A novel biomimetic olfactory cell-based biosensor with DNA-directed site-specific immobilization of cells on a microelectrode array

The coupling of cells with transducers is a key step to develop cell-based biosensors in order to meet the specific performance requirements for biomedical applications. This study describes a novel biomimetic olfactory cell-based biosensor by the employment of a DNA-directed site-specific cell immobilization method, which can achieve controllable and high-efficient coupling between olfactory cells and the microelectrode array (MEA) chip. A pair of complementary thiol-modified single-stranded DNA (ssDNA) was designed and synthesized. One of them was covalently attached to the plasma membrane of olfactory cells that were isolated from rats. The other one was used as ssDNA probes and immobilized on the gold surface of microelectrodes on MEA chip. Based on the mechanism of complementary ssDNA hybridization, olfactory cells were site-specifically immobilized on the surface of microelectrodes. The distribution of olfactory cells on the surface of MEA chip was controlled by the pattern of ssDNA probes on the sensor surface. The fluorescent staining results indicate that olfactory cells were site-specifically coupled with the microelectrode array on the surface of a MEA chip, which formed a desirable olfactory cell array. In addition, extracellular recordings from the coupled olfactory cells demonstrate that microelectrodes can efficiently monitor the membrane potential changes originated from olfactory cells in response to odorant stimulations. This biomimetic olfactory cell-based biosensor can not only be used for the detection of odorant molecules, but also be applied for the research on the olfactory signal transduction mechanisms. This DNA-directed cell immobilization method provides a novel approach for controllable cell immobilization on solid support and consequently, contributes to the development of cell micro arrays for cell-based biosensors.