Piezoelectric biosensor based on olfactory receptor expressed in a heterologous cell system for drug discovery

Nowadays, there is an urgent need to find novel tools and approaches to improve the overall efficiency of drug discovery. In the present study, we developed a quartz crystal microbalance (QCM)-based biosensor in which olfactory receptor expressed in a heterologous cell system was used as sensitive elements. An olfactory receptor protein of C. elegances, ODR-10, which was serve as a model of G-protein-coupled receptors (GPCRs), was expressed on the plasma membrane of human embryonic kidney (HEK)-293 cells. For targeting the ODR-10 on the surface of cell membrane, the rho-tag import sequence was inserted into the N-terminus of the ODR-10. The membrane expression of ODR-10 was shown by the enhanced green fluorescent protein (EGFP) which sequences was inserted into the C-terminus of the ODR-10. After that, the membrane fraction of HEK-293 cells containing ODR-10 was extracted and then coated on the electrode surface of QCM. The interactions between odorant molecules and olfactory receptors were monitored by QCM. The results indicate that ODR-10 was functionally expressed on the plasma membrane of HEK-293 cells and it can respond to diacetyl with high specificity, which is a natural ligand for ODR-10. All the results suggest one conclusion: this novel QCM-olfactory receptor hybrid biosensor can be used to detect the interactions between GPCRs and their ligands, and suggest it could be a potential tool for drug discovery and even for drug evaluation.