Interaction and actuation of lipid membranes with magnetic nanoparticles.

Cell membranes contain a large part of the delicate machinery of life and comprise the barriers controlling access to and from the interior of the cell. With the increasing use of nanoparticles (NPs) in medical imaging, drug delivery, cosmetics and materials the need is great and increasing to understand how NPs physically interact with cell membranes. On the one hand it is important to understand mechanisms to control risks of novel nanomaterials and to design therapeutic agents which can enter cells specifically and non-destructively. On the other hand, the structure and function of biological membranes inspire development of biomimetic smart materials for biotechnological applications which exploit or are modeled on biological membranes, but given enhanced functionality and external control of properties through incorporation of functional NPs. The aim of the proposed work is to develop understanding of the biophysical interaction of functional NPs with lipid membranes, in particular NP incorporation into and penetration through lipid membranes. Further, the aim is, based on that knowledge, to understand and control the self-assembly of superparamagnetic NPs into synthetic and cell lipid membranes to actuate them and control their physical properties in pursuit of novel biomimetic smart materials and cell analytical methods. Recent advances in NP design and synthesis are creating opportunities to use NPs to both probe biological matter in new ways on close to the molecular length scale and to interact with and affect its function on the same scale. I will build on these advances to use superparamagnetic NPs on the size scale of proteins with the important physical properties such as morphology, size, mechanical (soft shell, hard core) and surface energy under detailed control on the sub-nm scale. This is ensured by combining state-of-the-art Fe3O4 NP synthesis with sub-molecular control of the shell properties using a toolbox of nitrocatechol-anchored dispersants recently developed in my group. The binding, penetration and integration into lipid membranes of NPs is a very complex process which has to be understood by extracting detailed information on varying the physical properties of both the particles and the membranes. This level of control has until recently not been possible to achieve, but can now be achieved using the Fe3O4 NP platform and surface-based and vesicular membrane model systems of tuned composition that I have developed. This combination makes it possible to apply the full range of surface based sensing and imaging techniques developed by me and others during the last decade to probe membrane systems as well as colloidal characterization and imaging techniques developed for NP and cell characterization. Going one step further, I will combine the mechanical manipulation or heating by external magnetic fields of NPs precisely positioned and tailored into lipid membranes with the self-organizing, responsive and biocompatible properties of lipid membranes. The result will be breakthrough concepts for biomimetic smart materials with particular application in drug delivery, cell manipulation, intra-cellular targeting and nanoscale material transport.