Bacterial Attachment Research Articles

Covalent Inhibition of a Host-Pathogen Protein-Protein Interaction Reduces the Infectivity of Streptococcus pneumoniae.

The ever-expanding antibiotic resistance urgently calls for novel antibacterial therapeutics, especially those with a new mode of action. We report herein our exploration of protein-protein interaction (PPI) inhibition as a new mechanism to thwart bacterial pathogenesis. Specifically, we describe potent and specific inhibitors of the pneumococcal surface protein PspC, an important virulence factor that facilitates the infection of Streptococcus pneumoniae. Specifically, PspC has been documented to recruit human complement factor H (hFH) to suppress host complement activation and/or promote the bacterial attachment to host tissues. The CCP9 domain of hFH was recombinantly expressed to inhibit the PspC-hFH interaction as demonstrated on live pneumococcal cells. The inhibitor allowed for the first pharmacological intervention of the PspC-hFH interaction. This PPI inhibition reduced pneumococci's attachment to epithelial cells and also resensitized the D39 strain of S. pneumoniae for opsonization. Importantly, we have further devised covalent versions of CCP9, which afforded long-lasting PspC inhibition with low nanomolar potency. Overall, our results showcase the promise of PPI inhibition for combating bacterial infections as well as the power of covalent inhibitors.

Adaptive attenuation of virulence in hypervirulent carbapenem-resistant Klebsiella pneumoniae.

The emergence of nosocomial infections caused by hypervirulent and carbapenem-resistant K. pneumoniae (hv-CRKP) has become a significant public health challenge. The genetic traits of virulence and resistance plasmids in hv-CRKP have been extensively studied; however, research on the adaptive evolution strategies of clinical strains inside the host was scarce. This study aimed to understand the effects of antibiotic treatment on the phenotype and genotype characteristics of hv-CRKP. We investigated the evolution of hv-CRKP strains isolated from the same patient to elucidate the transition between hospital invasion and colonization. A comparative genomics analysis was performed to identify single nucleotide polymorphisms in the rmpA promoter. Subsequent validation through RNA-seq and gene deletion confirmed that distinct rmpA promoter sequences exert control over the mucoid phenotype. Additionally, biofilm experiments, cell adhesion assays, and animal infection models were conducted to illuminate the influence of rmpA promoter diversity on virulence changes. We demonstrated that the P12T and P11T promoters of rmpA possess strong activity, which leads to the evolution of CRKP into infectious and virulent strains. Meanwhile, the specific sequence of polyT motifs in the rmpA promoter led to a decrease in the lethality of hv-CRKP and enhanced cell adhesion and colonization. To summarize, the rmpA promoter of hv-CRKP is utilized to control capsule production, thereby modifying pathogenicity to better suit the host's ecological environment.IMPORTANCEThe prevalence of hospital-acquired illness caused by hypervirulent carbapenem-resistant Klebsiella pneumoniae (hv-CRKP) is significant, leading to prolonged antibiotic treatment. However, there are few reports on the phenotypic changes of hv-CRKP in patients undergoing antibiotic treatment. We performed a comprehensive examination of the genetic evolutionary traits of hv-CRKP obtained from the same patient and observed variations in the promoter sequences of the virulence factor rmpA. The strong activity of the promoter sequences P11T and P12T enhances the consistent production of capsule polysaccharides, resulting in an invasive strain. Conversely, weak promoter activity of P9T and P10T is advantageous for exposing pili, hence improving bacterial cell attachment ability and facilitating bacterial colonization. This finding also explains the confusion of some clinical strains carrying wild-type rmpA but exhibiting a low mucoid phenotype. This adaptive alteration facilitates the dissemination of K. pneumoniae within the hospital setting.

BPP0974 is a Bordetella parapertussis adhesin expressed in the avirulent phase, implicated in biofilm formation and intracellular survival

B. parapertussis is a bacterium that causes whooping cough, a severe respiratory infection disease, that has shown an increased incidence in the population. Upon transmission through aerosol droplets, the initial steps of host colonization critically depend on the bacterial adhesins. We here described BPP0974, a B. parapertussis protein that exhibits the typical domain architecture of the large repetitive RTX adhesin family. BPP0974 was found to be retained in the bacterial membrane and secreted into the culture medium. This protein was found overexpressed in the avirulent phase of B. parapertussis, the phenotype proposed for initial host colonization. Interestingly, BPP0974 was found relevant for the biofilm formation as well as involved in the bacterial attachment to and survival within the respiratory epithelial cells. Taken together, our results suggest a role for BPP0974 in the early host colonization and pathogenesis of B. parapertussis.

Silver-Doped Titanium Oxide Layers for Improved Photocatalytic Activity and Antibacterial Properties of Titanium Implants.

Titanium has a long history of clinical use, but the naturally forming oxide is not ideal for bacterial resistance. Anodization processes can modify the crystallinity, surface topography, and surface chemistry of titanium oxides. Anatase, rutile, and mixed phase oxides are known to exhibit photocatalytic activity (PCA)-driven bacterial resistance under UVA irradiation. Silver additions are reported to enhance PCA and reduce bacterial attachment. This study investigated the effects of silver-doping additions to three established anodization processes. Silver doping showed no significant influence on oxide crystallinity, surface topography, or surface wettability. Oxides from a sulfuric acid anodization process exhibited significantly enhanced PCA after silver doping, but silver-doped oxides produced from phosphoric-acid-containing electrolytes did not. Staphylococcus aureus attachment was also assessed under dark and UVA-irradiated conditions on each oxide. Each oxide exhibited a photocatalytic antimicrobial effect as indicated by significantly decreased bacterial attachment under UVA irradiation compared to dark conditions. However, only the phosphorus-doped mixed anatase and rutile phase oxide exhibited an additional significant reduction in bacteria attachment under UVA irradiation as a result of silver doping. The antimicrobial success of this oxide was attributed to the combination of the mixed phase oxide and higher silver-doping uptake levels.

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.

Antifouling nanoplatform for controlled attachment of E. coli

Biofouling is the most common cause of bacterial contamination in implanted materials/devices resulting in severe inflammation, implant mobilization, and eventual failure. Since bacterial attachment represents the initial step toward biofouling, developing synthetic surfaces that prevent bacterial adhesion is of keen interest in biomaterials research. In this study, we develop antifouling nanoplatforms that effectively impede bacterial adhesion and the consequent biofilm formation. We synthesize the antifouling nanoplatform by introducing silicon (Si)/silica nanoassemblies to the surface through ultrafast ionization of Si substrates. We assess the effectiveness of these nanoplatforms in inhibiting Escherichia coli (E. coli) adhesion. The findings reveal a significant reduction in bacterial attachment on the nanoplatform compared to untreated silicon, with bacteria forming smaller colonies. By manipulating physicochemical characteristics such as nanoassembly size/concentration and nanovoid size, we further control bacterial attachment. These findings suggest the potential of our synthesized nanoplatform in developing biomedical implants/devices with improved antifouling properties.

Orthotic Thermoplastic Demonstrates a Similar Contamination Potential with Bacillus Bacteria Recovered from Thermoplastic Radiation Therapy Patient Masks

Thermoplastics used to construct a variety of patient medical devices can become contaminated by harmful bacteria. We investigated whether two different Bacillus species recovered from patient radiation therapy thermoplastic masks could similarly contaminate thermoplastic material used to construct patient orthoses (splints). Bacillus bacteria form dormant spores, which have been shown to enhance its attachment to thermoplastics. Bacterial attachment and recovery were examined using an orthotic thermoplastic with an anti-stick coating being compared to uncoated material used in radiation therapy applications. Triplicate sample squares were seeded with a saline suspension of either B. cereus (MAB03F) or B. megaterium (DAB01F) containing a similar number of spores. Squares were subsequently sampled at 1 h, 1 week, 2 weeks, 4 weeks, and 8 weeks. The number of recovered bacteria was counted. Differences in material hydrophobicity were determined by water contact angle analysis. Both Bacillus species attached to each material within 1 h, and their spores were recovered at 8 weeks. However, a decreasing trend in adhesion, over time, was noted to the coated material with an opposite increasing trend in the uncoated material. Decreased Bacillus species spore adhesion to coated material with a lower hydrophobicity suggests a greater potential for spore transfer to patients wearing contaminated orthoses.

An adjustable bio-sealing method for rock fracture leakage mitigation

This study proposed a repeated adjustable mixture injection strategy (RAM) based microbial induced carbonate precipitation (MICP) for efficient mitigation of rock fracture leakage. Granite fractures with small apertures were investigated, and bio-sealing experiments were conducted using five different cementation solution (CS) concentrations (0.25−2 M). The results showed that the RAM-based bio-sealing method can seal and bond the small aperture rock fractures with high efficiency and uniform precipitation by adjusting the CS concentration. The RAM-based bio-sealing mechanism is attributed to the following four stages: (1) fixation of bacterial flocs onto the fracture surfaces, (2) precipitation of CaCO3 onto the fracture surfaces, (3) growth of pre-precipitated CaCO3 and adhesion of new-suspended CaCO3, and (4) bridging and clogging processes. The optimal CS concentration of 1 M resulted in a fracture filling rate up to 85%, a transmissivity reduction of 4 orders of magnitude, and a shear strength ranging from 512 kPa to 688 kPa. The bio-sealing effect was found to be influenced by the CS concentration on bacterial attachment, calcium carbonate yield and calcium carbonate bulk density. The CS concentration of 1 M promoted bacterial attachment, and increased calcium carbonate yield as well as calcium carbonate bulk density, while concentrations above 1 M had the opposite effect. The bulk density of calcium carbonate played a crucial role in the sealing and bonding performance of bio-sealed fractures, particularly at comparable filling ratios and bridging areas. The bulk density was regulated by the size of calcium carbonate crystals and was determined by Ca2+ concentration in the CS. This study provides valuable insights into the RAM-based bio-sealing method, highlighting its potential for efficient rock fracture leakage mitigation through precise control of CS concentration and understanding the underlying mechanisms.

Pseudomonas aeruginosa senses and responds to epithelial potassium flux via Kdp operon to promote biofilm.

Mucosa-associated biofilms are associated with many human disease states, but the host mechanisms promoting biofilm remain unclear. In chronic respiratory diseases like cystic fibrosis (CF), Pseudomonas aeruginosa establishes chronic infection through biofilm formation. P. aeruginosa can be attracted to interspecies biofilms through potassium currents emanating from the biofilms. We hypothesized that P. aeruginosa could, similarly, sense and respond to the potassium efflux from human airway epithelial cells (AECs) to promote biofilm. Using respiratory epithelial co-culture biofilm imaging assays of P. aeruginosa grown in association with CF bronchial epithelial cells (CFBE41o-), we found that P. aeruginosa biofilm was increased by potassium efflux from AECs, as examined by potentiating large conductance potassium channel, BKCa (NS19504) potassium efflux. This phenotype is driven by increased bacterial attachment and increased coalescence of bacteria into aggregates. Conversely, biofilm formation was reduced when AECs were treated with a BKCa blocker (paxilline). Using an agar-based macroscopic chemotaxis assay, we determined that P. aeruginosa chemotaxes toward potassium and screened transposon mutants to discover that disruption of the high-sensitivity potassium transporter, KdpFABC, and the two-component potassium sensing system, KdpDE, reduces P. aeruginosa potassium chemotaxis. In respiratory epithelial co-culture biofilm imaging assays, a KdpFABCDE deficient P. aeruginosa strain demonstrated reduced biofilm growth in association with AECs while maintaining biofilm formation on abiotic surfaces. Furthermore, we determined that the Kdp operon is expressed in vivo in people with CF and the genes are conserved in CF isolates. Collectively, these data suggest that P. aeruginosa biofilm formation can be increased by attracting bacteria to the mucosal surface and enhancing coalescence into microcolonies through aberrant AEC potassium efflux sensed by the KdpFABCDE system. These findings suggest host electrochemical signaling can enhance biofilm, a novel host-pathogen interaction, and potassium flux could be a therapeutic target to prevent chronic infections in diseases with mucosa-associated biofilms, like CF.

Vitamin D and vitamin K1 as novel inhibitors of biofilm in Gram-negative bacteria

BackgroundThe persistent surge in antimicrobial resistance represents a global disaster. The initial attachment and maturation of microbial biofilms are intimately related to antimicrobial resistance, which in turn exacerbates the challenge of eradicating bacterial infections. Consequently, there is a pressing need for novel therapies to be employed either independently or as adjuvants to diminish bacterial virulence and pathogenicity. In this context, we propose a novel approach focusing on vitamin D and vitamin K1 as potential antibiofilm agents that target Gram-negative bacteria which are hazardous to human health.ResultsOut of 130 Gram-negative bacterial isolates, 117 were confirmed to be A. baumannii (21 isolates, 17.9%), K. pneumoniae (40 isolates, 34.2%) and P. aeruginosa (56 isolates, 47.9%). The majority of the isolates were obtained from blood and wound specimens (27.4% each). Most of the isolates exhibited high resistance rates to β-lactams (60.7–100%), ciprofloxacin (62.5–100%), amikacin (53.6–76.2%) and gentamicin (65-71.4%). Approximately 93.2% of the isolates were biofilm producers, with 6.8% categorized as weak, 42.7% as moderate, and 50.4% as strong biofilm producers. The minimum inhibitory concentrations (MICs) of vitamin D and vitamin K1 were 625–1250 µg mL-1 and 2500–5000 µg mL-1, respectively, against A. baumannii (A5, A20 and A21), K. pneumoniae (K25, K27 and K28), and P. aeruginosa (P8, P16, P24 and P27) clinical isolates and standard strains A. baumannii (ATCC 19606 and ATCC 17978), K. pneumoniae (ATCC 51503) and P. aeruginosa PAO1 and PAO14. Both vitamins significantly decreased bacterial attachment and significantly eradicated mature biofilms developed by the selected standard and clinical Gram-negative isolates. The anti-biofilm effects of both supplements were confirmed by a notable decrease in the relative expression of the biofilm-encoding genes cusD, bssS and pelA in A. baumannii A5, K. pneumoniae K28 and P. aeruginosa P16, respectively.ConclusionThis study highlights the anti-biofilm activity of vitamins D and K1 against the tested Gram-negative strains, which emphasizes the potential of these vitamins for use as adjuvant therapies to increase the efficacy of treatment for infections caused by multidrug-resistant (MDR) strains and biofilm-forming phenotypes. However, further validation through in vivo studies is needed to confirm these promising results.

Biofilm ablation on titanium alloy surface by photothermal and chemotherapeutic synergistic therapy

With prolonged exposure in the human body, titanium alloy implants face challenges associated with bacterial attachment and proliferation, leading to implant failure and severe complications. Photothermal therapy (PTT) emerges as an efficient strategy for biofilm elimination. However, the local high temperature of PTT and incomplete bacteria ablation in low-temperature PTT pose risks of damage to normal tissues and biofilm recalcitrance, respectively. In this study, we synergistically combined photothermal therapy and chemotherapy to mildly disrupt biofilms of Staphylococcus aureus (S. aureus) to enhance the efficiency of biofilm ablation. The synergistic nanoplatform comprises near-infrared-light responsive conjugated polymers, heat-sensitive liposomes, and the antibiotic daptomycin for biofilm elimination. The heat generated by conjugated polymers, stimulated with 808 nm light, alters biofilm permeability and releases antibiotics locally to eradicate biofilm. The nanoparticles exhibit biofilm dispersion activity and can effectively inhibit biofilm growth for up to 5 days. Consequently, this nanoplatform based on conjugated polymers offers a reliable method for ablating biofilms on titanium alloy implant and exhibits potential in drug-resistant clinical applications.

Bacterial transport mediated by micro-nanobubbles in porous media

Determining the role of micro-nanobubbles (MNBs) in controlling the risk posed by pathogens to soil and groundwater during reclaimed water irrigation requires clarification of the mechanism of how MNBs block pathogenic bacteria. In this study, real-time bioluminescence imaging was used to investigate the effects of MNBs on the transport and spatiotemporal distribution of bioluminescent Escherichia coli 652T7 strain in porous media. The presence of MNBs significantly increased the retention of bacteria in the porous media, decreasing the maximum relative effluent concentration (C/C0) by 78 % from 0.97 (without MNBs) to 0.21 (with MNBs). The results suggested that MNBs provided additional sites at the air-water interface (AWI) for bacterial attachment and acted as physical obstacles to reduce bacterial passage. These effects varied with environmental conditions such as solution ionic strength and pore water velocity. The results indicated that MNBs enhanced electrostatic attachment of bacteria at the AWI and their mechanical straining in pores. This study suggests that adding MNBs in pathogen-containing water is an effective measure for increasing filtration efficiency and reducing the risk of pathogenic contamination during agricultural irrigation.

Effect of Bleaching Agents on Healthy Enamel, White Spots, and Carious Lesions: A Systematic Review and Meta-Analysis.

This systematic review examines studies focusing on tooth bleaching and its effects on healthy enamel or incipient caries and bacterial adhesion. The aim is to explore the impact of different bleaching agents on incipient caries lesions and healthy enamel. Clinical studies, in vitro studies, and observational studies that compared at least two groups were included. A search strategy was used to select studies from the MEDLINE via Pubmed and Scopus databases. Two evaluators performed data extraction, screening, and quality assessment independently. Only studies written in English were included. From 968 initial records, 28 studies were selected for a full-text evaluation. Of these, 7 studies were classified as cluster 1 (bacterial adherence on teeth), 12 studies as cluster 2 (no bacteria involved), 4 studies as cluster 3 (no teeth deployment), and 5 clinical studies were cluster 4. Of the selected studies, 6 (21.4%) supported increased bacterial attachment capacity and cariogenic dynamics, 4 (14.3%) decreased adhesion and cariogenic activity, 7 (25%) showed no difference, and 11 (39.3%) followed a different methodological approach and could not be categorized. The risk of bias appeared to be high, mainly because of the different methodologies in the studies, so we cannot reach a confident conclusion. Nevertheless, as far as carbamide peroxide bleaching is concerned, there does not seem to be a clinically significant alteration, neither in microorganism counts nor in enamel microstructure.

Electrochemical polymerization of PEDOT:PSS with graphene oxide and silver nanoparticles for antibacterial coating and SERS detection

This study involved the use of electrochemical polymerization to coat poly(3,4-ethylenedioxythiophene) (PEDOT), polystyrene sulfonate (PSS) and graphene oxide (GO) onto SUS316L stainless steel substrates, aiming to produce PEDOT:PSS and GO@PEDOT:PSS films. Following this, Ag@PEDOT:PSS and GO/Ag@PEDOT:PSS films were developed through the electrochemical deposition of silver nitrate. Electrochemical impedance spectroscopy (EIS) indicated that adding GO increased the impedance of film, while AgNPs deposition decreased it, thereby enhancing conductivity. Films with AgNPs showed surface enhanced Raman scattering (SERS) effects, as assessed using malachite green (MG). Compared to films without GO, the GO/Ag@PEDOT:PSS films exhibit enhanced conductivity and SERS detection performance due to the negatively charged functional groups on the GO surface forming a continuous layer of AgNPs. Moreover, antibacterial capabilities were evaluated through bacterial attachment and inhibition zone assays. Both Ag@PEDOT:PSS and GO/Ag@PEDOT:PSS films were effective in inhibiting bacterial adhesion, achieving up to 99.4 % and 99.0 % inhibition, respectively. In the inhibition zone assays, the GO/Ag@PEDOT:PSS film showed a 1.33 times increase in antibacterial efficacy compared to Ag@PEDOT:PSS. Furthermore, the effectiveness of electrodepositing antibiotics on these substrates was investigated, confirming optimal antibacterial performance. This efficacy is attributed to the synergistic interaction between silver nanoparticles and antibiotics, potentially reducing the need for antibiotics. The findings of this study highlight its significant potential for applications in antibacterial treatments and biomedical detection.

Current and emerging strategies to curb antibiotic-resistant urinary tract infections.

Rising rates of antibiotic resistance in uropathogenic bacteria compromise patient outcomes and prolong hospital stays. Consequently, new strategies are needed to prevent and control the spread of antibiotic resistance in uropathogenic bacteria. Over the past two decades, sizeable clinical efforts and research advances have changed urinary tract infection (UTI) treatment and prevention strategies to conserve antibiotic use. The emergence of antimicrobial stewardship, policies from national societies, and the development of new antimicrobials have shaped modern UTI practices. Future UTI management practices could be driven by the evolution of antimicrobial stewardship, improved and readily available diagnostics, and an improved understanding of how the microbiome affects UTI. Forthcoming UTI treatment and prevention strategies could employ novel bactericidal compounds, combinations of new and classic antimicrobials that enhance bacterial killing, medications that prevent bacterial attachment to uroepithelial cells, repurposing drugs, and vaccines to curtail the rising rates of antibiotic resistance in uropathogenic bacteria and improve outcomes in people with UTI.

Transparent and mechanically durable silicone/ZrO2 sol hybrid coating with enhanced antifouling properties

Achieving a delicate equilibrium between the mechanical and antifouling attributes of silicone-based coatings remains a formidable task. This research unveiled a novel approach to crafting a hybrid antifouling coating through the amalgamation of an amphiphilic telomer, Zirconia (ZrO2) sol, triethoxyoctylsilane (KH832) and tetraethyl orthosilicate (TEOS) using an uncomplicated sol–gel technique. The amphiphilic telomer, derived from a synthesized antibacterial acrylamide-benzothiazole small molecule, hydrophobic silanes/fluorosilanes, and hydrophilic monomers, was intricately tethered with the ZrO2 sol, synthesized through the hydrolysis of n-propyl zirconate. The resultant coating achieved exceptional transparency (>98 % transmittance), attributed to the covalent linkage between the robust zirconia structure and the pliable, long-chain telomer. This unique bonding imparted the coating with remarkable characteristics, including high hardness (4–6H), flexibility (∼5 mm bending diameter), wear resistance, and strong adhesion (∼2.89 MPa) to the substrate. Furthermore, the self-enrichment property of the non-leaching amphiphilic telomer within the hybrid matrix contributed to the coating’s outstanding self-cleaning capabilities, as well as its remarkable ability to resist fouling, including bacterial adhesion, protein attachment, diatom deposition, and biofilm formation. Overall, our research systematically explored the influence of composition and structure on both mechanical properties and antifouling performance. Ultimately, we sought to advance the development of a high-performance organic–inorganic hybrid antifouling coating poised to address the diverse requirements of applications spanning optical instruments, foldable displays, marine facilities, and various other fields.

Two-photon lithography for customized microstructured surfaces and their influence on wettability and bacterial load

BackgroundDevice-related bacterial infections account for a large proportion of hospital-acquired infections. The ability of bacteria to form a biofilm as a protective shield usually makes treatment impossible without removal of the implant. Topographic surfaces have attracted considerable attention in studies seeking antibacterial properties without the need for additional antimicrobial substances. As there are still no valid rules for the design of antibacterial microstructured surfaces, a fast, reproducible production technique with good resolution is required to produce test surfaces and to examine their effectiveness with regard to their antibacterial properties.MethodsIn this work various surfaces, flat and with microcylinders in different dimensions (flat, 1, 3 and 9 μm) with a surface area of 7 × 7 mm were fabricated with a nanoprinter using two-photon lithography and evaluated for their antibiofilm effect. The microstructured surfaces were cultured for 24 h with different strains of Pseudomonas aeruginosa and Staphylococcus aureus to study bacterial attachment to the patterned surfaces. In addition, surface wettability was measured by a static contact angle measurement.ResultsContact angles increased with cylinder size and thus hydrophobicity. Despite the difference in wettability, Staphylococcus aureus was not affected by the microstructures, while for Pseudomonas aeruginosa the bacterial load increased with the size of the cylinders, and compared to a flat surface, a reduction in bacteria was observed for one strain on the smallest cylinders.ConclusionsTwo-photon lithography allowed rapid and flexible production of microcylinders of different sizes, which affected surface wettability and bacterial load, however, depending on bacterial type and strain.

Superamphophilic antimicrobial membrane engineered with zinc-coordinated metallo-polymeric framework nanocoating

The combat against contamination by trace amounts of water and bacteria in aviation fuel remains a challenge, necessitating a comprehensive strategy. Here, a superamphophilic antimicrobial membrane is developed by featuring a stable zinc-coordinated polydopamine metallo-polymeric framework (PDA/Zn) on the skeleton of polyethylene terephthalate (PET) non-woven fabric. The formation of the PDA/Zn framework is streamlined through dopamine polymerization synchronized with metallo-ion coordination. This work delves into the intrinsic stability and superamphiphilic properties of the PDA/Zn framework, as well as systematically investigates its performance in fuel dehydration and carbophilus elimination. The resulting membrane exhibits a high gravity-driven flux and achieves a significant reduction in water content to below 10 ppm in aviation fuel, attributed to a demulsification and aggregation mechanism. Furthermore, our findings highlight the nearly complete antibacterial multifunctionality of the proposed membrane. It effectively prevents bacterial attachment at the liquid-solid interface and brings about bacterial eradication through the presence of Zn2+ ions and the mechanical puncturing effect of nanostructure cusps. This work not only advances applications in water dehydration and bacterial elimination but also pioneers opportunities for designing advanced functional membranes with multifaceted functionalities, including anti-fouling, self-cleaning, and antimicrobial properties, setting the stage for broader applications in membrane field.

One-step rapid formation of wrinkled fractal antibiofouling coatings from environmentally friendly, waste-derived terpenes

Wrinkled coatings are a potential drug-free method for mitigating bacterial attachment and biofilm formation on materials such as medical and food grade steel. However, their fabrication typically requires multiple steps and often the use of a stimulus to induce wrinkle formation. Here, we report a facile plasma-based method for rapid fabrication of thin (<250 nm) polymer coatings from a single environmentally friendly precursor, where wrinkle formation and fractal pattern development are controlled solely by varying the deposition time from 3 s to 60 s. We propose a mechanism behind the observed in situ development of wrinkles in plasma, as well as demonstrate how introducing specific topographical features on the surface of the substrata can result int the formation of even more complex, ordered wrinkle patterns arising from the non-uniformity of plasma when in contact with structured surfaces. Thus-fabricated wrinkled surfaces show good adhesion to substrate and an antifouling activity that is not observed in the equivalent smooth coatings and hence is attributed to the specific pattern of wrinkles.

Role of Staphylococcus aureus's Buoyant Density in the Development of Biofilm Associated Antibiotic Susceptibility.

Biofilms are clusters of microorganisms that form at various interfaces, including those between air and liquid or liquid and solid. Due to their roles in enhancing wastewater treatment processes, and their unfortunate propensity to cause persistent human infections through lowering antibiotic susceptibility, understanding and managing bacterial biofilms is of paramount importance. A pivotal stage in biofilm development is the initial bacterial attachment to these interfaces. However, the determinants of bacterial cell choice in colonizing an interface first and heterogeneity in bacterial adhesion remain elusive. Our research has unveiled variations in the buoyant density of free-swimming Staphylococcus aureus cells, irrespective of their growth phase. Cells with a low cell buoyant density, characterized by fewer cell contents, exhibited lower susceptibility to antibiotic treatments (100 μg/mL vancomycin) and favored biofilm formation at air-liquid interfaces. In contrast, cells with higher cell buoyant density, which have richer cell contents, were more vulnerable to antibiotics and predominantly formed biofilms on liquid-solid interfaces when contained upright. Cells with low cell buoyant density were not able to revert to a more antibiotic sensitive and high cell buoyant density phenotype. In essence, S. aureus cells with higher cell buoyant density may be more inclined to adhere to upright substrates.