The peculiarities of oxytocin, albumin and immunoglobulin adsorption by synthetic montmorillonites in a simulated body fluid

Abstract

In order to develop new effective medical sorbents, the sorption ability of synthetic montmorillonite of various compositions in relation to model protein molecules – oxytocin, albumin and immunoglobulin in a synthetic biological fluid (pH=7.2) was studied. Montmorillonites with varying degrees of isomorphic substitution of aluminium atoms for magnesium atoms in octahedral layers were synthesized under hydrothermal conditions (Na2x(Al2(1−x),Mg2x)Si4O10(OH)2.nH2O, where x = 0.5, 0.9 and 1). According to the SEM data, the samples had a layered morphology, forming spongy aggregates with secondary pores up to 300–350 nm in diameter. To model the kinetics of protein adsorption on montmorillonites, pseudo-first (PFO) and pseudo-second order (PSO) equations were used, and Langmuir, Freundlich and Temkin models were used to process isotherms. It has been found that the sorption capacity of synthetic montmorillonite in relation to proteins can be 2–4 times higher than that of raw clays, reaching 180, 315 and 900 mg/g for oxytocin, albumin and immunoglobulin, respectively. The existence of a competitive adsorption between proteins and components of simulated body fluid has been detected. The dependence of the adsorption capacity of the samples with respect to proteins of different molecular weights on the chemical composition of the montmorillonite and on the degree of isomorphic substitution of magnesium by aluminium in the octahedral layers has been established. The possibility of developing sorbents for the extracting of proteins from complex mixtures based on synthetic combined montmorillonites has been demonstrated.