Measuring Hydrolytic Enzyme Activity with Substrate-Wrapped Single Walled Carbon Nanotubes for Optimization of Biomass Conversion

Because single walled carbon nanotubes (SWNT) fluoresce in the near-infrared window, they make excellent biosensors for in situ detection. By wrapping SWNT with an amphiphilic polymer, they may be solubilized in water. Conversely, by altering or destroying the wrapping material, SWNT collapse back to aggregate form and their fluorescence is quenched. When wrapped with substrates for hydrolytic enzymes, the SWNT sensors can be used to quantitatively measure hydrolytic enzyme activity (turnover frequency and catalytic efficiency). We have tested SWNT with bovine serum albumin (BSA), potato starch, and pectin to confirm that this is a generalizable method to track hydrolytic activity. We discuss one application of this tool, which is the optimization of a hydrolytic enzyme cocktail for biomass conversion.