Metal complexes possess outstanding photophysical properties, such as large Stokes shifts, good photostability, long luminescent lifetimes, two-photon luminescent properties and so on. During the past years, metal complexes have attracted intensive research interest in biological imaging for their excellent properties. Moreover, they also have been applied for real-time tracking the cellular dynamics during a series of biological events. In this review, the essential requirements of the metal complexes for cellular dynamic real-time tracking are summarized. The specificity, the good photostability and the low cytotoxicity of metal complexes are the key factors for real-time tracking. According to the optical properties, the imaging modes (single photon imaging, multiphoton imaging, luminescence lifetime imaging) of the metal complexes for real-time tracking are outlined. Furthermore, the advantages and disadvantages of the imaging modes during cellular real-time dynamic tracking are compared. As for the objects of real-time tracking, the article focuses on the organelles and the microenvironment factors. The real-time dynamic tracking of organelles (mitochondria, lysosomes, lipid droplets) and microenvironment factors (hypoxia, pH, viscosity, temperature, polarity) are detailed overviewed and systemized the related research directions. In the end, some existing problems and the challenges of the metal complexes during real-time tracking are presented and discussed.
Contents
1 Introduction
2 The essential requirements of real-time tracking probes
3 The imaging modes of transition metal complexes
4 Cellular dynamics tracking
4.1 Tracking the dynamics of organelles
4.2 Tracking the dynamics of microenvironment factors
5 Conclusion and outlook