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Probing macromolecular adsorbed layer structure and history dependence via the interfacial cavity function
Yanrong Tie1, A Pascal Ngankam, Paul R Van Tassel
1Department of Chemical Engineering, Yale University, New Haven, Connecticut 06520-8286, USA.
Langmuir : the ACS Journal of Surfaces and Colloids
|November 17, 2004
Summary
Protein layers on surfaces change slowly over time. New methods reveal this structural relaxation and suggest protein clustering occurs later than previously thought.
Area of Science:
- Surface science
- Biophysics
- Physical chemistry
Background:
- Adsorbed protein layers exhibit slow structural relaxation, indicating out-of-equilibrium layer growth.
- Understanding the kinetics and structure of adsorbed macromolecules is crucial in various scientific fields.
Purpose of the Study:
- To introduce a method for determining the interfacial cavity function (Phi) using kinetic data.
- To utilize Phi as an in situ measure of history-dependent adsorbed layer structure.
- To investigate the structural relaxation dynamics of fibronectin and lysozyme layers.
Main Methods:
- Optical waveguide lightmode spectroscopy (OWLS) was employed to collect kinetic data.
- The interfacial cavity function (Phi) was calculated from the kinetic data.
- Phi was monitored over time to assess structural changes in adsorbed layers.
Main Results:
- The interfacial cavity function (Phi) was successfully determined using OWLS kinetic data.
- An increase in Phi with residence time was observed for fibronectin and lysozyme.
- This suggests post-adsorption clustering occurs on a longer timescale than predicted by surface diffusion models.
Conclusions:
- The interfacial cavity function (Phi) provides a continuous, in situ measure of adsorbed layer structure.
- Protein layer relaxation is a slow, out-of-equilibrium process.
- Post-adsorption clustering in protein layers occurs over extended timescales.