Nanoparticles for Cerenkov and Radioluminescent Light Enhancement for Imaging and Radiotherapy

Abstract

Cerenkov luminescence imaging and Cerenkov photodynamic therapy have been developed in recent years to exploit the Cerenkov radiation (CR) generated by radioisotopes, frequently used in Nuclear Medicine, to diagnose and fight cancer lesions. For in vivo detection, the endpoint energy of the radioisotope and, thus, the total number of the emitted Cerenkov photons, represents a very important variable and explains why, for example, 68Ga is better than 18F. However, it was also found that the scintillation process is an important mechanism for light production. Nanotechnology represents the most important field, providing nanosctructures which are able to shift the UV-blue emission into a more suitable wavelength, with reduced absorption, which is useful especially for in vivo imaging and therapy applications. Nanoparticles can be made, loaded or linked to fluorescent dyes to modify the optical properties of CR radiation. They also represent a useful platform for therapeutic agents, such as photosensitizer drugs for the production of reactive oxygen species (ROS). Generally, NPs can be spaced by CR sources; however, for in vivo imaging applications, NPs bound to or incorporating radioisotopes are the most interesting nanocomplexes thanks to their high degree of mutual colocalization and the reduced problem of false uptake detection. Moreover, the distance between the NPs and CR source is crucial for energy conversion. Here, we review the principal NPs proposed in the literature, discussing their properties and the main results obtained by the proponent experimental groups.

Psoralen as a Photosensitizers for Photodynamic Therapy by Means of In Vitro Cherenkov Light

“…Psoralen derivatives with a higher efficiency [ 41 ] or other photosensitizers better fitting the emission spectrum of the Cherenkov light [ 42 ] could be used. Furthermore, nanoparticles that supply a light amplification or a wavelength shift toward the red spectrum could be examined [ 25 , 33 , 43 , 44 ]. Thereby, enhancement of the effect by a factor of 3000 has been described [ 45 ].…”

PET/Fluorescence Imaging: An Overview of the Chemical Strategies to Build Dual Imaging Tools

“…On the other hand, CLI is made possible by the fact that a significant fraction of the β + particles emitted by positron emitters have an energy (Table ) above the Cerenkov threshold in tissue (219 keV) and therefore are able to produce a detectable amount of Cerenkov radiation. This is why radiotracers labeled with fluorine-18 or carbon-11 like [ 18 F]­FDG, − [ 18 F]­FET, [ 18 F]­FLT, [ 11 C]­choline, or peptides, proteins, antibodies, and nanovectors labeled with iodine-124 − or radiometals (copper-64, , gallium-68, − zirconium-89 − ) have been used for bimodal PET/FLI. Even if several preclinical proofs of concept have been established today, CLI suffers of several weaknesses.…”

A brief review of reporter gene imaging in oncolytic virotherapy and gene therapy

“… 141 , 142 CLI is attractive due to its optical nature, the detection instrumentation for which is much cheaper than RI modalities, and many of the most suitable radioisotopes are already clinically approved. 120 , 140 , 143 Several isotopes permit simultaneous radiotherapy, RI, and CLI. 144 The primary limitations of CLI are low light yield and the high absorption rate of ultraviolet-to-blue light in tissue.…”