Abstract
Solution-phase and intracellular biosensing has substantially enhanced our understanding of molecular processes foundational to biology and pathology. Optical methods are favored because of the low cost of probes and instrumentation. While chromatographic methods are helpful, fluorescent biosensing further increases sensitivity and can be more effective in complex media. Resonance energy transfer (RET)-based sensors have been developed to use fluorescence, bioluminescence, or chemiluminescence (FRET, BRET, or CRET, respectively) as an energy donor, yielding changes in emission spectra, lifetime, or intensity in response to a molecular or environmental change. These methods hold great promise for expanding our understanding of molecular processes not just in solution and in vitro studies, but also in vivo, generating information about complex activities in a natural, organismal setting. In this review, we focus on dyes, fluorescent proteins, and nanoparticles used as energy transfer-based optical transducers in vivo in mice; there are examples of optical sensing using FRET, BRET, and in this mammalian model system. After a description of the energy transfer mechanisms and their contribution to in vivo imaging, we give a short perspective of RET-based in vivo sensors and the importance of imaging in the infrared for reduced tissue autofluorescence and improved sensitivity.
Highlights
In recent years, in vivo luminescence biosensing has gained attention as a means to non-invasively probe living animals under physiological conditions with subcellular resolution [1]
Kang et al use bioresorbable silicon for continuous monitoring of intracranial pressure and temperature in rats [5]; Unruh et al demonstrate poly(2-hydroxyethyl methacrylate) hydrogel-based implantable sensors for the real-time measurement of glucose in pigs [6]; and Chang et al implement nanozymes—i.e., nanoparticles with enzymatic activity mimicking natural enzymes [7]—to monitor dynamic changes in glucose concentration in the striatum of living rats [8]. We expand on this literature survey by detailing examples of resonance energy transfer-based in vivo sensors sensitive enough to probe biological tissues at the nanometer scale
Muñoz-Losa et al showed through molecular dynamics simulations that when the molecules are in an isotropic set of relative orientations, the ideal dipole approximation is valid at donor–acceptor distances as low as ca. 2 nm [9,10]
Summary
In vivo luminescence biosensing has gained attention as a means to non-invasively probe living animals under physiological conditions with subcellular resolution [1]. Kang et al use bioresorbable silicon for continuous monitoring of intracranial pressure and temperature in rats [5]; Unruh et al demonstrate poly(2-hydroxyethyl methacrylate) (polyHEMA) hydrogel-based implantable sensors for the real-time measurement of glucose in pigs [6]; and Chang et al implement nanozymes—i.e., nanoparticles with enzymatic activity mimicking natural enzymes [7]—to monitor dynamic changes in glucose concentration in the striatum (brain) of living rats [8] We expand on this literature survey by detailing examples of resonance energy transfer-based in vivo sensors sensitive enough to probe biological tissues at the nanometer scale.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
