Initial Bacterial Adhesion Research Articles

InlL from Listeria monocytogenes Is Involved in Biofilm Formation and Adhesion to Mucin.

The bacterial etiological agent of listeriosis, Listeria monocytogenes, is an opportunistic intracellular foodborne pathogen. The infection cycle of L. monocytogenes is well-characterized and involves several key virulence factors, including internalins A and B. While 35 genes encoding internalins have been identified in L. monocytogenes, less than half of them have been characterized as yet. Focusing on lmo2026, it was shown this gene encodes a class I internalin, InlL, exhibiting domains potentially involved in adhesion. Following a functional genetic approach, InlL was demonstrated to be involved in initial bacterial adhesion as well as sessile development in L. monocytogenes. In addition, InlL enables binding to mucin of type 2, i.e., the main secreted mucin making up the mucus layer, rather than to surface-located mucin of type 1. InlL thus appears as a new molecular determinant contributing to the colonization ability of L. monocytogenes.

Efficacy of a mouthrinse based on hydroxyapatite to reduce initial bacterial colonisation in situ

ObjectiveThe present in situ - investigation aimed to specify the impact of pure hydroxyapatite microclusters on initial bioadhesion and bacterial colonization at the tooth surface. DesignPellicle formation was carried out in situ on bovine enamel slabs (9 subjects). After 1min of pellicle formation rinses with 8ml of hydroxyapatite (HA) microclusters (5%) in bidestilled water or chlorhexidine 0.2% were performed. As negative control no rinse was adopted. In situ biofilm formation was promoted by the intraoral slab exposure for 8h overnight. Afterwards initial bacterial adhesion was quantified by DAPI staining and bacterial viability was determined in vivo/in vitro by live/dead-staining (BacLight). SEM analysis evaluated the efficacy of the mouthrinse to accumulate hydroxyapatite microclusters at the specimens’ surface and spit-out samples of the testsolution were investigated by TEM. ResultsCompared to the control (2.36×106±2.01×106bacteria/cm2), significantly reduced amounts of adherent bacteria were detected on specimens rinsed with chlorhexidine 0.2% (8.73×104±1.37×105bacteria/cm2) and likewise after rinses with the hydroxyapatite testsolution (2.08×105±2.85×105bacteria/cm2, p<0.001). No demonstrable effect of HA-particles on Streptococcus mutans viability could be shown. SEM analysis confirmed the temporary adsorption of hydroxyapatite microclusters at the tooth surface. Adhesive interactions of HA-particles with oral bacteria were shown by TEM. ConclusionHydroxyapatite microclusters reduced initial bacterial adhesion to enamel in situ considerably and could therefore sensibly supplement current approaches in dental prophylaxis.

Impact of wall shear stress on initial bacterial adhesion in rotating annular reactor.

The objective of this study was to investigate the bacterial adhesion under different wall shear stresses in turbulent flow and using a diverse bacterial consortium. A better understanding of the mechanisms governing microbial adhesion can be useful in diverse domains such as industrial processes, medical fields or environmental biotechnologies. The impact of wall shear stress—four values ranging from 0.09 to 7.3 Pa on polypropylene (PP) and polyvinyl chloride (PVC)—was carried out in rotating annular reactors to evaluate the adhesion in terms of morphological and microbiological structures. A diverse inoculum consisting of activated sludge was used. Epifluorescence microscopy was used to quantitatively and qualitatively characterize the adhesion. Attached bacterial communities were assessed by molecular fingerprinting profiles (CE-SSCP). It has been demonstrated that wall shear stress had a strong impact on both quantitative and qualitative aspects of the bacterial adhesion. ANOVA tests also demonstrated the significant impact of wall shear stress on all three tested morphological parameters (surface coverage, number of objects and size of objects) (p-values < 2.10−16). High wall shear stresses increased the quantity of attached bacteria but also altered their spatial distribution on the substratum surface. As the shear increased, aggregates or clusters appeared and their size grew when increasing the shears. Concerning the microbiological composition, the adhered bacterial communities changed gradually with the applied shear.

Differences of Streptococcus mutans adhesion between artificial mouth systems: a dinamic and static methods

Background: Various materials have been used for treating dental caries. Dental caries is a disease that attacks hard tissues of the teeth. The initial phase of caries is a formation of bacterial biofilm, called as dental plaque. Dental restorative materials are expected for preventing secondary caries formation initiated by dental plaque. Initial bacterial adhesion is assumed to be an important stage of dental plaque formation. Bacteria that recognize the receptor for binding to the pellicle on tooth surface are known as initial bacterial colonies. One of the bacteria that plays a role in the early stage of dental plaque formation is Streptococcus mutans (S. mutans). Artificial mouth system (AMS) used in bacterial biofilm research on the oral cavity provides the real condition of oral cavity and continous and intermittent supply of nutrients for bacteria. Purpose: This study aimed to compare the profile of S. mutans bacterial adhesion as the primary etiologic agent for dental caries between using static method and using artificial mouth system, a dinamic. method (AMS). Method: The study was conducted at Faculty of Dentistry and Integrated Research and testing laboratory (LPPT) in Universitas Gadjah Mada from April to August 2015. Composite resin was used as the subject of this research. Twelve composite resins with a diameter of 5 mm and a width of 2 mm were divided into two groups, namely group using static method and group using dynamic method. Static method was performed by submerging the samples into a 100µl suspension of 1.5 x 108 CFU/ml S. mutans and 200µl BHI broth. Meanwhile AMS method was carried out by placing the samples at the AMS tube drained with 20 drops/minute of bacterial suspension and sterile aquadest. After 72 hours, five samples from each group were calculated for their biofilm mass using 1% crystal violet and read by a spectrofotometer with a wavelength of 570 nm. Meanwhile, one sample from each group was taken for its surface image using Scanning Electron Microscope (SEM). Result: The results showed that S. mutans biofilm mass in the group using static method was 0.34, while in the group using AMS method was 0.09. The results of the statistical analysis then showed that there was a significant difference (p=0.02) in the formation of bacterial biofilm mass between those groups. SEM image in the group using static method also showed that the attachment of S. mutans was more numerous and had a longer chain than in the group using AMS method. Conclusion: There is a difference in the profile of S. mutans bacterial adhesion between using AMS method and static method.

The response of human osteoblasts, epithelial cells, fibroblasts, macrophages and oral bacteria to nanostructured titanium surfaces: a systematic study.

Nanotopography modification is a major focus of interest in current titanium surface design; however, the influence of the nanostructured surface on human cell/bacterium behavior has rarely been systematically evaluated. In this study, a homogeneous nanofiber structure was prepared on a titanium surface (Nano) by alkali-hydrothermal treatment, and the effects of this Nano surface on the behaviors of human MG-63 osteoblasts, human gingival epithelial cells (HGECs) and human gingival fibroblasts (HGFs) were evaluated in comparison with a smooth titanium surface (Smooth) by polishing and a micro-rough titanium surface (Micro) by sandblasting and acid etching. In addition, the impacts of these different surface morphologies on human THP-1 macrophage polarization and Streptococcus mutans attachment were also assessed. Our findings showed that the nanostructured surface enhanced the osteogenic activity of MG-63 cells (Nano=Micro>Smooth) at the same time that it improved the attachment of HGECs (Nano>Smooth>Micro) and HGFs (Nano=Micro>Smooth). Furthermore, the surface with nanotexture did not affect macrophage polarization (Nano=Micro=Smooth), but did reduce initial bacterial adhesion (Nano<Smooth<Micro). These results suggest that the nanostructured titanium surface may promote bone and soft tissue healing, and thereby increase the success and survival of dental implants.

Non-thermal atmospheric pressure plasma functionalized dental implant for enhancement of bacterial resistance and osseointegration

ObjectiveEven though roughened titanium (Ti) and Ti alloys have been clinically used as dental implant, they encourage bacterial adhesion, leading to failure of the initial stability. Here, the non-thermal atmospheric pressure plasma jet (NTAPPJ) functionalized Ti and Ti alloy were investigated to promote cellular activities but inhibit the initial attachment of the adherent pioneer bacterium, Streptococcus sanguinis, without topographical changes. MethodsAfter the produced radicals from NTAPPJ were characterized, bacterial adhesion to specimens was assessed by PrestoBlue assay and live-dead staining with or without the NTAPPJ functionalizing. After the surface was characterized using optical profilometry, X-ray photoelectron spectroscopy and contact angle analysis, the ions released from the specimens were investigated. In vitro initial cell attachment (4h or 24h) with adhesion images and alkaline phosphatase activity (ALP, 14 days) measurements were performed using rat bone marrow-derived mesenchymal stem cells. ResultsThe initial bacterial adhesion to the Ti and Ti alloy was significantly inhibited after NTAPPJ functionalizing (p<0.05) compared to those without NTAPPJ functionalizing. The bacterial adhesion-resistance effect was induced by carbon cleaning, which was dependent on the working gas used on the Ti specimens (nitrogen>ammonia and air, p<0.05). The initial cell adhesion with well-developed vinculin localization and consequent ALP activity at 14days to the NTAPPJ-functionalized specimens were superior to the non-treated specimens. SignificanceFor the promising success of dental implants, NTAPPJ functionalizing is suggested as a novel surface modification technique; this technique can help ensure the success of integration between the dental implants and bone tissues with less concern of inflammation.

Elastic and viscous bond components in the adhesion of colloidal particles and fibrillated streptococci to QCM-D crystal surfaces with different hydrophobicities using Kelvin-Voigt and Maxwell models.

A quartz-crystal-microbalance with dissipation (QCM-D) can measure molecular mass adsorption as well as register adhesion of colloidal particles. However, analysis of the QCM-D output to quantitatively analyze adhesion of (bio)colloids to obtain viscoelastic bond properties is still a subject of debate. Here, we analyze the QCM-D output to analyze the bond between two hydrophilic streptococcal strains 91 nm long and without fibrillar surface appendages and micron-sized hydrophobic polystyrene particles on QCM-D crystal surfaces with different hydrophobicities, using the Kelvin-Voigt model and the Maxwell model. A Poisson distribution was implemented in order to determine the possible virtues of including polydispersity when fitting model parameters to the data. The quality of the fits did not indicate whether the Kelvin-Voigt or the Maxwell model is preferable and only polydispersity in spring-constants improved the fit for polystyrene particles. The Kelvin-Voigt and Maxwell models both yielded higher spring-constants for the bald streptococcus than for the fibrillated one. In both models, the drag coefficients increased for the bald streptococcus with the ratio of electron-donating over electron-accepting parameters of the crystal surface, while for the fibrillated strain the drag coefficient was similar on all crystal surfaces. Combined with the propensity of fibrillated streptococci to bind to the sensor crystal as a coupled-resonator above the crystal surface, this suggests that the drag experienced by resonator-coupled, hydrophilic particles is more influenced by the viscosity of the bulk water than by interfacial water adjacent to the crystal surface. Hydrophilic particles that lack a surface tether are mass-coupled just above the crystal surface and accordingly probe the drag due to the thin layer of interfacial water that is differently structured on hydrophobic and hydrophilic surfaces. Hydrophobic particles without a surface tether are also mass-coupled, but their drag coefficient decreases when the ratio of electron-donating over electron-accepting parameters increases, suggesting that hydrophobic particles experience less drag due to the structured water adjacent to the surface.

Reduced bacterial growth and increased osteoblast proliferation on titanium with a nanophase TiO2 surface treatment.

BackgroundThe attachment and initial growth of bacteria on an implant surface dictates the progression of infection. Treatment often requires aggressive antibiotic use, which does not always work. To overcome the difficulties faced in systemic and local antibiotic delivery, scientists have forayed into using alternative techniques, which includes implant surface modifications that prevent initial bacterial adhesion, foreign body formation, and may offer a controlled inflammatory response.ObjectiveThe current study focused on using electrophoretic deposition to treat titanium with a nanophase titanium dioxide surface texture to reduce bacterial adhesion and growth. Two distinct nanotopographies were analyzed, Ti-160, an antimicrobial surface designed to greatly reduce bacterial colonization, and Ti-120, an antimicrobial surface with a topography that upregulates osteoblast activity while reducing bacterial colonization; the number following Ti in the nomenclature represents the atomic force microscopy root-mean-square roughness value in nanometers.ResultsThere was a 95.6% reduction in Staphylococcus aureus (gram-positive bacteria) for the Ti-160-treated surfaces compared to the untreated titanium alloy controls. There was a 90.2% reduction in Pseudomonas aeruginosa (gram-negative bacteria) on Ti-160-treated surfaces compared to controls. For ampicillin-resistant Escherichia coli, there was an 81.1% reduction on the Ti-160-treated surfaces compared to controls. Similarly for surfaces treated with Ti-120, there was an 86.8% reduction in S. aureus, an 82.1% reduction in P. aeruginosa, and a 48.6% reduction in ampicillin-resistant E. coli. The Ti-120 also displayed a 120.7% increase at day 3 and a 168.7% increase at day 5 of osteoblast proliferation over standard titanium alloy control surfaces.ConclusionCompared to untreated surfaces, Ti-160-treated titanium surfaces demonstrated a statistically significant 1 log reduction in S. aureus and P. aeruginosa, whereas Ti-120 provided an additional increase in osteoblast proliferation for up to 5 days, criteria, which should be further studied for a wide range of orthopedic applications.

Antibacterial and anti-biofilm efficacy of fluoropolymer coating by a 2,3,5,6-tetrafluoro-p-phenylenedimethanol structure

Fluorinated polymers generally function as antibacterial agents, but their anti-biofilm effect remains unresolved. This study investigates the efficacy of fluoropolymers containing 2,3,5,6-tetrafluoro-p-phenylenedimethanol (TFPDM) in preventing biofilm formation by Bacillus subtilis and Escherichia coli (Gram-positive and Gram-negative bacterial species). To this end, TFPDM-based acrylate and epoxy polymers (AF and EF, respectively) and their structural analogues without TFPDM (A and E, respectively) were synthesized. All polymers were coated onto polyethylene terephthalate (PET) sheets. Relative to pristine PET, sheets coated with AF reduced the initial bacterial adhesion (72h) and biofilm formation (30days) of B. subtilis by 27.6% and 68.7% and of E. coli by 89.2% and 93.8%, respectively. The comparable antibacterial and anti-biofilm efficacies were obtained by sheets with EF. The biofilm detachment was substantially facilitated from the AF, compared with the structural analogue without TFPDM (A). In this comprehensive study, the bacterial adhesion and subsequent biofilm formation were prevented by TFPDM-containing polymers effectively.

A Multinuclear Metal Complex Based DNase-Mimetic Artificial Enzyme: Matrix Cleavage for Combating Bacterial Biofilms.

Extracellular DNA (eDNA) is an essential structural component during biofilm formation, including initial bacterial adhesion, subsequent development, and final maturation. Herein, the construction of a DNase-mimetic artificial enzyme (DMAE) for anti-biofilm applications is described. By confining passivated gold nanoparticles with multiple cerium(IV) complexes on the surface of colloidal magnetic Fe3 O4 /SiO2 core/shell particles, a robust and recoverable artificial enzyme with DNase-like activity was obtained, which exhibited high cleavage ability towards both model substrates and eDNA. Compared to the high environmental sensitivity of natural DNase in anti-biofilm applications, DMAE exhibited a much better operational stability and easier recoverability. When DMAE was coated on substratum surfaces, biofilm formation was inhibited for prolonged periods of time, and the DMAE excelled in the dispersion of established biofilms of various ages. Finally, the presence of DMAE remarkably potentiated the efficiency of traditional antibiotics to kill biofilm-encased bacteria and eradiate biofilms.

A Multinuclear Metal Complex Based DNase‐Mimetic Artificial Enzyme: Matrix Cleavage for Combating Bacterial Biofilms

AbstractExtracellular DNA (eDNA) is an essential structural component during biofilm formation, including initial bacterial adhesion, subsequent development, and final maturation. Herein, the construction of a DNase‐mimetic artificial enzyme (DMAE) for anti‐biofilm applications is described. By confining passivated gold nanoparticles with multiple cerium(IV) complexes on the surface of colloidal magnetic Fe3O4 /SiO2 core/shell particles, a robust and recoverable artificial enzyme with DNase‐like activity was obtained, which exhibited high cleavage ability towards both model substrates and eDNA. Compared to the high environmental sensitivity of natural DNase in anti‐biofilm applications, DMAE exhibited a much better operational stability and easier recoverability. When DMAE was coated on substratum surfaces, biofilm formation was inhibited for prolonged periods of time, and the DMAE excelled in the dispersion of established biofilms of various ages. Finally, the presence of DMAE remarkably potentiated the efficiency of traditional antibiotics to kill biofilm‐encased bacteria and eradiate biofilms.

Initial oral biofilm formation on titanium implants with different surface treatments: An in vivo study

ObjectiveThe aim of this study was to examine in vivo the initial bacterial adhesion on titanium implants with different surface treatments. DesignTen subjects wore oral splints containing machined pure titanium disks (Ti-M), acid-etched titanium (Ti-AE) and anodized and laser irradiated disks (Ti-AL) for 24h. After this period, disks were removed from the splints and adherent bacteria were quantified by an enzymatic assay to assess total viable bacteria and by Real Time PCR to evaluate total bacteria and Streptococcus oralis levels. Additionally, the initial adherent microorganisms were visualized by scanning electron microscopy (SEM). Titanium surface morphology was verified using SEM, and roughness was evaluated by profilometer analysis. ResultsRegarding titanium surface roughness, Ti-AL (1.423±0.397) showed significantly higher Ra values than did Ti-M (0.771±0.182) and Ti-AE (0.735±0.196) (p<0.05, ANOVA – Tahame). Ti-AE and Ti-AL presented roughened micro-structure surfaces characterized by open pores, whereas Ti-M showed long grooves alternating with planed areas. Comparing the Ti-M, Ti-AE and Ti-AL groups for viable bacteria (MTT assay), total bacteria and S. oralis quantification (qPCR), no significant differences were observed among these three groups (p>0.05, ANOVA – Tahame). SEM images showed similar bacterial adhesion on the three titanium surfaces, predominantly characterized by cocci and several bacilli, indicating an initial colonization of the oral biofilm. ConclusionIn conclusion, roughness and microtopography did not stimulate initial biofilm formation on titanium surfaces with different surface treatments.

Bacterial adhesion and biofilm formation on yttria-stabilized, tetragonal zirconia and titanium oral implant materials with low surface roughness - an in situ study.

Bacterially-driven mucosal inflammation and the development of periimplantitis can lead to oral implant failure. In this study, initial bacterial adhesion after 2 h, and biofilm formation after 1 day and 3 days, were analysed in situ on novel 3 mol % yttria-stabilized tetragonal zirconia polycrystal samples, as well as on alumina and niobium co-doped yttria-stabilized tetragonal zirconia samples. Pure titanium implant material and bovine enamel slabs served as controls. The initially adherent oral bacteria were determined by 4',6-diamidino-2-phenylindole-staining. Biofilm thickness, surface covering grade and content of oral streptococci within the biofilm were measured by fluorescence in situ hybridization. No significant differences between the ceramic and titanium surfaces were detectable for either initial bacterial adhesion or the oral streptococci content of the in situ biofilm. The oral biofilm thickness on the implant surfaces were almost doubled after three days compared to the first day of oral exposure. Nevertheless, the biofilm thickness values among the different implant surfaces and controls did not differ significantly for any time point of measurement after 1 day or 3 days of biofilm formation. Significant differences in the covering grade were only detected between day 1 and day 3 for each tested implant material group. The content of oral streptococci increased significantly in parallel with the increase in biofilm age from day 1 to day 3. In conclusion, oral implant zirconia surfaces with low surface roughness are comparable to titanium surfaces with respect to initial bacterial adhesion and biofilm formation.

Transcriptional profiling of Klebsiella pneumoniae defines signatures for planktonic, sessile and biofilm-dispersed cells.

BackgroundSurface-associated communities of bacteria, known as biofilms, play a critical role in the persistence and dissemination of bacteria in various environments. Biofilm development is a sequential dynamic process from an initial bacterial adhesion to a three-dimensional structure formation, and a subsequent bacterial dispersion. Transitions between these different modes of growth are governed by complex and partially known molecular pathways.ResultsUsing RNA-seq technology, our work provided an exhaustive overview of the transcriptomic behavior of the opportunistic pathogen Klebsiella pneumoniae derived from free-living, biofilm and biofilm-dispersed states. For each of these conditions, the combined use of Z-scores and principal component analysis provided a clear illustration of distinct expression profiles. In particular, biofilm-dispersed cells appeared as a unique stage in the bacteria lifecycle, different from both planktonic and sessile states. The K-means cluster analysis showed clusters of Coding DNA Sequences (CDS) and non-coding RNA (ncRNA) genes differentially transcribed between conditions. Most of them included dominant functional classes, emphasizing the transcriptional changes occurring in the course of K. pneumoniae lifestyle transitions. Furthermore, analysis of the whole transcriptome allowed the selection of an overall of 40 transcriptional signature genes for the five bacterial physiological states.ConclusionsThis transcriptional study provides additional clues to understand the key molecular mechanisms involved in the transition between biofilm and the free-living lifestyles, which represents an important challenge to control both beneficial and harmful biofilm. Moreover, this exhaustive study identified physiological state specific transcriptomic reference dataset useful for the research community.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2557-x) contains supplementary material, which is available to authorized users.

Quercitrin-nanocoated titanium surfaces favour gingival cells against oral bacteria.

Many dental implants fail due to the infection and inflammation that walk hand in hand with poor healing and soft tissue integration. Titanium surfaces were nanocoated with quercitrin, a natural flavonoid, with the aim to improve soft tissue integration and increase dental implants success. Streptococcus mutans attachment and biofilm formation was analysed. Then, the anti-inflammatory properties and the potential of quercitrin-nanocoated surfaces to boost soft tissue regeneration were tested using human gingival fibroblasts. An inflammatory situation was mimicked using interleulin-1-beta. We found that quercitrin-nanocoated surfaces decreased initial bacterial adhesion while increasing human gingival fibroblasts attachment. Furthermore, quercitrin-nanocoated Ti increased collagen mRNA levels and decreased matrix metalloproteinase-1/tissue inhibitor of metalloproteinanse-1 mRNA ratio, which is related to a reduced metalloproteinase-mediated collagen degradation, while also decreasing the pro-inflammatory prostaglandin E2 release under basal and inflammatory conditions. These results suggest that quercitrin-nanocoated surfaces could enhance the soft tissue integration and increase dental implants success.

Controlled release behaviour and antibacterial effects of antibiotic-loaded titania nanotubes

Bacterial infections have been identified as the main cause of orthopaedic implant failure. Owing to their high antibiotic delivery efficiency, titania nanotubes loaded with antibiotics constitute one of the most promising strategies for suppressing bacterial infections. However, it is difficult to control the drug-release behaviour of such nanotubes. Although sealing the nanotubes with a polymer solution provides sustained release effects to a certain extent, it inevitably influences their initial antibacterial activity. This study reports on the controlled release of gentamicin sulphate (GS) from titania nanotube surfaces whereby their initial antibacterial activity remains unaffected. Titania nanotubes were fabricated via electrochemical anodization and loaded with GS through physical adsorption. Experimental results showed that this loading method is feasible and efficient. The GS-loaded titania nanotubes were further covered by a thin film comprising a mixture of GS and chitosan (GSCH). The release kinetics confirmed that the drug release could be controlled by this thin film. Moreover, such a film was shown to not only inhibit initial bacterial adherence owing to its strong antibacterial properties but also enhance cell viability. Thus, GS-loaded titania nanotubes coated with GSCH have considerable potential as biomaterials for preventing initial release and peri-implant infection in the field of orthopaedics.

The impact of structure dimensions on initial bacterial adhesion.

Substrate topography can have profound effects on initial bacterial adhesion during biofilm formation. We applied Staphylococcus epidermidis and Escherichia coli cells onto periodically structured substrates with different structure dimensions, structure types and wetting properties. We found a strong dependence of cell retention on the structure dimensions of the applied substrates. Periodicities in the range of the cell size increased, whereas smaller periodicities decreased cell retention, independent of contact time (minutes to hours) and hydrophobicity. These novel insights on the role of surface topography on bacterial retention might facilitate the development of non-fouling surfaces in the future.

Impact of structure-dimensions on initial and short-term bacterial adhesion

Event Abstract Back to Event Impact of structure-dimensions on initial and short-term bacterial adhesion Ralf Helbig1*, Jens Friedrichs1, Andrés Lasagni2* and Carsten Werner1* 1 Leibniz Institue of Polymer Research, Institute of Biofunctional Polmer Materials, Germany 2 Dresden University of Technology, Large Area Based Surface micro-/nano-Structuring, Germany Introduction: Bacterial biofilms on man-made surfaces can cause a multitude of negative consequences in industrial and medical environments. A central process in the formation of biofilms is the initial transition of planktonic bacteria to a sessile state by attaching to a given substrate. Besides environmental conditions, such as pH, temperature, competing organisms and nutrition, the initial interactions between bacteria and substrate are mainly influenced by interfacial properties such as chemistry, polarity, mechanical properties and structure. Previous studies have demonstrated fundamental effects of substrate topography on the initial adhesion phase although a comprehensive picture is still missing. Here we applied periodically structured substrates with different structure dimensions, types and wetting properties to systematically study the effect of surface topography on bacterial adhesion. Material and Methods: Periodic line, post and hole structures were made by laser interference patterning from the slightly hydrophilic photoresist SU8. For each pattern geometry the spatial period was varied between 500 nm and 5000 nm. Surface wettability of the samples was varied by functionalization with aminosilan (APTES) or amorphous fluorpolymer TAF respectively. Structured samples were incubated in bacterial solutions (Staphylococcus epidermidis) at 37°C for 2 min or 24 hours with constant shaking. After the defined time periods samples were fixed, stained with DAPI and imaged. Results and Discussion: We could show that the initial interactions (minutes to hours) of bacterial cells with structured surfaces strongly depend on the structure dimensions (Figure 1). On structured surfaces with structure periods several times bigger than the cells size (i.e. 5000nm in this study) the number of adherent bacteria decreases (in comparison to an unstructured control) since cells are detached from structure tops due to increased shear forces induced by turbulent liquid flow. However, cells within depressions of the structure are protected from shear forces. For periods close to the cell size (i.e. 1000nm in this study), cell attachment increases because of a maximized net contact area between cells and surface. Smaller periods (i.e. 500nm in this study) decrease the net contact area between cells and surface resulting in increased cell retention. The observed effects were independent on the contact time between bacteria and substrate, the wetting properties of the substrate and the structure type. Conclusion: The presented results provide, for the first time, a comprehensive overview on the impact of surface topography on bacterial retention and may represent a foundation for the development of antifouling surfaces in the future. Figure 1: Schematic representation of the dependency of the structure period on initial bacterial attachment. Keywords: Bacteria, Cell Adhesion, nanotopography, Pattering Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: General Session Oral Topic: Nanotopography of biomaterials Citation: Helbig R, Friedrichs J, Lasagni A and Werner C (2016). Impact of structure-dimensions on initial and short-term bacterial adhesion. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.01503 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. * Correspondence: Dr. Ralf Helbig, Leibniz Institue of Polymer Research, Institute of Biofunctional Polmer Materials, Dresden, Germany, Email1 Dr. Andrés Lasagni, Dresden University of Technology, Large Area Based Surface micro-/nano-Structuring, Dresden, Germany, Email2 Dr. Carsten Werner, Leibniz Institue of Polymer Research, Institute of Biofunctional Polmer Materials, Dresden, Germany, Email3 Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Ralf Helbig Jens Friedrichs Andrés Lasagni Carsten Werner Google Ralf Helbig Jens Friedrichs Andrés Lasagni Carsten Werner Google Scholar Ralf Helbig Jens Friedrichs Andrés Lasagni Carsten Werner PubMed Ralf Helbig Jens Friedrichs Andrés Lasagni Carsten Werner Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. 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Antibacterial coating on biocomposites for cranio-facial reconstruction.

Background and aimsDespite the fact that implants are sterilized, antiseptic techniques are applied and systemic antibiotics are routinely administered prior to and after craniofacial surgery, infection rates between 3% and 40% are still reported for alloplastic implants, urging for implant removal. The present study focuses on the development of a fiber-reinforced composite (FRC) implant for craniofacial reconstruction with antimicrobial properties.MethodsA new fiber-reinforced composite coated with gentamicin was developed and tested for bacterial adherence and antibacterial efficiency, using two of the most involved bacterial strains in the postoperative infections: Staphylococcus aureus and Pseudomonas aeruginosa.ResultsBacteria were efficiently inactivated in direct contact with gentamicin coatings (p<0.05). The inhibition zone for Staphylococcus aureus ranged from 17.21 mm to 20.13 mm and for Pseudomonas aeruginosa ranged from 12.93 mm to 15.33 mm. Although no significant statistical results were found for bacterial adhesion and gentamicin concentration, (Staphylococcus aureus: β= −0.974; p=0.144>0.05 and Pseudomonas aeruginosa: β = −0.921; p=0.255>0.05), a negative relation was observed, indicating the reversed relation between the antibiotic dosage and the bacterial adherence.ConclusionThe results of the two applied microbiological protocols used in the study suggested that gentamicin eluting coating inhibited not only the bacterial growth, but also led to a lower initial bacterial adhesion to the surface of the implant. Thus, antibiotic coating of craniofacial implants may reduce the infection rate related to reconstructive surgery.

Acrylic polymers bearing superwetting silicone surfactants are candidates for bacterial adhesion-resistant biomaterials

Event Abstract Back to Event Acrylic polymers bearing superwetting silicone surfactants are candidates for bacterial adhesion-resistant biomaterials Madiha Khan1 and Michael A. Brook1, 2 1 McMaster University, Biomedical Engineering, Canada 2 McMaster University, Chemistry and Chemical Biology, Canada The increase in antibiotic resistant bacteria has necessitated the development of novel antibacterial surfaces[1], particularly in the context of silicone-based implants because the hydrophobicity of silicones has been linked to undesirable microbial adhesion[2]. Unfortunately, current mitigative strategies, such as pretreatment of surfaces with antiseptics/antibiotics do not always work, and can facilitate the prevalence of resistant pathogens by exposing bacteria to sublethal concentrations of biocides[3]. Therefore, scientific interest has shifted to preventing the initial bacterial adhesion that can lead to surface colonization via surface modification by surfactants[4]. The copolymerization of ACR-008UP (an acrylic-terminated superwetting silicone surfactant) in increasing weight percentages with butyl methacrylate (BMA) and/or methyl methacrylate (MMA) was performed. Interestingly, copolymers of 20wt% ACR showed at least 3x less adhesion by Escherichia coli than any other formulation. This is not a consequence of wettability, which followed a parabolic function with surfactant concentration, showing high sessile water droplet contact angles at both low (< 20 wt%) and high (>80 wt%) concentrations of the superwetter in the formulations. The contact angle at 20 wt% surfactant was 66°. We ascribe the lack of bacterial adhesion both to interactions between surfactant and the bacterial cell wall and to surfactant influenced water retention at the interface, and will discuss this proposal in light of ongoing studies of additional surfaces bearing superwetting groups. 20/20: NSERC Opthalmic Materials Network