Fig. 3: Intravital fluorescence imaging of cerebrovascular structure by using different RENPs.

a Schematic diagram of the energy-transfer process of Er-based RENPs doped with and without Ce³⁺ ions (left). Fluorescence images of cerebral vessels with Ce³⁺ doped Er-RENPs (right). Reprinted with permission from ref. ⁵³. Copyright 2017 Yeteng Zhong et al. b Energy level diagrams of the self-sensitized nanoparticles (left). Intravital fluorescence imaging of cerebral vessels after injection of NaErF₄:Yb³⁺@NaLuF₄ core/shell nanocrystals (right). Reprinted with permission from ref. ⁵⁶. Copyright 2018 Wiley-VCH GmbH. c Energy-transfer mechanisms of the NaErF₄:Tm³⁺@NaLuF₄ core-shell nanoparticles (left). The cerebrovascular images of the mice with a cranial window and with an intact skull under NIR excitation (right). Reprinted with permission from ref. ⁵⁹. Copyright 2021 The Royal Society of Chemistry