Figure 15.

(A) Synthetic scheme and characterization of radiolabeled gold nanoparticles (RIe-AuNPs). Schematic of synthesis of RIe-AuNPs. Modification of the chemical structures of adenine, using sulpho-SHPP for conjugation of a phenol moiety, allows radiolabeling with [¹²⁵I]NaI via aromatic electrophilic substitution. Adapted with permission from Lee et al., ref (209). Copyright 2016 Springer Nature under CC License [https://creativecommons.org/licenses/by/4.0/]. (B) Schematic showing the radiolabeling method used for gold nanoparticles used to radiolabel CAR T-cells. A DOTA-thioctic acid bioconjugate was used to bind to the gold nanoparticle surface. Adapted with permission from Bhatnagar et al., ref (210). Copyright 2012 Oxford University Press. (C) PET/MRI images of ¹⁸F-labeled Fe₃O₄@Al(OH)₃ NPs (left) and of mMSCs labeled with ¹⁸F-labeled Fe₃O₄@Al(OH)₃ (right). Bone uptake can be observed in the images. Adapted with permission from Belderbos et al., ref (214). Copyright 2020 Springer Nature under CC License [https://creativecommons.org/licenses/by/4.0/]. (D) A single MDA-MB-231 breast cancer cell radiolabeled with ⁶⁸Ga-labeled silica nanoparticles (70 Bq) was injected via butterfly catheter into the tail vein and imaged using PET/CT imaging. Dynamic trajectory reconstructed from the same list-mode data tracks the single cell as it travels through the bloodstream and arrests in the lungs (right). Adapted with permission from Jung et al., ref (217). Copyright 2020 Springer Nature. (E) Panels demonstrating the endocytic uptake a combination of SiNPs nanoparticles, heparin and protamine for the direct cell labeling of CAR T-cells. Top row is PET imaging of a vial containing the cells and the silica nanotag with and without protamine and heparin. Bottom row shows fluorescence microscopy of CAR T-cells stained with DAPI for nuclei and of the NIR fluorescent SiNP nanotags; with and without protamine and heparin. It is clear protamine and heparin allows increased uptake of the nanoprobe. Adapted with permission from Harmsen et al., ref (218). Copyright 2020 Elsevier.