Table 5.

Advantages and disadvantages associated with commonly used biomaterials in biosensors development

Biosensing material	Advantages	Disadvantages	Refs.
ORs	Can be acquired from a large variety of expression systems: S. cerevisiae, E. coli, and cell‐free. They generate changes in electrical properties within themselves upon odorant binding. Possibility for large scale production. Compared to olfactory cells and olfactory epithelium, they are easier to store for long periods and easier to use in practice, which contributes to the miniaturization and convenience of biosensors. Genetic engineering can be used to be able to add tags or other specific sequences to facilitate their purification and immobilization on the sensor. Very high sensitivity while using the whole protein. Can identify small variations in odorants based on their structural construction and concentration. Possibility of biomimetic approach and virtual design.	OR production is time‐consuming, labor‐intensive, and relatively inefficient. Complicated structure of ORs. Easily lose their functions by many external factors, such as heat and physical forces, which can affect the structure of OR proteins. Hard to immobilize onto the secondary transducer.	[131]
OBPs	Extremely stable to temperature, organic solvents, proteolytic digestion, pH, and proteases. Easier separation and purification than OR production methods. Can be tailored through mutagenesis.	Identifying olfactory OBP specific to an odorant may be time‐consuming, labor‐intensive, and expensive. High cost of production, difficult to manufacture, and high reproducibility of proteins.	[132]
Synthetic peptides	Excellent stability and reproducibility, Smaller size of the peptide makes it easier to fix it in an aligned and predetermined form on the surface of the secondary transducer. Possibility to synthesize different peptide sequence with Fmoc method. Can be stored for long periods of time, Keep intrinsic property of the ORs themselves. Can be easily modified in specific sites.	Synthesis limited to specific number of amino acids. Expensive Fmoc reagents and high volumes of toxic solvents and reagents during synthesis.	[133]
Olfactory cells	Generate signals which can be similar to those produced by ORNs. May facilitate the mechanism of OR sensing principles. Suitable for physical absorption. Can detect real‐time extracellular signals under odorant stimulations for prolonged periods. Very high sensitivity while using the whole protein. Provide insight into the physiological effect between odorant molecules and olfactory cells.	Hard to manufacture and store. Isolation and in vitro culturing of OSN cells is difficult, so their practical application is limited. Relatively high cost. Limited applicability to some secondary transducers. In mammalian systems, the ability to readily transfect reporter genes limits the cell types to those that are tumor derived. The potential can be measured only at a limited number of sites, such as the tip of an individual microelectrode.	[134]
Olfactory mucosa tissue	The functional receptor unit of cilia on each olfactory receptor cell would not be damaged. The intact epithelium allowed simpler acute preparation and easier visualization, without strictly controlled cell culture conditions (i.e., nutrient media, pH, temperature, and sterile environment). Extracellular compartments present in vivo (including supporting cells and basal cells) were preserved. Preserves natural state of the neuronal populations and can be obtained easily, The mucus layer with odorant binding protein generated by Bowman's glands and supporting cells were preserved. Signal of many cells can be detected synchronously.	Need to kill animals. Should be kept in standard perfusate with suitable temperature, humidity, and nutrient solution to maintain native state and their biological activities. Hard to manufacture with high repeatability. Significantly reduced signal strength and quality in long‐term usage.	[135]