Virginia Vadillo Rodríguez

Virginia Vadillo Rodríguez
Universidad de Extremadura | UNEX · Department of Applied Physics

PhD

About

35
Publications
2,871
Reads
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1,202
Citations
Additional affiliations
January 2009 - present
Universidad de Extremadura
Position
  • Ramon y Cajal Research Fellow
January 2006 - December 2008
University of Guelph
Position
  • Postdoctoral Position
June 2004 - May 2005
Pennsylvania State University
Position
  • Postdoctoral Position

Publications

Publications (35)
Article
Full-text available
Increased bacterial resistance to traditional antimicrobial agents has prompted the use of natural products with antimicrobial properties such as propolis, extensively employed since ancient times. However, the chemical composition of propolis extracts is extremely complex and has been shown to vary depending on the region and season of collection,...
Article
In this paper, a simple numerical procedure is presented to monitor the growth of Streptococcus sanguinis over time in the absence and presence of propolis, a natural antimicrobial. In particular, it is shown that the real-time decomposition of growth curves obtained through optical density measurements into growth rate and acceleration can be a po...
Article
In the present study, an effort has been made to understand the interaction mode of propolis, a natural substance produced by honey bees, with gram-positive and gram-negative bacterial cells by measuring alterations in cell surface physico-chemical properties following the incubation of the cells with different sub-inhibitory concentrations of this...
Article
Full-text available
Propolis is a natural product obtained from hives. Its chemical composition varies depending on the flora of its surroundings, but nevertheless, common for all types of propolis, they all exhibit remarkable biological activities. The aim of this study was to investigate the chemical composition and antimicrobial activity of a novel Spanish Ethanoli...
Article
Mechano-bactericidal materials rely on mechanical interactions between nanomaterials and bacteria, and are promising antimicrobial strategies that overcome bacterial resistance. However, the real effect of mechanical vs chemical action on their activity is under debate. In this paper we quantify the forces necessary to produce critical damage to th...
Article
In this study, the influence of nanometer scale roughness on bacterial adhesion and subsequent biofilm formation has been evaluated using spatially organized microtopographic surface patterns for four major opportunistic pathogens of the genus Staphylococcus (S. epidermidis and S. aureus) responsible for associated-biofilm infections on biomedical...
Article
Full-text available
We investigated a Ti6Al4V alloy modified by means of laser peening in the absence of sacrificial coatings. As a consequence of the temperature rise during laser focusing, melting and ablation generated an undulated surface that exhibits an important increase in the content of titanium oxides and OH- ions. Human mesenchymal stem cells and osteoblast...
Article
The influence of surface curvature on the adsorption of bovine serum albumin (BSA) was evaluated through the combination of two fairly simple techniques: electrophoretic light scattering and UV/vis spectroscopy. Measurements were carried out for a range of protein concentrations (0–320 μg/ml) at pH 3.5, 4.5 and 7 using hydrophobic polystyrene nanos...
Article
The influence of surface topography on bacterial adhesion have been investigated using a range of spatially organized microtopographic surface patterns generated on polydimethylsiloxane (PDMS) and three unrelated bacterial strains. The results presented indicate that bacterial cells actively choose their position to settle, differentiating upper an...
Article
In this study, the structure and mechanical stability of human plasma fibronectin (HFN), a major protein component of blood plasma, have been evaluated in details upon adsorption on the non-irradiated and irradiated Ti6Al4V material through the use of atomic force microscopy. The results indicated that the material surface changes occurring after t...
Article
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 expres...
Article
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...
Article
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...
Article
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...
Article
Full-text available
Bacterial cell envelopes are remarkable biological structures that allow cells to adapt to and survive changes in their external environment while maintaining their mechanical integrity as the cells grow and divide. We review efforts to characterize the mechanical properties of the bacterial cell envelope, and we highlight recent advances in measur...
Article
Full-text available
We have used atomic force microscopy (AFM) to measure the viscoelastic properties of individual Escherichia coli K12 cells under fully hydrated conditions by collecting AFM force–indentation and force–time curves. Spherical colloidal tips were used to reduce the local strain ensuring that the measurements were performed in the linear viscoelastic r...
Article
Full-text available
We used a novel atomic force microscopy (AFM)-based technique to compare the local viscoelastic properties of individual gram-negative (Escherichia coli) and gram-positive (Bacillus subtilis) bacterial cells. We found that the viscoelastic properties of the bacterial cells are well described by a three-component mechanical model that combines an in...
Article
We have used an AFM-based approach to probe the mechanical properties of single bacterial cells (gram-negative Escherichia coli K12) by applying a constant compressive force to the cell under fluid conditions while measuring the time-dependent displacement (creep) of a colloidal AFM tip due to the viscoelastic properties of the cell. We observed th...
Article
Full-text available
The cell envelope of gram-negative bacteria is responsible for many important biological functions: it plays a structural role, it accommodates the selective transfer of material across the cell wall, it undergoes changes made necessary by growth and division, and it transfers information about the environment into the cell. Thus, an accurate quant...
Article
Pull-off forces were measured between a silica colloid attached to an atomic force microscope (AFM) cantilever and three homopolymer surfaces representing constituents of extracellular polymeric substances (EPS). The pull-off forces were −0.84 (±0.16), −0.68 (±0.15), and −2.37 (±0.31) nN as measured in water for dextran, phosphorylated dextran, and...
Article
Bacterial adhesion to surfaces does not always proceed according to theoretical expectations. Discrepancies are often attributed to surface heterogeneities that provide localized, favorable sites for bacterial attachment. The presence of these favorable deposition sites for bacteria, however, has never been directly measured. Atomic force microscop...
Article
Exopolymers are thought to influence bacterial adhesion to surfaces, but the time-dependent nature of molecular-scale interactions of biopolymers with a surface are poorly understood. In this study, the adhesion forces between two proteins and a polysaccharide [Bovine serum albumin (BSA), lysozyme, or dextran] and colloids (uncoated or BSA-coated c...
Article
The S-layer present at the outermost cell surface of some lactobacillus species is known to convey hydrophobicity to the lactobacillus cell surface. Yet, it is commonly found that adhesion of lactobacilli to solid substrata does not proceed according to expectations based on cell surface hydrophobicity. In this paper, the role of cell surface hydro...
Article
Full-text available
Variations in surface hydrophobicity of six Lactobacillus strains with and without an S-layer upon changes in ionic strength are derived from contact angle measurements with low- and high-ionic-strength aqueous solutions. Cell surface hydrophobicity changed in response to changes in ionic strength in three out of the six strains, offering these str...
Article
Initial bacterial adhesion is considered to be reversible, but over time the adhesive bond between a bacterium and a substratum surface may strengthen, turning the process into an irreversible state. Microbial desorption has been studied in situ in controlled flow devices as a function of the organisms resident time on the surface (J. Colloid Inter...
Article
Full-text available
Atomic force microscopy (AFM) has emerged as a powerful technique for mapping the surface morphology of biological specimens, including bacterial cells. Besides creating topographic images, AFM enables us to probe both physicochemical and mechanical properties of bacterial cell surfaces on a nanometer scale. For AFM, bacterial cells need to be firm...
Article
Full-text available
Application of physico-chemical models to describe bacterial adhesion to surfaces has hitherto only been partly successful due to the structural and chemical heterogeneities of bacterial surfaces, which remain largely unaccounted for in macroscopic physico-chemical characterizations of the cell surfaces. In this study, the authors attempted to corr...
Article
This thesis represents a further attempt to correlate microscopic surface properties of bacterial species as derived from force-distance curve analyses to their macroscopic adhesion to solid substrata as directly observed under well-defined flow conditions. In order to formulate generic relations, bacterial species differing with respect to their o...
Article
Bacterial adhesion to substratum surfaces is determined by the combined action of a large number of different interactions, which have hitherto been inferred from macroscopic cell surface properties, such as electrostatic double-layer forces, hydrophobic interactions, hydrogen bonding, and steric interactions. The origin of these interactions arise...
Article
Chemical and structural complexity of bacterial cell surfaces complicate accurate quantification of cell surfaces properties. The presence of fibrils, fimbriae or other surface appendages on bacterial cell surfaces largely influence those properties and would therefore play a major function in interfacial phenomena as aggregation and adhesion. The...
Article
En: Cátedra Nova : Revista de Bachillerato Badajoz 1999, n. 9, junio; p. 245-256 Cuento que primeramente puede ser presentado en clase de lengua a los alumnos que comienzan el Bachillerato (LOGSE) para valorar el nivel de lectura comprensiva que han alcanzado con la ESO, y como ejercicio de comentario de texto. Pasado un tiempo prudencial, se retor...

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