Author ORCID Identifier
Candice M. Etson: 0000-0002-9796-269X
Document Type
Article
Publication Date
6-21-2012
Publication Title
Lab on A Chip
Abstract
This paper describes a novel method for fabricating and sealing high-density arrays of femtoliter reaction chambers. We chemically etch one end of a 2.3 mm diameter glass optical fiber bundle to create an array of microwells. We then use a contact printing method to selectively modify the surface of the material between microwells with a hydrophobic silane. This modification makes it possible to fill the wells with aqueous solution and then seal them with a droplet of oil, forming an array of isolated reaction chambers. Individual β-galactosidase molecules trapped in these reaction chambers convert a substrate into a fluorescent product that can be readily detected because a high local concentration of product is achieved. This binary readout can be used for ultra-sensitive measurements of enzyme concentration. We observed that the percentage of wells showing enzyme activity was linearly dependent on the concentration of soluble β-galactosidase in the picomolar range. A similar response was also observed for streptavidin-β- galactosidase captured by biotinylated beads. These arrays are also suitable for performing single-molecule kinetics studies on hundreds to thousands of enzyme molecules simultaneously. We observed a broad distribution of catalytic rates for individual β-galactosidase molecules trapped in the microwells, in agreement with previous studies using similar arrays that were mechanically sealed. We have further demonstrated that this femtoliter fiber-optic array can be integrated into a PDMS microfluidic channel system and sealed with oil on-chip, creating an easy to use and high-throughput device for single-molecule analysis.
Volume
12
Issue
12
First Page
2229
Last Page
2239
DOI
10.1039/c2lc21113k
ISSN
14730197
Recommended Citation
Zhang, Huaibin; Nie, Shuai; Etson, Candice M.; Wang, Raymond M.; and Walt, David R., "Oil-Sealed Femtoliter Fiber-Optic Arrays for Single Molecule Analysis" (2012). Physics: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/phy_facpubs/122
Comments
Peer reviewed accepted manuscript.