Using nanoparticles to trigger drug delivery

Spatial and temporal control over release of a drug is key for increasing drug efficacy. We are studying how to exploit the ability to heat magnetic nanoparticles with an external field to achieve this in thermosensitive liposomes. Liposomes are a well studied vehicle for drug delivery as they have a large internal aqueous space which can carry a payload. Upon heating these liposomes release their contents, so encapsulation of magnetic nanoparticles along with the drug of interest could enable externally triggered release.

We are studying how to encapsulate water soluble magnetic nanoparticles in liposomes at very high densities using the reverse-evaporation (REV) method. We have found that increasing the concentration of nanoparticles in liposomes can perturb the lipid phase diagram, and thus synthesis of large unilamellar vesicles encapsulating nanoparticles requires optimization of liposome synthesis parameters.

We are developing a means of orthogonally heating nanoparticles, so that magnetic fields of one frequency could be used to heat one type of nanoparticle, and another frequency could be used to heat another independently. We have devised a way to achieve this by exploiting the size and material dependence of magnetic field heating.

Along these lines, we are synthesizing magnetic nanoparticles of different materials such as Fe doped Au nanoparticles. These nanoparticles are magnetic while being able to be conjugated to proteins and DNA using typical thiol chemistry.

A. Wijaya and K. Hamad-Schifferli, "High density encapsulation of Fe₃O₄ nanoparticles in lipid vesicles," Langmuir, 2007, 23 (19) 9546-9550.
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Langmuir's Most-Accessed Articles: July-September, 2007

A. Wijaya, K. A. Brown, J.D. Alper, and K. Hamad-Schifferli, "Selective Heating of Multiple Nanoparticles," Proceedings from the Materials Research Society Symposium, Boston, MA, 2005, 900E, 0900-O09-40.1-6
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A. Wijaya, K. A. Brown, J.D. Alper, and K. Hamad-Schifferli, "Magnetic field heating study of Fe doped Au nanoparticles," Journal of Magnetism and Magnetic Materials, 2007, 309 (1) 15-19.
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