Radio-isotope doped copper sulfide nanoparticles: Labeling efficiency, stability, pharmacokinetic, and biodistribution

Objectives Radio-isotope labeling techniques have been widely used in evaluating in vivo biodistribution of nanoparticles (NPs). High radiolabeling efficiency and high radio-conjugate stability are essential features for successful radiolabeling of NPs. The purpose of this study was to synthesize copper sulfide (CuS) NPs doped with tracer amount of 111In and 68Ga for potential SPECT and PET imaging study of CuS NPs.

Methods [111In]CuS NPs and [68Ga]CuS NPs were prepared by doping CuS with the respective radioisotope during the formation of NPs. The label efficiencies and the stabilities of these chelator-free NPs in various mediums were investigated by instant thin-layer chromatographic (ITLC) method. Both [111In]CuS NPs and [68Ga]CuS NPs were evaluated for their pharmacokinetics and biodistribution.

Results [111In]CuS NPs and [68Ga]CuS NPs showed high label efficiency (>95%) and possessed excellent stability in various mediums up to 72 h. Pharmacokinetics study with [111In]CuS showed rapid clearance of the NPs in the body after i.v. injection. Biodistribution experiments with [111In]CuS in mice reveal high uptake of the NPs in the liver, kidney, and spleen.

Conclusions [111In]CuS NPs and [68Ga]CuS NPs are suitable for pharmacokinetics and biodistribution study. These chelator-free radiolabeled NPs may also be used in future nuclear imaging studies. The reported radioisotope doping method represents a new NP radiolableling technique for biomedical applications.