Interaction of proteins and substituted aromatic drugs with highly disperse oxides in aqueous suspension

Adsorption of bovine (BSA) and human serum albumin (HSA), egg albumin, gelatin and some substituted aromatic drug from aqueous solution onto the surface of fumed silica, alumina, titania, silica/titania, and silica/alumina was studied at different concentrations of the components. A maximal adsorption of albumin or drugs (in mg per m2 of the oxide surface area) was observed for titania or titania/silica having the smallest specific surface area (S). A maximal adsorption of drugs in per cent of the initial concentration in solution was found for silica possessing the highest S value among all the studied oxides. Adsorption of Verapamil hydrochloride and HSA from a mixed aqueous solution onto the silica surface showed a weak influence of the protein on the drug adsorption. At a small concentration of oxides in the aqueous suspension, BSA adsorption (in mg per g of oxide) increased exponentially with decreasing oxide concentration accompanied by decreasing the efficiency of albumin adsorption (in per cent of the initial concentration) from solution. Theoretical calculations of solvation effects for the drugs showed a dramatic increase in the solvation energy upon proton attachment to N atoms that could cause a relatively small adsorption of drug cations (as their hydrochlorides were used) onto the hydrophilic surface of oxides.