In vitro measurements of inhaled aerosols targeted via magnetic alignment of optimized iron oxide loaded high aspect ratio particles

Gillian E. S. Redman (1) and Warren H. Finlay (1)

(1) University of Alberta

     Abstract Number: 138
     Last modified: April 23, 2010

Abstract
In previous in vitro work we have shown that non-invasive magnetic targeting can increase deposition of high aspect ratio particles (HARPs) of cromoglycic acid (CA) loaded with iron oxide nanoparticles (VMD of 0.47±0.05 micro-meters and VML of 3.0±0.5 micro-meters) (1). To follow up on these positive results, an in vivo study was completed with 19 New Zealand White Rabbits exposed to a similar aerosol, where the subjects had a magnetic field selectively applied over one lung (2). Although the outcome of this study was promising, the inter-subject variability and low number of subjects led to results that were not statistically significant. To aid in overcoming the obstacle of this variability, the dimensions of the HARPs were optimized to further increase the probability of deposition with the application of a magnetic field. This study focuses on increasing the length of the CA particles which is restricted by the size of the droplets created. By using an ultrasonic atomizing nozzle (Sono-tek, Milton, NY, USA) larger droplets are created (MMAD of approximately 50 micro-meters). These larger droplets, sprayed into an evaporation chamber, have allowed longer CA particles to be collected (VML of 5.2±2.7 micro-meters). A model of an array of airway bifurcations, representative of the terminal bronchioles, is used to measure the change in deposition of the CA HARPs loaded with iron oxide nanoparticles both with and without a magnetic field present. It is expected the longer particles used in this study will show an even greater increase in deposition with the application of a magnetic field (1).

(1) Martin, A. R. and Finlay, W. H. “Enhanced Deposition of High Aspect Ratio Aerosols in Small Airway Bifurcations Using Magnetic Field Alignment”, J. Aerosol Sci. 39:679-690, 2008.
(2) Martin, A. R., Redman, G. E., Waszak, P., Thompson, R. B., Cheung, P., Thébaud, B., and Finlay, W. H., “Influence of an Externally Applied Magnetic Field on Regional Deposition Patterns of Iron Oxide Loaded High Aspect Ratio Particles in Mechanically Ventilated Rabbits”, Poster session at: Respiratory Drug Delivery, Orlando, FL, USA, April 25th-29th, 2010.