Chemical imaging of glucose by CARS microscopy

Glucose is one of the most fundamental molecules within life and bioengineering sciences. Present understanding of its role in cellular and bioengineering processes relies primarily on invasive, large-scale biochemical analysis, providing no spatial information on glucose pools or fluxes. This work identifies an emerging microscopy technique based on coherent anti-Stokes Raman scattering (CARS), which fulfills the need of quantitative imaging of glucose at the single-cell level with submicrometer resolution. No sample preparation with reporter molecules is required, ensuring that the low-weight metabolite is studied under natural conditions. The potential of CARS microscopy is illustrated by quantitatively mapping glucose fluxes and distributions in a microfluidic bioreactor and in lipid-bilayer vesicles, the latter as a model for glucose transmembrane transport. Furthermore, the metabolic response to a glucose pulse was monitored in living yeast cells. This study signifies a new era within CARS microscopy for its use of monitoring carbohydrates, in particular glucose which is one of the most abundant molecules in nature