Aptamer Biosensors for Label-Free Colorimetric Detection of Human IgE Based on Polydiacetylene (PDA) Supramolecules

In this study, we demonstrate an aptamer-based biosensor (apta-biosensor) using PDA liposomes for label-free detection of allergy diagnosis by hIgE detection. In order to detect the target hIgE, the surface of PDA liposome were functionalized with hIgE antibody and anti-hIgE aptamer as a receptor, and the target hIgE onto the receptors was detected by the change of fluorescence signal. The hIgE antibody-modified PDA liposome biosensor had a serious problem that the immune reaction between receptor and target could not powerfully affect the change of florescence signal on PDA liposome. In order to solve this problem, the anti-hIgE aptamer which was far smaller than whole antibody was introduced as the receptor for the PDA liposome system. An aptamer-based PDA liposome biosensor was able to measure a quantity of target protein with various concentrations and at this time the detection limit was 141 ng/mL of the hIgE concentration. These results enabled diagnosis of allergy disease by an aptamer-based PDA liposome biosensor because real allergic patients showed high concentration of hIgE in serum (greater than 290 ng/mL). Therefore, we suggest that aptamer-modified PDA supramolecules as promising candidates for development of label-free colorimetric biosensors.