ABSTRACT
Correction for 'Zn2SnO4:Cr,Eu ultra-small nanoparticles as new near infrared-emitting persistent luminescent nanoprobes for cellular and deep tissue imaging at 800 nm' by Hongwu Zhang et al., Nanoscale, 2017, 9, 8631-8638.
ABSTRACT
In vivo luminescent imaging in the second biological window (1000-1400 nm, NIR-II) has attracted increasing attention since it can provide high sensitivity to deep tissue in vivo imaging. Herein, we synthesized approximately 10-15 nm-sized NIR-II luminescent nanoparticles (CaF2:Nd3+ NPs). Furthermore, co-doped Y3+ was utilized to enhance the NIR-II luminescence of the CaF2:Nd3+ NPs via breaking the aggregation of Nd3+. The appearance of a (200) diffraction peak and the broadening of the interplanar spacing of the (111) plane both showed that the incorporated Y3+ can dissolve in CaF2 by occupying the Ca2+ sites to form a CaF2-YF3 solid solution. In particular, the addition of Y3+ can greatly enhance the of the NIR-II luminescence of CaF2:Nd3+ NPs. When the Y3+ doped concentration reached 0.30, the luminescence intensity of CaF2:Y3+,Nd3+ NPs was about 65 times that of CaF2:Nd3+ NPs. In addition, the quantum yield of Ca0.68Y0.30Nd0.02F2.32 NPs was 9.30% under the excitation of an 808 nm laser with 483 mW cm-2 power, which was about 3 times higher than that of CaF2:Nd3+ NPs (3.10%). The in vivo imaging results revealed that the in vivo imaging intensity of Ca0.68Y0.30Nd0.02F2.32 NPs was about 2.38-fold stronger than that of Ca0.98F2.02:Nd3+ 0.02 NPs. All of these results indicated that CaF2:Y3+,Nd3+ NPs can be regarded as potential in vivo imaging probes for biological imaging.
ABSTRACT
Until now, the afterglow emissions of most developed near infrared (NIR)-emitting persistent luminescent nanoparticles (NPLNPs) were located at approximately 700 nm, at the edge of the first tissue transparency window (from 650 to 900 nm), which resulted in relatively low tissue penetration and signal-to-noise ratio (SNR) for in vivo imaging. Herein, 5 nm ZnSn2O4:Cr,Eu (ZSO) NPLNPs with NIR afterglow emission at 800 nm are synthesized via a direct aqueous-phase synthesis method. The longer NIR afterglow emission of ZSO NPLNPs can easily penetrate approximately 3 cm of pork tissue. Furthermore, even though the backbones blocked part of the NIR afterglow light, high SNR (25.5) in vivo images of the backs of mice can be observed and can be maintained for more than 15 min. The ZSO nanoprobes conjugated with folic acid exhibited excellent in vitro and in vivo tumor targeting capacity, which was advantageous for accurate tumor diagnosis. More importantly, the ZSO NPLNPs can be re-excited in situ and in vivo using NIR light to realize renewable near-infrared persistent luminescence in vivo, which was helpful for very long term and higher SNR in vitro and in vivo imaging.