Science and Engineering

Purdue University

Ji-Xin Cheng
West Lafayette, IN
December 2014

Most knowledge about cellular content comes from in vitro analysis of cell homogenates.  Fluorescence imaging is the tool of choice for monitoring live cells in real time.  However, the fluorescent labels are too bulky for small molecules and thus “muddy” their biological functions.  Raman-scattering based vibrational spectroscopy, which pinpoints a molecule based on its fingerprint spectrum, provides more accuracy.  Yet, real-time vibrational imaging of living systems requires microsecond spectral acquisition speed for each pixel, which is not reachable by current Raman microscopy techniques.  The Purdue team proposes to tackle this challenge by developing a new imaging platform called modulation-multiplexed stimulated Raman scattering microscopy.  The approach will allow real-time spectroscopic imaging of an intact organism by spectrally coded excitation and efficient detection of scattered photons using a single, large-area detector placed close to the specimen.  In tandem with the new platform, the team will design and synthesize Raman probes of extremely large cross sections to further enhance the ability to detect specific molecules.  They will pursue vibrational spectroscopic imaging of membrane dynamics and metabolism in living cells to highlight the potential of the platform for real-time visualization of cellular functions.

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