Lab-on-a-Chip for Proteomics

Proteomics is a major component of systems biology. Mass spectrometry is an enabling technology for proteomics. To fully realize the enormous potential of lab-on-a-chip in proteomics, major advance in interfacing microfluidics with mass spectrometry is needed. We have demonstrated the monolithic integration of a microfluidic channel with multinozzle electrospray emitters via a novel silicon microfabrication process. These microfabricated monolithic multinozzle emitters (M3 emitters) can be readily mass-produced from silicon wafers. Each emitter consists of a parallel silica nozzle array protruding out from a hollow silicon sliver stem with the conduit size of 100×10 micron. The dimension and number of freestanding nozzles can be systematically and precisely controlled during the fabrication process. The M3 emitters showed comparable performance to that of the commercial tips in terms of stability and sensitivity for standard peptides and high molecular weight proteins. Multinozzle emitters are expected
to ease back pressure and clogging problem that single nozzle emitters have to cope with, especially as the channel downsizes to submicron scale. Our current work aims to further integrate M3 emitters with the front-end sample processing on a chip. New developments in optimizing the performance of M3 emitters for potential applications in single cell analysis will be discussed.