[ 99m Tc]Technetium-Labeled Niosomes: Radiolabeling, Quality Control, and In Vitro Evaluation.

The aim of this research was to develop technetium-99m ([ 99m Tc]Tc)-radiolabeled niosomes and evaluate the cancer cell incorporation capacity of radiolabeled niosomes. For this purpose, niosome formulations were developed by film hydration method, and prepared niosomes were characterized to particle size, polydispersity index (PdI), ζ-potential value, and image profile. Then, niosomes were radiolabeled with [ 99m Tc]Tc using stannous salts (chloride) as a reducing agent. The radiochemical purity (RP) and stability in different mediums of the niosomes were assessed by ascending radioactive thin-layer chromatography (RTLC) and radioactive ultrahigh-performance liquid chromatography (R-UPLC) methods. Also, the partition coefficient value of radiolabeled niosomes was determined. The cell incorporation of [ 99m Tc]Tc-labeled niosome formulations, as well as reduced/hydrolyzed (R/H)-[ 99m Tc]NaTcO 4 in the HT-29 (human colorectal adenocarcinoma) cells, was then assessed. According to the obtained results, the spherical niosomes had a particle size of 130.5 ± 1.364 nm, a PdI value of 0.250 ± 0.023, and a negative charge of -35.4 ± 1.06 mV. The niosome formulations were effectively radiolabeled with [ 99m Tc]Tc using 500 μg mL -1 stannous chloride for 15 min, and RP was found to be over 95%. [ 99m Tc]Tc-niosomes showed good in vitro stability in every system for up to 6 h. The log  P value of radiolabeled niosomes was found as -0.66 ± 0.02. Compared to R/H-[ 99m Tc]NaTcO 4 (34.18 ± 1.56%), the incorporation percentages of [ 99m Tc]Tc-niosomes (88.45 ± 2.54%) were shown to be higher in cancer cells. In conclusion, the newly developed [ 99m Tc]Tc-niosomes showed good prototype for potential use in nuclear medicine imaging in the near future. However, further investigations, such as drug encapsulation and biodistribution studies, should be performed, and our studies are continuing.