Basic Information
Abstract Number: 160-5    
Author Name: Shuwen Sun Affiliation: University of Michigan
Session Title: High-Throughput Chemical Analysis
Event Type: Oral
Event Title: High-Throughput Screening Using Droplet Microreactor System with Analysis by Electrospray Ionization Mass Spectrometry
Presider(s): Lynch, Garry J Start Time: 02:35 PM ( Slot # 6 )
Date: Sunday, March 11th, 2012 Location: 310B
Keywords: High Throughput Chemical Analysis, Lab-on-a-Chip/Microfluidics, Mass Spectrometry, Sample Handling/Automation

Kennedy, Robert TUniversity of Michigan

Abstract Content
High-throughput screening (HTS) is used in many fields including drug discovery and biotechnology. Conventional approaches involve screening compounds for particular properties by performing optical assays in microplates. Recently, interest in segmented flow, wherein samples are manipulated as nanoliter droplets separated by immiscible oil within a tube, for HTS has grown because of its potential for miniaturization. Mass Spectrometry, as an analyzing method, is attractive for HTS since it avoids the impact of incorporating labels on the chemistry being studied. We have developed an approach of analyzing sample droplets by electrospray ionization mass spectrometry (ESI-MS), in which nanoliter samples are directly pumped through an emitter and detected at rates up to 7 Hz. This label-free method has been demonstrated in screening inhibitors of two different enzymes. Further, we developed methods for conducting the entire reaction in droplets using a microfluidic system. Compared with conventional approaches, our system reduces the reagent consumption to nanogram-scale per reaction and overcomes the impediment of evaporation. The feasibility of this microreactor system is assessed by screening Cathepsin B inhibitors. Cathepsin B is a lysosomal cysteine protease involved in intracellular protein turnover, cancer invasion, and Alzheimer’s disease. Analytes screened for inhibition effect are stored as nanoliter droplets in a Teflon tube. Enzyme and substrate are sequentially added into the droplets for reaction via a microfabricated device. The strength of inhibitors is indicated by their impact on signal intensity of the product in MS spectra. High efficiency, high reproducibility and low cross-contamination of the system have been achieved.