- Cushing, K. W. and Piyasena, M. E. and Carroll, N. J. and Maestas, G. C. and Lopez, B. A. and Edwards, B. S. and Graves, S. W. and Lopez, G. P., Elastomeric Negative Acoustic Contrast Particles for Affinity Capture Assays,
Analytical Chemistry, vol. 85 no. 4
pp. 2208--2215 [doi] .
(last updated on 2013/06/21)
This report describes the development of elastomeric capture microparticles (EC mu Ps) and their use with acoustophoretic separation to perform microparticle assays via flow cytometry. We have developed simple methods to form EC mu Ps by cross-linking droplets of common commercially available silicone precursors in suspension followed by surface functionalization with biomolecular recognition reagents. The EC mu Ps are compressible particles that exhibit negative acoustic contrast in ultrasound when suspended in aqueous media, blood serum, or diluted blood. In this study, these particles have been functionalized with antibodies to bind prostate specific antigen and immunoglobulin (IgG). Specific separation of the EC mu Ps from blood cells is achieved by flowing them through a microfluidic acoustophoretic device that uses an ultrasonic standing wave to align the blood cells, which exhibit positive acoustic contrast, at a node in the acoustic pressure distribution while aligning the negative acoustic contrast EC mu Ps at the antinodes. Laminar flow of the separated particles to downstream collection ports allows for collection of the separated negative contrast (EC mu Ps) and positive contrast particles (cells). Separated EC mu Ps were analyzed via flow cytometry to demonstrate nanomolar detection for prostate specific antigen in aqueous buffer and picomolar detection for IgG in plasma and diluted blood samples. This approach has potential applications in the development of rapid assays that detect the presence of low concentrations of biomarkers in a number of biological sample types.