Analyzing the binding affinity of aptamer quantum dot conjugates to VEGF

Aptamers are single-stranded oligonucleotides which fold into a three-dimensional structure allowing the specific recognition of a molecular target. Therefore, they might be an alternative to antibodies as detection molecules in biosensors. Aptamers are well-suited for this application since they can be directed against almost every molecular target, and show high binding affinities to their corresponding binding partner. Aptamers with a terminal amino-group can be coupled to organic or inorganic fluorophores via amide bonds to enable their optical detection. In this study Vascular Endothelial Growth Factor(VEGF)-binding aptamers were conjugated with quantum dot molecules. This immobilization may inhibit the correct aptamer folding and consequently lead to a declined target-binding activity. Therefore, MST technology was used to determine whether quantum dot conjugation affects the VEGF- binding affinity of aptamers.