1.Efficient dermal delivery of retinyl palmitate: Progressive polarimetry and Raman spectroscopy to evaluate the structure and efficacy. 2.Liquid crystal nanoparticle formulation as an oral drug delivery system for liver-specific distribution.

Abstract

Part I. Efficient dermal delivery of retinyl palmitate: Progressive polarimetry and Raman spectroscopy to evaluate the structure and efficacy Over the past decades, there has been a growing interest in dermal drug delivery. Although various novel delivery devices and methods have been developed, dermal delivery is still challenging because of problems such as poor drug permeation, instability of vesicles and drug leakage from vesicles induced by fusion of vesicles. To solve the vesicle instability problems in current dermal delivery systems, we developed materials comprised of liquid crystals as a new delivery vehicle of retinyl palmitate and report the characterization of the liquid crystals using a Mueller matrix polarimetry. The stability of the liquid-crystal materials was evaluated using the polarimeter as a novel evaluation tool along with other conventional methods. The dermal delivery of retinyl palmitate was investigated through the use of confocal Raman spectroscopy. The results indicate that the permeation of retinyl palmitate was enhanced by up to 106% compared to that using an ordinary emulsion with retinyl palmitate. Part II. Liquid crystal nanoparticle formulation as an oral drug delivery system for liver-specific distribution Liquid crystal nanoparticles have been utilized as an efficient tool for drug delivery with enhanced bioavailability, drug stability, and targeted drug delivery. However, the high energy requirements and the high cost of the liquid crystal preparation have been obstacles to their widespread use in the pharmaceutical industry. In this study, we prepared liquid crystal nanoparticles using a phase-inversion temperature method, which is a uniquely low energy process. Particles prepared with above method were estimated to be around 100 nm in size and exhibited a lamellar liquid crystal structure with orthorhombic lateral packing. Pharmacokinetic and tissue distribution studies of a hydrophobic peptide-based drug candidate formulated with the liquid crystal nanoparticles showed a five-fold enhancement of bioavailability, sustained release, and liver-specific drug delivery compared to a host–guest complex formulation.