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.

Bacterial adhesion has become a significant problem in industry and in the domicile, and much research has been done for deeper understanding of the processes involved. A generic biological model of bacterial adhesion and population growth called the bacterial biofilm growth cycle, has been described and modified many times. The biofilm growth cycle encompasses bacterial adhesion at all levels, starting with the initial physical attraction of bacteria to a substrate, and ending with the eventual liberation of cell clusters from the biofilm matrix. When describing bacterial adhesion one is simply describing one or more stages of biofilm development, neglecting the fact that the population may not reach maturity. This article provides an overview of bacterial adhesion, cites examples of how bacterial adhesion affects industry and summarises methods and instrumentation used to improve our understanding of the adhesive properties of bacteria.

/pdf/bacterial-adhesion-and-biofilms-on-surfaces-153vag9bcp.pdf

Bacterial adhesion and biofilms on surfaces

In the aquatic environment, microplastic (MP; <5 mm) is a cause of concern because of its persistence and potential adverse effects on biota. Studies of microlitter impacts are mostly based on virgin and spherical polymer particles as model MP. However, in pelagic and benthic environments, surfaces are always colonized by microorganisms forming so-called biofilms. The influence of such biofilms on the fate and potential effects of MP is not understood well. Here, we review the physical interactions of early microbial colonization on plastic surfaces and their reciprocal influence on the weathering processes and vertical transport as well as sorption and release of contaminants by MP. Possible ecological consequences of biofilm formation on MP, such as trophic transfer of MP particles and potential adverse effects of MP, are virtually unknown. However, evidence is accumulating that the biofilm−plastic interactions have the capacity to influence the fate and impacts of MP by modifying the physical propertie...

http://pubs.acs.org/doi/pdf/10.1021/acs.estlett.7b00164

Impacts of Biofilm Formation on the Fate and Potential Effects of Microplastic in the Aquatic Environment

https://www.edwinvanderpol.com/publications/manuscripts/van_der_pol_2014_JTH_Vesicle_size_distribution.pdf

Particle size distribution of exosomes and microvesicles determined by transmission electron microscopy, flow cytometry, nanoparticle tracking analysis, and resistive pulse sensing.

On a role

Substratum surface roughness has a well documented effect on the retention of microorganisms. Implications of this encompass problems in hygiene, infection, fouling, equipment function, corrosion and cleanability. This paper reviews methods used for visualising surface topography and measuring roughness which are pertinent to microbiologists, and notes limitations of some of the descriptors of surface roughness. A major issue is the scale on which the surface defects are examined: measurements may now be made in nanometers, but the significance of surface texture at this scale in terms of microbial retention has yet to be investigated in detail. Stainless steel and ceramics are commonly used as hygienic food preparation surfaces. Their wear has been visualised, with roughness measured on a nanometer scale using the atomic force microscope (AFM), and the effect on surface wear of cleanability using microbial and organic soil investigated. Surface analytical methods such as X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToFSIMS) provided information on the chemical structure at the uppermost atomic layer and demonstrate that microorganisms were removed more rapidly than organic material from the worn surfaces, and that organic soil conditioned the surfaces prior to microbial contamination. On this scale, the dimensions of surface defects were more suited to soil retention than to microbial cell retention. Traditional microscopic methods were not able to differentiate adequately between soil and microbial removal. Surface analytical techniques provide the opportunity to measure and visualise surface roughness and its effect on microbial and organic soiling on a hitherto unavailable level of detection.

The relationship between substratum surface roughness and microbiological and organic soiling: A review

Changes in surface roughness and topography on the macroscopic scale are known to affect bacterial attachment and retention. Little quantitative information is available as to how changes in surface topography on the micron and submicron scale affect the strength of bacterial attachment to substrata. A novel method is described using the atomic force microscope where a varying shear/lateral force (in nanonewtons) is used to detach individual bacterial cells from various substrata of different surface topographies. Lateral changes of 0.1 μm in the surface topography are sufficient to affect the strength of bacterial attachment. An increase in applied force from 4 to 8 nN was necessary to move bacteria retained in surface defects of approximately 1 μm wide and 0.2 μm deep compared with cells attached on smooth surfaces.

Use of the atomic force microscope to determine the effect of substratum surface topography on bacterial adhesion

Bioconjugation and characterisation of gold colloid-labelled proteins.

New approach to inter-technique comparisons for nanoparticle size measurements; using atomic force microscopy, nanoparticle tracking analysis and dynamic light scattering.

The chemical and physical effects incurred at the surface of biaxially oriented polypropylene film during silent discharge plasma treatment have been investigated using XPS, NMR, TOF-SIMS, and AFM techniques It is found that chain scission accompanied by oxidative attack leads to the formation of low molecular weight oxidized material which agglomerates into globules at the surface due to a large difference in interfacial free energy between the underlying hydrophobic substrate and the oxygenated overlayer

Robert D. Boyd

Papers

The relationship between substratum surface roughness and microbiological and organic soiling: A review

Use of the atomic force microscope to determine the effect of substratum surface topography on bacterial adhesion

Bioconjugation and characterisation of gold colloid-labelled proteins.

New approach to inter-technique comparisons for nanoparticle size measurements; using atomic force microscopy, nanoparticle tracking analysis and dynamic light scattering.

Atmospheric nonequilibrium plasma treatment of biaxially oriented polypropylene