Ji-Xin Cheng

Laboratory for Label-free In Vivo Spectroscopic Imaging 

Optical spectroscopy has been a powerful tool for quantitative analysis by measuring quantized electronic and vibrational transitions in molecules. Over the past, such measurements were restricted to molecules that are extracted from cells and tissues, or biopsies extracted from a human body. Such in vitro  spectroscopy measurements lack the capabilities of tracing molecules in intact, live tissue environment. Spectroscopic imaging by measuring molecular fingerprint spectrum at each pixel, thus providing both molecular information and spatial resolution, would offer a new window for seeing a hidden world of biology. Five to ten years ago, spectroscopic imaging of living systems from single cell to human body was considered to be impossible. This “mission impossible” can be summarized as the following tasks: (1) Can we perform real time spectroscopic imaging of a live cell? (2) Can we derive meaningful information from the crowded fingerprint spectra recorded from an intact, extremely complicated biological complex? (3) Can we measure a spectrum in vivo from a target tissue that is a few cm underneath the skin?

My research group has been tackling the “mission impossible” very persistently. Our recent research endeavours have generated promising solutions allowing for spectroscopic imaging of life. We have two consecutive inventions that enabled fast spectroscopic imaging with a pixel dwell time of 10 microseconds, which is nearly 1 million times faster than conventional Raman spectroscopy. We have successfully bridged multivariate analysis tools with spectroscopic imaging. Such integration has allowed label-free imaging of biomolecules, such as cholesterol, in an intact tissue using their fingerprint bands. We have launched a novel imaging platform based on acoustic detection of chemical bond vibration. Continuous development of this method has allowed us to record a spectrum from a target tissue that is 3 cm deep below the surface.


11-13-2013 Rui Li passed his M.S. thesis defense and will continue as a PhD candidate.

11-8-2013 Shuhua Yue passed her PhD thesis defense.