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. Biosamples 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 k a and k d for a model protein-small molecule interaction pair are extracted from a plugtrain signal and are shown to be in reasonable agreement with our previous reports.

Melting analysis on microbeads in rapid temperature-gradient inside microchannels for single nucleotide polymorphisms detection

“…Finally, this mechanism can potentially be adapted to a microfluidic droplet platform, where individual droplets enclose distinct target and reagents, with the same temperature gradient along the channel. [39][40][41][42] The droplet functions like the microbeads as a mobile object to carry the target DNA and fluorescent dye for the melting analysis. While the droplet platform can possibly simplify the DNA immobilization step, the microbeads will provide better signal-to-noise ratio for this continuousflow melting analysis in temperature-gradient channels.…”

A multiplexed immunoaggregation biomarker assay using a two-stage micro resistive pulse sensor

“…1932-1058/2016/10(2)/024109/11/$30.00 V C 2016 AIP Publishing LLC 10, 024109-1 colorimetric 32,33 ), electrochemical, 23,[34][35][36] SPR, [37][38][39][40] surface-enhanced Raman scattering (SERS), 41,42 and capillary electrophoretic immunoassays (CEIA). 43,44 However, these methods require complex setups, expensive detectors, and/or complicated encoding and decoding process, 45 making them impediment for point-of-care biomarker detection for applications including disease diagnosis and therapy monitoring.…”