Scientists reach holy grail in label-free cancer marker detection: Single molecules

Just months after setting a record for detecting the smallest single virus in solution, researchers at the Polytechnic Institute of New York University (NYU-Poly) have announced a new breakthrough:

They used a nano-enhanced version of their patented microcavity biosensor to detect a single cancer marker protein, which is one-sixth the size of the smallest virus, and even smaller molecules below the mass of all known markers. This achievement shatters the previous record, setting a new benchmark for the most sensitive limit of detection, and may significantly advance early disease diagnostics. Unlike current technology, which attaches a fluorescent molecule, or label, to the antigen to allow it to be seen, the new process detects the antigen without an interfering label.

Stephen Arnold, university professor of applied physics and member of the Othmer-Jacobs Department of Chemical and Biomolecular Engineering, published details of the achievement in Nano Letters, a publication of the American Chemical Society.

In 2012, Arnold and his team were able to detect in solution the smallest known RNA virus, MS2, with a mass of 6 attograms. Now, with experimental work by postdoctoral fellow Venkata Dantham and former student David Keng, two proteins have been detected: a human cancer marker protein called Thyroglobulin, with a mass of just 1 attogram, and the bovine form of a common plasma protein, serum albumin, with a far smaller mass of 0.11 attogram. "An attogram is a millionth of a millionth of a millionth of a gram," said Arnold, "and we believe that our new limit of detection may be smaller than 0.01 attogram."