Microscopy Focus: B22

Infrared (IR) spectromicroscopy has been increasingly used for the study of cells and tissues as it can quickly determine the identity, concentration, and biochemical properties of the components of a sample. Of particular interest is the new capability for characterising biochemical reactions in living cells via synchrotron IR imaging.

A novel method called Correlated Cellular Spectromicroscopy (CSM) was recently developed, which relies on 2-dimensional correlation spectroscopy to cluster absorption bands that belong to the same molecule. The technique enables metabolic reactions to be followed in real time, such as the rate of metabolite formation and consumption.

Such an approach was used to detect the metabolites of glycolysis (one of the cellular pathways to produce energy from glucose) in a well-characterised lung cancer cell line. The cells were held in a custom-built liquid sample holder that was maintained at 37 °C under the IR microscope. The samples were analysed with Fourier Transform IR imaging being conducted on single cells and small cell clusters to detect variations of metabolite concentrations in time and space across the sample.

The combination of IR imaging and CSM was able to track the distribution of metabolite formation in the lung cancer cells. It successfully detected lactate as well as other glycolytic products (see figure). The molecular detail provided by this approach could allow it to be used for in vitro drug testing, for instance in multicellular assemblies that model living organs.

Adapted from Quaroni et al. with permission of The Royal Society of Chemistry.