title: On-chip integration of droplet microfluidics and nanostructure-initiator mass spectrometry for enzyme screening.
abstract: Biological assays often require expensive reagents and tedious manipulations. These shortcomings can be overcome using digitally operated microfluidic devices that require reduced sample volumes to automate assays. One particular challenge is integrating bioassays with mass spectrometry based analysis. Towards this goal we have developed μNIMS, a highly sensitive and high throughput technique that integrates droplet microfluidics with nanostructure-initiator mass spectrometry (NIMS). Enzyme reactions are carried out in droplets that can be arrayed on discrete NIMS elements at defined time intervals for subsequent mass spectrometry analysis, enabling time resolved enzyme activity assay. We apply the μNIMS platform for kinetic characterization of a glycoside hydrolase enzyme (CelE-CMB3A), a chimeric enzyme capable of deconstructing plant hemicellulose into monosaccharides for subsequent conversion to biofuel. This study reveals NIMS nanostructures can be fabricated into arrays for microfluidic droplet deposition, NIMS is compatible with droplet and digital microfluidics, and can be used on-chip to assay glycoside hydrolase enzyme in vitro.
authors.affiliation: Joint Bioenergy Institute, Emeryville, California 94608, USA and Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. trnorthen@lbl.gov.
authors.forename: Joshua
authors.initials: J
authors.lastname: Heinemann
authors.affiliation: Joint Bioenergy Institute, Emeryville, California 94608, USA and Sandia National Laboratories, Livermore, California 94551, USA.
authors.forename: Kai
authors.initials: K
authors.lastname: Deng
authors.affiliation: Department of Electrical and Computer Engineering, Concordia University, Montreal, Quebec, Canada.
authors.forename: Steve C C
authors.initials: SC
authors.lastname: Shih
authors.affiliation: Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. trnorthen@lbl.gov.
authors.forename: Jian
authors.initials: J
authors.lastname: Gao
authors.affiliation: Joint Bioenergy Institute, Emeryville, California 94608, USA and Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. trnorthen@lbl.gov and Department of Bioengineering, University of California, Berkeley, California, 94720, USA.
authors.forename: Paul D
authors.initials: PD
authors.lastname: Adams
authors.affiliation: Joint Bioenergy Institute, Emeryville, California 94608, USA and Sandia National Laboratories, Livermore, California 94551, USA.
authors.forename: Anup K
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Joint Bioenergy Institute, Emeryville, California 94608, USA and Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. trnorthen@lbl.gov and Joint Genome Institute, Walnut creek, California, 94598, USA.
authors.forename: Trent R
authors.initials: TR
authors.lastname: Northen
mesh_terms: D057075:Enzyme Assays / Q000295:instrumentation*; D006026:Glycoside Hydrolases / Q000378:metabolism*; D056656:Lab-On-A-Chip Devices; D013058:Mass Spectrometry; D049329:Nanostructures
chemical_list: D006026:Glycoside Hydrolases