Another fascinating article from Janelia Research Campus in the Current Issue of Nature Methods. Dr. Lavis and his team introduced a new group of red shifted dye called 'Janelia Fluor' (JF) group. They outlined a general rubric that directly correlates the lactone–zwitterion equilibrium constant (KL–Z) to performance in biological environments. They compared a series of JF rhodamines with different fluorophoric systems. They developed a rubric to relate the performance of simple rhodamine dyes to a single parameter, KL–Z (Figure below), and discovered an inverse correlation between KL–Z and λabs. They hope these new findings help us to design fine-tuned dyes for specific biological applications. Such a great study!
Phenomenological plot categorizing the properties of different dyes based on KL–Z (left) and plot of KL–Z vs. λabs for JF dyes and general tuning strategies for dyes with short or long λabs.