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Automated signal amplification for high sensitivity diagnostics

Nearly all laboratory assays rely on multiple chemical steps carried out in a timed sequence by a trained operator or a machine. A classic example is the amplified detection of biomarkers by enzyme-linked immunosorbent assay (ELISA). In contrast, classic lateral flow tests (LFTs) are limited to assays that can be carried out in a single chemical step, so high performance methods, including signal amplification, are not available. Two-dimensional paper networks (2DPNs) can be “programmed” to automatically carry out sophisticated processes. The figure below shows a 2DPN that uses different leg lengths and volume-limited fluid source pads to deliver fluids to a detection zone in a timed sequence.

By staging the delivery of reagents to a particular section of membrane, catalytic assay labels can be used to amplify signals and improve the performance of diagnostic tests

In the lower images, gold nanoparticles (small pad) are captured by an immobilized capture spot (white arrow), excess gold is washed away (middle pad), and a gold deposition solution amplifies the signal of the captured gold nanoparticles. Amplified 2DPNs could provide sensitivity comparable to laboratory tests, like ELISA, in a format that is as easy to use and as inexpensive as LFTs.

For more information see:

“Chemical signal amplification in two-dimensional paper networks,” Sensors and Actuators B, 149, 325-328 (2010)

Elain Fu, Peter Kauffman, Barry Lutz, Paul Yager

Department of Bioengineering, University of Washington, Seattle, WA, USA

 

“Controlled reagent transport in disposable 2D paper networks,” Lab on a Chip, 10(7), 918-920 (2010).

Elain Fu, Barry Lutz, Peter Kauffman, Paul Yager

Department of Bioengineering, University of Washington, Seattle, WA, USA