Vibrational Imaging May Improve Drug Monitoring

Vibrational Imaging May Improve Drug Monitoring
Label-free imaging tracks molecules in living cells

An imaging modality that detects the vibrations in chemical bonds may improve the monitoring of drug delivery in tissue, according to researchers at Harvard University.
In principle, if we can image tissues with Raman contrasts, we can study the efficacy of topically applied medicines.—X. Sunney Xie, PhD, Harvard University

The three-dimensional vibrational imaging technique, called stimulated Raman scattering (SRS), provides specific vibrational signatures of chemical bonds at much greater sensitivity than other imaging methods, the research team reported. The technology works without the need for fluorescent labeling of the molecules being tracked, the researchers said. (Freudiger CW, Min W, Saar BG, et al. Label-free biomedical imaging with high sensitivity by stimulated Raman scattering microscopy. Science. 2009;322(5909):1857-1861.)
“In principle, if we can image tissues with Raman contrasts, we can study the efficacy of topically applied medicines,” said X. Sunney Xie, PhD, a professor of chemistry at Harvard, in an e-mail to PFQ. “In practice, any kind of imaging methods cannot determine efficacy alone; other methods, such as proteomics and genomics, are needed. SRS can do metabolomics very well.” Metabolomics is the study of specific chemical “fingerprints” left behind by cellular processes.
The researchers described use of the technology for a number of biomedical applications, including differentiating between omega-3 fatty acids and other types of fats in living tissue and monitoring the diffusion of topically applied medications through the epidermis.
Dr. Xie said SRS may allow the tracking of drugs in the human body, “as long as the medicine has specific vibrational frequencies. We are developing an endoscope based on coherent Raman scattering contrast, which, I hope, will make this possible.”