In this work, two antifouling polymer brushes were tested at different shear stress conditions to evaluate their performance in reducing the initial adhesion of Escherichia coli. Assays were performed using a parallel plate flow chamber and a shear stress range between 0.005 and 0.056 Pa. These shear stress values are found in different locations in the human body where biomedical devices are placed. The poly(MeOEGMA) and poly(HPMA) brushes were characterized and it was shown that they can reduce initial adhesion up to 90% when compared to glass. Importantly, the performance of these surfaces was not affected by the shear stress, which is an indication that they do not collapse under this shear stress range. The brushes displayed a similar behavior despite the differences in their chemical composition and surface energy. Both surfaces have shown ultra-low adsorption of macromolecules from the medium when tested with relevant biological fluids (urine and serum). This indicates that these surfaces can potentially be used in biomedical devices to reduce initial bacterial colonization and eventually reduce biofilm formation on these devices.

• MeSH
• bakteriální adheze fyziologie   MeSH
• biofilmy růst a vývoj   MeSH
• Escherichia coli MeSH
• lidé MeSH
• mechanický stres MeSH
• pevnost ve smyku fyziologie   MeSH
• polymery chemie   MeSH
• povrchové vlastnosti MeSH
• tělesné tekutiny mikrobiologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

A novel biofilm model is described which systemically couples bacteria, extracellular polymeric substances (EPS) and solvent phases in biofilm. This enables the study of contributions of rheology of individual phases to deformation of biofilm in response to fluid flow as well as interactions between different phases. The model, which is based on first and second laws of thermodynamics, is derived using an energetic variational approach and phase-field method. Phase-field coupling is used to model structural changes of a biofilm. A newly developed unconditionally energy-stable numerical splitting scheme is implemented for computing the numerical solution of the model efficiently. Model simulations predict biofilm cohesive failure for the flow velocity between [Formula: see text] and [Formula: see text] m s(-1) which is consistent with experiments. Simulations predict biofilm deformation resulting in the formation of streamers for EPS exhibiting a viscous-dominated mechanical response and the viscosity of EPS being less than [Formula: see text]. Higher EPS viscosity provides biofilm with greater resistance to deformation and to removal by the flow. Moreover, simulations show that higher EPS elasticity yields the formation of streamers with complex geometries that are more prone to detachment. These model predictions are shown to be in qualitative agreement with experimental observations.

• MeSH
• Bacteria cytologie   MeSH
• bakteriální adheze fyziologie   MeSH
• bakteriální polysacharidy metabolismus   MeSH
• biofilmy růst a vývoj   MeSH
• biologické modely * MeSH
• fyziologie bakterií MeSH
• mechanický stres MeSH
• mikrofluidika metody   MeSH
• modul pružnosti fyziologie   MeSH
• pevnost ve smyku fyziologie   MeSH
• počítačová simulace MeSH
• velikost buňky MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

Several constitutive models have been proposed for description of mechanical behaviour of soft tissues containing collagen fibres. The model with aligned fibres is modified in this paper to take the dispersion of fibre orientations into account through angular integration and it is compared with the model that is defined through generalized structure tensor. The paper is focused on the effect of fibre dispersion on the resulting stress-strain behaviour predicted by both models analyzed. Analytical calculations are used for the comparison of the mechanical behaviour under a specific biaxial tension mode. The two models have been implemented into commercial finite element code ANSYS via user subroutines and used for numerical simulation resulting in a non-homogeneous stress field. The effects of the fibre dispersion predicted by both models being compared differ significantly, e.g., the resulting stress difference between both models is lower than 10% only in the case of extremely small dispersion of collagen fibres orientation (κ< (0.01 to 0.03)). These results are consistent with those of other related literature. The applicability of the model defined through the generalized structure tensor is discussed.

• MeSH
• anizotropie MeSH
• arterie fyziologie   ultrastruktura   MeSH
• fibrilární kolageny fyziologie   ultrastruktura   MeSH
• konformace proteinů MeSH
• lidé MeSH
• mechanický stres MeSH
• modely kardiovaskulární * MeSH
• modul pružnosti fyziologie   MeSH
• pevnost v tahu fyziologie   MeSH
• pevnost v tlaku fyziologie   MeSH
• pevnost ve smyku fyziologie   MeSH
• počítačová simulace MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH

Cardiovascular prosthetic bypass grafts do not endothelialize spontaneously in humans, and so they pose a thrombotic risk. Seeding with cells improves their performance, particularly in small-caliber applications. Knitted tubular polyethylene-terephthalate (PET) vascular prostheses (6 mm) with commercial type I collagen (PET/Co) were modified in the lumen by the adsorption of laminin (LM), by coating with a fibrin network (Fb) or a combination of Fb and fibronectin (Fb/FN). Primary human saphenous vein endothelial cells were seeded (1.50 × 10(5)/cm(2)), cultured for 72 h and exposed to laminar shear stress 15 dyn/cm(2) for 40 and 120 min. The control static grafts were excluded from shearing. The cell adherence after 4 h on PET/Co, PET/Co +LM, PET/Co +Fb and PET/Co +Fb/FN was 22 %, 30 %, 19 % and 27 % of seeding, respectively. Compared to the static grafts, the cell density on PET/Co and PET/Co +LM dropped to 61 % and 50 %, respectively, after 120 min of flow. The cells on PET/Co +Fb and PET/Co +Fb/FN did not show any detachment during 2 h of shear stress. Pre-coating the clinically-used PET/Co vascular prosthesis with LM or Fb/FN adhesive protein assemblies promotes the adherence of endothelium. Cell retention under flow is improved particularly on fibrin-containing (Fb and Fb/FN) surfaces.

• MeSH
• časové faktory MeSH
• cévní protézy normy   MeSH
• endoteliální buňky fyziologie   MeSH
• kolagen typu I aplikace a dávkování   MeSH
• lidé MeSH
• mechanický stres MeSH
• pevnost ve smyku fyziologie   MeSH
• polyestery normy   MeSH
• skot MeSH
• vena saphena cytologie   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

A commonly used method to determine the strength of adhesion between adhering lipid vesicles is measuring their effective contact angle from experimental images. The aim of this paper is to estimate the interobserver variations in vesicles effective contact angle measurements and to propose a new method for estimating the strength of membrane vesicle adhesion. Theoretical model shows for the old and for the new measure a monotonic dependence on the strength of adhesion. Results obtained by both measuring techniques show statistically significant correlation and high interobserver reliability for both methods. Therefore the conventional method of measuring the effective contact angle gives qualitatively relevant results as the measure of the lipid vesicle adhesion. However, the new measuring technique provides a lower variation of the measured values than the conventional measures using the effective contact angle. Moreover, obtaining the adhesion angle can be automatized more easily than obtaining the effective contact angle.

• MeSH
• adhezivita MeSH
• biomechanika MeSH
• cytoplazmatické vezikuly chemie   fyziologie   MeSH
• lipidy chemie   fyziologie   MeSH
• mechanický stres MeSH
• membrány chemie   fyziologie   MeSH
• mikroskopie fázově kontrastní MeSH
• odchylka pozorovatele MeSH
• pevnost ve smyku fyziologie   MeSH
• statistické modely MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH