Disease Proteins Spotted In Minutes

A microfluidic chip containing silicon nanowires pulls out biomarker proteins from blood and identifies them in less than 10 minutes (Nano Lett., DOI: 10.1021/nl3021889). To diagnose patients quickly, doctors would like to be able to detect specific proteins that appear in patients’ blood in the early stages of disease. To help meet that goal, Fernando Patolsky, a professor of chemistry at Tel Aviv University, in Israel, designed a chip consisting of two chambers. A user adds a 250-µL blood sample to the separation chamber, which contains a forest of vertically oriented silicon nanowires coated with antibodies that bind the protein of interest. After washing salts and cells out of this chamber, the user adds a buffer that triggers the antibodies to release the biomarkers. The solution then travels to the sensing chamber, which contains horizontal silicon nanowires coated with the same antibodies. There, the proteins bind to the nano­wires, change the wires’ conductance, and produce an easily detectable electrical signal. The researchers tested the device with human blood samples spiked with the protein troponin T, a biomarker for heart attacks. In less than 10 minutes, the chip detected the protein at subpicomolar concentrations.