Super-resolution chemical imaging advances drug discovery and the creation of new materials

Chemistry Innovator: Stephan Stranick

Location: National Institute of Standards and Technology

How do things behave that are too small for us to see? Understanding how materials interact on a micro- or even nano-scale has many applications from drugs that treat viruses to new materials for ultra-high capacity batteries. For years, there was a strict limit to how far an image can be magnified by optical microscopes. This in turn limited the pace of improvement of technologies in numerous other fields. However, this limit has been recently broken by innovative techniques developed by the National Institute of Standards and Technology (NIST).

Dr. Stephan Stranick of NIST has spearheaded this effort. His super-resolution chemical-imaging microscopy system has made large impact on imaging the super small. Stranick’s microscope can magnify living and non-living objects to around 100 nanometers, surpassing the 200 nanometer threshold that was previously the limit for conventional light microscopy.

Many traditional imaging systems, such as electron microscopes, require the viewing sample to be frozen so that it can be put into a vacuum and then bombarded with an electron stream to excite its molecules. This causes the molecules to illuminate so that they can then be viewed in a contrast composite image. Super-resolution chemical-imaging looks at samples differently. It exploits Coherent Raman Spectroscopy to measure the unique vibrational signatures of molecules (Raman spectroscopy is form of spectroscopy often used in physics and chemistry that measures the nuclear vibrations between chemical bonds) and create an image by interpreting this data. Super-resolution chemical-imaging doesn’t rely on exciting materials with lasers to produce fluorescence for contrast in order to see them; the Raman technique allows for true molecular contrast, meaning that the image produced has intrinsic contrast and therefore artificial dyes or stains are not needed. Additionally, Stranick’s chemical-imaging microscope is an important step forward in imaging technology as it does not require that the viewing sample to be frozen; it can be living tissue from an organism. However this doesn’t mean that the microscope only has biochemical applications; it has industrial ones as well, as it can view materials such as silicon with great detail.

Stranick is currently engaged in collaborative research with Dr. Subramaniam of the National Institutes of Health’s National Cancer Institute. The pair is applying Stranick’s advanced microscope technology to an ongoing investigation on how cells and viruses interact with one another. Super-resolution chemical-imaging microscopy has allowed Stranick and Subramaniam to look specifically at the chemical processes going on within cells before, during, and after contact with viruses such as HIV, at a level of magnification never before achieved. Being able to observe these interactions more closely and in real time is a large step forward in understanding how they work. Once these chemical mechanisms are better understood manipulation will be possible and options for prevention and treatment will expand.

By John Czerwinski, ACS
August 9, 2011