NT-08 * A NOVEL HIGH-THROUGHPUT MICROFLUIDIC DEVICE DESIGNED TO ACCELERATE THE DISCOVERY OF GLIOBLASTOMA-TARGETING LIGANDS FROM OBOC LIBRARIES

Abstract

Molecular targeting using ligands specific to glioblastoma (GBM) markers has shown great promise for the early detection of the pathology and directed therapy of the disease. Although conventional screening strategies of combinatorial libraries have demonstrated great potential for the discovery of novel targeting ligands, it is usually challenging and immensely costly. High-throughput screening approaches that exploit the tendency of magnetic prey beads (2-microns) coated with the target protein to specifically associate with the larger peptide-coated bait library beads (90-microns) are inexpensive, and have significantly accelerated the identification of targeting probes from one-bead-one-compound (OBOC) libraries. Using this approach, our objective is to utilize magnetic beads coated with a GBM-specific target protein to screen and capture novel GBM-binding peptides from an OBOC library. To facilitate high-throughput separation of positive hit beads from the rest of the library, we implemented a microfluidic magnetic flow system of our own design. Here, we describe a miniature microfluidic device designed to divert library beads coated with magnetic beads from one laminar flow path to another using an external magnetic force. Microfluidic channels connected to two inlets and two outlets are built using soft lithography, with dimensions of 2cm x 0.6mm x 0.2mm (L x W x H). A negative mold is created using SU-8 photoresist, and poly(dimethylsiloxane) (PDMS) is poured onto the mold to fabricate the channels. A strong neodymium magnet is placed adjacent to the channel to pull positive magnetic beads from the source flow path into the collection flow stream, allowing these beads to exit through the collection outlet. This novel on-chip technology can facilitate screening of large OBOC libraries (> 1 million beads) with great accuracy in a matter of hours, paving the way for rapid and efficient identification of targeting ligands specific to pathological targets in brain cancer and other diseases.