In present work, carbon nanomaterials (CNMs) are investigated as potential carriers of 68Ga, which is widely used in positron emission tomography (PET) in nuclear medicine. Sorption behavior of 68Ga was studied onto CNMs of various structures and chemical compositions: nanodiamonds (ND), reduced graphite oxide (rGiO) and multi-walled carbon nanotubes (MWCNT), as well as their oxidized (ND-COOH) or reduced (rGiO-H, MWCNT-H) forms. The physicochemical properties of the nanoparticles were determined by high resolution transmission electron microscopy, x-ray photoelectron spectroscopy, dynamic light scattering and potentiometric titration. The content of 68Ga in the solutions during the study of sorption was determined by gamma-ray spectrometry. The highest degree of 68Ga sorption was observed on ND and ND-COOH samples, and the optimal sorption conditions were determined: an aqueous solution with a pH of 5-7, m/V ratio of 50 μg/mL and a room temperature (25 °C). The 68Ga@ND and 68Ga@ND-COOH conjugates were found to be stable in a model blood solution-phosphate-buffered saline with a pH of 7.3, containing 40 g/L of bovine serum albumin: 68Ga desorption from these samples in 90 minutes was no more than 20% at 25 °С and up to 30% at 37 °С. Such a quantity of desorbed 68Ga does not harm the body and does not interfere with the PET imaging process. Thus, ND and ND-COOH are promising CNMs for using as carriers of 68Ga for PET diagnostics.
Keywords: 68Ga; carbon nanomaterials (CNMs); multi-walled carbon nanotubes (MWCNT); nanodiamond (ND); positron–emission tomography (PET); reduced graphite oxide (rGiO); sorption and desorption; surface functionalization.