Fluorinated Hafnium and Zirconium Coenable the Tunable Biodegradability of Core–Multishell Heterogeneous Nanocrystals for Bioimaging
Qiang Wang, Hang Shangguan, Hongtao Yu, Xinli Rong, Boyi Zhou, Zhengyang Tang, Chunsheng Li, Shuang Liu, Lu Yong, Jiating Xu
Abstract
Upconversion (UC)/downconversion (DC)-luminescent lanthanide-doped nanocrystals (LDNCs) with near-infrared (NIR, 650–1700 nm) excitation have been gaining increasing popularity in bioimaging. However, conventional NIR-excited LDNCs cannot be degraded and eliminated eventually in vivo owing to intrinsic “rigid” lattices, thus constraining clinical applications. A biodegradability-tunable heterogeneous core–shell–shell luminescent LDNC of Na 3 HfF 7:Yb,Er@Na 3 ZrF 7:Yb,Er@CaF 2:Yb,Zr (abbreviated as HZC) was developed and modified with oxidized sodium alginate (OSA) for multimode bioimaging. The dynamic “soft” lattice-Na 3 Hf(Zr)F 7 host and the varying Zr 4+ doping content in the outmoster CaF 2 shell endowed HZC with tunable degradability. Through elaborated core–shell–shell coating, Yb 3+ /Er 3+ -coupled UC red and green and DC second near-infrared (NIR-II) emissions were, respectively, enhanced by 31.23-, 150.60-, and 19.42-fold when compared with core nanocrystals. HZC generated computed tomography (CT) imaging contrast effects, thus enabling NIR-II/CT/UC trimodal imaging. OSA modification not only ensured the exemplary biocompatibility of HZC but also enabled tumor-specific diagnosis. The findings would benefit the clinical imaging translation of LDNCs.