Efeito do pH, tempo e adição de nanocelulose sobre sistemas aquosos binários e ternários de sais de bile

Abstract

This work evaluated how self-aggregated systems of the bile salts sodium deoxycholate (NaDC), sodium taurodeoxycholate (NaTDC), and sodium cholate (NaC), in aqueous medium, are affected by time, pH variations, the ratio between the bile salts, and the addition of nanocellulose. The rheological properties of aqueous binary NaDC:NaTDC systems showed changes as a function of time and the addition of nanocellulose. Control systems containing bile salts formed hydrogels only twelve weeks after preparation, while systems containing cellulose nanofibrils (CNFs) formed stronger hydrogels one week after preparation (G'⁄G" = 1.709 for the control system and 10.178 for the system containing CNFs). Binary and ternary aqueous systems of NaDC, NaTDC, and NaC showed changes in their colloidal stability and rheological properties as a function of pH variation. Systems containing NaDC and NaC formed precipitates in acidic medium. At pH 5, the systems showed greater viscoelasticity compared to the systems at pH 10, as evidenced by the formation of stronger and more intertwined hydrogels for the 100:50 mM NaDC:NaC aqueous system containing CNFs in acidic medium (G'⁄G" = 11.592 with G0 = 3679) compared to the systems prepared in basic medium (G'⁄G" = 0.62605 with G0 = 0.12119). SAXS analyses suggested the formation of mixed structures of cylindrical aggregates and spheres for the NaDC:NaTDC systems, in addition to indicating the formation of anisotropic structures in acidic medium and isotropic structures in basic medium. The data obtained in this work contributed to a better understanding of the phenomena and structures obtained from the modulation of bile salt self-aggregates, enabling advances in the formulation of tunable colloids for applications such as modified drug delivery platforms.