Bacterial Adhesion Research Articles

Harmonizing Thickness and Permeability in Bone Tissue Engineering: A Novel Silk Fibroin Membrane Inspired by Spider Silk Dynamics.

Guided bone regeneration gathers significant interest in the realm of bone tissue engineering; however, the interplay between membrane thickness and permeability continues to pose a challenge that can be addressed by the water-collecting mechanism of spider silk, where water droplets efficiently move from smooth filaments to rough conical nodules. Inspired by the natural design of spider silk, an innovative silk fibroin membrane is developed featuring directional fluid transportation via harmoniously integrating a smooth, dense layer with a rough, loose layer; conical microchannels are engineered in the smooth and compact layer. Consequently, double-layered membranes with cone-shaped microporous passageways (CSMP-DSF membrane) are designed for in situ bone repair. Through extensive in vitro testing, it is noted that the CSMP-DSF membrane guides liquid flow from the compact layer's surface to the loose layer, enabling rapid diffusion. Remarkably, the CSMP-DSF membrane demonstrates superior mechanical properties and resistance to bacterial adhesion. When applied in vivo, the CSMP-DSF membrane achieves results on par with the commercial Bio-Gide collagen membranes. This innovative integration of a cross-thickness wetting gradient structure offers a novel solution, harmonizing the often-conflicting requirements of material transport, mechanical strength, and barrier effectiveness, while also addressing issues related to tissue engineering scaffold perfusion.

Dynamic membrane filtration accelerates electroactive biofilms in bioelectrochemical systems

Bioelectrochemical systems (BES) have emerged as a dual-function technology for treating wastewater and recovering energy. A vital element of BES is the rapid formation and maintenance of electroactive biofilms (EABs). Previous attempts to accelerate EAB formation and improve electroactivities focused on enhancing the bacterial adhesion process while neglecting the rate-limiting step of the bacterial transport process. Here, we introduce membrane filtration into BES, establishing a dynamic membrane filtration system that enhances overall performance. We observed that optimal membrane flux considerably reduced the startup time for EAB formation. Specifically, EABs established under a 25 L m−2 h−1 flux (EAB25 LMH) had a formation time of 43.8 ± 1.3 h, notably faster than the 51.4 ± 1.6 h in the static state (EAB0 LMH). Additionally, EAB25 LMH exhibited a significant increase in maximum current density, approximately 2.2 times higher than EAB0 LMH. Pearson correlation analysis indicated a positive relationship between current densities and biomass quantities and an inverse correlation with startup time. Microbial analysis revealed two critical findings: (i) variations in maximum current densities across different filtration conditions were associated with redox-active substances and biomass accumulation, and (ii) the incorporation of a filtration process in EAB formation enhanced the proportion of viable cells and encouraged a more diverse range of electroactive bacteria. Moreover, the novel electroactive membrane demonstrated sustained current production and effective solid-liquid separation during prolonged operation, indicating its potential as a viable alternative in membrane-based systems. This approach not only provides a new operational model for BES but also holds promise for expanding its application in future wastewater treatment solutions.

A Hypothetical Approach to Concentrate Microorganisms from Human Urine Samples Using Paper-Based Adsorbents for Point-of-Care Molecular Assays.

This hypothesis demonstrates that the efficiency of loop-mediated isothermal amplification (LAMP) for nucleic acid detection can be positively influenced by the preconcentration of microbial cells onto hydrophobic paper surfaces. The mechanism of this model is based on the high affinity of microbes towards hydrophobic surfaces. Extensive studies have demonstrated that hydrophobic surfaces exhibit enhanced bacterial and fungal adhesion. By exploiting this inherent affinity of hydrophobic paper substrates, the preconcentration approach enables the adherence of a greater number of target cells, resulting in a higher concentration of target templates for amplification directly from urine samples. In contrast to conventional methods, which often involve complex procedures, this approach offers a simpler, cost-effective, and user-friendly alternative. Moreover, the integration of cell adhesion, LAMP amplification, and signal readout within paper origami-based devices can provide a portable, robust, and highly efficient platform for rapid nucleic acid detection. This innovative hypothesis holds significant potential for point-of-care (POC) diagnostics and field surveillance applications. Further research and development in this field will advance the implementation of this technology, contributing to improved healthcare systems and public health outcomes.

Recent Progress in antibacterial hydrogel coatings for targeting biofilm to prevent orthopedic implant-associated infections.

The application of orthopedic implants for bone tissue reconstruction and functional restoration is crucial for patients with severe bone fractures and defects. However, the abiotic nature of orthopedic implants allows bacterial adhesion and colonization, leading to the formation of bacterial biofilms on the implant surface. This can result in implant failure and severe complications such as osteomyelitis and septic arthritis. The emergence of antibiotic-resistant bacteria and the limited efficacy of drugs against biofilms have increased the risk of orthopedic implant-associated infections (OIAI), necessitating the development of alternative therapeutics. In this regard, antibacterial hydrogels based on bacteria repelling, contact killing, drug delivery, or external assistance strategies have been extensively investigated for coating orthopedic implants through surface modification, offering a promising approach to target biofilm formation and prevent OIAI. This review provides an overview of recent advancements in the application of antibacterial hydrogel coatings for preventing OIAI by targeting biofilm formation. The topics covered include: (1) the mechanisms underlying OIAI occurrence and the role of biofilms in exacerbating OIAI development; (2) current strategies to impart anti-biofilm properties to hydrogel coatings and the mechanisms involved in treating OIAI. This article aims to summarize the progress in antibacterial hydrogel coatings for OIAI prevention, providing valuable insights and facilitating the development of prognostic markers for the design of effective antibacterial orthopedic implants.

(Invited) Advanced Scanning Probe Microscopy for Studying Biofilm Formation and Single Cell Entities at Electrified Interfaces

Advanced scanning probe microscopy techniques such as atomic force – scanning electrochemical microscopy (AFM-SECM) und scanning electrochemical microscopy (SECM) are highly attractive hybrid techniques for studying biomedically relevant samples down to the single entity level. Our group introduced a new type of AFM-SECM probe having a conductive colloid instead of a sharp AFM tip. As this spherical microelectrode, which is located at the end of an electrically insulated AFM cantilever can be easily modified by electrodeposition with e.g., conductive polymers and electrocatalytic layers, single cell force spectroscopy under potential control allows studying adhesion properties [1,2]. Cell adhesion is a crucial parameter not only for developing new materials serving as substrates for neural scaffolds, electrodes, and biomedical devices but also in biofilm formation. Biofilms are well-organized aggregates of bacteria able to attach to and proliferate at almost every type of solid surface resulting in increased resistance to conventional antimicrobial and antibiofouling agents [3].The first attachment of bacterials is a process highly influenced by the nature of the surface, such as hydrophobicity, chemical structure, surface charge, and presence of antimicrobials [4].In this contribution, we present the potential of various scanning probe microscopy techniques, as suitable tools to locally investigate the early stages of biofilm formation and the effects of various antibiofouling and antimicrobial systems against Escherichia coli and Pseudomonas fluorescens. For example, the properties of polydopamine, a bio-compatible polymer, are studied in respect to early stages of bacterial adhesion in dependence of surface charge density and applied potential [5]. Colloidal conductive AFM probes can also be modified electrocatalytic layers, suitable for detecting signaling molecules and at the same time allow electrochemical force spectroscopy at soft samples like biomedically relevant single entities.

Extraction and purification of biosurfactant by locally isolated Enterococcus faecium bacteria and study of its antimicrobial activity

In this research, the biosurfactant production by Enterococcus faecium isolated from Raw cow's milk was studied when growing in the MRS medium containing Lactose as a carbon source without Tween-80. E.faecium supernatant exhibited emulsion action of 60% towards kerosene oil as oil in water, while the surface activity was 34 mm. Biosurfactants with surface tension activity properties were extracted and partially purified from E. faecium by cold acetone 3:1, The chemistry structure of the biosurfactant was analyzed, which indicated that it is a glycol-lipo-peptide. Biosurfactant that purified from E. faecium showed antibacterial activity by reducing growth of several pathogenic G-ve and G+ve bacteria, including aureus, Staphylococcus epidermidis, Streptococcus sp., Staphylococcus Escherichia coli, Klebsiella sp., Pseudomonas aeroginosa, Acinetobacter sp. and Serratia sp. The inhibitory activity of biosurfactant against pathogenic bacteria was studied by using agar diffusion method, where the biosurfactant had higher inhibitor activity against E. coli, where highest diameter of inhibition zone was (23mm). At all concentrations examined, a biosurfactant derived from E. faecium considerably decreased bacterial adhesion, albeit to a lower amount. Keyword: Enterococcus faecium, LAB, Biosurfactant, Antibacterial and Antiadhesive activity.

Exploring In Vitro the Combination of Cistus × incanus L. and Castanea sativa Mill. Extracts as Food Supplement Ingredients against H. pylori Infection.

Cistus spp. have been traditionally used for inflammatory and infectious disorders, including gastrointestinal ailments, in the Mediterranean area. Among them, Cistus × incanus L. is one of the most frequently cited species in the literature for a variety of biological activities which include inflammatory diseases. Cistus spp. aerial parts are rich in polyphenols such as condensed and hydrolysable tannins, procyanidins, and flavonoids, which show gastroprotective activities. The purpose of the present study is to investigate the biological activities of a hydroalcoholic extract from Cistus × incanus L. aerial parts in gastric epithelial cells (GES-1) infected with H. pylori. The extracts inhibited IL-8 and NF-κB induced by H. pylori and showed antibacterial activity after simulated digestion. Since our previous paper reported interesting results on the ability of Castanea sativa Mill. leaf extract to decrease inflammatory conditions in H. pylori-infected gastric cells, the combination of Castanea sativa and Cistus × incanus extracts was also investigated, showing strong anti-inflammatory activity and inhibition of bacterial adhesion. This association of botanicals is proposed herein as a novel food supplement capable of counteracting gastric inflammatory conditions.

HMO-primed bifidobacteria exhibit enhanced ability to adhere to intestinal epithelial cells.

The ability of gut commensals to adhere to the intestinal epithelium can play a key role in influencing the composition of the gut microbiota. Bifidobacteria are associated with a multitude of health benefits and are one of the most widely used probiotics for humans. Enhanced bifidobacterial adhesion may increase host-microbe, microbe-nutrient, and/or microbe-microbe interactions, thereby enabling consolidated health benefits to the host. The objective of this study was to determine the ability of human milk oligosaccharides (HMOs) to enhance bifidobacterial intestinal adhesion in vitro. This study assessed the colonisation-promoting effects of HMOs on four commercial infant-associated Bifidobacterium strains (two B. longum subsp. infantis strains, B. breve and B. bifidum). HT29-MTX cells were used as an in vitro intestinal model for bacterial adhesion. Short-term exposure of four commercial infant-associated Bifidobacterium strains to HMOs derived from breastmilk substantially increased the adherence (up to 47%) of these probiotic strains. Interestingly, when strains were incubated with HMOs as a four-strain combination, the number of viable bacteria adhering to intestinal cells increased by >90%. Proteomic analysis of this multi-strain bifidobacterial mixture revealed that the increased adherence resulting from exposure to HMOs was associated with notable increases in the abundance of sortase-dependent pili and glycosyl hydrolases matched to Bifidobacterium bifidum. This study suggests that HMOs may prime infant gut-associated Bifidobacterium for colonisation to intestinal epithelial cells by influencing the expression of various colonization factors.

Csu pili dependent biofilm formation and virulence of Acinetobacter baumannii

Acinetobacter baumannii has emerged as one of the most common extensive drug-resistant nosocomial bacterial pathogens. Not only can the bacteria survive in hospital settings for long periods, but they are also able to resist adverse conditions. However, underlying regulatory mechanisms that allow A. baumannii to cope with these conditions and mediate its virulence are poorly understood. Here, we show that bi-stable expression of the Csu pili, along with the production of poly-N-acetyl glucosamine, regulates the formation of Mountain-like biofilm-patches on glass surfaces to protect bacteria from the bactericidal effect of colistin. Csu pilus assembly is found to be an essential component of mature biofilms formed on glass surfaces and of pellicles. By using several microscopic techniques, we show that clinical isolates of A. baumannii carrying abundant Csu pili mediate adherence to epithelial cells. In addition, Csu pili suppressed surface-associated motility but enhanced colonization of bacteria into the lungs, spleen, and liver in a mouse model of systemic infection. The screening of c-di-GMP metabolizing protein mutants of A. baumannii 17978 for the capability to adhere to epithelial cells led us to identify GGDEF/EAL protein AIS_2337, here denoted PdeB, as a major regulator of Csu pili-mediated virulence and biofilm formation. Moreover, PdeB was found to be involved in the type IV pili-regulated robustness of surface-associated motility. Our findings suggest that the Csu pilus is not only a functional component of mature A. baumannii biofilms but also a major virulence factor promoting the initiation of disease progression by mediating bacterial adherence to epithelial cells.

The use of microbial fuel cell for efficient treatment of cauliflower waste and generation of electricity

ABSTRACT Microbial fuel cell (MFC) is an alternative way for household organic waste treatment as it produces sustainable clean energy. Chemical parameters of the cauliflower leaf waste before treatment were 143.5 mg/g COD, 0.90 mg/g ammoniacal nitrogen, 67.8 mg/g phosphorous, 214.8 mg/g total reducing sugar and 0.53 mg/g soluble reducing sugar. After eight days of treatment in MFC at the optimised condition of multiwalled carbon nanotubules (MWCNT)’ coated graphite as anode and potassium ferricyanide added phosphate buffer as catholyte with an external resistance of 1000 Ω showed a reduction in COD, ammoniacal nitrogen, phosphorous and total reducing sugar by 24.7, 76.9, 22.5 and 53.4%, respectively, along with a maximum power density of 10.1 W/m3. Scanning electron microscopy (SEM) showed bacterial adherence in the graphite electrode and its molecular characterisation using 16S rRNA sequencing confirmed as Bacillus sps.

Immunorecognition of Streptococcus mutans secreted proteins protects against caries by limiting tooth adhesion

IntroductionChildhood caries, a prevalent chronic disease, affects 60–90 % of children in industrialized regions, leading to lesions in both primary and permanent teeth. This condition precipitates hospital admissions, emergency room visits, elevated treatment costs, and missed school days, thereby impeding the child's academic engagement and increasing the likelihood of caries into adulthood. Despite multiple identified risk factors, significant interpersonal variability remains unexplained. The immune system generates a unique antibody repertoire, essential for maintaining a balanced and healthy oral microbiome. Streptococcus mutans is a primary contributor to the development of caries. MethodsEmploying mass spectrometry, we investigated the S. mutans proteins targeted by antibodies in children both with and without caries, delineating a fundamental suite of proteins discernible by the immune systems of a majority of individuals. Notably, this suite was enriched with proteins pivotal for bacterial adhesion. To ascertain the physiological implications of these discoveries, we evaluated the efficacy of saliva in thwarting S. mutans adherence to dental surfaces. ResultsAntibodies in most children recognized a core set of ten S. mutans proteins, with additional proteins identified in some individuals. There was no significant difference in the proteins identified by children with or without caries, but there was variation in antibody binding intensity to some proteins. Functionally, saliva from caries-free individuals, but not children with caries, was found to hinder the binding of S. mutans to teeth. These findings delineate the S. mutans proteome targeted by the immune system and suggest that the inhibition of bacterial adherence to teeth is a primary mechanism employed by the immune system to maintain oral balance and prevent caries formation. ConclusionsThese findings enhance our knowledge of the immune system's function in oral health maintenance and caries prevention, shedding light on how immunoglobulins interact with S. mutans proteins. Clinical SignificanceTargeting S. mutans proteins implicated in bacterial adhesion could be a promising strategy for preventing childhood caries.

Effect of wax chain length on the adhesion dynamics and interfacial rigidity of Salmonella Typhimurium LT2

The wax layer on the surface of fruits and vegetables is the first line of defense against a range of environmental stresses. The initial stage in the etiology of bacterial foodborne illnesses involves the bacterial adhesion and colonization on the wax layer of food commodities. Herein, we report a systematic study that provides new insights into dynamics of interfacial nanoscale processes associated with the transition of bacteria from a planktonic state to a sessile state at the early stages. To achieve this, we coated a piezoelectric sensor with model waxes containing linear alkyl carbon chains of varying lengths (from 6 to 18 carbons) via chemisorption. The process of bacterial adhesion to these wax-coated sensors was monitored using the Quartz Crystal Microbalance with Dissipation (QCM-D) technique, which offers nanogram-level gravimetric accuracy and millisecond time resolution. Our findings revealed that surfaces with higher hydrophobicity are more susceptible to Salmonella adhesion. Furthermore, we conduct a comparative analysis of the viscoelastic properties of the adhered layer, revealing distinct behaviors: Salmonella adhered to C6-wax exhibited solid-like characteristics, while adherence to C18-wax rendered a more liquid-like response. This observation underscores the role of interfacial energy in governing bacterial adhesion, as interpreted through the thermodynamic and surface science model, ultimately influencing rigidity. This investigation offers valuable insights into the initial adhesion to surfaces and has potential implications for surface design and modification within the food industry and other relevant applications, while also contributing to our understanding of bacterial contamination in food commodities.

Characterization of Three New Outer Membrane Adhesion Proteins in Fusobacterium necrophorum.

Fusobacterium necrophorum, an anaerobic Gram-negative pathogen, causes necrotic cattle infections, impacting livestock health and the US feedlot industry. Antibiotic administration is the mainstay for treating F. necrophorum infections, although resistance hampers their effectiveness. Vaccination, especially targeting outer membrane proteins (OMPs) due to their antigenic properties and host specificity, offers an alternative to antibiotics. This study identified high-binding-affinity adhesion proteins from F. necrophorum using binding and pull-down assays with bovine adrenal gland endothelial cells (EJG). Four OMP candidates (17.5 kDa/OmpH, 22.7 kDa/OmpA, 66.3 kDa/cell surface protein (CSP), and a previously characterized 43 kDa OMP) were expressed as recombinant proteins and purified. Rabbit polyclonal antibodies to recombinant OMPs were generated, and their ability to inhibit bacterial binding in vitro was assessed. The results show that treatment with individual polyclonal antibodies against 43 kDa significantly inhibited bacterial adhesion, while other antibodies were less potent. However, combinations of two or more antibodies showed a more prominent inhibitory effect on host-cell adhesion. Thus, our findings suggest that the identified OMPs are involved in fusobacterial attachment to host cells and may have the potential to be leveraged in combination for vaccine development. Future in vivo studies are needed to validate their roles and test the feasibility of an OMP-based subunit vaccine against fusobacterial infections.

Effect of co-trimoxazole and N-acetylcysteine alone and in combination on bacterial adherence on ureteral stent surface

To assess the effect of co-trimoxazole and N-acetylcysteine (NAC), alone and in combination, on bacterial adherence to biofilm formed on ureteral stent surfaces. This prospective randomized study was conducted on 636 patients who underwent double J ureteral stent insertion after variable urological procedures. Patients were randomized into four groups: A (n = 165), no antibiotics or mucolytics during stent indwelling; B (n = 153), oral NAC (200 mg/day for children aged < 12 years old and 600 mg/day for adults) during stent indwelling; C (n = 162), oral co-trimoxazole (2 mg TMP/kg/day) during stent indwelling; and D (n = 156), both oral NAC and co-trimoxazole during stent indwelling. Two weeks following double J stent (JJ stent) insertion, urinalysis was performed on all patients and urine culture was done for all the patients at the day of double J stent removal. The stent was removed 2 weeks postoperatively, and a stent segment sized 3–5 cm from the bladder segment of the stent was sent for culture. Positive stent cultures were found in 63.6% (105/165), 43.1% (66/153), 37% (60/162), and 19.2% (30/156) patients of groups A, B, C, and D, respectively. E. coli was the organism most commonly isolated from the stent culture in all groups. The combination of co-trimoxazole and NAC was more effective in reducing bacterial adherence on ureteral stent surfaces than either alone.

Geometric constraint-triggered collagen expression mediates bacterial-host adhesion

Cells living in geometrically confined microenvironments are ubiquitous in various physiological processes, e.g., wound closure. However, it remains unclear whether and how spatially geometric constraints on host cells regulate bacteria-host interactions. Here, we reveal that interactions between bacteria and spatially constrained cell monolayers exhibit strong spatial heterogeneity, and that bacteria tend to adhere to these cells near the outer edges of confined monolayers. The bacterial adhesion force near the edges of the micropatterned monolayers is up to 75 nN, which is ~3 times higher than that at the centers, depending on the underlying substrate rigidities. Single-cell RNA sequencing experiments indicate that spatially heterogeneous expression of collagen IV with significant edge effects is responsible for the location-dependent bacterial adhesion. Finally, we show that collagen IV inhibitors can potentially be utilized as adjuvants to reduce bacterial adhesion and thus markedly enhance the efficacy of antibiotics, as demonstrated in animal experiments.

Oil-infused feed spacers for biofouling inhibition

A novel approach is investigated for preventing biofouling of spacer filaments, which are an essential part of spiral-wound modules used in membrane-based desalination. Biofouling, caused by the growth and multiplication of microorganisms on the membrane surface, can significantly impact the efficiency and cost-effectiveness of the desalination process. Herein, a method is proposed for fabricating modified feed spacers based on oil-infused slippery substrates made of polydimethylsiloxane (PDMS). These feed spacers, when infused with silicone oil, create a stable, extremely slippery interface that exhibits exceptionally low bacterial adhesion and prevents biofilm formation, especially under flow conditions. By examining the effect of the silicone oil's viscosity, we determined the optimal ratio of the curing agent for fabricating the oil-infused feed spacer. Results showed a substantial reduction of bacterial adhesion to the surface for all tested oil viscosities, particularly under dynamic conditions. Furthermore, even where bacterial adhesion occurred, primarily on samples infused with lower-viscosity oil, it could be easily removed by simple rinsing. Overall, the oil-infused feed spacer demonstrated exceptional biofilm inhibition, providing preliminary indication of the potential offered by this promising approach.

Flexible Poly(vinyl chloride) with Durable Antibiofouling Property via Blending Star-Shaped Amphiphilic Poly(ε-caprolactone)-block-poly(methacryloxyethyl sulfobetaine).

Flexible poly(vinyl chloride) (PVC) plastics have been widely used in medical devices, but the preparation of antibiofouling flexible PVC materials that can maintain their antibiofouling performance when suffering deformation is still a challenge. In this work, we synthesized a series of amphiphilic star-shaped three-arm block copolymers SPCL-b-PSB, consisting of hydrophobic inner blocks poly(ε-caprolactone) (PCL) and hydrophilic outer blocks poly(methacryloxyethyl sulfobetaine) (PSB). Then, flexible PVC films were prepared by blending SPCL-b-PSB with PVC and plasticizer. Benefiting from the specific star-shaped topological structure of SPCL-b-PSB, hydrophilic PSB blocks of the copolymer could efficiently migrate to the surface of the film via annealing treatment, which give the film surface excellent hydrophilicity, while the latch-like entanglements between hydrophobic PCL blocks and PVC give the hydrophilic surface excellent stability. Antibiofouling properties of the blended films were investigated. The optimized blended film could reduce ∼94% of bovine serum albumin adsorption, ∼ 87% of lysozyme adsorption, and ∼89% of platelet adhesion and resist bacterial adhesion effectively. What is more, the blended films could maintain their antibiofouling performance when suffering stretching, rubbing, or bending. More than 86% of bovine serum albumin adsorption could be reduced, even when the film was stretched by 50%. This work provides a new strategy for the preparation of durable antibiofouling flexible plastics.

Electrosprayed zein nanoparticles as antibacterial and anti-thrombotic coatings for ureteral stents

Ureteral stents are among the most frequently used human implants, with urothelium trauma, blood clots, and bacterial colonization being their main reasons for failure. In this study, berberine-loaded zein (ZB) nanoparticles with high drug encapsulation efficiency (>90 %) were fabricated via electrospray on flat and 3D stainless steel structures. Physico-chemical characterization revealed that the ZB nanoparticles created a highly hydrophilic, antioxidant, and scratch-resistant continuous coating over the metal structure. Results showed that the drug release rate was faster at neutral pH (i.e., PBS pH 7.4) than in an artificial urine medium (pH 5.3) due to the different swelling behavior of the zein polymeric matrix. In vitro evaluation of ZB particles onto human dermal fibroblasts and blood cells demonstrated good cell proliferation and enhanced anti-thrombotic properties compared to bare stainless steel. The ability of the electrosprayed zein particles to resist bacterial adherence and proliferation was evaluated with Gram-negative (Escherichia coli) bacteria, showing high inhibition rates (−29 % and −46 % for empty and berberine-loaded particles, respectively) compared to the medical-grade metal substrates. Overall, the proposed composite coating fulfilled the requirements for ureteral applications, and can advance the development of innovative biocompatible, biodegradable, and antibacterial coatings for drug-eluting stents.

Preparation and properties of PTFE@TiO2/epoxy superhydrophobic coating

The problem of bacterial adhesion has been a challenge in everyday life and industry for decades. In this paper, polytetrafluoroethylene(PTFE) micropowder, titanium dioxide(TiO2) nanopowder, ethyl acetate and epoxy resin were sequentially added to a beaker and stirred well, then the nanoparticles were modified using perfluorooctyltriethoxysilane (POTS), and finally superhydrophobic coatings were fabricated on the surface of an aluminium sheet by spraying process. Characterisation was carried out using scanning electron microscopy and contact angle measurement, and the coating wettability, chemical stability and mechanical stability properties were investigated, and finally the coating was tested for antimicrobial properties. The study suggests that the hydrophobicity of the sample was optimal at a contact angle of 163.3° and a rolling angle of 3.2° when the ratio of PTFE micropowder to nano-TiO2 by mass was 1:4 and the ration between POTS and nanoparticles by mass was 12%. The contact angles were 137.8° and 143.6° after 25 and 32 hours of soaked in an anhydrous solution with a pH of 14 and 1, respectively. Most importantly, it exhibits good antimicrobial properties.

Anti-OmpA antibodies as potential inhibitors of Acinetobacter baumannii biofilm formation, adherence to, and proliferation in A549 human alveolar epithelial cells

Outer membrane protein A (OmpA) is a critical virulence factor in Acinetobacter baumannii, influencing adhesion, biofilm formation, host immune response, and host cell apoptosis. We investigated the invasion of A549 alveolar epithelial cells by A. baumannii and examined how anti-OmpA antibodies impact these interactions. OmpA was expressed and purified, inducing anti-OmpA antibodies in BALB/c mice. The potential toxicity of OmpA was evaluated in mice by analyzing histology from six organs. A549 cells were exposed to A. baumannii strains 19606 and a clinical isolate. Using cell culture and light microscopy, we scrutinized the effects of anti-OmpA sera on serum resistance, adherence, internalization, and proliferation of A. baumannii in A549 cells. The viability of A549 cells was assessed upon exposure to live A. baumannii and anti-OmpA sera. OmpA-induced antibody demonstrated potent bactericidal effects on both strains of A. baumannii. Both strains formed biofilms, which were reduced by anti-OmpA serum, along with decreased bacterial adherence, internalization, and proliferation in A549 cells. Anti-OmpA serum improved the survival of A549 cells post-infection. Pre-treatment with cytochalasin D hindered bacterial internalization, highlighting the role of actin polymerization in invasion. Microscopic examination revealed varied interactions encompassing adherence, apoptosis, membrane alterations, vacuolization, and damage. A549 cells treated with anti-OmpA serum exhibited improved structures and reduced damage. The findings indicate that A. baumannii can adhere to and proliferate within epithelial cells with OmpA playing a pivotal role in these interactions, and the complex nature of these interactions shapes the intricate course of A. baumannii infection in host cells.