Cell-Based Sensing

Nose on a Chip

I am collaborating with Pamela Abshire (ECE), Ricardo Araneda (Department of Biology), Abhinav Shrivastava (Computer Science), and David Tomblin (Science, Technology, and Society) at the University of Maryland to develop an "e-nose" for odorant identification.

In earlier work (see “Olfaction on a chip”), we had shown that olfactory sensory neurons cultured on integrated circuit chips can detect odorants.

We are now working with an engineered insect cell line, in collaboration with researchers Takahiro Kikawada and Richard Cornette in the Extremotolerance Biotechnology Group, Institute of Agrobiological Science, NARO in Tsukuba, Japan. These cells fluoresce upon odorant binding.

Biological olfactory sensors have, as yet, no equal in human-made devices.

1. Cells can be engineered to express odorant receptors (ORs) and to give a fluorescence signal upon odorant binding.
   These signal can be detected extra-cellularly, with the fluorescece intensity correlated with the odorant concentration.
2. A cell line derived from the insect Polypedilum vanderplanki (sleeping chronomid) maintains the desiccation tolerance of the larval stage.
   Desiccation of cells on chip would allow storage of the cells in an inert state until use, overcoming a major obstacle to cell-based sensing.
3. Insect cells can be cultered in permissive conditions.
   There is no requirement for strict temperature control to maintain 37 C and no need for CO₂. The cells grow in suspension, so large numbers can be produced rapidly.
4. The odorant receptor (OR) in insect cells opens to allow cation influx directly upon odorant binding.
   Calcium influx then binds to the fluorescence report, in our case GCaMP6f.
   

We have shown that Pv11-00443-Or47a), which is desiccatable, responds to both pentyl acetate (the ligand for DmOr47a) and VUAA1 (the agonist to Orco), the latter just 1 h after rehydration. Thus, a transmembrane protein can be dry-stored, the first step toward practical portable cell-based senor devices.

For further information, see:

• "An anhydrobiotic cell line expressing odorant receptors shows odorant responses after dry storage," H. Fuse, R. Cornette, Y. Miyata, S. Tokumoto, S. Shimura, R. C. Araneda, P. Abshire, T. Kikawada, R. Anderson, R. Haider, and E. Smela, Sci. Rep., 15, 35533 (2025).