Protein Adsorption - A New Paradigm
Z. Adamczyk
Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Science, ul. Niezapominajek 8, 30-239 Cracow, Poland
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Protein adsorption/desorption phenomena at solid electrolyte interfaces are reviewed. In theoretical calculations emphasis is focused on coarse-grained methods, exploiting the efficient bead models of protein molecules. Using this approach basic physicochemical properties of protein molecules, are calculated using the Stokes and Poisson-Boltzmann equations. Additionally, the surface blocking functions and jamming coverages for such model shapes are determined using the random sequential adsorption (RSA) modeling. Knowing the jamming coverage and blocking functions, boundary conditions for bulk transport equations are formulated. Solutions of these equations for the convection and diffusion-controlled transport are discussed. The theoretical results are exploited for the interpretation of protein adsorption kinetics studied by AFM, QCM-D and in situ electrokinetic methods (streaming potential, electrophoresis). Application of such hybrid approaches enabled one to quantitatively determine protein adsorption/desorption mechanisms on various solid substrates including polymeric micro-particles (polystyrene latexes). It is shown that protein adsorption is mainly governed by the discrete electrostatic interactions among ion pairs with negligible role of other interaction types. Anomalous adsorption of proteins at surfaces bearing like surface charges, where the classical, mean-field theories fail, is explained in terms of heterogeneous charge distributions on protein molecules. By exploiting these experimental data, the validity of the coarse grained approaches combined with solutions of the continuity equation for quantitatively predicting protein adsorption kinetics is confirmed. The experimental data also allow one to optimize the efficiency of biosensensors and various immunological assays.
Acknowledgements: This work was financially supported by the Research Grants: POIG 01.01.02-12-028/ 09-00 and the NCN Grant UMO-2012/07/B/ST4/00559.
