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Control of Biological Function via Interaction with Nanoparticles
Kimberly Hamad-Schifferli, Assistant Professor in Biological and Mechanical Engineering, Massachusetts Institute of Technology
January 19, 2007
Abstract
Nanoparticles are highly suitable for interfacing to biological systems, as most proteins and DNA fall into the nanoscale size regime. We describe a method for using nanoparticles to control biological function of DNA, proteins and cells. We utilize alternating magnetic fields to heat magnetic nanoparticles, such as Fe3O4, Fe2O3, CoFe2O4, and Fe doped Au, in the size range of d =1-15nm. If the nanoparticles are linked to biomolecules or co-encapsulated with them in a vesicle of some sort, the biomolecule can be denatured and inactivated, or it can be released from the vesicle. Issues that are relevant in this are the ability to characterize the interface between the biological molecule and the nanoparticle. We covalently link nanoparticles to proteins in a way that is site-specific, i.e., on a specific amino acid. We study how the protein structure is affected by nanoparticle size, material, coating ligand, in addition to the labeling site on the protein. The structural behavior of the protein can be explained in terms of electrostatic interactions of the residues in the local vicinity of the nanoparticle labeling site. In addition, we study magnetic field heating of nanoparticles, which is strongly dependent on nanoparticle size and material. We study the size dependence of magnetic field heating with the goal of exploiting these properties for orthogonal heating, where one frequency can heat one type of nanoparticle and not the other. Heating is quantified as a function of field frequency and strength for Fe3O4, CoFe2O4, and MnFe2O4 nanoparticles with d=1-20nm, and compared to power loss equations describing the heating mechanism. In addition, magnetic nanoparticles can be incorporated into thermosensitive polymers, lipid vesicles and/or cells. This provides a system with unique properties that can be turned on by applying a field. For example, we study how field heating of the nanoparticles can induce release of a molecule from liposomes. Synthesis of liposomes encapsulating 10nm Fe3O4 nanoparticles and a dye are described.
Biography
Kimberly Hamad-Schifferli received her S.B. in chemistry from MIT and Ph.D. in chemistry from the University of California at Berkeley. Following this she did postdoctoral research at MIT and then joined the faculty at MIT in 2002. She has been the recipient of the ONR Young Investigator Award.