Adhesion Of Bacteria Research Articles

Bacterial adhesion and surface properties of computer-aided design-computer-aided manufacturing restorative materials.

This study aimed to evaluate the surface properties and bacterial adhesion of computer-aided design-computer-aided manufacturing (CAD-CAM) restorative materials. Four CAD-CAM resin-based blocks (Vita Enamic, Shofu block HC, Cerasmart [CS] and Lava Ultimate [LU]) and a leucite-reinforced glass ceramic block (IPS Empress CAD) were used in the present study. Specimens prepared with dimensions of 10 × 10 × 1 mm were polished. Surface characteristics were assessed with hydrophobicity and surface free energy (SFE) analysis. Surface roughness was measured using a profilometer, and elemental and topographic evaluations were performed with SEM-EDX analysis. After being kept in artificial saliva for 1 h, Streptococcus mutans (S. mutans) and Streptococcus mitis (S. mitis) were incubated separately in 5% CO2 atmosphere at 37°C for 24 h. The adhered bacteria were counted as ×108 CFU/mL. Surface roughness, contact angle and SFE measurement values were found to be in the range of 0.144-0.264 Ra, 28.362°-70.074° and 39.65-63.62 mN/m, respectively. The highest adhered amount of S. mutans was found in CS and the lowest in LU, while there was no significant difference between the amounts of adhered S. mitis. Despite differences in the surface properties of the materials used for the study, the materials exhibited identical properties with respect to bacterial adhesion.

Co-Expression of type 1 fimbriae and flagella in Escherichia coli: consequences for adhesion at interfaces.

Escherichia coli expresses surface appendages including fimbriae, flagella, and curli, at various levels in response to environmental conditions and external stimuli. Previous studies have revealed an interplay between expression of fimbriae and flagella in several E. coli strains, but how this regulation between fimbrial and flagellar expression affects adhesion to interfaces is incompletely understood. Here, we investigate how the concurrent expression of fimbriae and flagella by engineered strains of E. coli MG1655 affects their adhesion at liquid-solid and liquid-liquid interfaces. We tune fimbrial and flagellar expression on the cell surface through plasmid-based inducible expression of the fim operon and fliC-flhDC genes. We show that increased fimbrial expression increases interfacial adhesion as well as bacteria-driven actuation of micron-sized objects. Co-expression of flagella in fimbriated bacteria, however, does not greatly affect either of these properties. Together, these results suggest that interfacial adhesion as well as motion actuated by adherent bacteria can be altered by controlling the expression of surface appendages.

Fibrous capsule-resistant, controllably degradable and functionalizable zwitterion-albumin hybrid hydrogels.

Foreign body response (FBR) represents an immune-mediated cascade reaction capable of inducing the rejection of foreign implants, thereby compromising their in vivo performance. Pure zwitterionic hydrogels have demonstrated the ability to resist long-term FBR, owing to their outstanding antifouling capabilities. However, achieving such a robust anti-FBR effect necessitates stringent requirements concerning the purity of zwitterionic materials, which constrains their broader functional applications. Herein, we present a biocompatible, controllably degradable, and functionalizable zwitterion-albumin hybrid hydrogel. The zwitterionic hydrogel crosslinked with serum albumin exhibits controllable degradation and excels in preventing the adsorption of various proteins and adhesion of cells and bacteria. Moreover, the hydrogel significantly alleviates the host's FBR compared with PEG hydrogels and particularly outperforms PEG-based cross-linker crosslinked zwitterionic hydrogels in reducing collagen encapsulation when subcutaneously implanted into mice. The zwitterion-albumin hybrid hydrogel shows potential as a functionalizable anti-FBR material in the context of implantable materials and biomedical devices.

Bioinspired active hemocompatible coating systems for mechanical circulatory support devices: when engineering meets nano and molecular technology

Industrial manufacturing is undergoing a biological transformation, which has become a growing part of current research in production engineering. The technologies involved help to translate innovative approaches into existing or novel medical devices. Currently, however, even the most advanced blood contacting medical devices fail to be sufficiently inert to blood, thus causing acute effects – coagulation, inflammation, embolism, stroke – as well as chronic ones – inflammation and chronic use of anticoagulants. We present the marriage of advanced molecular science, nanotechnology and advanced production engineering to improve the hemocompatibility of hemodynamic systems, such as artificial hearts. Our consortium has joined forces to develop nature-inspired coating systems that improve hemocompatibility, prohibit adhesion of bacteria and minimize the growth of dangerous large thrombi. We achieve this by (1) concealing the presence of the titanium surface, thereby minimizing the activation of inflammatory and coagulatory reactions, (2) locally inactivating those molecules that cause uncontrolled coagulation, (3) directing the blood to use its own fibrinolytic system to digest the clot and (4) introducing micro surface patterns that interfere with the flow near the surface generating shear, which in turn prohibits dangerous clots from growing. In vitro tests demonstrate considerable improvement in hemocompatibility.

Comprehensive Guidance for the Prevention of Periprosthetic Joint Infection After Total Joint Arthroplasty and Pitfalls in the Prevention.

Total joint arthroplasty (TJA) is a surgical procedure, in which parts of damaged joints are removed and replaced with a prosthesis. The main indication of TJA is osteoarthritis, and the volume of TJA is rising annually along with the increase of aged population. Hip and knee are the most common joints, in which TJAs are performed. The TJA prosthesis is composed of metal, plastic, or ceramic device. Even though TJA is the most successful treatment for end-stage osteoarthritis, it is associated with various complications, and periprosthetic joint infection (PJI) is the most serious complication after TJA. With the increasing volume of TJAs, there is a simultaneous rise in the incidence of PJI. Contamination of the surgical wound and the adherence of bacteria to the surface of prosthetic component represent the initial step in the pathogenesis of PJI. The main sources of the contamination are 1) patient's own flora, 2) droplets in the operation room air, and 3) surgical gloves and instruments. Even though modern techniques have markedly reduced the degree of contamination, TJAs cannot be done in completely germ-free conditions and some degree of contamination is inevitable in all surgical procedures. However, not all contamination leads to PJI. It develops when the burden of contamination exceeds the immune threshold or the colony forming units (CFUs) and various factors contribute to a decrease in the CFU level. Surgeons should be aware of the germ burden/CFU concept and should monitor sources of contamination to maintain the germ burden below the CFU to prevent PJI.

Molecular mechanism of Hfq-dependent sRNA1039 and sRNA1600 regulating antibiotic resistance and virulence in Shigella sonnei

Bacillary dysentery caused by Shigella spp. is a significant concern for human health. Small non-coding RNA (sRNA) plays a crucial role in regulating antibiotic resistance and virulence in Shigella spp. However, the specific mechanisms behind this phenomenon are still not fully understood. This study discovered two sRNAs (sRNA1039 and sRNA1600) that may be involved in bacterial resistance and virulence. By constructing deletion mutants (WT/ΔSR1039 and WT/ΔSR1600), this study found that the WT/ΔSR1039 mutants caused a two-fold increase in sensitivity to ampicillin, gentamicin and cefuroxime, and the WT/ΔSR1600 mutants caused a two-fold increase in sensitivity to cefuroxime. Furthermore, the WT/ΔSR1600 mutants caused a decrease in the adhesion and invasion of bacteria to HeLa cells (P<0.01), and changed the oxidative stress level of bacteria to reduce their survival rate (P<0.001). Subsequently, this study explored the molecular mechanisms by which sRNA1039 and sRNA1600 regulate antibiotic resistance and virulence. The deletion of sRNA1039 accelerated the degradation of target gene cfa mRNA and reduced its expression, thereby regulating the expression of pore protein gene ompD indirectly and negatively to increase bacterial sensitivity to ampicillin, gentamicin and cefuroxime. The inactivation of sRNA1600 reduced the formation of persister cells to reduce resistance to cefuroxime, and reduced the expression of type-III-secretion-system-related genes to reduce bacterial virulence by reducing the expression of target gene tomB. These results provide new insights into Hfq-sRNA-mRNA regulation of the resistance and virulence network of Shigella sonnei, which could potentially promote the development of more effective treatment strategies.

Adhesion of Escherichia coli and Lactobacillus fermentum to Films and Electrospun Fibrous Scaffolds from Composites of Poly(3-hydroxybutyrate) with Magnetic Nanoparticles in a Low-Frequency Magnetic Field.

The ability of materials to adhere bacteria on their surface is one of the most important aspects of their development and application in bioengineering. In this work, the effect of the properties of films and electrospun scaffolds made of composite materials based on biosynthetic poly(3-hydroxybutyrate) (PHB) with the addition of magnetite nanoparticles (MNP) and their complex with graphene oxide (MNP/GO) on the adhesion of E. coli and L. fermentum under the influence of a low-frequency magnetic field and without it was investigated. The physicochemical properties (crystallinity; surface hydrophilicity) of the materials were investigated by X-ray structural analysis, differential scanning calorimetry and "drop deposition" methods, and their surface topography was studied by scanning electron and atomic force microscopy. Crystal violet staining made it possible to reveal differences in the surface charge value and to study the adhesion of bacteria to it. It was shown that the differences in physicochemical properties of materials and the manifestation of magnetoactive properties of materials have a multidirectional effect on the adhesion of model microorganisms. Compared to pure PHB, the adhesion of E. coli to PHB-MNP/GO, and for L. fermentum to both composite materials, was higher. In the magnetic field, the adhesion of E. coli increased markedly compared to PHB-MNP/GO, whereas the effect on the adhesion of L. fermentum was reversed and was only evident in samples with PHB-MNP. Thus, the resultant factors enhancing and impairing the substrate binding of Gram-negative E. coli and Gram-positive L. fermentum turned out to be multidirectional, as they probably have different sensitivity to them. The results obtained will allow for the development of materials with externally controlled adhesion of bacteria to them for biotechnology and medicine.

(Invited) A Flexible Anti-Biofilm Hygiene Coating for Water Devices

Biofilm is a microbiome complex comprising different bacterial colonies that typically adhere to device surfaces in water, which causes serious medical issues such as indwelling infections and outbreaks. Here we introduce a non-nanoparticle, flexible anti-biofilm hygiene coating consisting of lithocholic acid (LCA), zinc pyrithione (Zn) and cinnamaldehyde (Cn) (named as LCA-Zn-Cn) that largely prevents the bacteria adhesion to various water device surfaces such as stainless steel and glass through a synergistic mechanism (ACS Applied Bio Materials, 5 (2022) 3991). The existing chelated groups on LCA and Cn attract plenty of bacteria via hydrophobic interaction. Both bactericidal reaction by grafting biocidal groups from both LCA and Cn and bacteriostatic reaction by inhibiting cell division via zinc ions (Zn) lead to a largely improved bacteria/biofilm prevention. The antibacterial performance was assessed by using JIS Z 2801/ISO 22196 method. The designed LCA-Zn-Cn coating displayed log10 reduction of 4.23 (99.9% reduction) of E. coli and log10reduction of 3.51 (99.8% reduction) of E. faecalis on stainless steel, which are much higher than the control samples, demonstrating a promising colonization inhibition. Due to the strong crosslinked configuration, the coating still showed >90.9% bacterial reduction after 3000 abrasion cycles and over 99.9% bacteria reduction after a high flow velocity of 1.99 m/s test, which confirmed the enhanced mechanical durability. By applying either spray or dip-coating, the designed polymer composite can be coated on a variety of irregular water devices with mass production using auto-controlled robot arm. The desired hybrid coating provides an effective solution to prevent bacterium and biofilm formation on flexible water devices. Keywords: Anti-biofilm; Anti-bacteria; Coating; Water devices; Flexibility

Inhibition of biofilm formation and settlement of barnacle larvae by a biosurfactant produced from a marine biofilm-forming Exiguobacterium sp. R58

Natural product based antifouling strategies are promising alternatives for achieving biofouling control with minimal environmental burden. Although microbial biosurfactants have shown antimicrobial and antibiofilm activities, their efficacy on settlement of barnacles, among the most problematic of biofouling organisms in the marine environment, has not be evaluated. Biofilm-forming bacteria isolated from the seawater cooling system of a power plant were screened for biosurfactant production and one of the promising strains was identified as Exiguobacterium sp. R58. Production, characterization and anti-biofouling activity of the biosurfactant was determined. Emulsifying activity of 68–89% was achieved at 4−100 °C, 2–12% salinity and 2–12 pH. Biofilm formation by Escherichia coli, Staphylococcus aureus, Salinococcus sp., and Marinobacter sp. was strongly inhibited (80–92%) in the presence of 2000 μg/mL biosurfactant. Cypris larval settlement was impaired by the biosurfactant without causing mortality. Biosurfactant coated surfaces prevented biofilm formation and cypris settlement. Adhesion of bacteria on biosurfactant coated surfaces was 75–93% lower as compared to control. Cypris settlement was inhibited completely in Petri dishes coated with 5.6–22.7 mg/cm2 in no-choice assays and 1.3 mg/cm2 in choice assays. Antibiofouling activity of the biosurfactant was related to surface modification, thus promising for developing non-toxic antifouling materials.

Mitigation of transparent exopolymer particles-induced membrane biofouling by the coupling process of magnetic ion exchange resin/ultrafiltration

The significant effects of transparent exopolymer particles (TEP) on membrane fouling have attracted the attention of several researchers. Finding an effective method for controlling membrane biofouling caused by TEP is essential for the long-term stable operation of membrane systems. The results of this experimental study show that the coupling process of magnetic ion exchange resin (MIEX)/Ultrafiltration (UF) can significantly mitigate membrane biofouling induced by TEP. Compared with the UF process, the irreversible growth rate of TEP on the membrane in the MIEX/UF process decreased by 75.9%, and the synergistic irreversible accumulation rate of TEP and bacteria decreased by 81.2%. The irreversible adhesion of bacteria to the membrane was significantly reduced, effectively inhibiting the formation of the primary level of biofilm and the development of biofouling. Further analysis showed that the MIEX inhibited the conversion of TEP precursors to TEP, and the quaternary ammonium salt functional groups on the surface of the MIEX sterilized bacteria and inhibited their proliferation in water. More importantly, because the interfacial forces between TEP/bacteria and MIEX were much higher than those between them and the UF membrane, the deposition of MIEX on the membrane surface not only prevented TEP and bacteria from reaching the membrane surface, but also removed the deposited TEP and bacteria from the membrane surface by hydraulic backwashing.

Super-hydrophilic nano-structured surface with antibacterial properties

Adhesion of bacteria to a surface followed by biofilm formation causes many problems in human health care and, in some cases, can even cause human death. Therefore, reducing bacterial attachment to surfaces and antibacterial surface fabrication are two of the most important issues in many applications, including healthcare, medical, food packaging, etc. Polycarbonate (PC) is one of the most widely used polymers in medicine. However, it does not have antibacterial properties. On the other hand, laser treatment is used as a standard method for surface modification of different materials. In this paper, excimer laser irradiation at a fluence below the ablation threshold was used for surface patterning and modification of the polycarbonate sample, aiming to improve its antibacterial properties. The results show that super-hydrophilic nanostructured polycarbonate surfaces have antibacterial properties compared to non-treated PC, which has no antibacterial properties.

The influence of surface topography and microstructure of zirconia on initial bacterial adhesion of streptococcus mutans– in vitro study

The purpose of this research in this paper is to study the physical and chemical characteristics of the surfaces and the topography of the surfaces of zirconium materials used for the processing of fixed prosthetic works and their influence on the surface adhesion of Streptococcus mutans bacteria. The samples used for examination are produced from zircon material, they are divided into two groups, the first group after sintering are polished without glaze, while the second group, after sintering, are covered with a layer of glaze. For the realization of the experimental part of this research, the following methods and analyzes were used: surface roughness measurement (SR), contact angle measurement, surface free energy determination (SFE), biofilm formation and preparation for scanning with a microscope electronic (SEM) Specimens produced from zirconia, polished but unglazed showed higher contact angle values 90.340, while glazed samples showed lower values than unglazed ones 61.640, Surface free energy measurements of zirconia samples polished without glaze showed significantly lower values (24.31mJ/m2 ) compared to the values obtained in the zircon samples covered with glaze (40.66mJ/m2 ), The surface roughness values are higher in unglazed zirconia samples and is 0.65μm, while in the polished and glazed zirconia samples, the roughness of the surfaces is less 0.29μm, SEM analysis results show that the smallest number of attached bacteria is found on the surfaces of samples with unglazed zircon (8 bacteria), while in samples with zircon covered with glaze, a much larger number of bacteria (26 bacteria) were found on their surfaces. The roughness of the surfaces was shown to have no effect on the bacterial surface adhesion of these samples.

ИЗУЧЕНИЕ ОЧИЩАЮЩЕГО ЭФФЕКТА СПРЕЯ ДЛЯ ПРОФИЛАКТИКИ КАРИЕСА, СОДЕРЖАЩЕГО STREPTOCOCUS THERMOPHILUS ЛИЗАТ И ПРЕБИОТИКИ, КАК ПРОМЕЖУТОЧНОГО СРЕДСТВА ГИГИЕНЫ РТА

Background. The problem of controlling the formation and development of dental plaque as a risk factor for the development of dental diseases is leading in preventing a decrease in the level of oral hygiene. In this regard, it remains relevant to study the preventive effects of liquid oral hygiene products with an anti-carious effect. Spray for the prevention of caries «DentaBalance®» synbiotic complex including lysate from Streptococcus Thermophilus and prebiotics, plant extracts that prevent the adhesion of bacteria to the surface of the teeth. At the same time, the metabolism of microorganisms that form plaque is disrupted, leading to their death, and the amount of acids produced by bacteria is also reduced, which increases the level of dental health.&#x0D; Material and methods. In the conditions of the clinic, a spray for the prevention of caries was tested in order to determine its cleansing effect as an intermediate oral hygiene product used during the day. The spray for the prevention of caries «DentaBalance®» synbiotic complex was used by probants independently 2 times a day for 30 days for intermediate use during the day. Repeated examinations were carried out every two weeks, for 4 weeks. The control of the cleansing effect of the intermediate liquid oral hygiene product was carried out for 30 days. The assessment was carried out according to the Green-Vermillion index using indicators of dental deposits.&#x0D; Results. Based on the results of the study, the cleansing effect according to the Green - Vermillion index was established in persons who used the spray for the prevention of caries «DentaBalance®» synbiotic complex during the day, by the end of 4 weeks was 50.66 ± 0.51. The data obtained were confirmed by statistical processing of the results of the study.&#x0D; Conclusion. It has been established that the spray for the prevention of caries «DentaBalance®» synbiotic complex has a pronounced cleansing effect when used during the day, which is confirmed by its cleansing effectiveness. Batch spraying of liquid hygiene products in the dosage form of the spray effectively delivers microparticles with their active components, and also ensures its mobility in use.

Shock Wave-Activated Silver-Loaded Biopolymer Implant Coating Eliminates Staphylococcus epidermidis on the Surface and in the Surrounding of Implants.

Bacterial biofilms on foreign surfaces are considered a primary cause of implant-related infections, which are challenging to treat. A new implant coating was developed, containing anti-infective silver within a biocompatible polymer carrier substance. In addition to its passive effect on the implant surface, highly concentrated anti-infective silver can be released as needed via the application of high-energy shock waves. This intervention could be applied transcutaneously in a clinical setting without the need for additional surgery. We investigated the inhibition of biofilm formation and the effectiveness of eradication after activation of the coating via shock waves in an in vitro biofilm model using Staphylococcus epidermidis RP62A. This was performed via scanning electron microscopy and quantitative microbiology. Additionally, we examined the cytotoxicity of the new coating on normal human fibroblasts and Saos-2 osteoblast-like cells, depending on the silver concentration. All studies were compared to uncoated titanium surfaces Ti6Al4V and a conventional electroplated silver coating. Cytotoxicity toward normal human fibroblasts and Saos-2 osteoblast-like cells increased with higher silver content but remained tolerable at 6%. Compared to uncoated Ti6Al4V and the electroplated silver coating, the new coating with a silver content of 4% and 6% exhibited a significant reduction in adherent bacteria by a factor of approximately 1000. This was also evident via microscopic examination of the surface morphology of the biofilms. Furthermore, following shock wave activation, no bacteria were detectable on either the implant or in the surrounding fluid after a 24 h period.

Microbiological Load on the Various Surfaces

Microorganisms are ubiquitous, including within habitats, and they have a negative impact on human health, sanitation, and living situations. Surface microbial load is affected by various factors such as location, usage, cleaning, and environment. Kitchen countertops, toilet fittings, doorknobs, electrical appliances, and fabrics can harbor bacteria, viruses, fungi, and archaea. These pathogens may originate from persons, air or external sources. It is known that high microbial loads on surfaces cause health hazards. Pathogenic bacteria can live for extended durations on surfaces, causing infections by contact or aerosolization. Surface microbial load can be decreased through cleaning and disinfection processes. Reducing microbiological contamination requires the use of appropriate cleaning products, and procedures. In antimicrobial coatings, silver ions and other disinfectants can inhibit surface bacterium adhesion and growth. To mitigate health risks, it is necessary to comprehend microbial colonization and survival on various surfaces. This article examines common surface bacteria, microbial load factors, transmission pathways, and their impact on human health.

Influence of multi-walled carbon nanotubes/N, N-dimethylformamide slurry amount on fouling release performance of silicone coatings

MWCNTs reinforced silicone coatings were prepared by mechanically mixing hydroxyl-capped polydimethylsiloxane (PDMS) and multi-walled carbon nanotubes/N, N-dimethylformamide (MWCNTs/DMF) slurries. The effects of MWCNTs/DMF slurry amount on the fouling release performance of silicone coatings were investigated. Incorporation of 5 wt% MWCNTs/DMF slurry increased the elongation and reduced Young's modulus, Shore's hardness, and roughness observed. As a result, an excellent silicone coating was fabricated with stable surface properties, fouling release performance, economic savings, and prolonged longevity for marine applications. Silicone coatings reinforced by MWCNTs were prepared by mechanical blending. MWCNTs are tubular crystals 30–80 nm in diameter and less than 10 μm long. The effects of MWCNTs/DMF slurry amount on the coating properties were investigated by dispersion properties, surface properties, mechanical properties, marine bacteria adhesion, and Navicula tenera adhesion test. The most favorable fouling release performance with the lowest roughness (0.168 ± 0.008 μm), the minimum Shore's hardness (18.47 HA), and the minimum relative adhesion factor (5.88 RAF) were shown for the silicone coatings prepared with 5 wt% MWCNTs/DMF slurry.

Run-and-tumble motion in trapping environments

Complex or hostile environments can sometimes inhibit the movement capabilities of diffusive particles or active swimmers, who may thus become stuck in fixed positions. This occurs, for example, in the adhesion of bacteria to surfaces at the initial stage of biofilm formation. Here we analyze the dynamics of active particles in the presence of trapping regions, where irreversible particle immobilization occurs at a fixed rate. By solving the kinetic equations for run-and-tumble motion in one space dimension, we give expressions for probability distribution functions, focusing on stationary distributions of blocked particles, and mean trapping times in terms of physical and geometrical parameters. Different extensions of the trapping region are considered, from infinite to cases of semi-infinite and finite intervals. The mean trapping time turns out to be simply the inverse of the trapping rate for infinitely extended trapping zones, while it has a nontrivial form in the semi-infinite case and is undefined for finite domains, due to the appearance of long tails in the trapping time distribution. Finally, to account for the subdiffusive behavior observed in the adhesion processes of bacteria to surfaces, we extend the model to include anomalous diffusive motion in the trapping region, reporting the exact expression of the mean-square displacement.

Long-lasting anti-bacterial face masks enabled by combining anti-bacterial materials and superhydrophobic coating

Face masks are widely used for protecting against the COVID-19 pandemic and other diseases. However, the lack of virucidal properties in conventional face masks increases the risk of cross-infection and potential contamination. Here, we report preparation of a superhydrophobic and anti-bacterial polypropylene fabric by in turn incorporation of ZnO nanoparticles and perfluorodecyl polysiloxane modified SiO2 nanoparticles. The fabric exhibits high superhydrophobicity with a water shedding angle of ~6° and excellent moisture resistance, which enable maintenance of functionality effectiveness of the face masks in cold weather conditions. When utilized as a middle layer in face masks, the fabric demonstrates remarkable anti-bacterial activity against E. coli in both laboratory and outdoor environments. This anti-bacterial performance is attributed to the synergistic effect of superhydrophobicity and the ZnO nanoparticles. The excellent superhydrophobicity significantly reduces adhesion of E. coli on the fabric. Meanwhile, the embedded ZnO nanoparticles can eliminate the small number of adhered bacteria through their inherent anti-bacterial property. The combination of superhydrophobicity and anti-bacterial property in the fabric presents a promising solution for enhancing the performance of face masks. The superhydrophobic anti-bacterial fabric holds great potential for various practical applications in the field of personal protective equipment, healthcare, and disease prevention.

Enhanced anti-bacterial adhesion effect of FDMA/SR833s based dental resin composites by using 1H,1H-heptafluorobutyl methacrylate as partial diluent

With the purpose of further reducing surface free energy to achieve better anti-bacterial adhesion effect of fluorinated dimethacrylate (FDMA)/tricyclo (5.2.1.0) decanedimethanol diacrylate (SR833s) based dental resin composites (DS), 1H,1H-heptafluorobutyl methacrylate (FBMA) was used to partially replace SR933s as reactive diluent. According to the degree of substitution, the obtained resin composites were marked as DSF-1 (20 wt.% of SR833s was replaced by FBMA), DSF-2 (40 wt.% of SR833s was replaced by FBMA), and DSF-3 (60 wt.% of SR833s was replaced by FBMA). Bisphenol A glycidyl dimethacrylate (Bis-GMA)/triethylene glycol dimethacrylate (TEGDMA) based resin composite (BT) was used as control. The influence of FBMA concentration on double bond conversion (DC), contact angle, surface free energy, anti-bacterial adhesion effect against Streptococcus mutans (S. mutans), volumetric shrinkage (VS) and shrinkage stress (SS), flexural strength (FS) and modulus (FM), water sorption (WS) and solubility (SL) were investigated. The results showed that FBMA addition could reduce surface free energy from 44.6 mN/m for DS to 32.9 mN/m for DSF-3, and lead to better anti-bacterial adhesion effect (the amounts of adherent bacteria decreased from 2.03 × 105 CFU/mm2 for DS to 6.44 × 104 CFU/mm2 for DSF-3). The FBMA had no negative effects on DC, VS, SS, WS, and SL. Too high a concentration of FBMA reduced FS and FM before water immersion, but the values were still higher than those of BT.

Improving antifouling functions of titanium alloys by robust slippery liquid-infused porous surfaces with tailored multiscale structures

The practical applications of delicate micro/nanostructures with extraordinary functions are severely limited by the insufficient mechanical stability. To address this challenge, the incorporation of protective “armor” for fragile micro/nanostructures has emerged as a promising approach to endow mechanical robustness. In this study, we have employed the concept of “armor” by fabricating honeycomb concave cells on surfaces of large-size Ti-6Al-4V (TC4) plates using screen-printed etching, followed by anodic oxidation to establish an array of multiscale structures. A new type of slippery liquid-infused porous surface (TC4-SLIPS) has been further produced by the infusion of lubricants into the exquisite multiscale structures. The results show that the tailored multiscale structures enhance stabilization of the lubricant layer, which can retain surface hydrophobicity (WCAs ∼ 104.8°) even after artificial seawater washout for 30 days. Moreover, the multiscale structures improve resistance to external mechanical abrasion, resulting in the robust hydrophobic nature of the SLIPS. Attractively, TC4-SLIPS can effectively inhibit the adhesion and proliferation of Pseudoalteromonas bacteria, and thereby prevent the formation and proliferation of bacterial biofilms. Therefore, the state-of-the-art TC4-SLIPS with multiscale structures has shown significance for the long-term antifouling of titanium alloys in practical applications.