Mark Schnepper, Ph.D.

Postdoctoral Researcher, University of Central Florida
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Presented: October 22 and 23, 2020

“Non-Linear Inverse Liquid-Solid Chromatography as a Methodology to Characterize Drug Concentration Losses to Polymeric Materials Used in Body-on-a-Chip Devices for Drug Discovery”

Body-on-a-chip and human-on-a-chip systems are currently being used to augment and could eventually replace animal models in drug discovery and basic biological research. However, hydrophobic molecules, especially therapeutic compounds, tend to adsorb to the polymer materials used to create these microfluidic platforms, which may distort the dose-response curves that feed into Pharmacokinetic/Pharmacodynamic (PK/PD) models which translate preclinical data into predictions of clinical outcomes. Adsorption of hydrophobic molecules to these polymer materials needs better characterization.

Inverse Liquid-Solid Chromatography paired with a numerical optimization based on the Langmuir model of adsorption was used to characterize the adsorption isotherm parameters of selected drugs to polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA), polymers commonly used in these platforms after extensive modification to an existing HPLC-MS instrument.

Surface modification by organosilanes is one method being explored to modify PDMS, but the effect of organosilanes on drug adsorption isotherms are not well characterized. We utilized Inverse Liquid-Solid Chromatography (ILC) to characterize the adsorption parameters of the selected drugs with native PDMS and organosilane-modified (fluoropolymer (13F) and polyethylene glycol (PEG)) PDMS surfaces to correlate the modifications to changes in drug adsorption.

We found that the organosilane modifications significantly changed the energy of adsorption.

Mark Schnepper, Postdoctoral Researcher, University of Central Florida

Mark Schnepper recently graduated from the University of Central Florida with his Ph.D. in materials science and engineering in the summer of 2020 from Dr. James J. Hickman’s Group. He obtained his masters also at the University of Central Florida in M.S. and engineering in 2014 and his B.S. in chemistry from Whitman College in 2008. Before entering his graduate career, he worked at the Energy Biosciences Institute located on the University of California, Berkeley campus as an analytical chemist from 2009 to 2010.