Light-emitting crystals of aptamer-hybrid organic semiconductor signaling on human cells expressing EpCAM

In this study, we successfully performed protein-cell recognition by combining an organic light-emitting diode (OLED) material and an aptamer with a three-dimensional DNA structure. Tris (8-hydroxyquinoline) aluminum (Alq₃), one of the most widely used green OLED components used in displays, was chosen as an emitter. Epithelial cell adhesion molecule (EpCAM) was selected as a target because it is well-established in cancer studies. The generated micrometer-sized particles exhibited increased luminous intensity based on the specific recognition to proteins and cells on hybrid interfaces, proving that the aptamer maintained its three-dimensional structure while binding to its target. Interestingly, only human cells expressing EpCAMs were distinguishable, whereas mouse carcinoma cells were not. Furthermore, use of graphene oxide as a quencher made these aptamer-Alq₃ microrods 2-fold more effective at enhancing the fluorescence signal upon interaction with human oral squamous carcinoma cells. This new approach, which imparts biometric functionality to organic semiconductor materials, will provide a new platform for the evolution of OLED hybrid materials.