Rapid Analysis of DOXIL Stability and Drug Release from DOXIL by HPLC Using a Glycidyl Methacrylate-Coated Monolithic Column.

In recent years, nanomedicines have received growing attention in a range of medical applications, including selective drug delivery technology. In this context, the analysis of liposome stability and drug release from liposomes is of particular importance, as the efficacy of a nanomedicine is determined by the release of the encapsulated drug. We investigated the influence of the surrounding environment on the stability and release of the encapsulated drug (i.e., doxorubicin) from DOXIL. Thus, for the purpose of this study, we selected the liposomal anticancer drug, DOXIL, as a typical nanomedicine, and investigated the influence of the surrounding environment on release of doxorubicin from DOXIL. We found that two pathways existed for doxorubicin release, namely the collapse of DOXIL, and an increase in the permeability of the lipid bilayer. DOXIL collapse occurred upon the addition of high concentrations (>60%) of a methanol solution, while an increase in permeability occurred at temperatures above the phase transition temperature of the DOXIL lipid bilayer, under basic conditions, and in the presence of membrane-permeable bases (e.g., Tris). As DOXIL is particularly stable and limited collapse of DOXIL occurred under physiological conditions, it is expected that doxorubicin release within the body took place through permeability changes in the lipid bilayer of the DOXIL structure.

High performance liquid chromatography analysis of 100-nm liposomal nanoparticles using polymer-coated, silica monolithic columns with aqueous mobile phase.

Recently, nanoparticles have garnered considerable attention, and the demand for a rapid and simple method for their analysis has increased accordingly. The bimodal pores (few µm- and few tens nm-sized pores) of monolithic columns were thought to be suitable for the separation of nanoparticles and small molecules; however, the residual silanol groups on the column surface resulted in the strong adsorption of liposomes and hindered their analysis. To overcome this problem, we modified the surface of the silica monolith via a two-step process and developed three silica monolithic columns coated with three different polymers: glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (HEMA), and N-vinylpyrrolidone (VP). These were used for the analysis of 100-nm liposomal nanoparticles. Since 15% polymer coating prevented the nanoparticle adsorption, liposomes (AmBisome®) and pegylated liposomes (DOXIL®) were eluted rapidly (within 1min) using these columns, without using organic solvents in the mobile phase. Molecular leaching from the liposomes, as well as protein adsorption to the liposomes (corona formation) could be evaluated using the polymer-coated columns, thus illustrating their utility in the rapid and simple analysis of 100-nm liposomal nanoparticles.