A neutron reflectivity study of a spread monolayer of bovine serum albumin

Eaglesham, A.; Herrington, Thelma M.; Penfold, J.

doi:10.1016/0166-6622(92)80170-7

Cited by 35 publications

(15 citation statements)

References 10 publications

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“…Only in the single case at pH 5 and the higher BLG concentration (Figure A2), an additional, thicker but less dense layer is formed adjacent to the primary monolayer, as evidenced from the bimodal protein distribution, in the following termed secondary sublayer. Extended surface density profiles have been found as well for layers of other proteins: lysozyme, bovine serum albumin (BSA), , HSA and myoglobin . For BLG, such profiles (with an ACMW subphase) have been previously resolved for adsorption layers at pH 7 but only at higher protein concentrations of ≈5.5 × 10 –5 and ≈5.5 × 10 –4 M and in the presence of 20 and 50 mM buffer, respectively (note that at comparable BLG concentrations and pH 7, but at very low electrolyte content, homogeneous layers were found , ).…”

Section: Resultsmentioning

confidence: 90%

β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 3. Neutron Reflectometry Study on the Effect of pH

et al. 2019

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Several characteristics of β-lactoglobulin (BLG) layers adsorbed at the air/water interface exhibit a strong pH dependence, but our knowledge on the underlying structure−property relations is still fragmental. Here, we therefore extend our recent studies by neutron reflectometry (NR) and provide a comprehensive overview through direct measurements of the surface excess Γ and the layers' molecular structure. This enables comparison with available literature data to draw general conclusions. The NR experiments were performed at various pH values and within a wide range of protein concentrations, C BLG . Adsorption kinetics measurements in air-contrast-matched-water and over a narrow Q z range enabled direct quantification of the dynamic surface excess Γ(t) and are found to be consistent with ellipsometry data. Near the isoelectric point, pI, the rates of adsorption and Γ are maximal but only at sufficiently high C BLG . NR data collected over a wider Q z range and in two aqueous isotopic contrasts revealed the structure of adsorbed BLG layers at a steady state close to equilibrium. Independent of the pH, BLG was found to form dense monolayers with average thicknesses of 1.1 nm, suggesting flattening of the BLG globules upon adsorption as compared with their bulk dimensions (≈3.5 nm). Near pI and at sufficiently high C BLG , a thick (≈5.5 nm) but looser secondary sublayer is additionally formed adjacent to the dense primary monolayer. The thickness of this sublayer can be interpreted in terms of disordered BLG dimers. The results obtained and notably the specific interfacial structuring of BLG near pI complement previous observations relating the impact of solution pH and C BLG on other interfacial characteristics such as surface pressure and surface dilational viscoelasticity modulus.

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Section: Resultsmentioning

confidence: 90%

β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 3. Neutron Reflectometry Study on the Effect of pH

et al. 2019

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“…β-Lactoglobulin is surface active 5 and has been shown to adsorb at the air-water interface to give a monolayer that is thinner (thickness is about 3 nm) and value of surface coverage is about 1.7 mg m −2 using neutron reflectivity measurements. 6 The adsorbed globular protein layer can probably be regarded as a pseudo-two-dimensional system of densely packed deformable particle. 7 This adsorbed globular protein layer may further interact with components at the environment by a combination of electrostatic, hydrophobic, and hydrogen bonds to form a multilayer.…”

Section: Introductionmentioning

confidence: 99%

Formation of Multilayers at the Interface of Oil-in-Water Emulsion via Interactions between Lactoferrin and β-Lactoglobulin

Singh

2007

Food Biophysics

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The interactions between negatively charged β-lactoglobulin and the positively charged lactoferrin at the droplet surface to form a multi-protein surface layer were examined. Addition of lactoferrin to the aqueous phase of emulsions formed with β-lactoglobulin at pH 7.0 caused an increase in the K-potential of emulsion droplets, and the K-potential became positive as the concentration of added lactoferrin was higher than 1% in the system. It is found that lactoferrin binds to adsorbed β-lactoglobulin at droplet surface probably via electrostatic interactions. The amount of lactoferrin at interface increased with increasing the concentration of added lactoferrin, but it decreased with a decrease in the pH. No lactoferrin was observed at interface at pH 3 and 4. By contrast, when β-lactoglobulin was added in the emulsions formed with lactoferrin at pH 7.0, the K-potential of emulsions changed from positive to negative as the concentration of added β-lactoglobulin increased. The amount of β-lactoglobulin at surface increased correspondingly with increasing the concentration of added β-lactoglobulin. However, in this case, β-lactoglobulin remained bound at interface even at pH 3 and 4 where both lactoferrin and β-lactoglobulin are positively charged. The association of lactoferrin or β-lactoglobulin with the surface proteins that have oppositely charge is probably mainly through electrostatic interactions between the two proteins. It appears that alternative layers of these proteins could be created at the droplet surface.

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“…Recently the specular reflection of neutrons has been used to characterize the adsorbed layer of albumin on lipid bilayers prepared on a silicon substrate [8] on a poly(acrylic acid) brush on silicon substrate [9], on self-assembled monolayers [10][11][12], on quartz [13], on silicon/water interfaces [14][15][16], on a hydrogel polymer [17], at air/water interfaces [18,19] the adsorption of lysozyme on silicon oxide and octadecyltrichlorosilane [20][21][22][23][24], and the adsorption of fibrinogen on silicon [25]. The use of neutron reflectivity in protein adsorption studies is very attractive because it can potentially give information about adsorbed layer profiles at subnanometer resolution.…”

Section: Introductionmentioning

confidence: 99%

Surface enrichment of proteins at quartz/water interfaces: A neutron reflectivity study

Forciniti

Hamilton

2005

Journal of Colloid and Interface Science

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A neutron reflectivity study of a spread monolayer of bovine serum albumin

Cited by 35 publications

References 10 publications

β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 3. Neutron Reflectometry Study on the Effect of pH

β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 3. Neutron Reflectometry Study on the Effect of pH

Formation of Multilayers at the Interface of Oil-in-Water Emulsion via Interactions between Lactoferrin and β-Lactoglobulin

Surface enrichment of proteins at quartz/water interfaces: A neutron reflectivity study

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