Photocatalytic Aptamer Chemiluminescent System for a Homogeneous, Reliable, Label-Free, Generic Assay of Small Molecules

Chemiluminescence is a powerful analytical technique with many advantages, while aptamers are well-known as good molecular recognition units. However, many aptamer-based chemiluminescence assays employed interface sensing, which often needed several immobilization, separation, and washing steps. To minimize the risks of contamination and false-positive, we for the first time proposed a photocatalytic aptamer chemiluminescent system for a homogeneous, label-free, generic assay of small molecules. After binding to a DNA aptamer, thioflavin T has a unique photocatalytic oxidase activity to activate the system's luminol chemiluminescence. Then, the specific binding between the aptamer and target molecules will compete with the above process. Therefore, we can realize the efficient assay of different analytes including estradiol and adenosine. Such a homogeneous chemiluminescent system allowed a direct assay of small molecules with limits of detection in a nM level. Several control tests were carried out to avoid possible false-positive results, which were originated from the interactions between analytes and sensing interfaces previously. This homogeneous chemiluminescent system provides a useful strategy to reliably assay various analytes in the pharmacy or biology field.