Trivalent lanthanide ions (Ln3+) doped inorganic nanocrystals (NCs) have currently attracted reviving interest
and come to the forefront in nanophotonics owing to their potential applications in diverse fields such as luminescent
biodetection and bioimaging. As an alternative to conventional biolabels, Ln3+-doped NCs show superior features
including large stokes shift, multicolor fine-tuning, narrow emission band widths, high photostability, and low toxicity.
Particularly, the long-lived luminescence and distinct upconversion (UC) of Ln3+-doped NCs are desirable for various
bioapplications. The long-lived luminescence of Ln3+ combined with time-resolved technique can efficiently suppress the
interference from short-lived background, resulting in a high signal-to-noise ratio (S/N) and background-free
measurements. Near-infrared excited UC emissions of Ln3+ can bring no autofluorescence and no photodamage to cells or
tissues, and thus UC NCs have been regarded as one of the most useful in vivo optical contrast agents. In this review, we
outline the most recent development of Ln3+-doped NCs as biolabels from the controlled synthesis and surface
functionalization of NCs to their bioapplications in heterogeneous and homogeneous biodetection as well as in vitro and
in vivo bioimaging.
Keywords: Biodetection, bioimaging, biolabels, lanthanide, nanocrystals, luminescent biodetection, upconversion (UC), signal-to-noise ratio, bioimaging, autofluorescence
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Published on: 01 July, 2012
Page: [580 - 594]