Theoretical Aspects Of Human Serum Albumin Adsorption On Spherical And Fibrous Carbon Adsorbents
Theoretical aspects of human serum albumin adsorption on spherical and fibrous carbon adsorbents
E. Eretskaya1, Yu. Shulepov2, E. Eretsky2
1Institute of Material Sciences of National academy of science
of Ukraine, Kyiv, Ukraine
2Institute of Colloid and Water Chemistry of National academy of science
of Ukraine, Kyiv, Ukraine
The interest to study of HSA adsorption process on a surface of various activated carbons is caused by that this process, being primary, determines character of the subsequent changes both in a superficial layer and in volume of a solution, together with dependence of these changes on properties of a adsorption surface.
It have been established the distinctions in character of adsorption of both free and protein-bounded low / middle molecular hydrophobic substances as well as in character of adsorption of the blood proteins by spherical (SKN) and fibrous (CFA) carbon adsorbents in clinical and experimental investigations. The fundamental researches of the superficial phenomena on the interface of the carbon surface - HSA solution and theoretical analysis of obtained results are very topical for an explanation of these distinctions.
We presume internal diffusion mode of adsorption process of HSA on the carbons SKN and CFA considered a ratio of the sizes of prevailing pores in carbon adsorbents (r
Effective diffusion factor HSA in pores, designed on the basis of adsorption kinetic curves, makes for various types of carbons SKN from 1,1·10-11 up to 2,0·10-10 ñì2·ñ-1, and for CFA - about 0,5·10-16 ñì2·ñ-1. At the same time, diffusion factor of HSA molecules in the albumin solution near the surface of
the carbon fibre, designed without the consideration of conformational changes, makes 5,9·10-7 ñì2·ñ-1.
The greater relaxation time observed in experiments in comparison with the designed one in the adsorption process show a presence of conformational changes of HSA molecules at contact with the carbon surface.
The values of Kd, which in a case of CFA are 5-7 degrees less, than for SKN, prove the phenomenon of conformational changes, which accompanied by significant energetic transformations and intensification of hydrophobic interactions. At the same time even for SKN the values of Kd designed on the basis of experimental data are anomaly low owing to conformational changes of HSA molecules proceeding in the adsorption process. Hence, at adsorption HSA molecules on CFA undergo the much more essential changes of their conformation.
Thus, the results of the theoretical analysis prove, that HSA adsorption on adsorbents SKN and CFA proceeds on an external geometrical surface with brightly expressed conformational changes of protein molecules, and in the greater degree it is shown in a case CFA, that is determined its very large external geometrical surface.
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