Magnetically actuable delivery vehicles
Oliver Bixner, Mag
Date of Issue2017-05-08
Interdisciplinary Graduate School (IGS)
Stimuli-responsive amphiphilic superstructures comprise some of the most successful drug delivery systems in clinical use. Vesicular assemblies in particular, have long been recognized as excellent carrier systems for diagnostic and therapeutic agents due to their potential to encapsulate, transport and release various cargo upon local changes; the latter in response to the microenvironment. Structural incorporation of biocompatible, functional nanomaterials such as superparamagnetic iron oxide nanoparticles can be employed to design universal delivery systems, whose release profiles can be controlled externally by application of a magnetic field. The aim of this work is to establish a theranostic platform by incorporating hydrophobic SPIONs of controlled size and interfacial chemistry into stimuli-responsive amphiphilic superstructures and to demonstrate externally triggered release of a model compound via magnetic actuation. The synthesis of monodisperse nanocrystals and complete exchange of the native hydrophobic dispersant shell for irreversibly grafted nitrocatechol-derived anchors at maximal ligand density is exemplified and shown crucial for controlled capsule assembly. A method for efficient encapsulation of SPION into amphiphile membranes is outlined that allows for direct and quantitative co-self-assembly of bilayer forming amphiphiles with hydrophobic nanoparticles into controlled magnetosomes. The novel method allowed for controlling the vesicle size, lamellarity and the nanoparticle concentration in the membrane with retained vesicle stability. Various capsule systems comprising polymeric superamphiphiles and mixed lipid/superamphiphile blends were investigated and their magnetothermal release efficiencies using alternating magnetic field irradiation to cause local hyperthermia were compared. Mixed membrane capsules were found to combine efficient magnetothermal actuation with the high stability of purely polymeric membrane systems.