Lanthanides are chemical elements in the rare earth family that have formidable luminescence properties. For this reason, they are essential components in many of today's technologies (lasers, lighting devices, screens, anti-counterfeiting inks for banknotes, etc). Their luminescence properties are very specific compared with those of fluorescent organic molecules and could be of interest for applications in biological or medical microscopy imaging.
In this article, researchers at LCBM [Collaboration] describe a new step towards this goal. Lanthanide emission is distinguished from that of fluorescent organic molecules by very fine emission lines, at fixed wavelengths characteristic of each lanthanide, and by very long light emission, of the order of microseconds to milliseconds instead of nanoseconds for natural luminescence from cells or biological fluids. Their emission can therefore be easily distinguished from endogenous biological luminescence during microscopy experiments, which is of major interest. Lanthanides, in the form of cations, are toxic and must be encapsulated in a molecule – this is referred to as a metal complex or lanthanide complex - if they are to be used in living organisms. Until now, the difficulty with lanthanide complexes has been the lack of control over their penetration into cells and their distribution within them, with most of the lanthanide complexes described in the scientific literature as capable of penetrating cells ending up in the lysosomes, which is the cells' dustbin. Researchers at LCBM have grafted lanthanide complexes onto peptides that are capable of entering living cells and reaching the cytosol to distribute themselves uniformly throughout them. Microscopic images were thus obtained, showing the distribution of the lanthanide throughout the cell.
This study is a first step towards the creation and use by biologists of intelligent probes for microscopy, based on lanthanides and capable of detecting and locating molecules of interest present in cells and better understanding their metabolism.
Microscope study of cells and identification of the characteristic emission of terbium, one of the 15 lanthanides.
Photo: Christian Morel / LCBM / CNRS
Microscopic images: cells containing terbium emitting green light (left); cells containing europium emitting red light (right).
Fundings
- Aviesan, programme ITMO Cancer PCSI
- Projet ANR RECODNA
- CEA, programme FOCUS Biomarqueurs
Collaboration
- École Normale Supérieure, Lyon
- Institut pour l’Avancée des Biosciences, Grenoble