Abstract: Objective To develop a CD20 aptamer that may potentially serve as a tumor-homing ligand for targeted therapy against Non-Hodgkin’s lymphoma (NHL). Methods A single-stranded 59nt DNA library containing 21nt random oligonucleotides was synthesized. A new CD20 aptamer termed CE4-1 was developed with SELEX technique, using a CD20 epitope as the target. Flow cytometry was performed to monitor the enrichment of the selected DNA pool, and the binding properties of CE4-1 towards CD20 structure and CD20-positive cells. The structure of CE4-1 was predicted by MFold software. Results The DNA aptamer CE4-1 could selectively bind with CD20 structure and CD20-positive cells, with minimal cross reactivity to BSA and CD20-negative cells. Additionally, trypsin treatment greatly reduced the binding of CE4-1 to CD20-positive cells. Conclusions A novel CD20 aptamer CE4-1 could recognize CD20 structure and CD20-positive cells selectively, which may have application potentials in targeted therapy against the CD20-positive tumors.

Key words: aptamer, SELEX, CD20