Red-shifted bioluminescence Resonance Energy Transfer: Improved tools and materials for analytical in vivo approaches

Bioluminescence Resonance Energy Transfer (BRET) has been proven as a highly sensitive optical transduction system for bio-imaging and a variety of analytical approaches. Its use for quantitative imaging of physiological changes in vivo or in vitro of blood samples has been hindered due to signal attenuation of the blue/green light-emitting bioluminescence agents. The field of luciferase-luciferin pairs as well as energy accepting molecules such as fluorescent proteins, organic dyes and quantum dots is rapidly growing. In the present article, progress in the development of red-shifted BRET components that are less affected by light-attenuation and scattering are analysed. Recently developed NanoLuc variants, Firefly luciferases and luciferin analogues greatly expand options for efficient red-shifted BRET systems. These luciferases in combination with new large Stokes-shifted fluorophores allow quantitative imaging in deep-tissues of living subjects. In addition, we point towards yet untested BRET strategies to assist those developing new analytical techniques and BRET tools. (C) 2019 Commonwealth Scientific and Industrial Research Organisation (CSIRO). Published by Elsevier B.V.