Oxidation of Low-Density Lipoproteins in the Presence of a Fullerene-Containing Silica Gel

The results of a study on the oxidation of low-density lipoproteins (LDLs) in the presence of a fullerene-containing silica gel in the sorbent phase (a solid stationary phase) and in the phase of an LDL solution (a liquid mobile phase) are presented. It was found that the main distinctive feature of the process of LDL oxidation in the presence of a fullerene-containing silica gel consists in its heterogeneity; that is, the oxidation simultaneously occurs in both of the phases. In this case, the effect of the oxidation process in a solid phase on the kinetics in a liquid phase can be described in terms of the nonuniform distribution of reactant concentrations in the phases of the system and the formation of a donor–acceptor complex. It was found that the concentration of oxidation products is an exponential function of LDL concentration; this fact is indicative of a free-radical chain mechanism of the LDL oxidation reaction in the presence of the sorbent. This relationship was described by an empirical equation, which is the same for either of the phases, and the parameters of this equation have precise physical meanings. It was found from calculations that both the formation of donor–acceptor complexes and the nonuniform distribution of LDL in the two-phase system are responsible for a considerable difference between the kinetics of sorbent-initiated LDL oxidation in the sorbent phase and the solution phase.