An aptamer-based, fluorescent and radionuclide dual-modality probe.

Aptamers which are promising and effective molecular probes, can deliver either fluorescent materials or radionuclides to tumors. This study aimed to develop a novel both fluorescent and radionuclide dual-modality probe based on a truncated aptamer and evaluate its stability and binding affinities in vitro. The aptamer JHIT2 with binding specifically to HepG2 cells was previously generated by Cell-SELEX. Using mfold and RNAstructure software to predict the secondary structure folded by a middle random sequence to truncate the primer sequences at both ends of the aptamer JHIT2 to yield the aptamer JHIT2e, with a similar secondary structure to JHIT2 and the same specificity and affinity as JHIT2. Attaching carboxyfluorescein (FAM) readily to the aptamer JHIT2e and then attaching iodine-131 to the FAM moiety which has multiple sites for iodine labeling to develop a novel both fluorescent and radionuclide dual-modality probe, termed 131I-FAM-JHIT2e. Cell uptake and fluorescence imaging assays in vitro confirmed that 131I-FAM-JHIT2e had both FAM fluorescence signal and radio-activity signal and maintained specific binding ability to the human hepatoma cell line HepG2. This work formed a basis for aptamer-based, dual-modality imaging probe that contains both fluorescent and radionuclide tags, which also is potential for theranostics. Image 1 • Truncating the primer sequences at both ends of aptamer JHIT2 to yield JHIT2e. • JHIT2e has the same specificity and affinity as JHIT2. • 131I-FAM-JHIT2e was prepared by attaching iodine-131 to FAM of FAM-JHIT2e. • 131I-FAM-JHIT2e has both FAM fluorescence and radio-activity signal. • 131I-FAM-JHIT2e has specific binding ability to HepG2 cells. [ABSTRACT FROM AUTHOR]