Morphology control of molecular assemblies prepared from bio-based amphiphilic polymers with a helical hydrophobic unit and application as nanocarriers for contrast agents and/or drug delivery

Abstract

Bio-based amphiphilic polymers with a helical hydrophobic unit have been studied extensively with regard to molecular assemblies and their morphology. To use specific characteristics of the helical units, such as coiled-coil and stereocomplex formation between the right- and left-handed helices, morphologies more complex than conventional tubes and vesicles must be prepared. Membranes based on stereocomplex formation were sufficiently stable to induce phase separation, which led to a unique self-assembly, 'patchwork self-assembly'. The molecular assemblies generated were thermodynamically stable and, in certain cases, exhibited membrane fluidity because the regularly aligned helical hydrophobic units contribute to the molecular assembly and allow for translational diffusion of the helices in the assemblies. The molecular assembly physical properties can be finely tuned, and the assemblies were used as carriers for drug delivery systems (DDSs). The lactosome is a polymeric micelle 35 nm in diameter. In in vivo experiments using transplanted tumor model mice, the lactosome selectively accumulated at tumor regions through an enhanced permeability and retention (EPR) effect, and its entrapment by self-defense systems of living organisms was significantly suppressed. Therefore, the lactosome is likely an excellent carrier for DDS.