title: Label-free measurements of reaction kinetics using a droplet-based optofluidic device.
abstract: Label-free measurements of the reaction kinetics of a small sample volume are essential for efficient drug discovery, requiring methods and systems that are rapid, accurate, and cost-effective. Herein, we present an integrated optofluidic system for label-free characterization of reactions in a nanoliter reagent volume. This system contains a droplet-based microfluidic sampling section and an optical fiber-based spectroscopy detection section. By manipulating droplets containing reagents at certain concentrations at different times, quantifiable measurements via absorption spectroscopy can be made in a simple, sensitive, and high-throughput manner. We have demonstrated our system's capability by performing potency (IC50) assays of an inhibitor in a TEM-1 β-lactamase (enzyme) and nitrocefin (substrate) system. This integrated platform can potentially provide an automated, label-free, and low-cost method for many other assays of reaction kinetics.
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Zhangming
authors.initials: Z
authors.lastname: Mao
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Guo
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA Department of Chemical Engineering, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Yuliang
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Michael Ian
authors.initials: MI
authors.lastname: Lapsley
authors.affiliation: Ascent Bio-Nano Technologies, Inc., State College, PA, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong SAR.
authors.forename: John D
authors.initials: JD
authors.lastname: Mai
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA.
authors.forename: Francesco
authors.initials: F
authors.lastname: Costanzo
authors.affiliation: Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, USA junhuang@psu.edu.
authors.forename: Tony Jun
authors.initials: TJ
authors.lastname: Huang
mesh_terms: D055808:Drug Discovery / Q000379:methods*; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D004791:Enzyme Inhibitors / Q000378:metabolism; D057166:High-Throughput Screening Assays / Q000295:instrumentation / Q000379:methods; D020128:Inhibitory Concentration 50; D007700:Kinetics; D044085:Microfluidics / Q000295:instrumentation* / Q000379:methods*; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods*; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1
keywords: absorption spectroscopy; droplet; label-free detection; microfluidics; optofluidics; reaction kinetics