According to the National Institutes of Health (NIH), nanoscale devices smaller than 5onm can easily enter most cells, while those smaller than 20 nanometers can transit out of blood vessels, offering the possibility that nanoscale devices will be able to penetrate biological barriers such as the blood-brain barrier to improve efficacy of therapeutic and imaging agents in the treatment of cancers and other diseases. However, the lack of knowledge concerning the health and safety of nanomaterials may become an obstacle in the rapid implementation of nanotechnology in medicine. Nanoparticles of various materials are currently being considered for medical use because they are similar in size range to many common biomolecules. Thus, it might be possible for certain drugs to be reversibly bound to the surface of certain nanomaterials and injected intravenously into specific sites of a patient, delivering concentrated, site-specific doses of medicine.

Certain nanomaterials might serve as excellent vehicles for site-specific drug delivery, but the biotoxicity of many nanomaterials is not fully understood. Therefore, it has become crucial to develop a broader understanding of how nanoparticles can so easily transmigrate throughout bioorganisms. Although endocytotic mechanisms for cellular uptake of nanoparticles are established, nonendocytotic mechanisms do seem to exist. And the research contained here represents one endeavor to understand nonendocytotic mechanisms of transmembrane transport of nanoscale solids across phospholipid membranes using liposome model systems and planar bilayer model systems. A novel synthesis for magnetite nanoparticles and novel fabrication methods of insulator-based dielectrophoretic separation devices are also presented. The cumulative and preliminary results presented here tend to support the occurrence of an opportunistic diffusion of nanoparticles, possibly created by local entropy increases due to temporal bilayer defects, associated with normal cellular regenerative functions such as the insertion of integral proteins into cell membranes.