Handheld Device for Rapid Detection of miRNA based on a Ratiometric Transmittance Scheme.

MicroRNAs (miRNAs) are a novel class of biomarkers that can be present in different biological samples, which can be related to many diseases. Controlled aggregation of gold nanoparticles (GNPs) in the presence of miRNAs can be used to perform a rapid detection of miRNAs based on color change. Sometimes the color change can be observed with the naked eye; however, this is not always possible. This work proposes the design of a novel instrumental prototype that allows performance of simultaneous transmittance measurements at different wavelengths. Once the signals are obtained, the system calculates the 525nm/650nm transmittance ratio and the miRNA concentration, displaying and recording the results in a smartphone. This prototype has been validated to detect the miRNA \"miR146a,\" which is found in higher concentrations in milk and tissues in cases of bovine mastitis.