Long-term two-photon neuroimaging with a photostable AIE luminogen.

In neuroscience, fluorescence labeled two-photon microscopy is a promising tool to visualize ex vivo and in vivo tissue morphology, and track dynamic neural activities. Specific and highly photostable fluorescent probes are required in this technology. However, most fluorescent proteins and organic fluorophores suffer from photobleaching, so they are not suitable for long-term imaging and observation. To overcome this problem, we utilize tetraphenylethene-triphenylphosphonium (TPE-TPP), which possesses aggregation-induced emission (AIE) and two-photon fluorescence characteristics, for neuroimaging. The unique AIE feature of TPE-TPP makes its nanoaggregates resistant to photobleaching, which is useful to track neural cells and brain-microglia for a long period of time. Two-photon fluorescence of TPE-TPP facilitates its application in deep in vivo neuroimaging, as demonstrated in the present paper.