Measurement of Surface Tension/Contact Angle of Saturated Fatty Solution for Developing <i>In Situ </i>Forming Drug Delivery Systems

Abstract

Naturally-occurring saturated fatty acids have been classified as the interesting biomaterials. Typically, the interfacial tension and wettability relying on intermolecular forces relate to the well-fitted performance with any target sites of in situ forming matrix. This research aimed to determine surface tension/contact angle of several saturated fatty acids in selected aprotic solvents commonly used in in situ forming system by varying fatty acid concentrations and molecular weights. Six fatty acids were dissolved in the aprotic solvents, namely 2-pyrrolidone (PYR), N-methyl-2-pyrrolidone (NMP) and dimethyl sulfoxide (DMSO). As fatty acid concentrations in binary mixtures increased, surface tension and contact angle became diminished except where DMSO was used as a solvent. The longer chain of fatty acid, the lower the surface tension except when C14-16 fatty acid was dissolved in NMP. Contact angle was also decreased as the chain of fatty acid increased except for C14-16 fatty acid-based preparation due to their viscosity. Understanding these fatty acid solution's surface tension/contact angle behaviors is useful for designing the suitable fatty acid-based in situ forming system.