Iridium complex nanoparticle mediated radiopharmaceutical-excited phosphorescence imaging

Abstract

We firstly perpared liposome coated [Ir(pq)2(bpy)]Cl (Ir@liposome) as a transducer for radiopharmaceutical (18F-FDG) excited phosphorescence imaging (REPI).

Shining New Light on Biological Systems: Luminescent Transition Metal Complexes for Bioimaging and Biosensing Applications

“…Wang, Yang, Yang, and co-workers have utilized 18 F-FDG as an internal radioactive source to excite an iridium(III) complex (202) (Chart 93) for radiopharmaceutical-excited phosphorescence imaging (REPI). 393 The iridium(III) complex acts as a transducer to convert the UV-to-blue Cherenkov radiation emitted by 18 F-FDG into orange-red phosphorescence. This method overcomes the limited penetration depth of Cherenkov radiation, allowing background-free imaging with improved penetration depth in vivo.…”

“…(c) The signal-to-noise ratio ((tumor signal intensity – background signal intensity)/background signal intensity) measured with different in vivo optical imaging techniques. Adapted with permission from Ref . Copyright 2019 Royal Society of Chemistry.…”

Cerenkov radiation-activated probes for deep cancer theranostics: a review

“…Table 1 lists radioisotopes that emit energy over the CR threshold, such that they induce CR emission [23]. Positron emitters in clinical use of positron emission tomography (PET) include 18 F, 64 Cu, 68 Ga, 74 As, 89 Zr, and 124 I. Electron emitters in clinical use include 32 P, 90 Y, 131 I, 177 Lu, and 198 Au, which can also be used for radiotherapy of cancer.…”

“…[Ir(pq)2(bpy)]Cl has been encapsulated into liposomes to formulate Ir@liposome, then irradiated with 18 F-FDG, leading to imaging of deep tissue with a high signal-to-noise ratio [74]. Pluronic F127 silica NPs doped with five dyes have been constructed to absorb strongly in the visible range, leading to the efficient shift of CR towards NIR emission with a quantum yield of 0.12 [75].…”

Cerenkov radiation-mediated in situ activation of silicon nanocrystals for NIR optical imaging

“…10,16,17 Despite the challenge of the blue-weighted spectrum, nanophosphor-mediated CR provides a way to enhance the luminescence signal by Cerenkov resonance energy transfer (CRET), such as in quantum dots, 18,19 gold clusters, 20 persistent luminescence nanoparticles, 21,22 and organic nanoparticles. 20,23 All these mentioned nanophosphors have the excitation spectra between 200 nm and 500 nm, which can highly efficiently utilize the energy of CR for photon transfer. As SiNCs also have a very strong ultraviolet (UV) excitation spectrum, 9 it is anticipated that CR from radionuclides can be used as an effective excitation source for SiNCs.…”