Effective collection of volatile organic compounds in water using rimming flow with odorant-binding proteins

Water solution of volatile organic compounds (VOCs) in air, especially explosive materials, is required to detect VOCs by biosensors efficiently. We developed a collecting device like olfactory mechanism of animals: thin film of water including odorant binding proteins (OBPs), which play a major role in transport of hydrophobic odor molecules to olfactory receptors. Thin liquid film was generated using rimming flow on the inner surface of a rotating glass cylinder. Two kinds of OBPs derived from Bombyx mori (Pheromone Binding Protein 1: PBP1, General Odorant Binding Protein 2: GOBP2) were used as additive in pure water. Eugenol was used to simulate an explosive substance for collection. The sample gas including dilute eugenol was collected by the rimming flow device. The concentration of eugenol in solution was measured by gas chromatography. The experimental results showed that the efficiency for the collection of eugenol increased with the revolution rate of the cylinder. Increase in the efficiency was mainly attributed to the spread of the liquid in the cylinder. Furthermore, as the revolution rate was increased, the mole fraction of eugenol near the inside wall was higher than at the axis of rotation by centrifugal force. This might enhance the dissolution of eugenol in water. The collection efficiency further increased by the adding of both proteins and PBP1 exhibited higher affinity for eugenol.