Moving Toward Single-Molecule Mass Spec

Caltech scientists report the first mass spectra obtained with ultra-high-frequency nanocantilever resonators as ultrasensitive mass detectors (Nat. Nanotechnol., DOI: 10.1038/nnano.2009.152). Physicist Michael L. Roukes and coworkers use these NEMS (nanoelectromechanical systems) resonators to detect individual biomolecules and nanoparticles. The resonators vibrate at an ultrahigh frequency that depends on the total mass of the device and changes when even a single molecule adsorbs to the device surface. Measuring mass with microscale devices is well-known, but Roukes and coworkers' device is more miniaturized than previous ones and uses different components, such as electrospray ionization source and ion optics, to deliver ions to the detectors. They collected NEMS mass spectra of bovine serum albumin monomers and oligomers and colloidal gold nanoparticles. The Roukes group has accomplished a "breakthrough achievement," Thomas G. Thundat of Oak Ridge National Laboratory says. "This can potentially lead to a miniature mass spectrometer with single-molecule sensitivity." R. Graham Cooks, a mass spectrometrist at Purdue University, notes, "Much remains to be done, but this is an exciting demonstration of feasibility."