Sara Lien

Project title: Nanoparticle Deposition in an Air Liquid Interface Cell Culture Exposure Chamber

Degree: MS (Thesis) | Program: Occupational & Environmental Exposure Sciences (OEES) | Project type: Project
Completed in: 2014 | Faculty advisor: Michael G. Yost


Engineered nanoparticles are being rapidly incorporated into consumer products. The small size of the particles combined with their high surface area to volume ratio have made these particles ideal candidates for many of the proposed advances in medicine. The strong and uniquely versatile fluorescent properties of quantum dots allow for better in vivo medical imaging than what is currently possible. When combined with the high surface area to volume ratio that allows for the conjugation of multiple biologically active molecules for specific cellular targeting for uses such as simultaneous medical imaging and drug delivery.

In order to test the toxicity of Qdots to human lung cells, a cell culture exposure system must be developed and tested. The goal of this experiment is develop a cell culture exposure system and to characterize the flux density and the dose delivered by it. Using a solution of either sodium chloride or rubidium chloride that is then aerosolized and dried to nanosized particles of salt, the nanoparticle generation system was developed to deliver a stream of particle containing air to an exposure chamber designed to deliver particles to the surface of the air liquid interface insert of a 24-well plate. Filters were used in place of cells to determine the amount of salt deposited. Experiments that measured the deposition of particles over time were used to calculate the deposition velocity and the transfer efficiency of the process.

While high environmental background levels of sodium chloride made the accurate characterization of deposition difficult, the use of the rare rubidium chloride showed more promising results. Though increasing exposure times did not yield a linearly increasing mass deposition, there was a generally increasing trend. It is possible that either electrostatic charge saturation or a decreasing particle count were responsible for the lack of increase. The transfer efficiency was found to be constant at 1.6 to 1.7% suggesting that diffusion is a viable if inefficient method for nanoparticle deposition. Continued improvements to the system including a more efficient ionizer and more stable method of measurement of particle concentration could yield more conclusive results in future experiments.