Circulating TGF- is one of the key regulators of cardiovascular health. The extremely low abundance of circulating TGF- in the blood is one of the major challenges in on-chip purification and extraction. This paper reports numerical modeling and simulation of more than 25000 folds concentration gain of TGF- in a 2D cascade microchannel using isotachophoresis (ITP).  The 4.3 cm long microfluidic channel with 250 times reduction in cross-sectional area from inlet to outlet was used for ITP simulation. The initial cross-sectional area was 1250 micrometer x 100 micrometer and the final cross-sectional area was 50 micrometer x 10 micrometer with 2D step changed.  The reduction in the cross-sectional area was used to complement ITP concentration gain. COMSOL Multiphysics 5.2 was used to simulate the separation and concentration of two proteins- TGF- and albumin. The model used the Nernst-Planck equations to predict protein stacking and separation in the sample solution. Microchip with 1D and 2D step changed microfluidic channels were also explored using numerical simulations.  In the simulation, the leading electrolyte (LE) was 10mM Hydrochloric acid (HCl) adjusted to a pH of 9.5 with Tris (1M) and the trailing electrolyte (TE) consisted of 60 mM DNP- epsilon -amino-n-caproic acid (EACA) adjusted to a pH of 10.0 with Tris (1M).  A constant DC electric potential of 200 V was applied between anode and cathode reservoir. The proteins migration was observed under a fluorescence microscope and images of proteins band in different locations were taken. The initial concentration of TGF- and albumin was 1.25 microgram/ml and after ITP concentration, each protein exhibited more than 25000 folds (~33 mg/ml) concentration gain. This is a significant improvement in the protein concentration factor compared to our previous report in an ITP microchip. This demonstration can be utilized in the development of an integrated microchip to detect low abundant proteins. The demonstration of ITP modeling and simulation will help to develop the experiment and in the long term, TGF- extraction, purification, and concentration can be materialized in a microchip.<br/>

Numerical modeling and simulation of a microfluidic platform for enrichment of low abundance proteins

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.