Rethinking Thin-Layer\nChromatography for Screening\nTechnetium-99m Radiolabeled Polymer Nanoparticles

Thin-layer chromatography (TLC) is commonly employed\nto screen\ntechnetium-99m labeled polymer nanoparticle batches for unreduced\npertechnetate and radio-colloidal impurities. Although this method\nis widely accepted, our findings applying radiolabeled PLGA/PLA–PEG\nnanoparticles underscore its lack of transferability between different\nsettings and its limitations as a standalone quality control tool.\nWhile TLC profiles may appear similar for purified and radiocolloid\ncontaining nanoparticle formulations, their in vivo behavior can vary\nsignificantly, as demonstrated by discrepancies between TLC results\nand single-photon emission computed tomography (SPECT) and biodistribution\ndata. This highlights the urgent need for a case-by-case evaluation\nof TLC methods for each specific nanoparticle type. Our study revealed\nthat polymeric nanoparticles cannot be considered analytically uniform\nentities in the context of TLC analysis, emphasizing the complex interplay\nbetween nanoparticle composition, radiolabeling conditions, and subsequent\nbiological behavior.