Ultrasensitive detection of microRNAs using nanoengineered micro gold shells and laser desorption/ionization time-of-flight MS.

We report on a simple, fast, and highly sensitive method that allows femtomolar detection of microRNAs (miRNAs) without the need of polymerase chain reaction using a nanoengineered micro gold shell (μAuS) and laser desorption/ionization time-of-flight (LDI-TOF) mass spectrometry (MS). Target miRNAs are selectively captured by a chemically decorated gold chip and a μAuS, which carries with it a large number of small molecules, termed amplification tags (Am-tags). Subsequent LDI-TOF MS analysis allows a highly amplified mass signal of Am-tags for the presence of target miRNAs in a sample, resulting in ultrasensitive detection.