Analyzing the binding affinity of aptamer quantum dot conjugates to VEGF

Aptamers are single-stranded oligonucleotideswhich fold into a three-dimensional structureallowing the specific recognition of amolecular target. Therefore, they might be analternative to antibodies as detectionmolecules in biosensors. Aptamers are wellsuited for this application since they can bedirected against almost every molecular target,and show high binding affinities to theircorresponding binding partner. Aptamers witha terminal amino-group can be coupled toorganic or inorganic fluorophores via amidebonds to enable their optical detection. In thisstudy Vascular Endothelial Growth Factor(VEGF)-binding aptamers were conjugatedwith quantum dot molecules. Thisimmobilization may inhibit the correct aptamerfolding and consequently lead to a declinedtarget-binding activity. Therefore, MSTtechnology was used to determine whetherquantum dot conjugation affects the VEGF- binding affinity of aptamers.