Neodymium-Doped LaF 3 Nanoparticles for Fluorescence Bioimaging in the Second Biological Window

The future perspective of fluorescence imaging for real in vivo application are based on novel efficient nanoparticles which is able to emit in the second biological window (1000-1400 nm). In this work, the potential application of Nd3+-doped LaF3 (Nd3+:LaF3) nanoparticles is reported for fluorescence bioimaging in both the first and second biological windows based on their three main emission channels of Nd3+ ions: (F3/2I9/2)-F-4-I-4, (F3/2I11/2)-F-4-I-4 and (F3/2I13/2)-F-4-I-4 that lead to emissions at around 910, 1050, and 1330 nm, respectively. By systematically comparing the relative emission intensities, penetration depths and subtissue optical dispersion of each transition we propose that optimum subtissue images based on Nd3+:LaF3 nanoparticles are obtained by using the (F3/2I11/2)-F-4-I-4 (1050 nm) emission band (lying in the second biological window) instead of the traditionally used (F3/2I9/2)-F-4-I-4 (910 nm, in the first biological window). After determining the optimum emission channel, it is used to obtain both in vitro and in vivo images by the controlled incorporation of Nd3+:LaF3 nanoparticles in cancer cells and mice. Nd3+:LaF3 nanoparticles thus emerge as very promising fluorescent nanoprobes for bioimaging in the second biological window.