The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Roger E Marchant - One of the best experts on this subject based on the ideXlab platform.
-
surfactant polymers designed to suppress bacterial staphylococcus Epidermidis Adhesion on biomaterials
Journal of Biomedical Materials Research, 2000Co-Authors: Katanchalee Vacheethasanee, Roger E MarchantAbstract:We describe a series of surfactant polymers designed as surface-modifying agents for the suppression of bacterial Adhesion on biomaterials. The surfactant polymers consist of a poly(vinyl amine) backbone with hydrophilic poly(ethylene oxide) (PEO) and hydrophobic hexanal (Hex) side chains (PVAm/PEO:Hex). Surface modification is accomplished by simple dip coating from aqueous solution, from which surfactant polymers undergo spontaneous surface-induced assembly on hydrophobic biomaterials. The stability of PVAm/PEO:Hex on pyrolytic graphite (HOPG) and polyethylene (PE) was demonstrated by the absence of detectable desorption under flow conditions of pure water over a 24-h period. PEO surfactant polymers with four different PEO:Hex ratios (1:1.4, 1:2.5, 1:4.6, and 1:10.7) and a dextran surfactant polymer were compared with respect to S. Epidermidis Adhesion under dynamic flow conditions. Suppression of S. Epidermidis Adhesion was achieved for all modified surfaces over the shear range 0–15 dyn/cm2. The effectiveness depended on the surfactant polymer composition such that S. Epidermidis Adhesion to modified surfaces decreased significantly with increasing PEO packing density. Modified HOPG was more effective in reducing bacterial Adhesion compared with the corresponding modification on PE, which we attribute to the presence of defects in surfactant polymer assembly on PE. Our results are discussed from the perspective of critical factors, such as optimal PEO packing density and hydration thickness, that contribute to the effectiveness of surfactant polymers to shield a biomaterial from adhesive bacterial interactions. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 50, 302–312, 2000.
-
nonspecific staphylococcus Epidermidis Adhesion
2000Co-Authors: Katanchalee Vacheethasanee, Roger E MarchantAbstract:In this chapter, we examine the contribution of material physicochemical surface properties on nonspecific Staphylococcus Epidermidis Adhesion under dynamic flow conditions in phosphate buffered saline (PBS). These are conditions that are relevant to pre-implantation conditions in the absence of adsorbing biological components such as proteins. In addition, the applied shear stress provides a quantitative measure of the strength of the bacteria—material surface Adhesion. Here, we describe the influence of material surface hydrophobicity on S. Epidermidis RP62A Adhesion in 132.7 mM PBS using four self assembled monolayer (SAM) surfaces bearing a net negative, positive, or neutral charge and five biomedical polymers. Materials with higher surface hydrophobicity show statistically higher bacterial Adhesion at shear stresses of 0 to 32 dyne/cm2, demonstrating the contribution of material surface hydrophobicity on nonspecific Adhesion. However, this positive correlation is limited to materials with water contact angles of >70° at 0–8 dyne/cm2, and >100° at higher shear stresses (16–32 dyne/cm2). For materials with contact angles below these critical values (θcrit), S. Epidermidis Adhesion was found to be relatively independent of material surface hydrophobicity, indicating that a minimum number of bacteria can adhere to biomaterials independent of surface energy. This behavior is explained by a proposed model of nonspecific interactions based on DVLO forces, hydrodynamic effect and fimbriae formation. The contribution of material surface charge to Adhesion was assessed by quantifying Adhesion of S. Epidermidis RP62A to charged surfaces in PBS of increasing ionic strength under shear stresses of 0–15 dyne/cm2. Both repulsive and attractive interactions were found to be involved in S. Epidermidis Adhesion, but only the attractive interaction was found to significantly alter Adhesion in buffered saline (132.7 mM ion concentration) at zero shear stress.
-
Adhesion of staphylococcus Epidermidis and transposon mutant strains to hydrophobic polyethylene
Journal of Biomedical Materials Research, 1998Co-Authors: Julie M Higashi, James M Anderson, Iwen Wang, David M Shlaes, Roger E MarchantAbstract:Staphylococcus Epidermidis capsular polysaccharide adhesin (PS/A) and slime were studied as possible mediators of bacterial Adhesion to NHLBI polyethylene (PE) under dynamic flow. This putative interaction was examined by quantifying the Adhesion of M187 (PS/A+, slime+) parent strain and isogenic transposon mutant strain sn3 (PS/A−, slime−) to polyethylene (PE) under a range of physiologic shear stress conditions in both phosphate-buffered saline (PBS) and 1% platelet poor plasma (PPP). No significant differences in Adhesion were noted between the M187 and sn3 strains in either test medium. However, Adhesion of both strains in 1% PPP was decreased 75–95% compared to Adhesion in PBS. In PBS, Adhesion was shear stress dependent from 0–15 dyne/cm2, after which Adhesion was comparatively shear stress independent. Adhesion in 1% PPP was independent of shear stress. Epifluorescent imaging of both strains labeled for slime confirmed the presence of slime on the surface of M187 and suggested that PS/A and slime promote the formation of large aggregates, as aggregates were totally absent in the images of the sn3 strain. The results suggest that PS/A and slime do not mediate S. Epidermidis Adhesion to bare PE or PE with adsorbed plasma proteins, but may be necessary for intercellular Adhesion, which is important for biofilm formation. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 39, 341–350, 1998.
-
Adhesion of staphylococcus Epidermidis to biomedical polymers contributions of surface thermodynamics and hemodynamic shear conditions
Journal of Biomedical Materials Research, 1995Co-Authors: Iwen W Wang, James M Anderson, Michael R Jacobs, Roger E MarchantAbstract:Adhesion studies of Staphylococcus Epidermidis RP62A were conducted using a rotating disk system to determine the roles of surface physicochemistry and topographies under physiologic shear conditions. Six materials were investigated: biomedical reference polyethylene and polydimethylsiloxane; argon plasma-treated reference polyethylene (Ar-PE); Silastic®; expanded polytetrafluoroethylene; and woven Dacron. All of the polymers except Dacron demonstrated reduced bacterial Adhesion with increasing shear stress. Argon plasma treatment of polyethylene reduced the level of staphylococcal Adhesion. Adsorption of human plasma proteins effected significantly lower numbers of adherent bacteria. The lowest Adhesion was observed for Ar-PE in 1% human plasma protein solution, whereas Dacron had the highest number of adherent bacteria. The high Adhesion on Dacron was attributed to increased bacterial flux caused by topography-induced turbulent flow and physical entrapment of the bacteria in the fiber interstices. The results indicate that the driving force for S. Epidermidis Adhesion is strongly influenced by substrate physicochemistry, but this may be dominated by physical forces such as shear and turbulence. © 1995 John Wiley & Sons, Inc.
-
platelet mediated Adhesion of staphylococcus Epidermidis to hydrophobic nhlbi reference polyethylene
Journal of Biomedical Materials Research, 1993Co-Authors: Iwen W Wang, James M Anderson, Roger E MarchantAbstract:The effects of platelets and plasma proteins on the Adhesion of Staphylococcus Epidermidis strain RP62A to hydrophobic NHLBI reference polyethylene was quantitatively studied using a rotating disk system to generate well-defined shear conditions simulating the hemodynamics of human blood circulation. Bacterial Adhesion was quantified by adhesive coefficient, the percentage of bacteria transported to the surface that becomes adherent. The results showed that surface modification by adsorption of plasma proteins reduced the Adhesion of S Epidermidis as compared to the bare polymer surface. This surface modification was not sufficient to eliminate completely bacterial Adhesion, even at the highest physiologic shear stress level. S Epidermidis did adhere strongly to polyethylene surface modified by platelets. This is readily evident as approximately 50% of the adherent S Epidermidis were bound to contact-activated platelets which occupied only 4% of the surface area. Adhesive coefficients to platelets were significantly greater than to the protein-adsorbed polyethylene surface by at least one order of magnitude (P ≤ .01) across the range of physiological shear conditions investigated. These studies show that it is biologic surface modification by contact-activated platelets, and not plasma proteins, which mediates S Epidermidis Adhesion to polyethylene. © 1993 John Wiley & Sons, Inc.
Yannis F. Missirlis - One of the best experts on this subject based on the ideXlab platform.
-
Fluid Flow and Sub-Bactericidal Release of Silver from Organic Nanocomposite Coatings Enhance ica Operon Expression in Staphylococcus Epidermidis
Journal of Biomaterials and Nanobiotechnology, 2013Co-Authors: Maria G. Katsikogianni, I. Spiliopoulou, Antigoni Foka, Eloisa Sardella, C. Ingrosso, Pietro Favia, Annarosa Mangone, Yannis F. MissirlisAbstract:The present study investigates the effect of a silver (Ag)-containing nanocomposite coating on Staphylococcus Epidermidis Adhesion and icaA gene expression. Bacterial interactions with organic coatings with and without Ag nanoclusters were assessed through a combination of both conventional phenotypic analysis, using microscopy, and genotypic analysis, using the relative reverse transcription Real-Time Polymerase Chain Reaction (RT-PCR). The results suggest that the incorporation of Ag in organic coatings can significantly decrease bacterial Adhesion and viability with time, in comparison to the organic coating alone. The initial Ag release though at concentrations lower than the bactericidal, significantly increased icaA gene expression for the bacteria interacting with the Ag containing coating two hours post Adhesion, especially under the higher shear rate. Stress-inducing conditions such as sub-bactericidal concentrations of Ag and high shear rate can therefore increase icaA expression, indicating that analysis of gene expression can not only refine our knowledge of bacterial-material interactions, but also yield novel biomarkers for potential use in assessing biomaterials antimicrobial performance.
-
the combined effect of surface chemistry and flow conditions on staphylococcus Epidermidis Adhesion and ica operon expression
European Cells & Materials, 2012Co-Authors: Antigoni Foka, Maria G. Katsikogianni, I. Spiliopoulou, Evangelos D Anastassiou, Yannis F. MissirlisAbstract:The assessment of biomaterial susceptibility to infection relies mainly on the analysis of macroscopic bacterial responses to material interactions, usually under static conditions. However, new technologies permit a more profound understanding of the molecular basis of bacteriabiomaterial interactions. In this study, we combine both conventional phenotypic analysis – using confocal microscopy – and genotypic analysis – using the relative reverse transcription polymerase chain reaction (RT-PCR) – to examine the interaction of bacteria with OH- and CH 3 terminated glass surfaces, under dynamic flow conditions. Bacterial Adhesion, as well as slime production and biofilm formation, was much higher on the CH 3 -terminated than on the OH-terminated glass – for four Staphylococcus Epidermidis strains. This was in agreement with the icaA and icaD gene expression results that showed increased expression for the bacteria adhering to the CH 3 -terminated substrate, especially under the higher shear rate. Therefore, the combined effect of the surface chemistry and shear significantly influence the Adhesion and phenotype of interacting bacterial cells, while there are putative links between phenotypic responses to bacteria-material interactions and gene-expression profile alterations. This indicates that analysis of gene expression not only can greatly refine our knowledge of bacteria-material interactions, but also yield novel biomarkers for potential use in biocompatibility assessment.
-
staphylococcus Epidermidis Adhesion to he he o2 plasma treated pet films and aged materials contributions of surface free energy and shear rate
Colloids and Surfaces B: Biointerfaces, 2008Co-Authors: Maria G. Katsikogianni, E Amanatides, D Mataras, Yannis F. MissirlisAbstract:Adhesion studies of bacteria (Staphylococcus Epidermidis) to plasma modified PET films were conducted in order to determine the role of the surface free energy under static and dynamic conditions. In particular, we investigated the effect of the ageing time on the physicochemical surface properties of helium (He) and 20% of oxygen in helium (He/O2) plasma treated polyethylene terephthalate (PET) as well as on the bacterial Adhesion. Treatment conditions especially known to result in ageing sensitive hydrophilicity (hydrophobic recovery) were intentionally chosen in an effort to obtain the widest possible range of surface energy specimens and also to avoid strong changes in the morphological properties of the surface. Both plasma treatments are shown to significantly reduce bacterial Adhesion in comparison to the untreated PET. However, the ageing effect and the subsequent decrease in the surface free energy of the substratum surfaces with time – especially in the case of He treated samples – seem to favor bacterial Adhesion and aggregation. The dispersion-polar and the Lifshitz–van der Waals (LW) acid–base (AB) thermodynamic approaches were applied to calculate the Gibbs free energy changes of Adhesion (ΔGadh) of S. Epidermidis interacting with the substrates. There was a strong correlation between the thermodynamic predictions and the measured values of bacterial Adhesion, when Adhesion was performed under static conditions. By decoupling the (ΔGadh) values into their components, we observed that polar/acid–base interactions dominated the interactions of bacteria with the substrates in aqueous media. However, under flow conditions, the increase in the shear rate restricted the predictability of the thermodynamic models.
-
Plasma Treated and a‐C:H Coated PET Performance in Inhibiting Bacterial Adhesion
Plasma Processes and Polymers, 2007Co-Authors: Maria G. Katsikogianni, Christos S. Syndrevelis, Eleftherios Amanatides, Dimitrios Mataras, Yannis F. MissirlisAbstract:A comparative study of the effects of plasma deposited amorphous carbon (a-C:H) thin film and He/O2 plasma surface treatment of PET on the physicochemical surface properties and the initial bacterial (Staphylococcus Epidermidis) Adhesion was performed. CH4/H2 RF discharges with different substrate bias voltages were used for the deposition of a-C:H thin films while He/O2 plasmas with different O2 fractions were used for the surface treatment of PET. All the plasma modifications were shown to significantly reduce the bacterial Adhesion in comparison to the untreated PET; however, the reduction was greater for the He/O2 surface treatment. The increase in the surface free energy of the substrate surfaces due to He/O2 plasma treatments seems to inhibit bacterial Adhesion and aggregation.
-
Adhesion of slime producing staphylococcus Epidermidis strains to pvc and diamond like carbon silver fluorinated coatings
Journal of Materials Science: Materials in Medicine, 2006Co-Authors: Maria G. Katsikogianni, I. Spiliopoulou, D. P. Dowling, Yannis F. MissirlisAbstract:Staphylococcus Epidermidis has emerged as a pathogen associated with infections of implanted medical devices. Bacterial Adhesion is a crucial step in infection on biomaterial surfaces. To quantitatively determine the relationship between poly (vinyl chloride) (PVC) surface properties and bacterial Adhesion, we have compared attachment of slime-producing S. Epidermidis strains on PVC and various coatings under flow conditions. Bacterial Adhesion and colonization was quantified by counting the viable organisms on the adherent surface as well as by scanning electron microscopy, epifluorescence microscopy and atomic force microscopy. Fluorination of the PVC surface encourages S. Epidermidis Adhesion whereas; diamond-like carbon (DLC) and especially silver (Ag) coatings seem to inhibit its Adhesion. In most materials, the number of adherent bacteria decreased with the increase of shear rate. These results indicate that bacterial Adhesion is influenced by the chemical properties of the polymeric surfaces, the surface roughness and the associated flow conditions.
Y. F. Missirlis - One of the best experts on this subject based on the ideXlab platform.
-
Bacterial Adhesion onto materials with specific surface chemistries under flow conditions
Journal of Materials Science: Materials in Medicine, 2010Co-Authors: M. G. Katsikogianni, Y. F. MissirlisAbstract:Staphylococcus Epidermidis Adhesion onto materials with specific chemical functionalities, under flow, was investigated by using surfaces prepared by self-assembly of alkyl silane monolayers on glass. Terminal methyl (CH_3) and amino (NH_2) groups were formed by chemical vapor deposition of silanes, at elevated temperature. Carboxyl (COOH) terminated groups were prepared by further modification of NH_2 groups with succide anhydride and positively charged NH_2 groups by adsorption of poly- l -lysine hydrobromide. Hydroxyl (OH) terminated glass was used as control. Surface modification was verified by contact angle measurements, atomic force microscopy and X-ray photoelectron spectroscopy. A parallel plate flow chamber was used to evaluate bacterial Adhesion at various shear rates. Adhesion was found to be depended on the monolayer’s terminal functionality. It was higher on the CH_3 followed by the positively charged NH_2, the non-charged NH_2 groups, the COOH and minimal on the OH-terminated glass. The increase in the material surface free energy significantly reduced the Adhesion of a hydrophilic bacterial strain, and this is in accordance with the predictions of the thermodynamic theory. However, the increase in the shear rate restricted the predictability of the theory and revealed macromolecular interactions between bacteria and NH_2- and COOH-terminated surfaces.
-
Adhesion of slime producing Staphylococcus Epidermidis strains to PVC and diamond-like carbon/silver/fluorinated coatings
Journal of Materials Science: Materials in Medicine, 2006Co-Authors: M. Katsikogianni, I. Spiliopoulou, D. P. Dowling, Y. F. MissirlisAbstract:Staphylococcus Epidermidis has emerged as a pathogen associated with infections of implanted medical devices. Bacterial Adhesion is a crucial step in infection on biomaterial surfaces. To quantitatively determine the relationship between poly (vinyl chloride) (PVC) surface properties and bacterial Adhesion, we have compared attachment of slime-producing S. Epidermidis strains on PVC and various coatings under flow conditions. Bacterial Adhesion and colonization was quantified by counting the viable organisms on the adherent surface as well as by scanning electron microscopy, epifluorescence microscopy and atomic force microscopy. Fluorination of the PVC surface encourages S. Epidermidis Adhesion whereas; diamond-like carbon (DLC) and especially silver (Ag) coatings seem to inhibit its Adhesion. In most materials, the number of adherent bacteria decreased with the increase of shear rate. These results indicate that bacterial Adhesion is influenced by the chemical properties of the polymeric surfaces, the surface roughness and the associated flow conditions.
Maria G. Katsikogianni - One of the best experts on this subject based on the ideXlab platform.
-
Fluid Flow and Sub-Bactericidal Release of Silver from Organic Nanocomposite Coatings Enhance ica Operon Expression in Staphylococcus Epidermidis
Journal of Biomaterials and Nanobiotechnology, 2013Co-Authors: Maria G. Katsikogianni, I. Spiliopoulou, Antigoni Foka, Eloisa Sardella, C. Ingrosso, Pietro Favia, Annarosa Mangone, Yannis F. MissirlisAbstract:The present study investigates the effect of a silver (Ag)-containing nanocomposite coating on Staphylococcus Epidermidis Adhesion and icaA gene expression. Bacterial interactions with organic coatings with and without Ag nanoclusters were assessed through a combination of both conventional phenotypic analysis, using microscopy, and genotypic analysis, using the relative reverse transcription Real-Time Polymerase Chain Reaction (RT-PCR). The results suggest that the incorporation of Ag in organic coatings can significantly decrease bacterial Adhesion and viability with time, in comparison to the organic coating alone. The initial Ag release though at concentrations lower than the bactericidal, significantly increased icaA gene expression for the bacteria interacting with the Ag containing coating two hours post Adhesion, especially under the higher shear rate. Stress-inducing conditions such as sub-bactericidal concentrations of Ag and high shear rate can therefore increase icaA expression, indicating that analysis of gene expression can not only refine our knowledge of bacterial-material interactions, but also yield novel biomarkers for potential use in assessing biomaterials antimicrobial performance.
-
the combined effect of surface chemistry and flow conditions on staphylococcus Epidermidis Adhesion and ica operon expression
European Cells & Materials, 2012Co-Authors: Antigoni Foka, Maria G. Katsikogianni, I. Spiliopoulou, Evangelos D Anastassiou, Yannis F. MissirlisAbstract:The assessment of biomaterial susceptibility to infection relies mainly on the analysis of macroscopic bacterial responses to material interactions, usually under static conditions. However, new technologies permit a more profound understanding of the molecular basis of bacteriabiomaterial interactions. In this study, we combine both conventional phenotypic analysis – using confocal microscopy – and genotypic analysis – using the relative reverse transcription polymerase chain reaction (RT-PCR) – to examine the interaction of bacteria with OH- and CH 3 terminated glass surfaces, under dynamic flow conditions. Bacterial Adhesion, as well as slime production and biofilm formation, was much higher on the CH 3 -terminated than on the OH-terminated glass – for four Staphylococcus Epidermidis strains. This was in agreement with the icaA and icaD gene expression results that showed increased expression for the bacteria adhering to the CH 3 -terminated substrate, especially under the higher shear rate. Therefore, the combined effect of the surface chemistry and shear significantly influence the Adhesion and phenotype of interacting bacterial cells, while there are putative links between phenotypic responses to bacteria-material interactions and gene-expression profile alterations. This indicates that analysis of gene expression not only can greatly refine our knowledge of bacteria-material interactions, but also yield novel biomarkers for potential use in biocompatibility assessment.
-
staphylococcus Epidermidis Adhesion to he he o2 plasma treated pet films and aged materials contributions of surface free energy and shear rate
Colloids and Surfaces B: Biointerfaces, 2008Co-Authors: Maria G. Katsikogianni, E Amanatides, D Mataras, Yannis F. MissirlisAbstract:Adhesion studies of bacteria (Staphylococcus Epidermidis) to plasma modified PET films were conducted in order to determine the role of the surface free energy under static and dynamic conditions. In particular, we investigated the effect of the ageing time on the physicochemical surface properties of helium (He) and 20% of oxygen in helium (He/O2) plasma treated polyethylene terephthalate (PET) as well as on the bacterial Adhesion. Treatment conditions especially known to result in ageing sensitive hydrophilicity (hydrophobic recovery) were intentionally chosen in an effort to obtain the widest possible range of surface energy specimens and also to avoid strong changes in the morphological properties of the surface. Both plasma treatments are shown to significantly reduce bacterial Adhesion in comparison to the untreated PET. However, the ageing effect and the subsequent decrease in the surface free energy of the substratum surfaces with time – especially in the case of He treated samples – seem to favor bacterial Adhesion and aggregation. The dispersion-polar and the Lifshitz–van der Waals (LW) acid–base (AB) thermodynamic approaches were applied to calculate the Gibbs free energy changes of Adhesion (ΔGadh) of S. Epidermidis interacting with the substrates. There was a strong correlation between the thermodynamic predictions and the measured values of bacterial Adhesion, when Adhesion was performed under static conditions. By decoupling the (ΔGadh) values into their components, we observed that polar/acid–base interactions dominated the interactions of bacteria with the substrates in aqueous media. However, under flow conditions, the increase in the shear rate restricted the predictability of the thermodynamic models.
-
Plasma Treated and a‐C:H Coated PET Performance in Inhibiting Bacterial Adhesion
Plasma Processes and Polymers, 2007Co-Authors: Maria G. Katsikogianni, Christos S. Syndrevelis, Eleftherios Amanatides, Dimitrios Mataras, Yannis F. MissirlisAbstract:A comparative study of the effects of plasma deposited amorphous carbon (a-C:H) thin film and He/O2 plasma surface treatment of PET on the physicochemical surface properties and the initial bacterial (Staphylococcus Epidermidis) Adhesion was performed. CH4/H2 RF discharges with different substrate bias voltages were used for the deposition of a-C:H thin films while He/O2 plasmas with different O2 fractions were used for the surface treatment of PET. All the plasma modifications were shown to significantly reduce the bacterial Adhesion in comparison to the untreated PET; however, the reduction was greater for the He/O2 surface treatment. The increase in the surface free energy of the substrate surfaces due to He/O2 plasma treatments seems to inhibit bacterial Adhesion and aggregation.
-
Adhesion of slime producing staphylococcus Epidermidis strains to pvc and diamond like carbon silver fluorinated coatings
Journal of Materials Science: Materials in Medicine, 2006Co-Authors: Maria G. Katsikogianni, I. Spiliopoulou, D. P. Dowling, Yannis F. MissirlisAbstract:Staphylococcus Epidermidis has emerged as a pathogen associated with infections of implanted medical devices. Bacterial Adhesion is a crucial step in infection on biomaterial surfaces. To quantitatively determine the relationship between poly (vinyl chloride) (PVC) surface properties and bacterial Adhesion, we have compared attachment of slime-producing S. Epidermidis strains on PVC and various coatings under flow conditions. Bacterial Adhesion and colonization was quantified by counting the viable organisms on the adherent surface as well as by scanning electron microscopy, epifluorescence microscopy and atomic force microscopy. Fluorination of the PVC surface encourages S. Epidermidis Adhesion whereas; diamond-like carbon (DLC) and especially silver (Ag) coatings seem to inhibit its Adhesion. In most materials, the number of adherent bacteria decreased with the increase of shear rate. These results indicate that bacterial Adhesion is influenced by the chemical properties of the polymeric surfaces, the surface roughness and the associated flow conditions.
Rosario Oliveira - One of the best experts on this subject based on the ideXlab platform.
-
Staphylococcus Epidermidis Adhesion on modified urea/urethane elastomers.
Journal of biomaterials science. Polymer edition, 2020Co-Authors: Pilar Teixeira, Rosario Oliveira, A C Trindade, M H Godinho, Joana Azeredo, Jose G FonsecaAbstract:Block urea/urethane co-polymer films present elastomeric properties with the possible tuning of their surface properties within a wide range and are therefore considered relevant surfaces for possible medical applications. In particular, thin free standing films of urea/urethane elastomers with two soft segments, polypropylene oxide and more hydrophobic polybutadiene, develop multistable states with surface topography features with remarkable regularity. Moreover, complex surface structures may be obtained by UV radiation treatment followed by suitable mechanical action and also by extraction of the elastomer with a suitable solvent. In the present work, different modified elastomer samples were assayed for Staphylococcus Epidermidis Adhesion during 2 h and the extent of bacterial Adhesion was evaluated by automatic cell enumeration. Bacterial Adhesion assays demonstrate that the typical trend relating the increase in the number of adhered bacteria with the increase of the surface roughness does not hold for all materials. Results may be interpreted taking into account both the surface topography and the different types of micro-phase segregation of hydrophobic and hydrophilic parts of the elastomer.
-
Reduction of Staphylococcus Epidermidis Adhesion to indwelling medical devices: a simple procedure
British Journal of Biomedical Science, 2020Co-Authors: Claudia Sousa, Mariana Henriques, Pilar Teixeira, Rosario OliveiraAbstract:The present study aims to find a method to reduce Staphylococcus Epidermidis Adhesion to acrylic and silicone ‐ two materials used commonly in medical devices, by heparin and gentian violet surface preconditioning. Different periods of heparin preconditioning are studied to evaluate the influence of preincubation time on the reduction of bacterial Adhesion. A two-hour period was chosen and applied in the Adhesion assays with either heparin or gentian violet. Squares of the materials with adhered cells were also analysed by scanning electron microscopy (SEM). Results of Adhesion assays showed a significant reduction (53‐90%, P 0.05) were found between the extent of Adhesion on silicone coupons pre-contacted either with heparin or gentian violet for each of the strains tested. On acrylic, heparin was more efficient (P
-
Staphylococcus Epidermidis Adhesion on modified urea/urethane elastomers
Journal of Biomaterials Science-polymer Edition, 2012Co-Authors: Pilar Teixeira, Rosario Oliveira, A C Trindade, M H Godinho, Joana Azeredo, Jose G FonsecaAbstract:Block urea/urethane co-polymer films present elastomeric properties with the possible tuning of their surface properties within a wide range and are therefore considered relevant surfaces for possible medical applications. In particular, thin free standing films of urea/urethane elastomers with two soft segments, polypropylene oxide and more hydrophobic polybutadiene, develop multi-stable states with surface topography features with remarkable regularity. Moreover, complex surface structures may be obtained by UV radiation treatment followed by suitable mechanical action and also by extraction of the elastomer with a suitable solvent. In the present work, different modified elastomer samples were assayed for Staphylococcus Epidermidis Adhesion during 2 h and the extent of bacterial Adhesion was evaluated by automatic cell enumeration. Bacterial Adhesion assays demonstrate that the typical trend relating the increase in the number of adhered bacteria with the increase of the surface roughness does not hold...
-
staphylococcus Epidermidis Adhesion to modified polycarbonate surfaces gold and sams coated
Journal of Adhesion Science and Technology, 2012Co-Authors: Claudia Sousa, Pilar Teixeira, Sandro Miguel Pinto Bordeira, Joao F B D Fonseca, Rosario OliveiraAbstract:Bacterial Adhesion to a biomaterial surface is thought to be the key step in the infection of indwelling medical devices and constitutes an object of study in the demand to reduce nosocomial infections. In this work, specific modifications on polycarbonate outer layer were utilized as model surfaces for the study of the Adhesion of Staphylococcus Epidermidis, one of the main microorganisms responsible for nosocomial infections. The effect of gold coating on staphylococcal Adhesion was assessed, as well as of subsequent coverage with different self-assembled monolayers (SAMs): two SAMs with a methyl terminal group and hydrophobic character and two hydrophilic SAMs with a carboxylic acid terminal group. Variations in the aliphatic chain length were also tested. A SAM with a calix-crown molecule was also created to immobilize a specific protein and its antibody. The extent of staphylococcal Adhesion to methyl terminated SAMS was reduced compared to the number of cells adhered to the carboxyl acid terminated ...
-
relevance of cell wall and extracellular matrix proteins to staphylococcus Epidermidis Adhesion and biofilm formation
Journal of Adhesion Science and Technology, 2009Co-Authors: Claudia Sousa, Mariana Henriques, Pilar Teixeira, Rosario OliveiraAbstract:In the present study, the protein profiles of the cell wall (CW) extracts of eight Staphylococcus Epidermidis strains were analysed. The protein pattern of the extracellular matrix (EM) of four S. Epidermidis good biofilm producer strains was also obtained. The main goal was to relate these protein patterns with their bacterial Adhesion and biofilm forming ability. For this purpose, 2 h Adhesion and 8 d-old biofilm assays were carried out, with the adhered cells and biomass quantified by microscopic observation and crystal violet quantification, respectively. CW and EM proteins were visualized by SDS–PAGE. According to the results, a significant percentage of the CW proteins detected was common to all the strains studied. However, the most adhering strains expressed a high number of proteins associated with the initial Adhesion process, and the strongest biofilm producers expressed proteins that were absent in the protein profile of the strains that produced lower amounts of biofilm. Therefore, the presen...