Development of a method for the preparation of zirconium-89 radiolabelled chitosan nanoparticles as an application for leukocyte trafficking with positron emission tomography

Highlights: • Zirconium-89 radiolabelled chitosan nanoparticles prepared for cell labelling. • Uptake and efflux of zirconium-89 chitosan nanoparticles studied in leukocyte cells. • Two step cell uptake mechanism proposed. - Abstract: Positron Emission Tomography is an attractive imaging modality for monitoring the migration of cells to pathological tissue. We evaluated a new method for radiolabelling leukocytes with zirconium-89 (⁸⁹Zr) using chitosan nanoparticles (CN, Z-average size 343 ± 210 nm and zeta potential +46 ± 4 mV) as the carrier. We propose that cell uptake of ⁸⁹Zr-loaded CN occurred in a two-step process; cell membrane interaction with ⁸⁹Zr-loaded CN was followed by a slower cell internalisation step.