Background and Aims: The aim of this study was to synthesize antibody-conjugated radioactive(thorium oxide) nanoparticles (ACRNPs) and folic acid-conjugated radioactive nanoparticles (FACRNPs).

Materials and Methods: After synthesis of nanoparticles, blood samples from CLL patients and normal subjects were obtained, and their mononuclear cells were isolated by Ficoll method. To evaluate cytotoxicity, serial concentrations of ACRNPs and FACRNPs were separately added to cancerous and normal mononuclear cells, incubated for 12 hours at 37 ºC, and then different assays including MTT, MTS, cell metabolic, and ATP assay were carried out. On the other hand, the mononuclear cells were captured by anti-CD20 antibody in the polystyrene tube, and then ACRNPs and FACRNPs were separately added to them. After washing, the radioactivity (counts per minute (CPM)) of each tube was read.

Results: The images obtained from electron microscopy showed that both ACRNPs and FACRNPs were spherical with the same size (near 50 nm). This study obviously demonstrated a direct relationship between CPM and concentration of ACRNPs and FACRNPs in both cancerous and normal samples. Also, there was a significant difference between CPM of cancerous and normal samples after treatment with ACRNPs or FACRNPs (P<0.05). However, an inverse relationship between concentration of ACRNPs or FACRNPs and their toxicity. Was found Significant difference was observed between toxicity of ACRNPs or FACRNPs on the cancerous and normal samples (P<0.05).

Conclusions: It can be concluded that both ACRNPs and FACRNPs have good efficacy for detection of CLL cells.