Adsorption Kinetics, Conformation, and Mobility of the Growth Hormone and Lysozyme on Solid Surfaces, Studied with TIRF

Buijs, Jos; Hlady, Vladimir

doi:10.1006/jcis.1997.4876

Cited by 158 publications

(136 citation statements)

References 27 publications

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“…In a previous publication 19 we reported that adsorption of hGH is dominated by hydrophobic interactions, as, for example, can be concluded when the hGH adsorption on the hydrophobic DDS is compared to that on hydrophilic silica. However, as shown in Figure 3a, both adsorption rates and amounts adsorbed are strongly reduced going from surfaces on which the alkyl chains are covalently attached (DDS and OTS) to surfaces on which the alkyl chains are physisorbed (ArAc and DPPC).…”

Section: Adsorption and Desorption Kineticsmentioning

confidence: 90%

“…19 All sorbent surfaces were prepared/cleaned within a few hours before use and mounted on top of a silicon rubber gasket which created a 0.5 mm space between the slide and an anodized aluminum support which could be filled with solutions. For slides covered with a surface layer of ArAc or DPPC head groups, this mounting was performed under water.…”

Section: Methodsmentioning

confidence: 99%

“…This type of desorption behavior was also observed in a previous study of hGH at solid surfaces. 19 Also, other studies have demonstrated that proteins can adsorb in two states with substantial differences in mobility 28 and biological activity. 5 The only exception to this two-state desorption process is seen for hGH on the DPPC tail surface, for which no fast initial desorption is observed.…”

Section: Adsorption and Desorption Kineticsmentioning

confidence: 99%

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Human Growth Hormone Adsorption Kinetics and Conformation on Self-Assembled Monolayers

1998

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The adsorption process of the recombinant human growth hormone on organic films, created by self-assembly of octadecyltrichlorosilane, arachidic acid, and dipalmitoylphosphatidylcholine, is investigated and compared to adsorption on silica and methylated silica substrates. Information on the adsorption process of human growth hormone (hGH) is obtained by using total internal reflection fluorescence (TIRF). The intensity, spectra, and quenching of the intrinsic fluorescence emitted by the growth hormone's single tryptophan are monitored and related to adsorption kinetics and protein conformation. For the various alkylated hydrophobic surfaces with differences in surface density and conformational freedom it is observed that the adsorbed amount of growth hormone is relatively large if the alkyl chains are in an ordered structure while the amounts adsorbed are considerably lower for adsorption onto less ordered alkyl chains of fatty acid and phospholipid layers. Adsorption on methylated surfaces results in a relatively large conformational change in the growth hormone's structure, as displayed by a 7 nm blue shift in emission wavelength and a large increase in the effectiveness of fluorescence quenching. Conformational changes are less evident for hGH adsorption onto the fatty acid and phospholipid alkyl chains. Adsorption kinetics on the hydrophilic head groups of the self-assembled monolayers are similar to those on solid hydrophilic surfaces. The relatively small conformational changes in the hGH structure observed for adsorption on silica are even further reduced for adsorption on fatty acid head groups.

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Section: Adsorption and Desorption Kineticsmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: Adsorption and Desorption Kineticsmentioning

confidence: 99%

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Human Growth Hormone Adsorption Kinetics and Conformation on Self-Assembled Monolayers

1998

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“…1a) is surprising in view of earlier studies 4,6,8,9,42,43 which reported that increasing ionic strength is causing a decrease in adsorption of lysozyme on silica surfaces. Tentatively, we attribute the observed insensitivity of the binding characteristics against salt to a compensation of two opposing effects: (a) increasing silanol dissociation due to the added salt; 45,46,49 (b) counter-ions of the salt competing with the protein for the charged surface sites.…”

Section: Protein Bindingmentioning

confidence: 94%

Bridging interactions of proteins with silica nanoparticles: The influence of pH, ionic strength and protein concentration

et al. 2014

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Charge-driven bridging of nanoparticles by macromolecules represents a promising route for engineering functional structures, but the strong electrostatic interactions involved when using conventional polyelectrolytes impart irreversible complexation and ill-defined structures. Recently it was found that the electrostatic interaction of silica nanoparticles with small globular proteins leads to aggregate structures that can be controlled by pH. Here we study the combined influence of pH and electrolyte concentration on the bridging aggregation of silica nanoparticles with lysozyme in dilute aqueous dispersions. We find that protein binding to the silica particles is determined by pH irrespective of the ionic strength. The hetero-aggregate structures formed by the silica particles with the protein were studied by small-angle X-ray scattering (SAXS) and the structure factor data were analyzed on the basis of a short-range square-well attractive pair potential (close to the sticky-hard-sphere limit). It is found that the electrolyte concentration has a strong influence on the stickiness near pH 5, where the weakly charged silica particles are bridged by the strongly charged protein. An even stronger influence of the electrolyte is found in the vicinity of the isoelectric point of the protein (pI ¼ 10.7) and is attributed to shielding of the repulsion between the highly charged silica particles and hydrophobic interactions between the bridging protein molecules.

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“…The experiments in the present study were carried out to investigate and compare the adsorption behaviour of these four proteins, under identical conditions, within the concentration ranges present in saliva (for lactoferrin and lactoperoxidase ≤10 g ml −1 [6,7], lysozyme ≤200 g ml −1 [6], and histatin 5 ≤45 g ml −1 [19]). Previously, studies have been performed on the adsorption of lactoferrin [20,21], lactoperoxidase [22] and lysozyme [20,[23][24][25][26][27], however these publications were carried out using different techniques to some extent, and additionally they were not performed using the same concentration ranges, buffer solutions (or, to some extent, substrates) as the present investigation. The adsorption behaviour of the four chosen proteins was investigated on two types of silica surfaces with different characters.…”

Section: Introductionmentioning

confidence: 99%

Adsorption behaviour and surfactant elution of cationic salivary proteins at solid/liquid interfaces, studied by in situ ellipsometry

Svendsen

Lindh

Arnebrant

2006

Colloids and Surfaces B: Biointerfaces

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Adsorption of the cationic salivary proteins lactoferrin, lactoperoxidase, lysozyme and histatin 5 to pure (hydrophilic) and methylated (hydrophobized) silica surfaces was investigated by in situ ellipsometry. Effects of concentration (≤10 g ml −1 , for lysozyme ≤200 g ml −1 ) and dependence of surface wettability, as well as adsorption kinetics and elutability of adsorbed films by buffer and sodium dodecyl sulphate (SDS) solutions were investigated. Results showed that the amounts adsorbed decreased in the order lactoferrin ≥ lactoperoxidase > lysozyme ≥ histatin 5. On hydrophilic silica, the adsorption was most likely driven by electrostatic interactions, which resulted in adsorbed amounts of lactoferrin that indicated the formation of a monolayer with both side-on and end-on adsorbed molecules. For lactoperoxidase the adsorbed amounts were somewhat higher than an end-on monolayer, lysozyme adsorption showed amounts corresponding to a side-on monolayer, and histatin 5 displayed adsorbed amounts in the range of a side-on monolayer. On hydrophobized substrata, the adsorption was also mediated by hydrophobic interactions, which resulted in lower adsorbed amounts of lactoferrin and lactoperoxidase; closer to side-on monolayer coverage. For both lysozyme and histatin 5 the adsorbed amounts were the same as on the hydrophilic silica. The investigated proteins exhibited fast adsorption kinetics, and the initial kinetics indicated mass transport controlled behaviour at low concentrations on both types of substrates. Buffer rinsing and SDS elution indicated that the proteins in general were more tightly bound to the hydrophobized surface compared to hydrophilic silica. Overall, the surface activity of the investigated proteins implicates their importance in the salivary film formation.

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Adsorption Kinetics, Conformation, and Mobility of the Growth Hormone and Lysozyme on Solid Surfaces, Studied with TIRF

Cited by 158 publications

References 27 publications

Human Growth Hormone Adsorption Kinetics and Conformation on Self-Assembled Monolayers

Human Growth Hormone Adsorption Kinetics and Conformation on Self-Assembled Monolayers

Bridging interactions of proteins with silica nanoparticles: The influence of pH, ionic strength and protein concentration

Adsorption behaviour and surfactant elution of cationic salivary proteins at solid/liquid interfaces, studied by in situ ellipsometry

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