Characterization of Self-Assembled Monolayers of Peptide Mimotopes of CD20 Antigen and Their Binding with Rituximab

CD20, expressed in greater than 90% of B-lymphocytic lymphomas, is a target for antibody therapy. Rituximab is a chimeric therapeutic monoclonal antibody (mAb) against the protein CD20, allowing it to destroy B cells and to treat lymphoma, leukemia, transplant rejection, and autoimmune disorder. In this work, the binding of rituximab to self-assembled monolayers (SAMs) of peptide mimotopes of CD20 antigen was systematically characterized. Four peptide mimotopes of CD 20 antigen were selected from the literature and redesigned to allow their SAM immobilizations on gold electrodes through a peptide linker with cysteine. The bindings of these peptides with rituximab and control mAbs (trastuzumab and bevacizumab) were characterized by quartz crystal microbalance (QCM). Among the four peptide mimotopes initially selected, the peptide designated as CN-14 (CGSGSGSWPRWLEN) was the most selective and sensitive for rituximab binding. The CN-14 SAM was further characterized by ellipsometry and atomic force microscop...