Colloidal behaviour of materials with ionizable group surfaces

Healy, Thomas W.; Chan, Derek H. H.; White, Lee R.

doi:10.1351/pac198052051207

Cited by 86 publications

(49 citation statements)

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“…As the bacterium approaches the surface, the charge regulation effect causes both and pH at the cell surface to vary as a function of separation distance (6,14,34,37,39). If the surface that the bacterium is approaching is negatively charged, such as the glass beads used in this study, the charge regulation effect results in a drop in pH at the cell surface.…”

Section: Discussionmentioning

confidence: 99%

“…Because of these processes, neither nor remains fixed during the approach of these surfaces. This is the well-known charge regulation effect (6,14,34,37,39), and the effects of the functional groups on and can be determined by solving the Poisson-Boltzmann equation using boundary conditions that consider the multiple dissociation equilibria of ionizable groups on each surface (34,37,39).…”

Section: Discussionmentioning

confidence: 99%

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Variation in Bacterial ATP Level and Proton Motive Force Due to Adhesion to a Solid Surface

Hong

Brown

2009

Appl Environ Microbiol

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Bacterial adhesion to natural and man-made surfaces can be beneficial or detrimental, depending on the system at hand. Of vital importance is how the process of adhesion affects the bacterial metabolic activity. If activity is enhanced, this may help the cells colonize the surface, whereas if activity is reduced, it may inhibit colonization. Here, we report a study demonstrating that adhesion of both Escherichia coli and Bacillus brevis onto a glass surface resulted in enhanced metabolic activity, assessed through ATP measurements. Specifically, ATP levels were found to increase two to five times upon adhesion compared to ATP levels in corresponding planktonic cells. To explain this effect on ATP levels, we propose the hypothesis that bacteria can take advantage of a link between cellular bioenergetics (proton motive force and ATP formation) and the physiochemical charge regulation effect, which occurs as a surface containing ionizable functional groups (e.g., the bacterial cell surface) approaches another surface. As the bacterium approaches the surface, the charge regulation effect causes the charge and pH at the cell surface to vary as a function of separation distance. With negatively charged surfaces, this results in a decrease in pH at the cell surface, which enhances the proton motive force and ATP concentration. Calculations demonstrated that a change in pH across the cell membrane of only 0.2 to 0.5 units is sufficient to achieve the observed ATP increases. Similarly, the hypothesis indicates that positively charged surfaces will decrease metabolic activity, and results from studies of positively charged surfaces support this finding.Bacterial adhesion and biofilm formation are important to a wide array of fields, such as environmental, chemical, and biomedical engineering; food processing; materials science; marine science; and ecology and environmental sciences. A key consideration in the development of a biofilm is the initial interaction between the bacterium and the substrata and the way in which these interactions affect the metabolic activity of the cells. If the metabolic activity increases, this would help the cells colonize the surface, whereas if the metabolic activity decreases, then the cells may become inactive or die.There have been a number of studies that have examined the effects of attachment on bacterial metabolic activity. The first reported observation of this effect was made in 1943, where it was found that bacterial activity increased in the presence of glass surfaces, particularly with low nutrient concentrations (54). Since this first study, researchers have examined how various materials, including glass and polymer surfaces (10, 11, 24-26, 40, 44, 47), silicone surfaces (52), ceramic surfaces (32), dialysis membranes (18), activated carbon (7), clays (43), sands (31, 48), estuary particles (19), and ion exchange resins (46), affect the metabolic activity of attached bacteria.Different mechanisms have been examined in an attempt to explain how surfaces affect bacterial metabo...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Variation in Bacterial ATP Level and Proton Motive Force Due to Adhesion to a Solid Surface

Hong

Brown

2009

Appl Environ Microbiol

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“…Additionally, table 1 provides literature for a more detailed study, sorted by the metals (Au, Ag) studied. [107][108][109][110][111]. At low pH, the surface can be charged positively by the adsorption of protons (MOH 2 þ ), whereas it will be negatively charged at high pH owing to depletion of protons (M-O 2 ).…”

Section: Ion Effectsmentioning

confidence: 99%

Interaction of colloidal nanoparticles with their local environment: the (ionic) nanoenvironment around nanoparticles is different from bulk and determines the physico-chemical properties of the nanoparticles

Pfeiffer

Rehbock

Hühn

et al. 2014

J. R. Soc. Interface.

331

301

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The physico-chemical properties of colloidal nanoparticles (NPs) are influenced by their local environment, as, in turn, the local environment influences the physico-chemical properties of the NPs. In other words, the local environment around NPs has a profound impact on the NPs, and it is different from bulk due to interaction with the NP surface. So far, this important effect has not been addressed in a comprehensive way in the literature. The vicinity of NPs can be sensitively influenced by local ions and ligands, with effects already occurring at extremely low concentrations. NPs in the Hü ckel regime are more sensitive to fluctuations in the ionic environment, because of a larger Debye length. The local ion concentration hereby affects the colloidal stability of the NPs, as it is different from bulk owing to Debye Hü ckel screening caused by the charge of the NPs. This can have subtle effects, now caused by the environment to the performance of the NP, such as for example a buffering effect caused by surface reaction on ultrapure ligandfree nanogold, a size quenching effect in the presence of specific ions and a significant impact on fluorophore-labelled NPs acting as ion sensors. Thus, the aim of this review is to clarify and give an unifying view of the complex interplay between the NP's surface with their nanoenvironment.

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“…Another option is to use the constant surface charge model, where the surface charge σ is fixed. However, in a real system neither the surface potential nor the surface charge are constant, but change as function of pore size, pH, and salt concentration (26). These effects are considered in the CR model which uses an expression for σ , additional to Eq.…”

Section: Theorymentioning

confidence: 99%

Application of the Charge Regulation Model to the Separation of Ions by Hydrophilic Membranes

Biesheuvel¹,

Lint²

2001

Journal of Colloid and Interface Science

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Colloidal behaviour of materials with ionizable group surfaces

Cited by 86 publications

References 0 publications

Variation in Bacterial ATP Level and Proton Motive Force Due to Adhesion to a Solid Surface

Variation in Bacterial ATP Level and Proton Motive Force Due to Adhesion to a Solid Surface

Interaction of colloidal nanoparticles with their local environment: the (ionic) nanoenvironment around nanoparticles is different from bulk and determines the physico-chemical properties of the nanoparticles

Application of the Charge Regulation Model to the Separation of Ions by Hydrophilic Membranes

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