Control Of Bacterial Adhesion Research Articles

Effect of Co-Sputtered Copper and Titanium Oxide Coatings on Bacterial Resistance and Cytocompatibility of Osteoblast Cells.

One of the primary risk factors for implant failure is thought to be implant-related infections during the early healing phase. Developing coatings with cell stimulatory behaviour and bacterial adhesion control is still difficult for bone implants. This study proposes an approach for one-step deposition of biocompatible and antimicrobial Cu-doped TiO2 coatings via glow-discharge sputtering of a mosaic target. During the deposition, the bias of the Ti6Al4V substrates was changed. Structure examination, phase analysis, and surface morphology were carried out using X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). The hardness values and hydrophilic and corrosion performance were also evaluated together with cytocompatible and antibacterial examinations against E. coli and S. aureus. The results show great chemical and phase control of the bias identifying rutile, anatase, CuO, or ternary oxide phases. It was found that by increasing the substrate bias from 0 to -50 V the Cu content increased from 15.3 up to 20.7 at% while at a high bias of -100 V, the copper content reduced to 3 at%. Simultaneously, apart from the Cu2+ state, Cu1+ is also found in the biased samples. Compared with the bare alloy, the hardness, the water contact angle and corrosion resistance of the biased coatings increased. According to an assessment of in vitro cytocompatibility, all coatings were found to be nontoxic to MG-63 osteoblast cells over the time studied. Copper release and cell-surface interactions generated an antibacterial effect against E. coli and S. aureus strains. The -50 V biased coating combined the most successful results in inhibiting bacterial growth and eliciting the proper responses from osteoblastic cells because of its phase composition, electrochemical stability, hydrophilicity, improved substrate adhesion, and surface roughness. Using this novel surface modification approach, we achieved multifunctionality through controlled copper content and oxide phase composition in the sputtered films.

Cellular automaton simulation of the diffusive motion of bacteria and their adhesion to nanostructures on a solid surface

The growth of a biofilm begins with the adhesion of bacteria to a solid surface. Consequently, biofilm growth can be managed by the control of bacterial adhesion. Recent experimental studies have suggested that bacterial adhesion can be controlled by modifying a solid surface using nanostructures. Computational prediction and analysis of bacterial adhesion behavior are expected to be useful for the design of effective arrangements of nanostructures for controlling bacterial adhesion. The present study developed a cellular automaton (CA) model for bacterial adhesion simulation that could describe both the diffusive motion of bacteria and dependence of their adhesion patterns on the distance between nanostructures observed in experimental studies. The diffusive motion was analyzed by the moment scaling spectrum theory, and the present model was confirmed to describe subdiffusion behavior due to obstacles. Adhesion patterns observed in experimental studies can be successfully simulated by introducing CA rules to describe a mechanism by which bacteria tend to move to increase the area of contact with nanostructures.

Control of bacterial adhesion and growth on honeycomb-like patterned surfaces

It is a great challenge to construct a persistent bacteria-resistant surface even though it has been demonstrated that several surface features might be used to control bacterial behavior, including surface topography. In this study, we develop micro-scale honeycomb-like patterns of different sizes (0.5–10μm) as well as a flat area as the control on a single platform to evaluate the bacterial adhesion and growth. Bacteria strains, Escherichia coli and Staphylococcus aureus with two distinct shapes (rod and sphere) are cultured on the platforms, with the patterned surface-up and surface-down in the culture medium. The results demonstrate that the 1μm patterns remarkably reduce bacterial adhesion and growth while suppressing bacterial colonization when compared to the flat surface. The selective adhesion of the bacterial cells on the patterns reveals that the bacterial adhesion is cooperatively mediated by maximizing the cell-substrate contact area and minimizing the cell deformation, from a thermodynamic point of view. Moreover, study of bacterial behaviors on the surface-up vs. surface-down samples shows that gravity does not apparently affect the spatial distribution of the adherent cells although it indeed facilitates bacterial adhesion. Furthermore, the experimental results suggest that two major factors, i.e. the availability of energetically favorable adhesion sites and the physical confinements, contribute to the anti-bacterial nature of the honeycomb-like patterns.

전기장을 이용한 미생물 부착과 생물막 제어

The use of electric field has been studied as an alternative for biofilm control dominated by disinfectants and antibiotics. This technology would be advantageous in the environmental respect that biofilm can be controlled based on electron transfer, not using chemical disinfectants and antibiotics. Control mechanisms which were reported by earlier studies are organized as; (1) bacterial adhesion control by electrostatic repulsion at a negative current, (2) bacterial adhesion control using bacterial motion and (3) bacterial inactivation by direct oxidation at a positive current, (4) bioelectric effect leading to biofilm inactivation. In this review article, we summarized the technologies for biofilm control using electric field and provided some application examples from previous studies.

Determination of the Shear Force at the Balance between Bacterial Attachment and Detachment in Weak-Adherence Systems, Using a Flow Displacement Chamber

We introduce a procedure for determining shear forces at the balance between attachment and detachment of bacteria under flow. This procedure can be applied to derive adhesion forces in weak-adherence systems, such as polymer brush coatings, which are currently at the center of attention for their control of bacterial adhesion and biofilm formation.

Direct Infrared Spectroscopic Evidence of pH- and Ionic Strength-Induced Changes in Distance of Attached Pseudomonas aeruginosa from ZnSe Surfaces

Control of bacterial adhesion is important in many industrial and medical applications. Ionic strength and pH are known to affect the process of attachment; however their influence on bacteria/surface distances has been inferred but not quantitatively established. The distances between attached bacteria and surfaces have only recently been measured. In this paper ATR-IR spectroscopy has been used to study the influence of pH and ionic strength on the distance of freshly attached Pseudomonas aeruginosa from ZnSe surfaces. Reversible changes in the absorbance of P. aeruginosa were observed for changes of pH between 4 and 10 at a constant ionic strength of 0.003 mol L-1 and for changes of ionic strength between 0 and 0.15 mol L-1 at a constant pH of 6.3. An increase in ionic strength from 0 to 0.003 mol L-1 led to an increase in amide II absorbance of 30%, which corresponds to an average movement of 120 nm toward the surface. A movement of this magnitude is likely to be due to changes in the length of bacter...

Interaction of streptococcal aggregating factors with thiol- and disulphide-reactive compounds

The saliva-dependent aggregation of two strains of Streptococcus sanguis is interfered with by reagents that react with sulphydryl or disulphide groups. Iodoacetamide, p-chloromercuribenzoate, ferricyanide, dithiothreitol, glutathione and thiodiglycol reduce aggregating activity significantly, although thiocyanate is without effect. lodoacetamide and cysteine exhibit maximal inhibition at about 2 mM. Experiments show that the inhibitory effect is due to an interaction with the salivary aggregating factor and not with the cells. The effect of iodoacetamide on the factor is irreversible, but cells that are already aggregated by saliva become dissociated following addition of the reagent. The aggregation of Streptococcus mitis strain 26 is not affected by iodoacetamide or ferricyanide but is inhibited by cysteine. The conclusion is made that thiol groups and disulphide linkages play a vital role in maintaining functional ability of the salivary aggregating factors. The differences in response between the sanguis and mitis factors reflect the basic structural dissimilarities of the molecules. Our findings also suggest that sulphur-containing products of metabolism that occur in the oral cavity may participate in the control of bacterial adhesion and colonization.