Bioelectronic nose and its application to smell visualization

Abstract

There have been many trials to visualize smell using various techniques in order to objectively express the smell because information obtained from the sense of smell in human is very subjective. So far, well-trained experts such as a perfumer, complex and large-scale equipment such as GC-MS, and an electronic nose have played major roles in objectively detecting and recognizing odors. Recently, an optoelectronic nose was developed to achieve this purpose, but some limitations regarding the sensitivity and the number of smells that can be visualized still persist. Since the elucidation of the olfactory mechanism, numerous researches have been accomplished for the development of a sensing device by mimicking human olfactory system. Engineered olfactory cells were constructed to mimic the human olfactory system, and the use of engineered olfactory cells for smell visualization has been attempted with the use of various methods such as calcium imaging, CRE reporter assay, BRET, and membrane potential assay; however, it is not easy to consistently control the condition of cells and it is impossible to detect low odorant concentration. Recently, the bioelectronic nose was developed, and much improved along with the improvement of nano-biotechnology. The bioelectronic nose consists of the following two parts: primary transducer and secondary transducer. Biological materials as a primary transducer improved the selectivity of the sensor, and nanomaterials as a secondary transducer increased the sensitivity. Especially, the bioelectronic noses using various nanomaterials combined with human olfactory receptors or nanovesicles derived from engineered olfactory cells have a potential which can detect almost all of the smells recognized by human because an engineered olfactory cell might be able to express any human olfactory receptor as well as can mimic human olfactory system. Therefore, bioelectronic nose will be a potent tool for smell visualization, but only if two technologies are completed. First, a multi-channel array-sensing system has to be applied for the integration of all of the olfactory receptors into a single chip for mimicking the performance of human nose. Second, the processing technique of the multi-channel system signals should be simultaneously established with the conversion of the signals to visual images. With the use of this latest sensing technology, the realization of a proper smell-visualization technology is expected in the near future.

Vapor detection and discrimination with a panel of odorant receptors

“…Previous biomimetic nose studies have provided limited knowledge in evaluating how much discriminability a given system has, since they used a small number of ORs (up to four) and primarily tested only known ligands 13 , 16 , 47 .…”

“…Since then, biomimetic “noses”, or devices to detect and discriminate target volatiles using OR proteins, have been proposed to replace trained animals. Previous studies using well-characterized model ORs have shown that various platforms can detect target odorants with high sensitivities 13 – 16 , raising the possibility that multiplexed OR-based sensors using specific receptors for targeted odorants would have high sensitivity and discriminability.…”

Explosive sensing with insect-based biorobots

“…Several approaches to augment the performance of machine olfactory systems [14,15], and even direct use of biological recognition elements (e.g. proteins, peptides) [16][17][18][19][20] or cultured cells/neurons [21][22][23][24] as transducers have been proposed. While these advances are significant, challenges remain in generating a rich repertoire of chemical transducers and translating the proposed approaches into low-cost, minimal-maintenance field-deployable units.…”

Agonist Binding to Chemosensory Receptors: A Systematic Bioinformatics Analysis

“…hORs belong to class A GPCRs, sharing with the other class A GPCRs several conserved motifs (de March et al, 2015a ) (see Table 1 ). They are expressed in different tissues, from the cilia of olfactory sensory neurons in the nose, to the testis, the gut, the skin, the tongue, leucocytes, thrombocytes, the skeletal muscle, primordial germ cells and oocytes, the atrioventricular node and the brain (Goto et al, 2001 ; Spehr et al, 2003 ; Durzynski et al, 2005 ; Feldmesser et al, 2006 ; Braun et al, 2007 ; Jenkins et al, 2009 ; Breer et al, 2012 ; Ansoleaga et al, 2013 , 2015 ; Flegel et al, 2013 , 2015 ; Garcia-Esparcia et al, 2013 ; Wijten et al, 2013 ; Busse et al, 2014 ; Grison et al, 2014 ; Malki et al, 2015 ; Ko and Park, 2016 ). Their functions span from olfaction to sperm chemotaxis, to regulation of renal function, to regeneration and migration in muscle cells, or to neuronal regulation (Spehr et al, 2004 ; Griffin et al, 2009 ; Pluznick et al, 2009 ; Grison et al, 2014 ; Ferrer et al, 2016 ).…”