Dendrimer-Based Fluorescent Indicators: In Vitro and In Vivo Applications

BACKGROUND: The development of fluorescent proteins and synthetic molecules whose fluorescence properties are controlled by the environment makes it possible to monitor physiological and pathological events in living systems with minimal perturbation. A large number of small organic dyes are available and routinely used to measure biologically relevant parameters. Unfortunately their application is hindered by a number of limitations stemming from the use of these small molecules in the biological environment. PRINCIPAL FINDINGS: We present a novel dendrimer-based architecture leading to multifunctional sensing elements that can overcome many of these problems. Applications in vitro, in living cells and in vivo are reported. In particular, we image for the first time extracellular pH in the brain in a mouse epilepsy model. CONCLUSION: We believe that the proposed architecture can represent a useful and novel tool in fluorescence imaging that can be widely applied in conjunction with a broad range of sensing dyes and experimental setups

Donor-two-acceptor dye design:a distinct gateway to NIR fluorescence

\u3cp\u3eThe detection of chemical or biological analytes upon molecular reactions relies increasingly on fluorescence methods, and there is a demand for more sensitive, more specific, and more versatile fluorescent molecules. We have designed long wavelength fluorogenic probes with a turn-ON mechanism based on a donor-two-acceptor π-electron system that can undergo an internal charge transfer to form new fluorochromes with longer π-electron systems. Several latent donors and multiple acceptor molecules were incorporated into the probe modular structure to generate versatile dye compounds. This new library of dyes had fluorescence emission in the near-infrared (NIR) region. Computational studies reproduced the observed experimental trends well and suggest factors responsible for high fluorescence of the donor-two-acceptor active form and the low fluorescence observed from the latent form. Confocal images of HeLa cells indicate a lysosomal penetration pathway of a selected dye. The ability of these dyes to emit NIR fluorescence through a turn-ON activation mechanism makes them promising candidate probes for in vivo imaging applications.\u3c/p\u3