Nano-Biosensors for Mimicking Gustatory and Olfactory Senses

In biological systems, low-molecular-weight chemical substances are detected by the gustatory and olfactory senses. Taste sensors and electronic noses can mimic the role of these senses, respectively. This chapter is devoted to the development of nano-biosensors, i.e., a taste sensor and electronic noses, to emulate these senses. The taste sensor, whose receptor utilizes a specific lipid/polymer membrane developed in Japan, can classify and quantify the taste of foods. It is now being put to practical use and is widely utilized in food and pharmaceutical companies worldwide. It is also being applied to the rapid and easy detection of pesticides in perishable foods such as vegetables and fruits. In addition, a miniaturized taste sensor has been developed for convenient use in field evaluations. One of the basic electronic noses, which adopts an electrochemical measurement based on the biological recognition mechanism of common properties of odorants, can make rough estimates of a smell and classify it in a similar way to Munsell's color wheel. In addition, a highly sensitive electronic nose, which can be called an electronic dog nose, has been developed to detect the faint smell of fragrant compounds remaining on the manufacturing line of beverages. This electronic nose comprises a surface plasmon resonance (SPR) sensor and a functional site to cause antigen-antibody interactions. As a result, the detection of about 10ppb for, for example, a typical peach flavor, benzaldehyde, was successful, while the human detection threshold is 300-350ppb.