Adsorption Kinetics of Protein Mixtures A Tentative Explanation of the Vroman Effect

Cuypers, P.A.; Willems, George M.; Hemker, H.C.; Hermens, Wim Th.

doi:10.1111/j.1749-6632.1987.tb33045.x

Cited by 38 publications

(21 citation statements)

References 16 publications

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“…Yet, we confirm that the standard deviation of the mode frequency can be measured in Fourier space with a precision much better than 1/T for large signal-to-noise ratios, in accordance with a previous time-domain calculation (Cuypers, 1987;Cuypers, 2008, private communication).…”

Section: Resultssupporting

confidence: 62%

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Fourier Analysis of Gapped Time Series: Improved Estimates of Solar and Stellar Oscillation Parameters

Stahn

Gizon

2008

Sol Phys

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Quantitative helioseismology and asteroseismology require very precise measurements of the frequencies, amplitudes, and lifetimes of the global modes of stellar oscillation. The precision of these measurements depends on the total length (T ), quality, and completeness of the observations. Except in a few simple cases, the effect of gaps in the data on measurement precision is poorly understood, in particular in Fourier space where the convolution of the observable with the observation window introduces correlations between different frequencies. Here we describe and implement a rather general method to retrieve maximum likelihood estimates of the oscillation parameters, taking into account the proper statistics of the observations. Our fitting method applies in complex Fourier space and exploits the phase information. We consider both solar-like stochastic oscillations and longlived harmonic oscillations, plus random noise. Using numerical simulations, we demonstrate the existence of cases for which our improved fitting method is less biased and has a greater precision than when the frequency correlations are ignored. This is especially true of low signal-to-noise solar-like oscillations. For example, we discuss a case where the precision of the mode frequency estimate is increased by a factor of five, for a duty cycle of 15%. In the case of long-lived sinusoidal oscillations, a proper treatment of the frequency correlations does not provide any significant improvement; nevertheless, we confirm that the mode frequency can be measured from gapped data with a much better precision than the 1/T Rayleigh resolution.

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Section: Resultssupporting

confidence: 62%

“…The theoretical value of the standard deviation of the mode frequency obtained by Cuypers (1987) can be extended to the case of gapped data (Cuypers, 2008, private communication) as follows:…”

Section: Sinusoidal Deterministic Oscillation Plus White Noisementioning

confidence: 99%

Fourier Analysis of Gapped Time Series: Improved Estimates of Solar and Stellar Oscillation Parameters

Stahn

Gizon

2008

Sol Phys

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“…Although the observable cooperative adsorption kinetics are similar there are widely differing concepts how to mathematically express the coverage dependence of the adsorption rate constant including square-root [154], linear [10] , or exponential [155] functions.…”

Section: Cooperative Effectsmentioning

confidence: 99%

“…Ellipsometry is based on the change of the polarization state of light after reflection from a surface and provides information about the mass of the adsorbed protein layer. ELM was used by a considerable number of researchers to measure adsorption kinetics [106,143,155,156,215,216]. The technique requires planar, reflecting substrates, preferably quartz, silicon, or silica, and a sufficiently strong change of the refractive index upon protein adsorption.…”

Section: Label-free Techniquesmentioning

confidence: 99%

Understanding protein adsorption phenomena at solid surfaces

Rabe

Verdes

Seeger

2011

Advances in Colloid and Interface Science

1,354

1,239

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Protein adsorption at solid surfaces plays a key role in many natural processes and has therefore promoted a widespread interest in many research areas. Despite considerable progress in this field there are still widely differing and even contradictive opinions on how to explain the frequently observed phenomena such as structural rearrangements, cooperative adsorption, overshooting adsorption kinetics, or protein aggregation. In this review recent achievements and new perspectives on protein adsorption processes are comprehensively discussed. The main focus is put on commonly postulated mechanistic aspects and their translation into mathematical concepts and model descriptions. Relevant experimental and computational strategies to practically approach the field of protein adsorption mechanisms and their impact on current successes are outlined.

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“…Therefore, considerable effort has been expended to elucidate the mechanism of protein adsorption and the role of adsorbed protein layer at the blood-material interface. Based on numerous protein adsorption studies, adsorbed proteins will be reoriented, denaturated and exchanged over time, being influenced by the surface characteristics of the materials [1][2][3][4][5][6][7][8][9][10]. However, these studies were performed mostly on in vitro diluted plasma system and ex vivo short-term experiments.…”

Section: Introductionmentioning

confidence: 99%

In vivo protein adsorption on polymers: visualization of adsorbed proteins on vascular implants in dogs

Nojiri

Okano

Koyanagi

et al. 1993

Journal of Biomaterials Science, Polymer Edition

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In vivo protein adsorption on polymers: visualization of adsorbed proteins on vascular implants in dogs CHISATO NOJIRI1,2*, TERUO OKANO3, HITOSHI KOYANAGI2, SEIICHI NAKAHAMA4, KI DONG PARK5 and SUNG WAN KIM5 1InstituteAbstract-The absorption of plasma proteins is an important event at the blood-material interface, and strongly affects subsequent cellular interaction and thrombus formation. Although considerable efforts have been expended to elucidate the mechanism of protein adsorption and the role of absorbed protein layer at the blood-material interface, there has been little knowledge of how the initial adsorbed proteins are maintained or changed in a time-variant process in in vivo long-term implantation.In this study, we described detailed analyses concerning the characterization of adsorbed proteins on HEMA-styrene block copolymer surfaces (HEMA-st) and poly(ethylene oxide)(PEO) grafted Biomer® (B-PE04K) for in vivo long-term canine vascular graft implants as well as in vitro short-term experiments. Biomer vascular grafts (6 mm I.D., 7 cm in length) were fabricated by a dip coating and the luminal surface was modified with PEO grafting, HEMA-st coating, or Biomer coating (control). These surface modified grafts were recirculated for different time intervals (5, 15, 30, 60 and 120 min) using citrated canine whole blood. The grafts were then implanted in the abdominal aortas of dogs and evaluated for graft patency and protein adsorption. The adsorbed proteins (albumin, IgG and fibrinogen) were quantified using an in situ radioimmunoassay. Surface protein layer thickness was measured by transmission electron microscopy (TEM). Visualization of absorbed plasma proteins (albumin, IgG and fibrinogen) was performed with TEM using an immunoperoxidase double antibody technique. In in vitro recirculation systems, albumin and IgG showed similar Langmuir type pattern onto all test surfaces. On B-PEO4K surfaces, fibrinogen adsorption kinetics demonstrated 'Vroman effect'. The Biomer and B-PE04K grafts occluded within 1 month, while HEMA-st grafts were patent for over 3 months. Biomer and B-PE04K showed thick multilayers of adsorbed proteins, and the thickness increased with implantation periods and the composition altered with time. In contrast, HEMA-st showed a monolayer-like adsorbed protein pattern, and the composition and thickness were consistent regardless of implantation time including in vitro short-time experiments, which may attribute to less conformational change of adsorbed proteins on HEMA-st surfaces. In terms of nonthrombogenicity, the stable monolayer-like adsorbed protein layer on HEMA-st surfaces exhibited improved blood compatibility over thick multilayered adsorbed proteins on Biomer and B-PE04K surfaces.

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Adsorption Kinetics of Protein Mixtures A Tentative Explanation of the Vroman Effect

Cited by 38 publications

References 16 publications

Fourier Analysis of Gapped Time Series: Improved Estimates of Solar and Stellar Oscillation Parameters

Fourier Analysis of Gapped Time Series: Improved Estimates of Solar and Stellar Oscillation Parameters

Understanding protein adsorption phenomena at solid surfaces

In vivo protein adsorption on polymers: visualization of adsorbed proteins on vascular implants in dogs

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