Properties of Some Biosurfactants and Their Applications

Functional properties and applications of several biosurfactants such as bile acids (BA), lung surfactants (LS) and so on have been so far studied particularly in the boundary fields between colloids and surface chemistry and medical science. The main themes are as follows; (1) Studies on colloidal and surface properties of various bile salts.Changes of the shapes and structures of mixed micelles prepared by mixing a bile salt with various mole fractions in aqueous solutions of the nonionic surfactant with homogeneous ethylene oxide chain length (C10E8) were estimated for various mixed ratios of bile salts. These are itemized as follows;(a) CMCs, structures, aggregation numbers and hydrophobicities of micelles for single bile salt systems and for aqueous binary mixed systems between one of bile salts and C10E8.(b) Absorption of vitamine E (VE) solubilized in micellar solutions of various bile salts by a rat small intestine.(2) Studies on the functions and developements of LS. The mechanism of a synthetic lung surfactant including surfactant proteins named “TA” developed by Fujiwara et al., being more effective for respiratory distress syndrome (RDS), was evaluated by surface rheology as follows;(a) Surface rheological properties of proteolipids, surfactant protein (SP-B, SP-C, SP-BC) and their mixtures containing lecithin, palmitic acid (PA) and egg phosphatidyl glycerol (EggPG) and the efficiency as LS.(3) Studies on the fundamental properties of liposomes.(a) Evaluation of phase transition temperature (Tc) of lipid liposomes by using a tautomerism of α-benzoylacetoanilide (BAA) and effects of addition of cholesterol.(b) Influences of addition of ionic and nonionic surfactants on the membrane of lipid liposomes.(4) Solubilities of insoluble drugs into water.(a) Dissolution of calcium bilirubinate disk as a model of a gallstone by some solvents.(b) Dissolution of dicrofenac sodium by the complexes formed among hydrotropic substances in water.