuxO nanoparticles are in situ grown on N-type piezoelectric Bi2MoO6 (BMO) nanoflakes (NFs) to construct heterostructured CuxO@BMO by interface engineering. CuxO deposition leads to lattice distortion of BMO NFs to improve piezoelectric response, and the strong interface electric field (IEF) suppresses PSE and increases piezopotential. The nonlocal piezopotential, local IEF, and glutathione (GSH) inoculation enhances electron-hole separation and increases peroxidase (POD)-like activity of BMO and GSH oxidase (GSHOx)-like activity of CuxO with high selectivity. The heterojunction formation causes the transfer and rearrangement of interface electrons, and the increased piezopotential accelerates electron transfer at interfaces with bacteria, thus increasing the production of reactive oxidative species and interfering with adenosine triphosphate synthesis. The heterostructured nanozymes produce abundant intracellular ·OH and achieve 4log magnitude reductions in viable bacteria and effective biofilm dispersion. This study elucidates integral mechanisms of nanozyme and acoustic catalysis and opens up a new way to synergize high piezopotential and nanozyme-catalyzed therapy.

Biomimetic Materials for Antibacterial Applications

The rise of antibiotic resistance poses a critical threat to global health, necessitating the development of novel antibacterial strategies to mitigate this growing challenge. Biomimetic materials, inspired by natural biological systems, have emerged as a promising solution in this context. These materials, by mimicking biological entities such as plants, animals, cells, viruses, and enzymes, offer innovative approaches to combat bacterial infections effectively. This review delves into the integration of biomimicry with materials science to develop antibacterial agents that are not only effective but also biocompatible and less likely to induce resistance. The study explores the design and function of various biomimetic antibacterial materials, highlighting their therapeutic potential in anti-infection applications. Further, the study provides a comprehensive summary of recent advancements in this field, illustrating how these materials have been engineered to enhance their efficacy and safety. The review also discusses the critical challenges facing the transition of these biomimetic strategies from the laboratory to clinical settings, such as scalability, cost-effectiveness, and long-term stability. Lastly, the study discusses the vast opportunities that biomimetic materials hold for the future of antibacterial therapy, suggesting that continued research and multidisciplinary collaboration will be essential to realize their full potential.

Programming Surface Motility and Modulating Physiological Behaviors of Bacteria via Biosurfactant-Mimetic Polyurethanes

Modulating microbial motility and physiology can enhance the production of bacterial macromolecules and small molecules. Herein, a platform of water-soluble and amphiphilic peptidomimetic polyurethanes is reported as a means of regulating bacterial surface behavior and the concomitant production of extracellular polymeric substances (EPS). It is demonstrated that carboxyl (-COOH)-containing polyurethanes exhibited 17-fold and 80-fold enhancements in Pseudomonas aeruginosa (P. aeruginosa) swarming and twitching areas, respectively. Conversely, an amine (-NH2)-functionalized polyurethane reduces the P. aeruginosa swarming area by 58%. Similar influences on the surface motility of Escherichia coli (E. coli) and a nonswarming P. aeruginosa mutant strain are also observed. Notably, -COOH polyurethanes completely wet the agar hydrogel surface and promote bacterial surface proliferation, resulting in enhanced EPS and rhamnolipid production. The programming of bacterial spatial migration into designed patterns is achieved by leveraging the opposing influences of -NH2 and -COOH polyurethanes. The results highlight the potential of this synthetic polyurethane platform and potentially other polymer systems as an exciting approach to control bacterial surface behaviors and influence the production of engineered living materials.

Intrinsic antimicrobial resistance: Molecular biomaterials to combat microbial biofilms and bacterial persisters

The escalating rise in antimicrobial resistance (AMR) coupled with a declining arsenal of new antibiotics is imposing serious threats to global public health. A pervasive aspect of many acquired AMR infections is that the pathogenic microorganisms exist as biofilms, which are equipped with superior survival strategies. In addition, persistent and recalcitrant infections are seeded with bacterial persister cells at infection sites. Together, conventional antibiotic therapeutics often fail in the complete treatment of infections associated with bacterial persisters and biofilms. Novel therapeutics have been attempted to tackle AMR, biofilms, and persister-associated complex infections. This review focuses on the progress in designing molecular biomaterials and therapeutics to address acquired and intrinsic AMR, and the fundamental microbiology behind biofilms and persisters. Starting with a brief introduction of AMR basics and approaches to tackling acquired AMR, the emphasis is placed on various biomaterial approaches to combating intrinsic AMR, including (1) semi-synthetic antibiotics; (2) macromolecular or polymeric biomaterials mimicking antimicrobial peptides; (3) adjuvant effects in synergy; (4) nano-therapeutics; (5) nitric oxide-releasing antimicrobials; (6) antimicrobial hydrogels; (7) antimicrobial coatings. Particularly, the structure-activity relationship is elucidated in each category of these biomaterials. Finally, illuminating perspectives are provided for the future design of molecular biomaterials to bypass AMR and cure chronic multi-drug resistant (MDR) infections.

From dansyl-modified biofilm disruptors to β-cyclodextrin-optimized multifunctional supramolecular nanovesicles: their improved treatment for plant bacterial diseases

BACKGROUND

Bacterial diseases caused by phytopathogenic Xanthomonas pose a significant threat to global agricultural production, causing substantial economic losses. Biofilm formation by these bacteria enhances their resistance to environmental stressors and chemical treatments, complicating disease control. The key to overcoming this challenge lies in the development of multifunctional green bactericides capable of effectively breaking down biofilm barriers, improving foliar deposition properties, and achieving the control of bacterial diseases.

RESULTS

We have developed a kind of innovative green bactericide from small-molecule conception to eco-friendly supramolecular nanovesicles (DaPA8@β -CD) by host-guest supramolecular technology. These nanoscale assemblies demonstrated the ability to inhibit and eradicate biofilm formation, while also promoted foliar wetting and effective deposition properties, laying the foundation for improving agrochemical utilization. Studies revealed that DaPA8@β -CD exhibited significant biofilm inhibition (78.66% at 7.0 µ g mL- 1) and eradication (83.50% at 25.0 µ g mL- 1), outperforming DaPA8 alone (inhibition: 59.71%, eradication: 66.79%). These nanovesicles also reduced exopolysaccharide formation and bacterial virulence. In vivo experiments showed enhanced control efficiency against citrus bacterial canker (protective: 78.04%, curative: 50.80%) at a low dose of 200 µ g mL- 1, superior to thiodiazole-copper-20%SC and DaPA8 itself.

CONCLUSION

This study demonstrates the potential of DaPA8@β -CD nanovesicles as multifunctional bactericides for managing Xanthomonas -induced plant diseases, highlighting the advantages of using host-guest supramolecular technology to enhance agrochemical bioavailability.

Designing Antibacterial-Based Quaternary Ammonium Coatings (Surfaces) or Films for Biomedical Applications: Recent Advances

Antibacterial coatings based on quaternary ammonium compounds (QACs) have been widely investigated in controlled release applications. Quaternary ammonium compounds are low-cost and easily accessible disinfectants that have been extensively used, especially after the COVID-19 outbreak. There has been a growing interest in developing a clearer understanding of various aspects that need to be taken into account for the design of quaternary ammonium compounds to be used in the biomedical field. In this contribution, we outline the mechanism of action of those materials as well as the key design parameters associated with their structure and antibacterial activity. Moreover, emphasis has been placed on the type of antibacterial coatings based on QACs and their applications in the biomedical field. A brief outlook on future research guidelines for the development of dual-function antibacterial coatings is also discussed.

Neutrophil Extracellular Traps-Inspired Bismuth-Based Polypeptide Nanonets for Synergetic Treatment of Bacterial Infections

Excessive use of antibiotics and the formation of bacterial biofilms can lead to persistent infections caused by drug-resistant bacteria, rendering ineffective immune responses and even life-threatening. There is an urgent need to explore synergistic antibacterial therapies across all stages of infection. Drawing inspiration from the antibacterial properties of neutrophil extracellular traps (NETs) and integrating the bacterial biofilm dispersal mechanism involving boronic acid-catechol interaction, the multifunctional bismuth-based polypeptide nanonets (PLBA-Bi-Fe-TA) are developed. These nanonets are designed to capture bacteria through a coordination complex involving cationic polypeptides (PLBA) with boronic acid-functionalized side chains, alongside metal ions (bismuth (Bi) and iron (Fe)), and tannic acid (TA). Leveraging the nanoconfinement-enhanced high-contact network-driven multiple efficiency, PLBA-Bi-Fe-TA demonstrates the excellent ability to swiftly capture bacteria and their extracellular polysaccharides. This interaction culminates in the formation of a highly hydrophilic complex, effectively enabling the rapid inhibition and dispersion of antibiotic-resistant bacterial biofilms, while Fe-TA shows mild photothermal ability to further assist fluffy mature biofilm. In addition, Bi is beneficial to regulate the polarization of macrophages to pro-inflammatory phenotype to further kill escaping biofilm bacteria. In summary, this novel approach offers a promising bionic optimization strategy for treating bacterial-associated infections at all stages through synergetic treatment.

Antibiofilm efficacy of plant extracts as root canal irrigants in endodontics: a systematic literature review

Background

To explore the antibiofilm efficacy of plant extracts against in vitro formed single and multispecies endodontic biofilms, in comparison to conventional root canal irrigants.

Methods

PubMed, Scopus, Web of Science, and EMBASE were searched up to April 2024. Studies investigating the antibiofilm efficacy, of at least one plant extract and one conventional root canal irrigant, against endodontic biofilms were reviewed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. Data were extracted, and studies were critically assessed using the Joanna Briggs Institute checklist.

Results

Among 78 articles, eight articles met the criteria and were eventually included in this review. One study showed a high risk of bias, six showed a moderate risk of bias, and one showed a low risk. A total of twelve plant extracts were tested for their antibiofilm efficacy against eight different single-species biofilms and one multispecies biofilm. A combination of microscopy methods and culturing techniques was used for the assessment of their efficacies. Plant extracts exhibited either a biofilm disruption and/or inhibition of biofilm formation. Psidium cattleianum extract and Psidium guajava exhibited enhanced efficacy compared to Chlorhexidine and NaOCl, respectively. Allium sativum demonstrated comparable efficacy to NaOCl. Furthermore, the combination of Cymbopogon martinii essential oil and NaOCl was found to be more effective than either alone when tested on a multispecies biofilm. However, the other plant extracts, such as Mikania Sprengel, Salvadora persica, Camellia sinensis, and Vitis vinifera showed efficacy but were still inferior compared to the control group.

Conclusions

Overall, the tested plant extracts demonstrated promising potential for combating in vitro endodontic biofilms. In that context, integrating conventional therapy protocols with plant-inspired treatments may allow effective endodontic biofilm eradication. Hence, future research should focus on optimizing the synergistic combinations of these extracts with NaOCl to maximize the therapeutic outcomes. Heterogeneity amongst the studies prevented a meta-analysis.

Coacervate Dense Phase Displaces Surface-Established Pseudomonas aeruginosa Biofilms

For millions of years, barnacles and mussels have successfully adhered to wet rocks near tide-swept seashores. While the chemistry and mechanics of their underwater adhesives are being thoroughly investigated, an overlooked aspect of marine organismal adhesion is their ability to remove underlying biofilms from rocks and prepare clean surfaces before the deposition of adhesive anchors. Herein, we demonstrate that nonionic, coacervating synthetic polymers that mimic the physicochemical features of marine underwater adhesives remove ∼99% of Pseudomonas aeruginosa (P. aeruginosa) biofilm biomass from underwater surfaces. The efficiency of biofilm removal appears to align with the compositional differences between various bacterial biofilms. In addition, the surface energy influences the ability of the polymer to displace the biofilm, with biofilm removal efficiency decreasing for surfaces with lower surface energies. These synthetic polymers weaken the biofilm-surface interactions and exert shear stress to fracture the biofilms grown on surfaces with diverse surface energies. Since bacterial biofilms are 1000-fold more tolerant to common antimicrobial agents and pose immense health and economic risks, we anticipate that our unconventional approach inspired by marine underwater adhesion will open a new paradigm in creating antibiofilm agents that target the interfacial and viscoelastic properties of established bacterial biofilms.

Bacterial-Infection-Triggered Release of Antibacterial Aldehyde from Triblock Copolyether Hydrogels

Bacterial infections pose a significant threat to public health worldwide. Hydrogel-based biomaterials have proven to be particularly useful in addressing persistent bacterial infections due to their stimuli-responsive degradability, high biocompatibility, ability to release antibacterial agents on demand, and long-lasting antibacterial activity. Herein, we fabricated ABA-type triblock copolyether hydrogels, wherein, hexanal, a bioactive aldehyde with antibacterial activity, was affixed to the hydrophobic micellar core via acetal linkage. The hydrogel exhibited degradation under acidic environment via the hydrolysis of acetal linkages, leading to the concomitant release of hexanal to exhibit highly potent bactericidal activity against both Escherichia coli and Staphylococcus aureus. Furthermore, a dual-mode release of the model therapeutic agent Nile Red from the hydrophobic micellar core of the hydrogel in conjunction with hexanal was demonstrated using this system. We anticipate that this study will provide a new platform for the development of hydrogels with tailorable release profiles for biologically active compounds that are activated by the acidification triggered by bacterial infection.

Artificial Phages with Biocatalytic Spikes for Synergistically Eradicating Antibiotic-Resistant Biofilms

Antibiotic-resistant pathogens have become a global public health crisis, especially biofilm-induced refractory infections. Efficient, safe, and biofilm microenvironment (BME)-adaptive therapeutic strategies are urgently demanded to combat antibiotic-resistant biofilms. Here, inspired by the fascinating biological structures and functions of phages, the de novo design of a spiky Ir@Co3O4 particle is proposed to serve as an artificial phage for synergistically eradicating antibiotic-resistant Staphylococcus aureus biofilms. Benefiting from the abundant nanospikes and highly active Ir sites, the synthesized artificial phage can simultaneously achieve efficient biofilm accumulation, extracellular polymeric substance (EPS) penetration, and superior BME-adaptive reactive oxygen species (ROS) generation, thus facilitating the in situ ROS delivery and enhancing the biofilm eradication. Moreover, metabolomics found that the artificial phage obstructs the bacterial attachment to EPS, disrupts the maintenance of the BME, and fosters the dispersion and eradication of biofilms by down-regulating the associated genes for the biosynthesis and preservation of both intra- and extracellular environments. The in vivo results demonstrate that the artificial phage can treat the biofilm-induced recalcitrant infected wounds equivalent to vancomycin. It is suggested that the design of this spiky artificial phage with synergistic "penetrate and eradicate" capability to treat antibiotic-resistant biofilms offers a new pathway for bionic and nonantibiotic disinfection.

Acinetobacter baumannii biofilm was inhibited by tryptanthrin through disrupting its different stages and genes expression

Biofilm formation plays a significant role in antibiotic resistance, necessitating the search for alternative therapies against biofilm-associated infections. This study demonstrates that 20 μg/mL tryptanthrin can hinder biofilm formation above 50% in various A. baumannii strains. Tryptanthrin impacts various stages of biofilm formation, including the inhibition of surface motility and eDNA release in A. baumannii, as well as an increase in its sensitivity to H202. RT-qPCR analysis reveals that tryptanthrin significantly decreases the expression of the following genes: abaI (19.07%), abaR (33.47%), bfmR (43.41%), csuA/B (64.16%), csuE (50.20%), ompA (67.93%), and katE (72.53%), which are related to biofilm formation and quorum sensing. Furthermore, tryptanthrin is relatively safe and can reduce the virulence of A. baumannii in a Galleria mellonella infection model. Overall, our study demonstrates the potential of tryptanthrin in controlling biofilm formation and virulence of A. baumannii by disrupting different stages of biofilm formation and intercellular signaling communication.

Cyanomethylquinolones as a New Class of Potential Multitargeting Broad-Spectrum Antibacterial Agents

This work identified a class of cyanomethylquinolones (CQs) and their carboxyl analogues as potential multitargeting antibacterial candidates. Most of the prepared compounds showed high antibacterial activities against most of the tested bacteria, exhibiting lower MIC values (0.125-2 μg/mL) than those of clinical norfloxacin, ciprofloxacin, and clinafloxacin. The low hemolysis, drug resistance, and cytotoxicity, as well as good predictive pharmacokinetics of active CQs and carboxyl analogues revealed their development potential. Furthermore, they could eradicate the established biofilm, facilitating bacterial exposure to these antibacterial candidates. These active compounds could induce bacterial death through multitargeting effects, including intercalating into DNA, up-regulating reactive oxygen species, damaging membranes directly, and impeding metabolism. Moreover, the highly active cyclopropyl CQ 15 exhibited more effective in vivo anti-MRSA potency than ciprofloxacin. These findings highlight the potential of CQs and their carboxyl analogues as multitargeting broad-spectrum antibacterial candidates for treating intractable bacterial infections.

Acidity-activated aggregation and accumulation of self-complementary zwitterionic peptide-decorated gold nanoparticles for photothermal biofilm eradication

Drug-resistant biofilm infection is an extremely serious clinical problem, that easily leads to failure of antibiotic treatment. Although gold nanoparticles (AuNPs) as photothermal agents have been widely used in biofilm eradication, there are still challenges to be addressed, such as insignificantly redshifted absorption and slow assembly process of aggregated AuNPs. Herein, we developed an acidity-activated dispersion-to-aggregation transition to enhance the accumulation of self-complementary zwitterionic peptide-decorated AuNPs for photothermal eradication of drug-resistant biofilm infections. AuNPs were decorated with self-complementary zwitterionic peptides (ZP1 and ZP2) coupled with pH-sensitive anhydride (DMA) and pH-insensitive anhydride (SA), respectively. ZP2-decorated AuNPs with DMA modification (AuNP@ZP2(DMA)) exhibited prolonged blood circulation and enhanced accumulation in acidic biofilm microenvironment. Moreover, the electrostatic attraction between self-complementary ligands drove AuNPs to form closely packed aggregates with strong near-infrared absorption, leading to in vivo photoacoustic imaging ability and photothermal effect against drug-resistant bacteria and fungus, as well as microbial biofilms. AuNP@ZP2(DMA) with longer charge domains and a polyethylene glycol oligomer spacer showed greater photothermal antimicrobial and biofilm resistance in vitro and in vivo. This study develops an innovative acidity-activated AuNP photothermal agent, which provides an effective approach for treatment of biofilm infections.

Engineering Platelet Membrane-Coated Bimetallic MOFs as Biodegradable Nanozymes for Efficient Antibacterial Therapy

Nanocatalytic-based wound therapeutics present a promising strategy for generating reactive oxygen species (ROS) to antipathogen to promote wound healing. However, the full clinical potential of these nanocatalysts is limited by their low reactivity, limited targeting ability, and poor biodegradability in the wound microenvironment. Herein, a bio-organic nanozyme is developed by encapsulating a FeZn-based bimetallic organic framework (MOF) (MIL-88B-Fe/Zn) in platelet membranes (PM@MIL-88B-Fe/Zn) for antimicrobial activity during wound healing. The introduction of Zn in MIL-88B-Fe/Zn modulates the electronic structure of Fe thus accelerating the catalytic kinetics of its peroxidase-like activity to catalytically generate powerful ROS. The platelet membrane coating of MOF innovatively enhanced the interaction between nanoparticles and the biological environment, further developing bacterial-targeted therapy with excellent antibacterial activity against both gram-positive and gram-negative bacteria. Furthermore, this nanozyme markedly suppressed the levels of inflammatory cytokines and promoted angiogenesis in vivo to effectively treat skin surface wounds and accelerate wound healing. PM@MIL-88B-Fe/Zn exhibited superior biodegradability, favourable metabolism and non-toxic accumulation, eliminating concerns regarding side effects from long-term exposure. The high catalytic reactivity, excellent targeting features, and biodegradability of these nanoenzymes developed in this study provide useful insights into the design and synthesis of nanocatalysts/nanozymes for practical biomedical applications.

Shining light on carbon dots: Toward enhanced antibacterial activity for biofilm disruption

In spite of tremendous efforts dedicated to addressing bacterial infections and biofilm formation, the post-antibiotic ear continues to witness a gap between the established materials and an easily accessible yet biocompatible antibacterial reagent. Here we show carbon dots (CDs) synthesized via a single hydrothermal process can afford promising antibacterial activity that can be further enhanced by exposure to light. By using citric acid and polyethyleneimine as the precursors, the photoluminescence CDs can be produced within a one-pot, one-step hydrothermal reaction in only 2 h. The CDs demonstrate robust antibacterial properties against both Gram-positive and Gram-negative bacteria and, notably, a considerable enhancement of antibacterial effect can be observed upon photo-irradiation. Mechanistic insights reveal that the CDs generate singlet oxygen (1O2) when exposed to light, leading to an augmented reactive oxygen species level. The approach for disruption of biofilms and inhibition of biofilm formation by using the CDs has also been established. Our findings present a potential solution to combat antibacterial resistance and offer a path to reduce dependence on traditional antibiotics.

Understanding the biofilm development of Acinetobacter baumannii and novel strategies to combat infection

Acinetobacter baumannii (A. baumannii) is a Gram-negative, nonmotile, and aerobic bacillus emerged as a superbug, due to increasing the possibility of infection and accelerating rates of antimicrobial agents. It is recognized as a nosocomial pathogen due to its ability to form biofilms. These biofilms serve as a defensive barrier, increase antibiotic resistance, and make treatment more difficult. As a result, the current situation necessitates the rapid emergence of novel therapeutic approaches to ensure successful treatment outcomes. This review explores the intricate relationship between biofilm formation and antibiotic resistance in A. baumannii, emphasizing the role of key virulence factors and quorum sensing (QS) mechanisms that will lead to infections and facilitate insight into developing innovative method to control A. baumannii infections. Furthermore, the review article looks into promising approaches for preventing biofilm formation on medically important surfaces and potential therapeutic methods for eliminating preformed biofilms, which can address biofilm-associated A. baumannii infections. Modern advances in emerging therapeutic options such as antimicrobial peptide (AMPs), nanoparticles (NPs), bacteriophage therapy, photodynamic therapy (PDT), and other biofilm inhibitors can assist readers understand the current landscape and future prospects for effectively treating A. baumannii biofilm infections.

Discovery of indolylacryloyl-derived oxacins as novel potential broad-spectrum antibacterial candidates

The emergence of serious bacterial resistance towards clinical oxacins poses a considerable threat to global public health, necessitating the development of novel structural antibacterial agents. Seven types of novel indolylacryloyl-derived oxacins (IDOs) were designed and synthesized for the first time from commercial 3,4-difluoroaniline via an eight-step procedure. The synthesized compounds were characterized by modern spectroscopic techniques. All target molecules were evaluated for antimicrobial activities. Most of the prepared IDOs showed a broad antibacterial spectrum and strong activities against the tested strains, especially ethoxycarbonyl IDO 10d (0.25-0.5 μg/mL) and hydroxyethyl IDO 10e (0.25-1 μg/mL) exhibited much superior antibacterial efficacies to reference drug norfloxacin. These highly active IDOs also displayed low hemolysis, cytotoxicity and resistance, as well as rapid bactericidal capacity. Further investigations indicated that ethoxycarbonyl IDO 10d and hydroxyethyl IDO 10e could effectively reduce the exopolysaccharide content and eradicate the formed biofilm, which might delay the development of drug resistance. Preliminary exploration of the antibacterial mechanism revealed that active IDOs could not only destroy membrane integrity, resulting in changes in membrane permeability, but also promote the accumulation of reactive oxygen species, leading to the production of malondialdehyde and decreased bacterial metabolism. Moreover, they exhibited the capability to bind with DNA and DNA gyrase, forming supramolecular complexes through various noncovalent interactions, thereby inhibiting DNA replication and causing bacterial death. All the above results suggested that the newly developed indolylacryloyl-derived oxacins should hold great promise as potential multitargeting broad-spectrum antibacterial candidates to overcome drug resistance.

Biofunctional lipid nanoparticles for precision treatment and prophylaxis of bacterial infections

The lack of bacterial-targeting function in antibiotics and their prophylactic usage have caused overuse of antibiotics, which lead to antibiotic resistance and inevitable long-term toxicity. To overcome these issues, we develop neutrophil-bacterial hybrid cell membrane vesicle (HMV)-coated biofunctional lipid nanoparticles (LNP@HMVs), which are designed to transport antibiotics specifically to bacterial cells at the infection site for the effective treatment and prophylaxis of bacterial infection. The dual targeting ability of HMVs to inflammatory vascular endothelial cells and homologous Gram-negative bacterial cells results in targeted accumulation of LNP@HMVs in the site of infections. LNP@HMVs loaded with the antibiotic norfloxacin not only exhibit enhanced activity against planktonic bacteria and bacterial biofilms in vitro but also achieve potent therapeutic efficacy in treating both systemic infection and lung infection. Furthermore, LNP@HMVs trigger the activation of specific humoral and cellular immunity to prevent bacterial infection. Together, LNP@HMVs provide a promising strategy to effectively treat and prevent bacterial infection.

Dynamic Antimicrobial Poly(disulfide) Coatings Exfoliate Biofilms On Demand Via Triggered Depolymerization

Bacterial biofilms are notoriously problematic in applications ranging from biomedical implants to ship hulls. Cationic, amphiphilic antibacterial surface coatings delay the onset of biofilm formation by killing microbes on contact, but they lose effectiveness over time due to non-specific binding of biomass and biofilm formation. Harsh treatment methods are required to forcibly expel the biomass and regenerate a clean surface. Here, a simple, dynamically reversible method of polymer surface coating that enables both chemical killing on contact, and on-demand mechanical delamination of surface-bound biofilms, by triggered depolymerization of the underlying antimicrobial coating layer, is developed. Antimicrobial polymer derivatives based on α-lipoic acid (LA) undergo dynamic and reversible polymerization into polydisulfides functionalized with biocidal quaternary ammonium salt groups. These coatings kill >99.9% of Staphylococcus aureus cells, repeatedly for 15 cycles without loss of activity, for moderate microbial challenges (≈105 colony-forming units (CFU) mL-1, 1 h), but they ultimately foul under intense challenges (≈107 CFU mL-1, 5 days). The attached biofilms are then exfoliated from the polymer surface by UV-triggered degradation in an aqueous solution at neutral pH. This work provides a simple strategy for antimicrobial coatings that can kill bacteria on contact for extended timescales, followed by triggered biofilm removal under mild conditions.

Investigating the in vitro antibacterial efficacy of composite bone cement incorporating natural product-based monomers and gentamicin

OBJECTIVE

The objective of this study is to investigate the impact of four natural product extracts, namely, aloe-emodin, quercetin, curcumin, and tannic acid, on the in vitro bacteriostatic properties and biocompatibility of gentamicin-loaded bone cement and to establish an experimental groundwork supporting the clinical utility of antibiotic-loaded bone cements (ALBC).

METHODS

Based on the components, the bone cement samples were categorized as follows: the gentamicin combined with aloe-emodin group, the gentamicin combined with quercetin group, the gentamicin combined with curcumin group, the gentamicin combined with tannic acid group, the gentamicin group, the aloe-emodin group, the quercetin group, the curcumin group, and the tannic acid group. Using the disk diffusion test, we investigated the antibacterial properties of the bone cement material against Staphylococcus aureus (n = 4). We tested cell toxicity and proliferation using the cell counting kit-8 (CCK-8) and examined the biocompatibility of bone cement materials.

RESULTS

The combination of gentamicin with the four natural product extracts resulted in significantly larger diameters of inhibition zones compared to gentamicin alone, and the difference was statistically significant (P < 0.05). Except for the groups containing tannic acid, cells in all other groups showed good proliferation across varying time intervals without displaying significant cytotoxicity (P < 0.05).

CONCLUSION

In this study, aloe-emodin, quercetin, curcumin, and tannic acid were capable of enhancing the in vitro antibacterial performance of gentamicin-loaded bone cement against S. aureus. While the groups containing tannic acid displayed moderate cytotoxicity in in vitro cell culture, all other groups showed no discernible cytotoxic effects.

Quaternary ammonium-tethered hyperbranched polyurea nanoassembly synergized with antibiotics for enhanced antimicrobial efficacy

The effective transportation of antibiotics to bacteria embedded within a biofilm consisting of a dense matrix of extracellular polymeric substances is still a challenge in the treatment of bacterial biofilm associated infections. Here, we developed an antibiotic nanocarrier constructed from quaternary ammonium-tethered hyperbranched polyureas (HPUs-QA), which showed high loading capacity for a model antibiotic, rifampicin, and high efficacy in the transportation of rifampicin to biofilms. The rifampicin-loaded HPUs-QA nanoassembly (HPUs-Rif/QA) demonstrated a synergistic antimicrobial effect in killing planktonic bacteria and eradicating the corresponding biofilms. Compared to the treatment of bacteria-infected chronic wounds by either HPUs-QA or rifampicin alone, HPUs-Rif/QA showed superior efficacy in promoting wound healing by more effectively inhibiting bacteria colonization. This study highlights the potential of the HPUs-QA nanoassembly in synergistic action with antibiotics for the treatment of biofilm associated infections.

Nano-Bio Interactions: Biofilm-Targeted Antibacterial Nanomaterials

Biofilm is a spatially organized community formed by the accumulation of both microorganisms and their secretions, leading to persistent and chronic infections because of high resistance toward conventional antibiotics. In view of the tunable physicochemical properties and the related unique biological behavior (e.g., size-, shape-, and surface charge-dependent penetration, protein corona endowed targeting, catalytic- and electronic-related oxidative stress, optical- and magnetic-associated hyperthermia, etc.), nanomaterials-based therapeutics are widely used for the treatment of biofilm-associated infections. In this review, the biological characteristics of biofilm are introduced. And the nanomaterials-based antibacterial strategies are further discussed via biofilm targeting, including preventing biofilm formation, enhancing biofilm penetration, disrupting the mature biofilm, and acting as drug delivery systems. In which, the interactions between biofilm and nanomaterials include mechanical disruption, electron transfer, enzymatic degradation, oxidative stress, and hyperthermia. Additionally, the current advances of nanomaterials for antibacterial nanomaterials by biofilm targeting are summarized. This review aims to present a complete vision of antibacterial nanomaterials-biofilm (nano-bio) interactions, paving the way for the future development and clinical translation of effective antibacterial nanomedicines.

Chemically Tailored Single Atoms for Targeted and Light-Controlled Bactericidal Activity

Single-atom (SA) nanoparticles exhibit considerable potential in terms of photothermal properties for bactericidal applications. Nevertheless, the restricted efficacy of their targeted and controlled antibacterial activity has hindered their practical implementation. This study aims to overcome this obstacle by employing chemical modifications to tailor SAs, thereby achieving targeted and light-controlled antimicrobial effects. By conducting atomic-level modifications on palladium SAs using glutathione (GSH) and mercaptophenylboronic acid (MBA), their superior targeted binding capabilities toward Escherichia coli cells are demonstrated, surpassing those of SAs modified with cysteine (Cys). Moreover, these modified SAs effectively inhibit wound bacteria proliferation and promote wound healing in rats, without inducing noticeable toxicity to major organs under 808 nm laser irradiation. This study highlights the significance of chemical engineering in tailoring the antibacterial properties of SA nanoparticles, opening avenues for combating bacterial infections and advancing nanoparticle-based therapies.

Copper(II)-infused porphyrin MOF: maximum scavenging GSH for enhanced photodynamic disruption of bacterial biofilm

Bacterial biofilm infection is a serious obstacle to clinical therapeutics. Photodynamic therapy (PDT) plays a dynamic role in combating biofilm infection by utilizing reactive oxygen species (ROS)-induced bacterial oxidation injury, showing advantages of mild side effects, spatiotemporal controllability and little drug resistance. However, superfluous glutathione (GSH) present in biofilm and bacteria corporately reduces ROS levels and seriously affects PDT efficiency. Herein, we have constructed a Cu2+-infused porphyrin metal-organic framework (MOF@Cu2+) for the enhanced photodynamic combating of biofilm infection by the maximum depletion of GSH. Our results show that the released Cu2+ from porphyrin MOF@Cu2+ could not only oxidize GSH in biofilm but also consume GSH leaked from ROS-destroyed bacteria, thus greatly weakening the antioxidant system in biofilm and bacteria and dramatically improving the ROS levels. As expected, our dual-enhanced PDT nanoplatform exhibits a strong biofilm eradication ability both in vitro and in an in vivo biofilm-infected mouse model. In addition, Cu2+ can promote biofilm-infected wound closing by provoking cell immigration, collagen sediment and angiogenesis. Besides, no apparent toxicity was detected after treatment with MOF@Cu2+. Overall, our design offers a new paradigm for photodynamic combating biofilm infection.

Sustainable Janus lignin-based polyurethane biofoams with robust antibacterial activity and long-term biofilm resistance

Conventional antibiotic therapies have been becoming less efficient due to increasingly, and sometimes fully, antibiotic-resistant bacterial strains, sometimes known as "superbacteria" or "superbugs." Thus, novel antibacterial materials to effectively inhibit or kill bacteria are crucial for humanity. As a broad-spectrum antimicrobial agent, silver nanoparticles (Ag NPs) have been the most widely commercialized of biomedical materials. However, long-term use of significant amounts of Ag NPs can be potentially harmful to human health through a condition known as argyria, in addition to being toxic to many environmental systems. It is, thus, highly necessary to reduce the amount of Ag NPs employed in medical treatments while also ensuring maintenance of antimicrobial properties, in addition to reducing the overall cost of treatment for humanitarian utilization. For this purpose, naturally sourced antimicrobial polylysine (PL) is used to partially replace Ag NPs within the materials composition. Accordingly, a series of PL, Ag NPs, and lignin-based polyurethane (LPU) composite biofoams (LPU-PL-Ag) were prepared. These proposed composite biofoams, containing at most only 2 % PL and 0.03 % Ag NPs, significantly inhibited the growth of both Gram-positive and Gram-negative bacteria within 1 h and caused irreversibly destructive bactericidal effects. Additionally, with a layer of polydimethylsiloxane (PDMS) on the surface, PDMS-LPU-PL(2 %)-Ag(0.03 %) can effectively prevent bacterial adhesion with a clearance rate of about 70 % for both bacterial biofilms within three days and a growth rate of more than 80 % for mouse fibroblasts NIH 3 T3. These lignin-based polyurethane biofoam dressings, with shorter antiseptic sterilization times and broad-spectrum antibacterial effects, are extremely advantageous for infected wound treatment and healing in clinical use.

Functional fluorescent nanomaterials for the detection, diagnosis and control of bacterial infection and biofilm formation: Insight towards mechanistic aspects and advanced applications

Infectious diseases resulting from the high pathogenic potential of several bacteria possesses a major threat to human health and safety. Traditional methods used for screening of these microorganisms face major issues with respect to detection time, selectivity and specificity which may delay treatment for critically ill patients past the optimal time. Thus, a convincing and essential need exists to upgrade the existing methodologies for the fast detection of bacteria. In this context, increasing number of newly emerging nanomaterials (NMs) have been discovered for their effective use and applications in the area of diagnosis in bacterial infections. Recently, functional fluorescent nanomaterials (FNMs) are extensively explored in the field of biomedical research, particularly in developing new diagnostic tools, nanosensors, specific imaging modalities and targeted drug delivery systems for bacterial infection. It is interesting to note that organic fluorophores and fluorescent proteins have played vital role for imaging and sensing technologies for long, however, off lately fluorescent nanomaterials are increasingly replacing these due to the latter's unprecedented fluorescence brightness, stability in the biological environment, high quantum yield along with high sensitivity due to enhanced surface property etc. Again, taking advantage of their photo-excitation property, these can also be used for either photothermal and photodynamic therapy to eradicate bacterial infection and biofilm formation. Here, in this review, we have paid particular attention on summarizing literature reports on FNMs which includes studies detailing fluorescence-based bacterial detection methodologies, antibacterial and antibiofilm applications of the same. It is expected that the present review will attract the attention of the researchers working in this field to develop new engineered FNMs for the comprehensive diagnosis and treatment of bacterial infection and biofilm formation.

In Situ Growth of Functional Hydrogel Coatings by a Reactive Polyurethane for Biomedical Devices

Surface modification of thermoplastic polyurethane (TPU) could significantly enhance its suitability for biomedical devices and public health products. Nevertheless, customized modification of polyurethane surfaces with robust interfacial bonding and diverse functions via a simple method remains an enormous challenge. Herein, a novel thermoplastic polyurethane with a photoinitiated benzophenone unit (BPTPU) is designed and synthesized, which can directly grow functional hydrogel coating on polyurethane (PU) in situ by initiating polymerization of diverse monomers under ultraviolet irradiation, without the involvement of organic solvent. The resulting coating not only exhibits tissue-like softness, controllable thickness, lubrication, and robust adhesion strength but also provides customized functions (i.e., antifouling, stimuli-responsive, antibacterial, and fluorescence emission) to the original passive polymer substrates. Importantly, BPTPU can be blended with commercial TPU to produce the BPTPU-based tube by an extruder. Only a trace amount of BPTPU can endow the tube with good photoinitiated capacity. As a proof of concept, the hydrophilic hydrogel-coated BPTPU is shown to mitigate foreign body response in vivo and prevent thrombus formation in rat blood circulation without anticoagulants in vitro. This work offers a new strategy to guide the design of functional polyurethane, an elastomer-hydrogel composite, and holds great prospects for clinical translation.

Antimicrobial Peptide-Inspired Design of Amino-Modified Lignin with Improved Antimicrobial Activities

A major challenge to make use of lignin as an antimicrobial material is the weak antimicrobial activity of industrial lignin. Inspired by the antimicrobial mechanism of actions of antimicrobial peptides, alkyldiamines were employed as lysine mimics for lignin modifications. Accordingly, aminoalkyl-modified lignins with different degrees of substitution of amino groups and different hydrophobicity were synthesized. The chemical structure, properties, and antimicrobial activities of the as-prepared aminoalkyl lignins were thoroughly characterized with state-of-the-art technologies. The results indicated that aminobutyl lignin showed enhanced antimicrobial activity against S. aureus and E. coli and performed even better than copper ions. The antimicrobial mechanism of action of the as-prepared aminobutyl lignin was similar to that of polylysine, which damaged the cell membrane, leading to the leakage of intracellular molecules and death of the cell. This study provides a feasible approach to afford modified lignin with enhanced antimicrobial performance, which would facilitate the high-value valorization of lignin as biological materials.

Confronting the Threat: Designing Highly Effective bis-Benzimidazolium Agents to Overcome Biofilm Persistence and Antimicrobial Resistance

The objective of this study is to take the initial steps toward developing novel antibiotics to counteract the escalating problem of antimicrobial and bacterial persistence, particularly in relation to biofilms. Our approach involves emulating the structural characteristics of cationic antimicrobial peptides. To circumvent resistance development, we have designed a library of bis-benzimidazolium salts that selectively target the microbial membranes in a nonspecific manner. To explore their structure-activity relationship, we conducted experiments using these compounds on various pathogens known for their resistance to conventional antibiotics, including Gram-positive methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecium (VRE), and Gram-negative Escherichia coli (E. coli). Notably, two bis-benzimidazolium salts exhibited robust antimicrobial activity while maintaining a high level of selectivity compared with mammalian cells. Our investigations revealed significant antibiofilm activity, as these compounds rapidly acted against established biofilms. In addition, bis-benzimidazolium compounds exhibited consistent results in resistance development and cross-resistance studies. Consequently, amphiphilic bis-benzimidazolium salts hold promise as potential candidates to combat resistance-associated infections.

Nanotechnology-Based Drug Delivery Systems to Control Bacterial-Biofilm-Associated Lung Infections

Airway mucus dysfunction and impaired immunological defenses are hallmarks of several lung diseases, including asthma, cystic fibrosis, and chronic obstructive pulmonary diseases, and are mostly causative factors in bacterial-biofilm-associated respiratory tract infections. Bacteria residing within the biofilm architecture pose a complex challenge in clinical settings due to their increased tolerance to currently available antibiotics and host immune responses, resulting in chronic infections with high recalcitrance and high rates of morbidity and mortality. To address these unmet clinical needs, potential anti-biofilm therapeutic strategies are being developed to effectively control bacterial biofilm. This review focuses on recent advances in the development and application of nanoparticulate drug delivery systems for the treatment of biofilm-associated respiratory tract infections, especially addressing the respiratory barriers of concern for biofilm accessibility and the various types of nanoparticles used to combat biofilms. Understanding the obstacles facing pulmonary drug delivery to bacterial biofilms and nanoparticle-based approaches to combatting biofilm may encourage researchers to explore promising treatment modalities for bacterial-biofilm-associated chronic lung infections.

An Immunomodulatory Biomimetic Single-Atomic Nanozyme for Biofilm Wound Healing Management

Nanozyme-driven catalytic antibacterial therapy has become a promising modality for bacterial biofilm infections. However, current catalytic therapy of biofilm wounds is severely limited by insufficient catalytic efficiency, excessive inflammation, and deep tissue infection. Drawing from the homing mechanism of natural macrophages, herein, a hollow mesoporous biomimetic single-atomic nanozyme (SAN) is fabricated to actively target inflamed parts, suppress inflammatory factors, and eliminate deeply organized bacteria for enhance biofilm eradication. In the formulation, this biomimetic nanozyme (Co@SAHSs@IL-4@RCM) consists of IL-4-loaded cobalt SANs-embedded hollow sphere encapsulate by RAW 264.7 cell membrane (RCM). Upon accumulation at the infected sites through the specific receptors of RCM, Co@SAHS catalyze the conversion of hydrogen peroxide into hydroxyl radicals and are further amplify by NIR-II photothermal effect and glutathione depletion to permeate and destroy biofilm structure. This behavior subsequently causes the dissociation of RCM shell and the ensuing release of IL-4 that can reprogram macrophages, enabling suppression of oxidative injury and tissue inflammation. The work paves the way to engineer alternative "all-in-one" SANs with an immunomodulatory ability and offers novel insights into the design of bioinspired materials.

Nitric Oxide-Assisted Photodynamic Therapy for Enhanced Penetration and Hypoxic Bacterial Biofilm Elimination

The presence of a biofilm matrix barrier and hypoxic microenvironment within the biofilm significantly impedes the efficacy of photodynamic therapy for bacterial biofilm infections. Herein, a phototherapeutic nanoagent with type-I photodynamic behavior and nitric oxide (NO) release performance is reported for overcoming biofilm-associated infectious diseases. Sodium nitroprusside (SNP), a NO donor, is loaded onto amino-modified mesoporous silica nanoparticles (MSN) to form MSN@SNP NPs. The resulting nanoparticles are further modified with a porphyrin-based metal-organic framework (Ti-TCPP MOF) to obtain MSN@MOF/SNP NPs (MMS NPs) for phototherapeutic applications. In the hypoxia biofilm microenvironment, the MMS NPs release NO to enhance the biofilm permeability and induce the generation of hydroxyl radical (•OH) and superoxide anion radical (O2 •- ) via Type-I photodynamic pathway under laser irradiation. Subsequently, the biofilm-associated infections are effectively eliminated through reactive oxygen species (ROS) and NO gas synergistic therapy. In addition, NO also stimulates collagen deposition and promotes angiogenesis in vivo. Therefore, the MMS NPs efficiently treat biofilm-related infections, providing an alternative approach to combat biofilm-associated infectious diseases.

Janus nanoparticles targeting extracellular polymeric substance achieve flexible elimination of drug-resistant biofilms

Safe and efficient antibacterial materials are urgently needed to combat drug-resistant bacteria and biofilm-associated infections. The rational design of nanoparticles for flexible elimination of biofilms remains challenging. Herein, we propose the fabrication of Janus-structured nanoparticles targeting extracellular polymeric substance to achieve dispersion or near-infrared (NIR) light-activated photothermal elimination of drug-resistant biofilms, respectively. Asymmetrical Janus-structured dextran-bismuth selenide (Dex-BSe) nanoparticles are fabricated to exploit synergistic effects of both components. Interestingly, Janus Dex-BSe nanoparticles realize enhanced dispersal of biofilms over time. Alternatively, taking advantage of the preferential accumulation of nanoparticles at infection sites, the self-propelled active motion induced by the unique Janus structure enhances photothermal killing effect. The flexible application of Janus Dex-BSe nanoparticles for biofilm removal or NIR-triggered eradication in vivo is demonstrated by Staphylococcus aureus-infected mouse excisional wound model and abscess model, respectively. The developed Janus nanoplatform holds great promise for the efficient elimination of drug-resistant biofilms in diverse antibacterial scenarios.

Size-Controlled Ammonium-Based Homopolymers as Broad-Spectrum Antibacterials

Ammonium group containing polymers possess inherent antimicrobial properties, effectively eliminating or preventing infections caused by harmful microorganisms. Here, homopolymers based on monomers containing ammonium groups were synthesized via Reversible Addition Fragmentation Chain Transfer Polymerization (RAFT) and evaluated as potential antibacterial agents. The antimicrobial activity was evaluated against Gram-positive (M. luteus and B. subtilis) and Gram-negative bacteria (E. coli and S. typhimurium). Three polymers, poly(diallyl dimethyl ammonium chloride), poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride), and poly(vinyl benzyl trimethylammonium chloride), were examined to explore the effect of molecular weight (10 kDa, 20 kDa, and 40 kDa) on their antimicrobial activity and toxicity to mammalian cells. The mechanisms of action of the polymers were investigated with dye-based assays, while Scanning Electron Microscopy (SEM) showed collapsed and fused bacterial morphologies due to the interactions between the polymers and components of the bacterial cell envelope, with some polymers proving to be bactericidal and others bacteriostatic, while being non-hemolytic. Among all the homopolymers, the most active, non-Gram-specific polymer was poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride), with a molecular weight of 40 kDa, with minimum inhibitory concentrations between 16 and 64 µg/mL, showing a bactericidal mode of action mediated by disruption of the cytoplasmic membrane. This homopolymer could be useful in biomedical applications such as surface dressings and in areas such as eye infections.

Chiral Sulfur Nanosheets for Dual-Selective Inhibition of Gram-Positive Bacteria

Elemental sulfur is the oldest known antimicrobial agent. However, conventional sulfur in the clinic suffers from poor aqueous solubility and limited antibacterial activity, greatly hindering its practical use. Herein, we report a reform strategy coupling dimension engineering with chirality transfer to convert conventional 3D sulfur particles into chiral 2D sulfur nanosheets (S-NSs), which exhibit 50-fold improvement of antibacterial capability and dual-selective inhibition against Gram-positive bacteria. Benefiting from the inherent selectivity of S-NSs and chirality selectivity from decorated d-histidine, the obtained chiral S-NSs are proven to precisely kill Gram-positive drug-resistant bacteria, while no obvious bacterial inhibition is observed for Gram-negative bacteria. Mechanism studies reveal that S-NSs produce numerous reactive oxygen specipoes and hydrogen sulfide after incubation with bacteria, thus causing bacterial membrane destruction, respiratory chain damage, and ATP production inhibition. Upon spraying chiral S-NSs dispersions onto MRSA-infected wounds, the skin healing process was greatly accelerated in 8 days due to metabolism inhibition and oxidative damage of bacteria, indicating the excellent treatment efficiency of MRSA-infected wounds. This work converts the traditional well-known sulfur into modern antibacterial agents with a superior Gram-selectivity bactericidal capability.

Interfacial assembly of chitin/Mn3O4 composite hydrogels as photothermal antibacterial platform for infected wound healing

To combat bacteria and even biofilm infections, developing alternative antibacterial wound dressings independent of antibiotics is imperative. Herein, this study developed a series of bioactive chitin/Mn3O4 composite hydrogels under mild conditions for infected wound healing application. The in situ synthesized Mn3O4 NPs homogeneously distribute throughout chitin networks and strongly interact with chitin matrix, and as well as endow the chitin/Mn3O4 hydrogels with NIR-assisted outstanding photothermal antibacterial and antibiofilm activities. Meantime, the chitin/Mn3O4 hydrogels exhibit favorable biocompatibility and antioxidant property. Furthermore, the chitin/Mn3O4 hydrogels with the assist of NIR show an excellent skin wound healing performance in a mouse full-thickness S. aureus biofilms-infected wound model, by accelerating the phase transition from inflammation to remodeling. This study broadens the scope for the fabrication of chitin hydrogels with antibacterial property, and offers an excellent alternative for the bacterial-associated wound infection therapy.

Aggregates-based fluorescence sensing technology for food hazard detection: Principles, improvement strategies, and applications

Aggregates often exhibit modified or completely new properties compared with their molecular elements, making them an extraordinarily advantageous form of materials. The fluorescence signal change characteristics resulting from molecular aggregation endow aggregates with high sensitivity and broad applicability. In molecular aggregates, the photoluminescence properties at the molecular level can be annihilated or elevated, leading to aggregation-causing quenching (ACQ) or aggregation-induced emission (AIE) effects. This change in photoluminescence properties can be intelligently introduced in food hazard detection. Recognition units can combine with the aggregate-based sensor by joining the aggregation process, endowing the sensor with the high specificity of analytes (such as mycotoxins, pathogens, and complex organic molecules). In this review, aggregation mechanisms, structural characteristics of fluorescent materials (including ACQ/AIE-activated), and their applications in food hazard detection (with/without recognition units) are summarized. Because the design of aggregate-based sensors may be influenced by the properties of their components, the sensing mechanisms of different fluorescent materials were described separately. Details of fluorescent materials, including conventional organic dyes, carbon nanomaterials, quantum dots, polymers and polymer-based nanostructures and metal nanoclusters, and recognition units, such as aptamer, antibody, molecular imprinting, and host-guest recognition, are discussed. In addition, future trends of developing aggregate-based fluorescence sensing technology in monitoring food hazards are also proposed.

PTT/ PDT-induced Microbial Apoptosis and Wound Healing Depend on Immune Activation and Macrophage Phenotype Transformation

Antibiotics show unsuccessful application in biofilm destruction, which induce chronic infections and emergence of antibiotic resistant bacteria. Photodynamic therapy (PDT) and photothermal therapy (PTT), as widely accepted antimicrobial tools of phototherapy, could effectively activate the immune system and promote the proliferation of wound tissue, thus becoming the most promising therapeutic strategy to replace antibiotics and avoid drug-resistant strains. However, there is no consensus on whether antibacterial and wound healing achieved by PDT/PTT depend not only on the cytotoxic effect of the treatment itself, but also on the activation of host immune system. In this study, CaSiO₃-ClO₂@PDA-ICG nanoparticles (CCPI NPs) were designed as PDT/PTT antimicrobial model material. With the comparison of healing effect between wide-type mice and severely immunodeficient (C-NKG) mice, the dependence of PDT/PTT-induced microbial apoptosis and wound healing on immune activation and macrophage phenotype transformation was explored and verified. Furthermore, the induced phenotypic transformation of macrophages during PDT/PTT treatment was demonstrated to play crucial role in the improvement of epithelial-mesenchymal transformation (EMT). In summary, this study represents great significance for further identifying the role of immune system activation in antibacterial phototherapy and developing new treatment strategies for biofilm-infected wound healing. STATEMENT OF SIGNIFICANCE: A PDT/PTT combination therapy model nanoparticle was established for biofilm-infected wounds. Both microbial apoptosis and wound healing achieved by PDT/PTT combination therapy were highly dependent on the activated immune system, especially the M2 macrophage phenotype. PDT/PTT could promote the polarization of monocytes to the phenotype of M2 macrophages, which promotes EMT behavior of the tissue at the edge of the wound through the secretion of TGF-β1, thus accelerating wound healing.

Combining SNAPs with antibiotics shows enhanced synergistic efficacy against S. aureus and P. aeruginosa biofilms

Biofilm infections are associated with a high mortality risk for patients. Antibiotics perform poorly against biofilm communities, so high doses and prolonged treatments are often used in clinical settings. We investigated the pairwise interactions of two synthetic nano-engineered antimicrobial polymers (SNAPs). The g-D50 copolymer was synergistic with penicillin and silver sulfadiazine against planktonic Staphylococcus aureus USA300 in synthetic wound fluid. Furthermore, the combination of g-D50 and silver sulfadiazine showed a potent synergistic antibiofilm activity against S. aureus USA300 using in vitro and ex vivo wound biofilm models. The a-T50 copolymer was synergistic with colistin against planktonic Pseudomonas aeruginosa in synthetic cystic fibrosis medium, and this pair showed a potent synergistic antibiofilm activity against P. aeruginosa in an ex vivo cystic fibrosis lung model. SNAPs thus have the potential for increased antibiofilm performance in combination with certain antibiotics to shorten prolonged treatments and reduce dosages against biofilm infection.