Exp Mol Med.  2012 Sep;44(9):554-561.

Cotinine-conjugated aptamer/anti-cotinine antibody complexes as a novel affinity unit for use in biological assays

• Park S
• Hwang D
• Chung J

Abstract

Aptamers are synthetic, relatively short (e.g., 20-80 bases) RNA or ssDNA oligonucleotides that can bind targets with high affinity and specificity, similar to antibodies, because they can fold into unique, three-dimensional shapes. For use in various assays and experiments, aptamers have been conjugated with biotin or digoxigenin to form complexes with avidin or anti-digoxigenin antibodies, respectively. In this study, we developed a method to label the 5' ends of aptamers with cotinine, which allows formation of a stable complex with anti-cotinine antibodies for the purpose of providing another affinity unit for the application in biological assays using aptamers. To demonstrate the functionality of this affinity unit in biological assays, we utilized two well-known aptamers: AS1411, which binds nucleolin, and pegaptanib, which binds vascular endothelial growth factor. Cotinine-conjugated AS1411/anti-cotinine antibody complexes were successfully applied to immunoblot, immunoprecipitation, and flow cytometric analyses, and cotinine-conjugated pegaptanib/anti-cotinine antibody complexes were used successfully in enzyme immunoassays. Our results show that cotinine-conjugated aptamer/anti-cotinine antibody complexes are an effective alternative and complementary technique for aptamer use in multiple assays and experiments.

Keyword

aptamers, nucleotide; cotinine; enzyme-linked immunosorbent assay; flow cytometry; immunoblotting; immunoprecipitation

MeSH Terms

Animals
Antibodies, Anti-Idiotypic/immunology/metabolism
*Aptamers, Nucleotide/chemistry/immunology
Biological Assay
*Cotinine/administration & dosage/chemistry
Flow Cytometry
Hep G2 Cells
Humans
Mice
NIH 3T3 Cells
Phosphoproteins/*chemistry/immunology
Protein Binding
RNA-Binding Proteins/*chemistry/immunology
*Vascular Endothelial Growth Factor A/chemistry/immunology