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Quaternary ammonium salts (QAS) are widely used in medicine, industry and agriculture as disinfectants, biocides, and fungicides. QAS have the ability to coat various surfaces, prevent adhesion of microorganisms to them and inhibit the formation of biofilm. A group of surfactants derived from benzoic acid with different chemical structures was tested: monomeric QAS with different alkyl chain lengths (C 12 , C 14 , C 16), gemini QAS containing 12-carbon alkyl chains and linkers of various lengths (3,4,6 methylene groups), as well as multifunctional QAS. Among the tested surfactants, monomeric QAS showed the highest bactericidal and fungicidal activity. All three groups of tested compounds inhibited the filamentation of C. albicans. The best antimicrobial activity was demonstrated by the monomeric surfactant C 12 AA, while the multifunctional equivalent (2xC 12 AA) was characterized by good anti-adhesive activity. All tested compounds are non-mutagenic and cause low hemolysis of sheep erythrocytes. Multifunctional and gemini surfactants are also non-toxic. [Display omitted] • Monomeric surfactants show strong activity against planktonic bacteria and fungi. • Multifunctional surfactant was characterized by good anti-adhesive activity. • Monomeric and gemini quaternary ammonium salts inhibit Candida albicans filamentation. • Gemini and monomeric quaternary ammonium salts are non-mutagenic. • Quaternary ammonium salts induce low hemolysis of sheep erythrocytes. [ABSTRACT FROM AUTHOR]

Surface structures in the nanometer range emerge as the next evolutionary breakthrough in the design of biomaterials with antimicrobial properties. However, in order to advance the application of surface nanostructuring strategies in medical implants, the very nature of the microbial repealing mechanism has yet to be understood. Herein, we demonstrate that the random immobilization of gold nanoparticles (AuNPs) on a material’s surface generates the possibility to explore microbial adhesion in dependence of contact point densities at the biointerface between the microbe, i.e., Escherichia coli and the material’s surface. By optimizing the contact point density defined by individual AuNPs, yet keeping the surface chemistry unchanged as evidenced by X-ray photoelectron spectroscopy, we show that the initial microbial adhesion can be successfully reduced up to 50%, compared to control (unstructured) surfaces. Furthermore, we observed a decrease in the size of microbial cells adhered to nanostructured surfaces. The results show that the spatial distance between the contact points plays a crucial role in regulating microbial adhesion, thus advancing our understanding of the microbial adhesion mechanism on nanostructured surfaces. We suggest that the introduced strategy for nanostructuring materials surfaces opens a research direction for highly microbial-resistant biomaterials. [ABSTRACT FROM AUTHOR]

Antifouling function of copper-based layers is usually gained through the release of cuprous or copper ions to damage most fouling species. In this research the intervening mechanisms of copper ions in formation of simplified conditioning layer comprising marine polysaccharide alginate and subsequent adhesion of typical marine bacteria and algae were studied. Fast interaction of Cu 2+ with alginate with the formation of copper alginate multimers was observed for the first time by negative-staining electron microscopy. Interconnecting chains of alginate and copper alginate upon adsorption on silicon wafer and tangled structure of the conditioning layer were further characterized by atomic force microscopy. Adhesion testing showed that consumption of copper ions by their linking with alginate in incubation solutions resulted in mitigated toxicity of the ions to the microorganisms Bacillus sp., Chlorella pyrenoidosa and Phaeodactylum tricornutum . The results would give insight into understanding and regulating the formation of conditioning layer for desired antifouling performances. [ABSTRACT FROM AUTHOR]

Although titanium dental implants are biocompatible, exhibit excellent corrosion resistance and high mechanical resistance, the material fails in providing resistance to infection because it exhibits poor antimicrobial activity. To address these issues, we deposited silver onto titanium abutments (Grade 5 titanium discs) using direct current (DC) sputtering and assessed the antimicrobial activity and biocompatibility of the modified implant material. Atomic absorption spectrometry and X-ray photoelectron spectroscopy were employed to investigate the concentration and elemental composition of the deposited silver. As expected, silver deposited using DC plasma was uniform and good control over the deposition could be achieved by varying the sputtering time. Moderate biocompatible responses (up to 69% viability) were observed in primary human gingival fibroblast cells incubated in the presence of Ti sputtered with Ag for 5 min. Silver deposited titanium (Ti-Ag) showed excellent antibacterial effects on Pseudomonas aeruginosa and Streptococcus mutans at a very low concentration (Ag content 1.2 and 2.1 μg/mm 2 ). However, higher concentration of silver (6 μg/mm 2 ) was required to achieve a reduction in cell viability of Staphylococcus aureus and Candida albicans . The silver sputtered Ti abutments could maintain a long-term antibacterial activity as evidenced by the release of silver up to 22 days in simulated body fluid. Our study illustrates that silver deposited titanium is indeed a promising candidate for soft tissue integration on dental abutments and prevents initial microbial adhesion. [ABSTRACT FROM AUTHOR]

Pathogenic bacteria contamination ubiquitously occurs on high-contact surfaces in hospitals and has long been a threat to public health, inducing severe nosocomial infections that cause multiple organ dysfunction and increased hospital mortality. Recently, nanostructured surfaces with mechano-bactericidal properties have shown potential for modifying material surfaces to fight against the spread of pathogenic microorganisms without the risk of triggering antibacterial resistance. Nevertheless, these surfaces are readily contaminated by bacterial attachment or inanimate pollutants like solid dust or common fluids, which has greatly weakened their antibacterial capabilities. In this work, we discovered that the nonwetting Amorpha fruticosa leaf surfaces are equipped with mechano-bactericidal capacity by means of their randomly-arranged nanoflakes. Inspired by this discovery, we reported an artificial superhydrophobic surface with similar nanofeatures and superior antibacterial abilities. Compared to conventional bactericidal surfaces, this bioinspired antibacterial surface was synergistically accompanied by antifouling performances, which significantly prevent either initial bacterial attachment or inanimate pollutants like dust covering and fluid contaminants. Overall, the bioinspired antifouling nanoflakes surface holds promise as the design of next-generation high-touch surface modification that effectively reduces the transmission of nosocomial infections. [Display omitted] • The nonwetting and mechano-bactericidal Amorpha fruticosa leaf was first revealed. • The unique natural structures and properties inspired the design of CuO nanoflakes. • Antibacterial ability and antifouling against inanimate pollutants was achieved. • The bioinspired surface remarkably impeded the initial microbial adhesion (< 0.1%). • The preparation method was cost-effective, the surface was mechanical robustness. [ABSTRACT FROM AUTHOR]

Microbial adhesion and formation of biofilms cause a serious problem in several areas including but not limited to food spoilage, industrial corrosion and nosocomial infections. These microbial biofilms pose a serious threat to human health since microbial communities in the biofilm matrix are protected with exopolymeric substances and difficult to eradicate with antibiotics. Hence, the prevention of microbial adhesion followed by biofilm formation is one of the promising strategies to prevent these consequences. The attachment of antimicrobial agents, coatings of nanomaterials and synthesis of hybrid materials are widely used approach to develop surfaces having potential to hinder bacterial adhesion and biofilm formation. In this study, epigallocatechin gallate (EGCG) is attached on p(HEMA-co-GMA) membranes to prevent the bacterial colonization. The attachment of EGCG to membranes was proved by Fourier-transform infrared spectroscopy (FT-IR). The synthesized membrane showed porous structure (SEM), and desirable swelling degree, which are ideal when it comes to the application in biotechnology and biomedicine. Furthermore, EGCG attached membrane showed significant potential to prevent the microbial colonization on the surface. The obtained results suggest that EGCG attached polymer could be used as an alternative approach to prevent the microbial colonization on the biomedical surfaces, food processing equipment as well as development of microbial resistant food packaging systems. [Display omitted] • EGCG was successfully attached on p(HEMA-co-GMA) membranes surface. • The membranes were characterized by FT-IR and SEM. • EGCG attached p(HEMA-co-GMA) membranes strongly prevented bacterial colonization. [ABSTRACT FROM AUTHOR]

Biofilms are three-dimensional structures formed as a result of microorganism's adhesion on a biotic or abiotic surface. Once a biofilm is established, it is onerous to eradicate it or kill the pathogens therein. Thus, targeting the microbial adhesion process, the initial stage of biofilm formation, is a reasonable approach to avoid challenges associated with subsequently formed biofilms. While many properties of interacting material that play significant roles in initial bacterial adhesion have been widely studied, the effect of surface stiffness on bacterial adhesion was relatively underexplored. In this study, we aimed to investigate the effect of surface stiffness on the adhesion of microbial species found in the oral cavity by employing representative oral bacteria, Streptococcus mutans and Streptococcus oralis, and the fungus, Candida albicans. We compared the adhesion behavior of these species alone or in combination toward various surface stiffness (0.06 – 3.01 MPa) by assessing the adhered and planktonic cell numbers at an early (4 h) adhesion stage under various carbon sources and the presence of conditioning film. Our data revealed that in general, a higher amount of microbial cells adhered to softer PDMS surfaces than stiffer ones, which indicates that surface stiffness plays a role in the adhesion of tested species (either single or co-cultured). This pattern was more obvious under sucrose conditions than glucose + fructose conditions. Interestingly, in monospecies, saliva coating did not alter the effect of surface stiffness on S. mutans adhesion while it diminished S. oralis and C. albicans adhesion. However, in the multispecies model, saliva coating rendered the percentage of all adhered microbes to varied PDMS not distinct. The data provide new insights into the role of surface stiffness on microbial mechanosensing and their initial adhesion behavior which may set a scientific foundation for future anti-adhesion strategies. [Display omitted] • Surface stiffness influenced the initial adhesion of oral microbes, demonstrating higher adhesion to a softer surface. • The binding patterns of individual microbes varied depending on the type of supplemented sugar. • Saliva coating did not affect S. mutans monospecies binding under sucrose-rich conditions. • Saliva coating rendered the effect of surface stiffness on all microbes' adhesion negligible when they are cocultured. [ABSTRACT FROM AUTHOR]

In the present investigation, novel strategy for the preparation of hybrid nanocomposite containing organic polymer (Chitosan) and inorganic (TiO 2 :Cu) nanoparticles (NPs) has been developed and demonstrated its biomedical application. The sol–gel and ultra-sonication method assisted for the preparation of uniformly distributed Chitosan-TiO 2 :Cu (CS-CT) nanocomposite. The structural properties of prepared CS-CT nanocomposite were studied by XRD and FTIR techniques. The XPS was used to estimate elemental composition of the nanocomposite. Thermal properties were studied using TGA. TEM and SEM analysis showed the non-spherical nature of NPs with the average mean diameter 16 nm. The optical properties were analyzed with UV–vis diffuse reflectance spectroscopy to confirm optical absorption in the visible region of light. Where CS-CT showed 200% enhanced light mediated photocatalytic antimicrobial activity against microorganism ( Escherichia coli and Staphylococcus aureus ) as compared with control. The antimicrobial activity of CS-CT nanocomposite in presence of light is found to be enhanced than that of its components, this is due to synergistic effect of organic and inorganic material complimenting each other’s activity. The OH radicals release studied by PL spectroscopy on the surface of nanocomposite was used to examine antibacterial activity. Cytotoxicity assessment of CS-CT on human fibroblast cells was performed by MTT assay. [ABSTRACT FROM AUTHOR]

Microbial adhesion to natural and synthetic materials surfaces is a key issue e.g. in food industry, sewage treatment and most importantly in the biomedical field. The current development and progress in nanoscale structuring of materials surfaces to control microbial adhesion requires an advanced understanding of the microbe-material-interaction. This study aimed to investigate the nanostructure of the microbe-material-interface and link it to microbial adhesion kinetics as function of titanium surface nanoroughness to gain new insight into controlling microbial adhesion via materials’ surface nanoroughness. Adhesion of Escherichia coli and Staphylococcus aureus was statistically significantly reduced (p ≤ 0.05) by 55.6 % and 40.5 %, respectively, on physical vapor deposited titanium thin films with a nanoroughness of 6 nm and the lowest surface peak density compared to 2 nm with the highest surface peak density. Cross-sectioning of the microbial cells with a focused ion beam (FIB) and SEM imaging provided for the first time direct insight into the titanium-microbe-interface. High resolution SEM micrographs gave evidence that the surface peaks are the loci of initial contact between the microbial cells and the material’s surface. In a qualitative model we propose that the initial microbial adhesion on nanorough surfaces is controlled by the titanium surface peak density via nano adhesion points. This new understanding will help towards the design of materials surfaces for controlling microbial adhesion. [ABSTRACT FROM AUTHOR]

Oral biofilms can be a major health problem causing infections and chronic inflammation of mucosal tissue. While much effort is put in the investigation of bacteria in biofilms, the role of fungi is often neglected, despite Candida albicans playing a key role in the formation of multispecies oral biofilms. With the rise of antibiotic resistance, new strategies to reduce microbial growth need to be found. Therefore, plant derived polyphenolic molecules have been suggested to reduce both adhesion and growth of pathogenic bacteria and fungi. In this study, we investigated the use of polyphenolic coatings to reduce adhesion and biofilm formation of C. albicans BWP17 on titanium implants. Tannic acid and pyrogallol coatings altered the hydrophobic and charge properties of titanium surfaces, and both compounds were gradually released as active molecules over time. Despite such effects, we found no significant inhibition on growth and biofilm formation of C. Albicans , indicating that the release of active molecules from the coatings did not reach relevant inhibitory concentrations. However, a potential antibiofilm effect was observed by the pH-dependent disassembly of the polyphenolic layer, which caused the biofilm to detach. Hence, further efforts are required to create tailored implant surfaces, which sustainably reduce microbial growth and adhesion. [Display omitted] • The antioxidant potential of polyphenolic coatings depends on coating condition. • Tannic acid and pyrogallol coatings affect protein adsorption compared to titanium. • Polyphenolic coatings did not reduce the growth and adhesion of Candida albicans. • Tannic acid coatings can act as sacrificial layer activated by acidic pH. [ABSTRACT FROM AUTHOR]

The effects of the presence or absence of microbial flagella and the microbial motility on the colloidal behaviors of microbial cells were quantitatively evaluated. The microbial cell attachment and detachment processes on a glass surface were observed directly using a parallel-plate flow chamber. Wild-type, flagellar paralyzed, and nonflagellated Escherichia coli strains were used as model microbial cells. In the cell attachment tests, the microbial adhesion rate in a 160 mM NaCl solution was approximately 10 times higher than that in a 10 mM solution, for all E. coli strains. The colloidal behavior of the microbial cells agreed well with the predictions of the DLVO theory. In addition, the microbial flagella and motility did not significantly affect the cell attachment, regardless of the existence of a potential barrier between the cell and the glass substratum. In the cell detachment tests, the cumulative number of microbial cells detached from the glass substratum with increasing flow rate was fit well with the Weibull distribution function. The list of strains arranged in order of increasing median drag force required to remove them was nonflagellated strain, flagellar paralyzed strain, and wild-type strain. These results indicated that the flagella and the flagellar motility inhibited the cell detachment from the glass substratum. Furthermore, a large external force would likely be required to inhibit the microbial adhesion in the early stage of the biofilm formation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Organisms tested have an overall negative electrophoretic mobility at pH 8 regardless of buffer strength. [•] High degree of variability in surface properties among Gram negative organisms tested. [•] Strains of E. coli are predicted to be the most difficult to remove using conventional treatment technologies. [ABSTRACT FROM AUTHOR]

Abstract: Attempts to measure the hydrophobicity of the cell surfaces of Gordonia amarae and Rhodococcus erythropolis, filamentous bacteria found in wastewater treatment plants, by several methods—microbial adhesion to hydrocarbons (MATH) or bacterial adhesion to hydrocarbons (BATH), contact angle, and micro-sphere adhesion to cells (MAC)—were unsuccessful. The results were erratic and inconsistent. This was in part because of the filamentous growth habit of G. amarae, but it was also a consequence of the fact that the ‘hydrophobicity’ of bacterial cells is not a clearly defined quantity. A technique is introduced in which bacteria are suspended in solutions of synthetic surfactants (non-ionic, cationic and anionic), and the suspensions aerated under defined conditions. The partitioning of bacterial cells between the foam and liquid phases was reproducible. The method was tested in model systems in which the bacteria were replaced by silica particles with defined surface modifications. Although this technique is not a direct measure of ‘hydrophobicity’, the partitioning of cells depends in part upon their surface hydrophobicity. In addition, qualitative information is gained about ionic interactions between the bacteria and the bubble surface. The results are pertinent to the problem of foaming in wastewater treatment plants. [Copyright &y& Elsevier]

Abstract: The antiadhesive action of a lipopeptide biosurfactant from a marine bacterium was investigated. The effect of cultivation conditions on the adhesion property of few bacterial strains was studied. It was observed that the static cultures showed greater adhesion due to scarcity of oxygen. The biosurfactant upon surface conditioning was found to be effective in removal of the microbial adhesion at a concentration as low as 0.1gL−1. The percentages of inhibition of adhesion against different test bacterial strains ranged from 15 to 89% using 0.1–10gL−1 of purified biosurfactant. These percentages of adhesion inhibition were found to be significantly higher than the previously reported values. The antiadhesive efficacy of the biosurfactant was also evident from confocal laser scanning microscopy studies. [Copyright &y& Elsevier]

Abstract: The electron donor–electron acceptor (acid–base properties) of cell surfaces of a series of bacteria were determined by two methods, namely, Microbial Adhesion to Solvents (MATS) and Contact Angle Measurements (CAM) combined with equation of Van Oss. The efficiency of these two methods was then compared. Pseudomonas aeruginosa ATCC 27853, Bacillus subtilis ILP 142B, Staphylococcus aureus ATCC 25923 and four Escherichia coli strains including HB101, AL52, O128B12 and ATCC 25922, acid–base properties were examined under the two different conditions mentioned above. The results showed that the correlation between acid–base properties determined by MATS and CAM was very weak. We have also found that when the microbial cell surface was electron donor by CAM method, similar result was found by MATS, but the reverse was not always true. In contrast, a good correlation between the two methods was obtained when the four E. coli strains were examined. [Copyright &y& Elsevier]

Abstract: Silicone rubber is a frequently used biomaterial in biomedical devices and implants, yet highly prone to microbial adhesion and the development of a biomaterial-centered infection. Effective coating of silicone rubber to discourage microbial adhesion has thus far been impossible due to the hydrophobic character of its surface, surface deterioration upon treatment and instability of coatings under physiological conditions. Here we present a method to successfully grow polyacrylamide (PAAm) brushes from silicone rubber surfaces after removal of low molecular weight organic molecules (LMWOM), such as silane oligomers. PAAm brush coating did not cause any surface deterioration and discouraged microbial adhesion, even after 1-month exposure to physiological fluids. The method presented opens many new avenues for the use of silicone rubber as a biomaterial, without the risk of developing a biomaterial-centered infection. [Copyright &y& Elsevier]

Abstract: Bacteria possess surface properties, related to their charge, hydrophobicity and Lewis acid/base characteristics, that are involved in the attachment processes of microorganisms to surfaces. Fermentation bulks and food matrixes are complex heterogeneous media containing various components with different physicochemical characteristics. The aim of the present study was to investigate whether (i) bacteria present in a food matrix, interacted physicochemically at their surface level with the other constituents and (ii) the diversity of bacterial surface properties could result in a diversity of microbial adhesion to components and thus in a diversity of tolerance to toxic compounds. The surface properties of 20 lactic acid bacteria were characterized by the MATS method showing their relatively hydrophilic and various basic characteristics. The results obtained from a set of representative strains showed that (i) the strains with higher affinity for apolar solvents adsorbed more to lipids and hydrophobic compounds, (ii) the more the strains adsorbed to a toxic solvent, the less they were tolerant to this solvent. A diversity of bacterial surface properties was observed for the strains in the same species showing the importance of choosing bacteria according to their surface properties in function of technological objectives. [Copyright &y& Elsevier]

Abstract: We present data and analyses concerning the adhesion of clinically relevant Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa (bacteria) and Candida albicans (yeast) to Zircaloy-2 (Zry-2) and Zircadyne-705 (Zr705) surfaces. These zirconium-based materials are similar to those now being used in total hip and knee replacements. Here we study clinical strains of microbes under shaken and stationary exposure conditions, and their ability to adhere to Zr surfaces having different oxide thicknesses. We use X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), viable counts, endotoxin assays, and statistical analysis methods, and demonstrate a predictive model for microbial adhesion based on XPS data. [Copyright &y& Elsevier]

Abstract: Microbial adhesion to surfaces often occurs despite high wall shear rates acting on the adhering microorganisms. In this paper, we compare the wall shear rates needed to prevent microbial adhesion to bare glass and poly(ethylene oxide) (PEO)-brush coated glass in a parallel plate flow chamber. Initial microbial deposition rates were determined for different wall shear rates between 4 and 1600s−1 on the top and bottom plates of the flow chamber. Deposition efficiencies α SL, based on the Smoluchowski–Levich approach, for Pseudomonas aeruginosa D1, Escherichia coli O2K2 and Candida tropicalis GB 9/9 decreased with increasing wall shear rates and were lower for PEO-brush coated glass than for bare glass. Characteristic shear rates preventing adhesion to the bottom plate were around 10 and 1.0s−1 for the bacteria on glass and the PEO-brush and 36 and 3.4s−1 for the yeast strain on glass and the PEO-brush, respectively. This demonstrates that the adhesive forces between microorganisms and a PEO-brush are comparatively weak, although some strains may have the ability to adhere to a PEO-brush under low shear conditions. Microbial deposition efficiencies α SL were much larger, however, than unity for bottom plate deposition, but could be reduced to realistic values by averaging the deposition rates found for the top (negative contribution of sedimentation) and bottom (positive contribution of sedimentation) plates. [Copyright &y& Elsevier]

Abstract: Surfaces were produced with defined topographical features and surface chemistry. Silicon wafers, and wafers with attached nucleopore filters and quantifoils were coated with titanium using ion beam sputtering technology. Irregularly spaced, but regularly featured surface pits, sizes 0.2 and 0.5μm, and regularly spaced pits with regular features (1 and 2μm) diameter were produced. The smallest surface feature that could be successfully produced using this system was of diameter 0.2μm. Ra, the average absolute deviation of the roughness irregularities from the mean line over one sampling length, Rz, the difference in height between the average of the five highest peaks, and the five lowest valleys along the assessment length of the profile and surface area values increased with surface feature size, with Ra values of 0.04–0.217μm. There was no significant difference between the contact angles observed for smooth titanium surfaces with 0.2 and 0.5μm features. However, a significant difference in contact angle was observed between the 1 and 2μm featured surfaces (p &#60;0.005). Substrata were used in microbial retention assays, using a range of unrelated, differently sized microorganisms. Staphylococcus aureus (cells 0.5–1μm diameter) were retained in the highest numbers. S. aureus was well retained in the 0.5μm sized pits and began to accumulate within larger surface features. Rod shaped Pseudomonas aeruginosa (1μm×3μm) were preferentially retained, often end on, within the 1μm surface features. Some daughter cells of Candida albicans blastospores were retained in 2μm pits. For S. aureus and P. aeruginosa, the greatest numbers of cells were retained in the largest (2μm) surface features. The number of C. albicans was similar across all the surfaces. The use of defined surfaces in microbial retention assays may lead to a better understanding of the interaction occurring between cells and surface features. [Copyright &y& Elsevier]

A novel approach to controlling unwanted microbial adhesion in clinical environments is to inhibit the initial attachment of bacteria, rather than trying to remove them once they have adhered. Previous investigations have established that antimicrobial peptides such as nisin can adsorb to surfaces and still retain sufficient activity to inhibit pathogenic bacteria. We examined techniques of application of nisin in vitro to elucidate those most effective and practical for use on biomedical implants in vivo. Nisin adsorbed quickly on Polyvinyl chloride (PVC) suction catheter tubing, with only a slight gain in nisin activity as contact times increased from 10 s to 8 h. The activity of nisin adsorbed on PVC suction catheter tubing increased as solution concentrations increased from 0.01 to 2.0 mg/ml, and it decreased with aging in protein-free phosphate buffer for 48 h and with drying for up to 2 months. When exposed to three species of Gram-positive bacteria, nisin-treated PVC tubing demonstrated an ability to inhibit bacterial growth, while bacteria grew unchecked on catheter material that was untreated. We then examined the ability of nisin to retain its activity in vivo when placed on implants in blood vessels or the upper airway and whether nisin causes tissue reactions greater than untreated implants placed in sheep and ponies. Freshly prepared nisin was applied to Teflon® FEP intravenous catheters and to PVC tracheotomy tubes at the time of placement, using a concentration of 1.0 mg/ml and 10-s contact time. Tissue reactions in response to nisin adsorbed on intravenous catheters or tracheotomy tubes did not occur in sheep or ponies, respectively. Nisin activity was retained for more than 5 h but less than 1 week on intravenous catheters placed in the jugular veins of sheep, and the veins with short-term catheters showed fewer and less severe histologic abnormalities compared with controls, indicating a possible protective effect on vascular endothelium. Nisin activity was retained on PVC tracheotomy tubes maintained for 1–2 h in ponies, but not on tubes in place for 24 h. As the first preclinical trial of nisin-treated implantable materials, this study represents an important first step for developing the potentially broad use of protein antimicrobial films on implantable medical devices. [Copyright &y& Elsevier]

[Display omitted] • Cathodic protection inhibits the microorganisms' adhesion to metallic surface. • The potential of −1000 mV Ag/AgCl stimulates the hydrogenase activity of SRB. • Low cathodic protection potential increases density and depth of pits. Metallic corrosion is a recurrent and costly problem to almost every industry; therefore, prevention strategies might be well-defined on a case-by-case basis. Commonly, cathodic protection (CP) is the world's most widely-adopted technique to guarantee the integrity of buried or submerged structures from corrosion. However, as current potential values are dependent on metal-structure and environmental features, the target shall be well-identified; otherwise, the intended effect will not be reached. In seawater, a protective current potential of −800 mV Ag/AgCl is recommended by technical standards, while a more negative potential (−900 mV Ag/AgCl) is the suggested criterion for the control of corrosion induced by sulfate-reducing bacteria (SRB), even though without proper scientific support. Thus, this study focused on evaluating the efficiency of different cathodic protection potentials (−800, −900 and, −1000 mV Ag/AgCl) on inhibiting SRB-mediated corrosion of AISI 1020 steel. Both unprotected and impressed current cathodically protected steel specimens were exposed to indigenous microorganisms in seawater for 7 days. The Most Probable Number (MPN) enumeration of sessile aerobic heterotrophic bacteria, acid-producing bacteria and, sulfate-reducing bacteria was performed at the beginning and at the end of the assays. Also, the reducing activity of hydrogenase-positive SRB strains was measured. Although the microbial colonization was greater on unprotected steel surfaces than on the cathodically protected ones, biofilm quantification of CP specimens did not show important differences regardless of the potential. However, hydrogenase-positive SRB counts increased with the reduction of CP potential value, promoting an increase in the number and depth of pits on specimens protected at −1000 mV Ag/AgCl when compared with those protected at −800 mV Ag/AgCl and unprotected ones. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microbial surface biofouling is a major problem in medicine and cause of infection. • MEG-OH is a thin and robust anti-fouling layer that reduces fouling and thrombosis. • MEG-OH was found to reduce biofouling by several pathogens on polyurethane tubing. • MEG-OH coatings were stable in storage, and through autoclave sterilization. Indwelling urinary catheters are a common medical device used to relieve urinary retention. Many patients who undergo urinary catheterization develop urinary tract infections (UTIs), which can lead to severe medical complications and high cost of subsequent treatment. Recent years have seen a number of attempts at reducing the rate of UTIs in catheterized patients via catheter surface modifications. In this work, a low cost, robust anti-thrombogenic, and sterilizable anti-fouling layer based on a covalently-bound monoethylene glycol hydroxide (MEG-OH) was attached to polyurethane, a polymeric material commonly used to fabricate catheters. Modified polyurethane tubing was compared to bare tubing after exposure to a wide spectrum of pathogens including Gram-negative bacteria (Pesudomonas aeruginosa, Escherichia coli), Gram-positive bacteria (Staphylococcus aureus) and a fungus (Candida albicans). It has been demonstrated that the MEG-OH monolayer was able to significantly reduce the amount of adhesion of pathogens present on the material surface, with between 85 and 96 % reduction after 24 h of exposure. Additionally, similar reductions in surface fouling were observed following autoclave sterilization, long term storage of samples in air, and longer exposure up to 3 days. [ABSTRACT FROM AUTHOR]

• The particle size affects the evaluation of the hydrophobic character by MATH. • The MATH method seems inappropriate for particles smaller than 1 μm. • Water contact angle is not affected by the microsphere size (from 0.2–4.5 μm). The current experimental study investigates the influence of latex microsphere particles' size on the assessment of their hydrophilic/hydrophobic character, using the method known as "Microbial Adhesion to Hydrocarbons" (MATH). Since bacteria surfaces often change according to the environment in which they find themselves, most of the experiments here were carried out using the calibrated latex microspheres Polybeads® and Yellow-green Fluoresbrite® (Polyscience) microspheres with diameters between 0.2 μm and 4.5 μm. All the beads had a density of ˜1.05 g/cm3. The first set of experiments was performed to adapt the procedure for measurements of water contact angles to microsphere lawns. It was found that all the microspheres tested were hydrophobic, when using a water contact angle of around 110-118°. However, wide differences were observed using the MATH method. The smaller microspheres (0.2 μm, 0.5 μm +/- 0.75 μm) exhibited a poor affinity to hexadecane, even after long contact times, suggesting a hydrophilic character. In contrast, larger microspheres quickly adhered to hexadecane, which is consistent with the values obtained for the water contact angles observed. These results suggest that, at least where hydrophobic particles are concerned, the MATH method is not suitable for the assessment of the hydrophobic character of particles with diameters of less than 1.0 μm. We lastly investigated whether the data obtained for Bacillus spores could also be affected by spore size. The hydrophobicity of spores of eight Bacillus strains was analysed by both MATH and contact angle. Some discrepancies were observed between both methods but could not be related their size (length or width). [ABSTRACT FROM AUTHOR]