Multiple MicroRNA Quantification Based on Acoustic Levitation of Single Microspheres after One-Pot Sandwich Interparticle Hybridizations.

We propose a scheme for the sensitive quantification of multiple microRNAs (miRNAs) on the basis of the levitation coordinate change (Δ z) of single microparticles of different sizes in a coupled acoustic-gravitational (CAG) field. This field transduces the density change of a microparticle into Δ z, which can be measured with high precision. The density of a microparticle is induced by the binding of gold nanoparticles (AuNPs) on it through the sandwich DNA hybridization with miRNA. Different probe DNAs are anchored onto microparticles of different sizes, which are clearly distinguishable on a microscopic view. The target miRNAs are captured by these particles having complementary nucleotide sequences and then entrap reporter-anchored AuNPs. Thus, the densities of the microparticles are modified according to the concentration of individual target miRNAs. The interparticle hybridizations for multiple target miRNAs are conducted in one-pot reactions before the levitation of the microparticles is measured in the CAG field. This principle is successfully applied to the quantification of miR-21 and miR-122 in the total RNA extracted from liver cancer tissues.