Trivalent rare-earth (RE3+) ions doped luminescent nanocrystals (NCs) of various compositions, albeit most of their bulk counterparts have been well studied previously, have attracted reviving interest and come to the forefront in nanophotonics owing to their potential applications in diverse fields such as biolabeling and bioimaging.These Ln3+ doped NCs show superior features including narrow emission band widths, long luminescence lifetime, low toxicity and high resistance to photobleaching, making them highly suitable for use as alternatives to organic fluorescent dyes or quantum dots (QDs) for various biological applications.