Dynamic Adhesive Behavior and Biofilm Formation of on Polylactic Acid Surfaces in Diabetic Environments.

Interest in biodegradable implants has focused attention on the resorbable polymer polylactic acid. However, the risk of these materials promoting infection, especially in patients with existing pathologies, needs to be monitored. The enrichment of a bacterial adhesion medium with compounds that are associated with human pathologies can help in understanding how these components affect the development of infectious processes.

Bacterial Response to the Surface Aging of PLA Matrices Loaded with Active Compounds.

The use of active components in biomaterials improves the properties of existing ones and makes it possible to obtain new devices with antibacterial properties that prevent infections after implantation, thus guaranteeing the success of the implant. In this work, cetyltrimethylammonium bromide (CTAB) and magnesium particles were incorporated into polylactic acid (PLA) films to assess the extent to which progressive aging of the new surfaces resists bacterial colonization processes. For this purpose, the films' surface was characterized by contact angle measurements, ToF-SIMS and AFM, and adhesion, viability and biofilm growth of bacteria on these films were also evaluated.

From radial to unidirectional water pumping in zeta-potential modulated Nafion nanostructures.

Chemically propelled micropumps are promising wireless systems to autonomously drive fluid flows for many applications. However, many of these systems are activated by nocuous chemical fuels, cannot operate at high salt concentrations, or have difficulty for controlling flow directionality. In this work we report on a self-driven polymer micropump fueled by salt which can trigger both radial and unidirectional fluid flows.

Effect of Spontaneous and Water-Based Passivation on Components and Parameters of Ti6Al4V (ELI Grade) Surface Tension and Its Wettability by an Aqueous Solution of Sucrose Ester Surfactants.

Solid wettability is especially important for biomaterials and implants in the context of microbial adhesion to their surfaces. This adhesion can be inhibited by changes in biomaterial surface roughness and/or its hydrophilic-hydrophobic balance. The surface hydrophilic-hydrophobic balance can be changed by the specifics of the surface treatment (proper conditions of surface preparation) or adsorption of different substances.

Influence of Solvent and Substrate on Hydrophobicity of PLA Films.

The study of the surface properties of materials is key in determining whether the material will be suitable for medical purposes. One of these properties is hydrophobicity, which is important when assessing its behavior against bacterial adhesion. In this work, we have studied the influence of the solvent (chloroform, acetone, and tetrahydrofuran) and the substrate (glass, PTFE, silicone, and Ti6Al4V) on which polylactic acid is deposited in solution to manufacture films by solvent-casting.

Surface Characterisation of Human Serum Albumin Layers on Activated Ti6Al4V.

Adpsortion of protein layers on biomaterials plays an important role in the interactions between implants and the bio-environment. In this context, human serum albumin (HSA) layers have been deposited on modified Ti6Al4V surfaces at different ultraviolet (UV-C) irradiation times to observe possible changes in the adsorbed protein layer. Protein adsorption was done from solutions at concentraions lower than the serum protein concentration, to follow the surface modifications at the beginning of the albumin adhesion process.

Modification of physico-chemical surface properties and growth of Staphylococcus aureus under hyperglycemia and ketoacidosis conditions.

Diabetes is a widely spread disease affecting the quality of life of millions of people around the world and is associated to a higher risk of developing infections in different parts of the body. The reasons why diabetes enhances infection episodes are not entirely clear; in this study our aim was to explore the changes that one of the most frequently pathogenic bacteria undergoes when exposed to hyperglycemia and ketoacidosis conditions. Physical surface properties such as hydrophobicity and surface electrical charge are related to bacterial growth behavior and the ability of Staphylococcus aureus to form biofilms.

Characterization of Magnesium-Polylactic Acid Films Casted on Different Substrates and Doped with Diverse Amounts of CTAB.

Polylactic acid (PLA) is a good candidate for the manufacture of polymeric biodegradable biomaterials. The inclusion of metallic particles and surfactants solves its mechanical limitations and improves its wettability, respectively. In this work, cetyltrimethylammonium bromide (CTAB) and magnesium particles have been incorporated into PLA films to evaluate the changes produced in the polymeric matrix cast on glass and silicone substrates.

3D-PLA-experimental set up to display the electrical background of the so-called geometric factor of electrokinetic cells.

The so-called geometric factor defined in electrokinetic cells, L/S (L being the length and S the cross-section of the channel), is relevant for providing the surface interaction electrical potential (zeta potential, ζ) of large surfaces, such as those used in the design of biomedical devices or water purification systems. Conversely, recent studies demonstrate that this factor is also employed to determine geometrical parameters, such as porosity in membrane-like systems. This factor, which has been attributed exclusively a geometrical character, can also be obtained from the electrical conductivity and resistance of the electrokinetic channel.

The role of magnesium in biomaterials related infections.

Magnesium is currently increasing interest in the field of biomaterials. An extensive bibliography on this material in the last two decades arises from its potential for the development of biodegradable implants. In addition, many researches, motivated by this progress, have analyzed the performance of magnesium in both in vitro and in vivo assays with gram-positive and gram-negative bacteria in a very broad range of conditions.

Kinetic of Adhesion of with Different EPS Production on Ti6Al4V Surfaces.

Controlling initial bacterial adhesion is essential to prevent biofilm formation and implant-related infection. The search for surface coatings that prevent initial adhesion is a powerful strategy to obtain implants that are more resistant to infection. Tracking the progression of adhesion on surfaces from the beginning of the interaction between bacteria and the surface provides a deeper understanding of the initial adhesion behavior.

Force spectroscopy-based simultaneous topographical and mechanical characterization to study polymer-to-polymer interactions in coated alginate microspheres.

Cell-laden hydrogel microspheres have shown encouraging outcomes in the fields of drug delivery, tissue engineering or regenerative medicine. Beyond the classical single coating with polycations, many other different coating designs have been reported with the aim of improving mechanical properties and in vivo performance of the microspheres. Among the most common strategies are the inclusion of additional polycation coatings and the covalent bonding of the semi-permeable membranes with biocompatible crosslinkers such as genipin.

Impact of PLA/Mg films degradation on surface physical properties and biofilm survival.

New biocompatible and bioabsorbable materials are currently being developed for bone regeneration. These serve as scaffolding for controlled drug release and prevent bacterial infections. Films of polylactic acid (PLA) polymers that are Mg-reinforced have demonstrated they have suitable properties and bioactive behavior for promoting the osseointegration process.

In vivo bactericidal efficacy of the Ti6Al4V surface after ultraviolet C treatment.

Background: Biomaterial-associated infections are one of the most important complications in orthopedic surgery. The main goal of this study was to demonstrate the in vivo bactericidal effect of ultraviolet (UV) irradiation on Ti6Al4V surfaces.

Materials And Methods: An experimental model of device-related infections was developed by direct inoculation of Staphylococcus aureus into the canal of both femurs of 34 rats.

Incorporation of Mg particles into PDLLA regulates mesenchymal stem cell and macrophage responses.

In this work, we investigated a new approach to incorporate Mg particles within a PDLLA matrix using a solvent-free commercially available process. PDLLA/Mg composites were manufactured by injection moulding and the effects of Mg incorporated into PDLLA on MSC and macrophage responses were evaluated. Small amounts of Mg particles (≤ 1 wt %) do not cause thermal degradation of PDLLA, which retains its mechanical properties.

Electrochemical analysis of the UV treated bactericidal Ti6Al4V surfaces.

This research investigates in detail the bactericidal effect exhibited by the surface of the biomaterial Ti6Al4V after being subjected to UV-C light. It has been recently hypothesized that small surface currents, occurring as a consequence of the electron-hole pair recombination taking place after the excitation process, are behind the bactericidal properties displayed by this UV-treated material. To corroborate this hypothesis we have used different electrochemical techniques, such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization plots and Mott-Schottky plots.

Surface-dependent mechanical stability of adsorbed human plasma fibronectin on Ti6Al4V: domain unfolding and stepwise unraveling of single compact molecules.

In this study, the structure and mechanical stability of human plasma fibronectin (HFN), a major protein component of blood plasma, have been evaluated in detail upon adsorption on the nonirradiated and irradiated Ti6Al4V material through the use of atomic force microscopy. The results indicated that the material surface changes occurring after the irradiation process reduce the disulfide bonds that typically preclude the mechanical denaturation of individual HFN domains and interfere significantly with the intraionic interactions stabilizing the compact conformation of the adsorbed HFN molecules. In particular, upon adsorption on this material, the molecules adopt a more flexible conformation and become mechanically more compliant.

Adsorption behavior of human plasma fibronectin on hydrophobic and hydrophilic Ti6Al4V substrata and its influence on bacterial adhesion and detachment.

Biomaterial implant-associated infections, a common cause of medical devices' failure, are initiated by bacterial adhesion to an adsorbed protein layer on the implant material surface. In this study, the influence of protein surface orientation on bacterial adhesion has been examined using three clinically relevant bacterial strains known to express specific binding sites for human plasma fibronectin (HFN). HFN was allowed to adsorb on hydrophobic Ti6Al4V and physically modified hydrophilic Ti6Al4V substrata.

The zeta potential of extended dielectrics and conductors in terms of streaming potential and streaming current measurements.

The electrical characterization of surfaces in terms of the zeta potential (ζ), i.e., the electric potential contributing to the interaction potential energy, is of major importance in a wide variety of industrial, environmental and biomedical applications in which the integration of any material with the surrounding media is initially mediated by the physico-chemical properties of its outer surface layer.

Insights into bacterial contact angles: difficulties in defining hydrophobicity and surface Gibbs energy.

One of the principal techniques for evaluating the surface hydrophobicity of biological samples is contact angle. This method, applied readily to flat-smooth-inert surfaces, gives rise to an important debate when implemented with microbial lawns. After its initial description, in 1984, several authors have carried out modifications of the technique but the results obtained have not been previously judged.

Direct adhesion force measurements between E. coli and human uroepithelial cells in cranberry juice cocktail.

Scope: Atomic force microscopy (AFM) was used to directly measure the nanoscale adhesion forces between P-fimbriated Escherichia coli (E. coli) and human uroepithelial cells exposed to cranberry juice, in order to reveal the molecular mechanisms by which cranberry juice cocktail (CJC) affects bacterial adhesion.

Methods And Results: Bacterial cell probes were created by attaching P-fimbriated E.

Bactericidal behaviour of Ti6Al4V surfaces after exposure to UV-C light.

TiO(2)-coated biomaterials that have been excited with UV irradiation have demonstrated biocidal properties in environmental applications, including drinking water decontamination. However, this procedure has not been successfully applied towards the killing of pathogens on medical titanium-based implants, mainly because of practical concerns related to irradiating the inserted biomaterial in situ. Previous researchers assumed that the photocatalysis on the TiO(2) surface during UV application causes the bactericidal effects.

In vitro biocompatibility and bacterial adhesion of physico-chemically modified Ti6Al4V surface by means of UV irradiation.

UV irradiation leads to a "spontaneous" wettability increase of the Ti6Al4V surface while preserving bulk properties of the alloy that are crucial for its performance as an orthopedic and dental implant. We hypothesized that UV treatment of Ti6Al4V may impair bacterial adhesion without compromising the good response of human bone-forming cells to this alloy. The in vitro biocompatibility of the Ti6Al4V surface, before and after UV irradiation, was analyzed by using human cells related to the osteoblastic phenotype.

Cranberry changes the physicochemical surface properties of E. coli and adhesion with uroepithelial cells.

Cranberries have been suggested to decrease the attachment of bacteria to uroepithelial cells (UC), thus preventing urinary tract infections, although the mechanisms are not well understood. A thermodynamic approach was used to calculate the Gibbs free energy of adhesion changes (DeltaG(adh)) for bacteria-UC interactions, based on measuring contact angles with three probe liquids. Interfacial tensions and DeltaG(adh) values were calculated for Escherichia coli HB101pDC1 (P-fimbriated) and HB101 (non-fimbriated) exposed to cranberry juice (0-27 wt.

Per-6-O-(tert-butyldimethylsilyl)cyclodextrins (TBDMS-CDs) in Langmuir monolayers: the importance of a spreading solvent in the preparation of LB layers suitable for sensor application.

Commercially available amphiphilic cyclodextrins, namely per-6-O-(tert-butyldimethylsilyl) alpha, beta and gamma cyclodextrins (TBDMS-alpha-, -beta-, and -gamma-CDs) were subjected to a thorough Langmuir monolayer characterization, using both traditional methods of surface manometry (pi/A isotherms, stability experiments) and modern micrometer/nanometer resolution (BAM, AFM) surface techniques. It has been found that inconsistent behavior regarding the isotherms reproducibility obtained upon compression of TBDMS-beta-CDs is due to the aggregation of the investigated molecules in chloroform and hexane, while good reproducibility ensured a mixed spreading solvent system of hexane/isopropanol 7:3 (v/v). Although the stability of films dropped from chloroform and hexane/isopropanol solvents below the equilibrium surface pressure (ESP) was comparable, pronounced differences were observed at pressures above ESP.