This article reviews the mechanisms of bacterial adhesion to biomaterial surfaces, the factors affecting the adhesion, the techniques used in estimating bacteria-material interactions and the models that have been developed in order to predict adhesion. The process of bacterial adhesion includes an initial physicochemical interaction phase and a late molecular and cellular one. It is a complicated process influenced by many factors, including the bacterial properties, the material surface characteristics, the environmental factors, such as the presence of serum proteins and the associated flow conditions. Two categories of techniques used in estimating bacteria-material interactions are described: those that utilize fluid flowing against the adhered bacteria and counting the percentage of bacteria that detach, and those that manipulate single bacteria in various configurations which lend themselves to more specific force application and provide the basis for theoretical analysis of the receptor-ligand interactions. The theories that are reviewed are the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the thermodynamic approach and the extended DLVO theory. Over the years, significant work has been done to investigate the process of bacterial adhesion to biomaterial surfaces, however a lot of questions still remain unanswered.

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Concise review of mechanisms of bacterial adhesion to biomaterials and of techniques used in estimating bacteria-material interactions.

Polymeric materials with antimicrobial activity

Numerous species of bacteria employ a mechanism of intercellular communication known as quorum sensing. This signaling process allows the cells comprising a bacterial colony to coordinate their gene expression in a cell-density dependent manner.1-3 Quorum sensing is mediated by small diffusible molecules termed autoinducers that are synthesized intracellularly (throughout the growth of the bacteria) and released into the surrounding milieu. As the number of cells in a bacterial colony increases, so does the extracellular concentration of the autoinducer. Once a threshold concentration is reached (at which point the population is considered to be “quorate”), productive binding of the autoinducer to cognate receptors within the bacterial cells occurs, triggering a signal transduction cascade that results in population-wide changes in gene expression.4-6 Thus, quorum sensing enables the cells within a bacterial colony to act cooperatively, facilitating population-dependent adaptive behavior.6 Quorum sensing has been shown to play a critical role in both pathogenic and symbiotic bacteria-host interactions.5 In symbionts, significant quorum sensing phenotypes include bioluminescence and root nodulation.7-11 Several clinically relevant pathogens use quorum sensing systems to regulate processes associated with virulence; this enhances the survival prospects of the bacteria because a coordinated attack on the host is only made when the bacterial population reaches a high population density, increasing the likelihood that the hosts defenses will be successfully overwhelmed.12,13 For example, in Pseudomonas aeruginosa, quorum sensing is involved in the formation of biofilms and their tolerance to antimicrobial agents14-17 and the innate host immune * To whom correspondence should be addressed. Tel.: +44 (0)1223 336498. Fax: +44 (0)1223 336362. E-mail: spring@ch.cam.ac.uk. † Department of Chemistry. ‡ Department of Biochemistry. Chem. Rev. 2011, 111, 28–67 28

http://www-spring.ch.cam.ac.uk/publications/pdf/2011_CR_28.pdf

Quorum sensing in Gram-negative bacteria: small-molecule modulation of AHL and AI-2 quorum sensing pathways.

Recently, biosynthesis of nanoparticles has attracted scientists’ attention because of the necessity to develop new clean, cost-effective and efficient synthesis techniques. In particular, metal oxide nanoparticles are receiving increasing attention in a large variety of applications. However, up to now, the reports on the biopreparation and characterization of nanocrystalline copper oxide are relatively few compared to some other metal oxides. In this paper, we report for the first time the use of brown alga (Bifurcaria bifurcata) in the biosynthesis of copper oxide nanoparticles of dimensions 5–45 nm. The synthesized nanomaterial is characterized by UV–visible absorption spectroscopy and Fourier transform infrared spectrum analysis. X-ray diffraction confirms the formation and the crystalline nature of copper oxide nanomaterial. Further, these nanoparticles were found to exhibit high antibacterial activity against two different strains of bacteria Enterobacter aerogenes (Gram negative) and Staphylococcus aureus (Gram positive).

/pdf/biosynthesis-characterization-and-antimicrobial-activity-of-51k2jtcqw8.pdf

Biosynthesis, characterization and antimicrobial activity of copper oxide nanoparticles (CONPs) produced using brown alga extract ( Bifurcaria bifurcata )

Recently investigated applications of polymeric materials for tissue engineering, regenerative medicine, implants, stents, and medical devices are described in the present review. Papers published during the last 2 years about polymeric materials used for preparation of various polymeric scaffolds, methods of fabrication of such scaffolds and their effectiveness in providing support for cell growth and development into various tissues and enhancing or mimicking an extracellular network (ECM's) have been cited. Papers describing the use of such polymeric materials for tissue engineering of cartilage and bones were cited. The exciting developments in the field of regenerative medicine, based on application of the self-assembled biocompatible polymeric scaffolds for regeneration of tissues and organs are described in some detail. The use of the biocompatible and biodegradable collapsible polymeric stents, as well as the use of biocompatible, but not necessarily biodegradable polymeric materials for protective coatings of metallic stents and reservoirs of drugs, preventing restenosis and other post-operative complications that may occur after insertion of a stent, have been reviewed. Clinical results pointing out the advantages of such treatments, as well as results indicating their limitations, have been cited. New formulas, for coating implants, stents, and other medical devices, have been discussed. Copyright © 2006 John Wiley & Sons, Ltd.

Polymers for tissue engineering, medical devices, and regenerative medicine. Concise general review of recent studies

Role of chemical interactions in bacterial adhesion to polymer surfaces.

Improvement of mechanical properties of a-C:H by silicon addition

The study of the adhesion of lipid vesicles on surfaces is of increasing interest in the field of medical implants and tissue engineering (protein-resistant surfaces), drug delivery, biosensors, and biochips In this work, lipid coverage was developed from PEG-coated vesicles (with sizes from 100 to 300 nm) by covalently binding poly(ethylene glycol)-α-disteroylphosphatidylethanolamine-ω-benzotriazole carbonate (DSPE-PEG-BTC) molecules onto the surface amine groups by carbamate chemistry Lipid surface density and the surface structure of multilamellar (MLVs) and extruded unilamellar (LUVs) vesicles deposited on three types of polystyrene (PS) well-plates were probed by fluorescence and atomic force microscopy (AFM) imaging A significant difference in the vesicle surface coverage of PS substrates was observed with a substantial increase in lipid multilayers on the amine-enriched PS surface using both unilamellar and multilamellar vesicles

M. Anderle

Papers

Role of chemical interactions in bacterial adhesion to polymer surfaces.

Improvement of mechanical properties of a-C:H by silicon addition

Covalently Anchored Lipid Structures on Amine-Enriched Polystyrene

Immobilization of cationic rifampicin-loaded liposomes on polystyrene for drug-delivery applications.

Organo-silane coated substrates for DNA purification