Abstract

Affinity Selection of Extracellular Vesicles using Plastic-based Microfluidic Devices for the Management of Different Diseases

Steve Soper, Foundation Distinguished Professor; Director, Center of BioModular Multi-scale System for Precision Medicine, Adjunct Professor, Ulsan National Institute of Science & Technology, The University of Kansas

We have been developing tools for the diagnosis of a variety of diseases. The commonality in these tools is that they consist of microfluidic devices made from plastics via injection molding. Thus, our tools can be mass produced at low-cost to facilitate bench-to-bed side transition and point-of-care testing (PoCT). We have also been generating novel assays focused on using liquid biopsy samples that are enabled using microfluidics. In this presentation, I will talk about the evolution of our fabrication efforts of plastic-based microfluidic and nanofluidic devices as well their surface modification to make the devices biocompatible for in vitro diagnostics. One tool that we have generated is a plastic device (38 × 42 mm) that consists of 1.5M pillars, which are surface decorated with affinity agents targeting certain disease-associated extracellular vesicles (EVs). The affinity agents are covalently attached to the surface of the microfluidic device using a bifunctional linker, which consists of a coumarin moiety to allow for the photolytic release of the captured EVs using a blue-light LED to minimize photodamage to the EVs’ molecular cargo. We have also developed a high-throughput nano-Coulter counter (nCC) made from a plastic via injection molding for the counting of captured EVs from clinical samples to allow their enumeration. The nCC consists of multiple pores that are ~350 nm to allow for high throughput counting with exquisite LODs (500 EVs/mL). In this presentation, I will discuss the utility of these microfluidic and nanofluidic devices in several diseases, for example, using EVs as a source of mRNAs for molecular sub-typing of breast cancer patients. EVs were affinity selected from breast-cancer patients’ plasma by searching for both epithelial and mesenchymal expressing EVs to allow for highly efficient sub-typing using the PAM50 gene panel. In an addition, the microfluidic and nanofluidic devices were integrated into a single platform (modular-based system) for PoCT to screen for early stage ovarian cancer. Affinity probes were used to target EVs specifically generated from tumor cells that signal early-stage ovarian cancer disease with the nCC used for enumerating the number of EVs captured. Finally, the modular system was used for the detection of COVID-19 at the PoC by affinity selecting SARS-CoV-2 viral particles. The integrated system could process saliva samples to search for the viral particles and count them in <20 min.