Researchers at Georgia Institute of Technology have made a probe that detects the biochemical makeup, as well as the complex topology, of biologic samples. Previous probes could only detect one or the other, and in many instances, the cells were destroyed while being prepared for scanning. The new probes should let scientists better understand cellular interactions and identify exactly what proteins do and how they respond to outside stimuli, such as exposure to drugs or environmental changes. The Scanning Mass Spectrometry probe lets scientists gently pull biomolecules at a specific point on the surface, ionize them, and produce so-called dry ions suitable for analysis. These ions are moved to the mass spectrometer for identification. The probe does this dynamically, imaging the surface and mapping cellular activities in real time.

The engineering challenge in building the probe was to devise a way to grab specific molecules from the sample, then get them to a dry and electrically charged state suitable for mass spectrometry. The team exploited strong capillary forces to confine the sample fluid within a small portion of the probe inlet. This lets the liquid and gaseous parts of the sample naturally separate. Next, they used Taylor electrohydrodynamics to make charged ions, but in reverse (to pull) rather than the more commonly used forward (push) mode. The SMS probe works with atomic force microscopes and can monitor changes in cell/tissue topology while imaging.