title: A droplet-based novel approach for viable and low volume consumption surface plasmon resonance bio-sensing inside a polydimethylsiloxane microchip.
abstract: Over the course of last two decades, surface plasmon resonance (SPR) has emerged as a viable candidate for label-free detection and characterization for a large pool of biological interactions, ranging from hybridization of oligonucleotides to high throughput drug-screening. Conventional SPR bio-sensing involves a step-response method where the SPR sensorgram in response to a switched sequential flow of analyte and buffer is plotted in real-time and fitted to an exponential curve to extract the associative and dissociative reaction rates. Such measurement schemes involve continuous flow conditions where a substantial reagent volume is consumed and is subject to dispersive mixing at flow switching zones. In this paper, we demonstrate a new plug-train SPR technique in a microfluidic chip that separates and singulates solvent plugs in analyte and buffer by an immiscible air phase. Bio-samples are first discretized within plug droplets with volumes in order of few hundred nanoliters or less followed by pressure-driven transport onto SPR sensing sites of this hydrophobically modified SPR microdevise. The kinetic constants ka and kd for a model protein-small molecule interaction pair are extracted from a plug-train signal and are shown to be in reasonable agreement with our previous reports.
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: T
authors.initials: T
authors.lastname: Ghosh
authors.affiliation: Electrical and Computer Engineering Department, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Xie
authors.affiliation: Department of Bioengineering, University of Utah, Salt Lake City, Utah 84112, USA ; Electrical and Computer Engineering Department, University of Utah, Salt Lake City, Utah 84112, USA.
authors.forename: C
authors.initials: C
authors.lastname: Mastrangelo