Fig. 13

Minimizing the tissue-heating effect through new sensitizer ion Nd₃₊: a Scheme of the Nd³⁺-Yb³⁺-activator energy-transfer process by introducing Nd³⁺/Yb³⁺ co-doped shell and in vivo UC imaging of a nude mouse subcutaneously injected with Er@Nd NPs. Laser irradiation with lasers at 980 and 808 nm, both with a power density of 200 mW/cm². Adapted with permission from Wang et al.⁴⁰ (copyright 2013 American Chemical Society). b Schematic illustration of the proposed energy-transfer mechanisms in the quenching-shield sandwich-structured UCNs upon 800 nm excitation. c Proposed energy-transfer mechanisms in the quenching-shield sandwich nanoparticle upon 800 nm diode-laser excitation. Adapted with permission from Zhong et al.¹⁰⁹ (copyright 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)