Lipidic Templates and Coatings for Designing Nanotheranostics
Lipidic platforms, such as liposomes, have been used for decades as drug delivery vehicles and remain as one of the most effective platforms. This stems in part from their biocompatibility, their ability to encapsulate hydrophilic and hydrophilic cargo, and their chemical and biophysical diversity. In the quest to improve the detection and treatment of diseases, there has been significant recent interest in capitalizing on these properties and creating nanoscale assemblies capable of combined diagnostics and therapy (i.e. nanotheranostics) by merging lipidic platforms with active or functional nanotechnologies. This presentation will focus on two examples where lipidic approaches are being used to design multifunctional nanotheranostics based on gold or iron oxide that respond to external stimuli. The first example is a templating technique where small hydrophobic nanoparticles (ca. 2-5 nm) are embedded within liposomal bilayers. The liposome templates the formation of a ‘loose’ nanoparticle shell and the embedded nanoparticles control the release of encapsulated molecules from within. This control stems from the coupled phase and transport behavior of the bilayers, which is dependent upon nanoparticle concentration and size. By using iron oxide nanoparticles, intracellular release of doxorubicin was achieved in vivo using an alternating electromagnetic field. The second example also involves iron oxide nanoparticles, but in this case the nanoparticles are larger (ca. 30 nm) and susceptible to permanent and alternating magnetic fields. A lipid monolayer shell is formed on the surface through a solvent exchange technique that yields monodispersed particles. The particles exhibit negative contrast for MRI imaging, achieve high uptake in vivo, and are able to control the loading and intracellular delivery of small interfering ribonucleic acid (siRNA). These examples highlight the role lipidic platforms can play in designing stimuli-responsive nanotheranostics that are capable of achieving multiple therapeutic objectives.
Geoff D. Bothun, PhD, is an Associate Professor of Chemical Engineering at the University of Rhode Island and the Director of the Rhode Island Nanoscience and Nanotechnology Consortium. He joined the University of Rhode Island in July 2006 after a Discovery Corps Postdoctoral Fellowship sponsored by the National Science Foundation (NSF). In this role, Bothun partnered with the NSF Science & Technology Center for Environmentally Responsible Solvents & Processes (CERSP) where he conducted research in the areas of non-aqueous membrane separations and enzyme catalysis, and established an undergraduate research and development program at North Carolina A&T State University, a historically black university. The goal of this program is to advance education and diversity in science and engineering. As a graduate student, Bothun’s research was multidisciplinary in nature, merging the fields of high-pressure bioprocessing, interfacial and colloidal phenomena, and thermodynamics. Before attending graduate school he was a Process Engineer with Geobiotics Inc., a mining technology company specializing in biooxidation.