Bile Acid Salt as a Vehicle for Solubilization and Electrodeposition of Drugs and Functional Biomolecules for Surface Modification of Materials

This investigation addresses the need in biocompatible biosurfactants for electrophoretic deposition (EPD) of biomaterials. It is motivated by unique multifunctional properties of bile acid salts. Sodium cholate CHOLNa is a primary bile acid salt, which can solubilize and disperse different functional biomaterials. The EPD mechanism of pure EPD involves electrophoresis (EP) of CHOL− micelles, their discharge and gelation of cholic acid (CHOLH) to form anodic CHOLH films. The EPD strategy for immobilization of different functional biomolecules is based on the formation and EP of mixed micelles. Curcumin(CCM), hydrocortisone (HCS), and indomethacin (IDM) are used as model electrically neutral water insoluble drugs for EPD of composite films. CHOLNa acts as a solubilizing agent, which forms mixed micelles with the electrically neutral drugs for their EPD and formation of composite films. The pH-dependent charge of various functional biomolecules and charge reversal at isoelectric points prevents their deposition. This problem is addressed by the use CHOLH for co-deposition with bovine serum albumin (BSA) and hemoglobin (Hb), which are used as model proteins for EPD of CHOLH-BSA and CHOLH-Hb films. Another challenge is related to EPD of functional biomolecules with pH-independent charge, such as heparin (HP). The feasibility of deposition of CHOLH-HP films is demonstrated. The deposition mechanisms, film composition, and films morphologies are discussed. The approach developed in this investigation offers advantages of the use of biosurfactants as charging and gel-forming agents and mild EPD conditions for fabrication of films for drug delivery, biosensors, and surface modification of biomedical implants.