Evaluation of interactions between liquid crystal films and silane monolayers by atomic force microscopy

Pluronic P123/DMSO Lyotropic Liquid Crystal for Incorporating Bioactive Substances for Topical Application

Lyotropic liquid crystals (LLCs) have attracted considerably growing interest in drug delivery applications over the last years. The structure of LLC matrices is complementary to cell membranes and provides an efficient, controlled, and selective release of drugs. In this work, a complex of experimental methods was used to characterize binary LLCs Pluronic P123/DMSO and triple LLC systems Pluronic P123/DMSO/Ibuprofen, which are interesting as transdermal drug delivery systems. Liquid crystalline, thermal, and rheological properties of LLCs were studied. Concentration and temperature areas of the lyomesophase existence were found, and phase transition enthalpies were evaluated. Intermolecular interactions among the components were studied by infrared (IR) spectroscopy. In vitro studies of Ibuprofen (Ibu) release from various LLCs allow differentiation of its release depending on the polymer content. Atomic force microscopy and contact angle methods were used to characterize the surface morphology of the hydrophobic membrane, which was used as a stratum corneum model, and also evaluate the adhesion work of the LLCs. A complex analysis of the results provided by these experimental methods allowed revealing correlations between the phase behavior and rheological characteristics of the LLCs and release kinetics of ibuprofen. The proposed biocompatible systems have considerable potential for a transdermal delivery of bioactive substances.

Evaluation of Surface Free Energy Inducing Interfacial Adhesion of Amphiphilic Cellulose Nanofibrils

Cellulose nanofibrils (CNFs) have been studied extensively over the past decade. Their applications, e.g., as fillers for nanocomposites, stabilizers for Pickering emulsions, and scaffolds for cell culture, are mostly dictated by interfacial adhesion. In general, the individual surface free energy values of the constituents of a material correlate with its adsorption and desorption behaviors. In the present study, we estimated the surface free energy values of thin films composed of CNFs using traditional contact angle methods based on the Wenzel equation and van Oss-Chaudhury-Good theory. The accuracy and utility of the estimated surface free energy values were verified by close matching between the obtained adhesion energy values and the actual interfacial adsorption behaviors of the CNFs. Therefore, the evaluated surface energy values are expected to be a feasible tool for designing of interfacial interactions between CNF surfaces and other materials.