Detection system for an electronic nose allowing a physicochemical classification of odours and electronic nose comprising such a system
A detection system for an electronic nose which allows a physicochemical classification of odors, that is to say a classification as a function of the physicochemical properties of the volatile compounds, or odorous molecules, making up these odors. This detection system comprises sensors with cross-reactivity with respect to volatile compounds, each sensor comprising a sensitive part functionalized by a receptor comprising a sequence formed by the repetition of an α-amino acid. The α-amino acid of the receptor of a sensor of a first series of sensors is hydrophilic, while the α-amino acid of the receptor of another sensor of the first series is hydrophobic, and the α-amino acids of the receptors of two sensors of a second series of sensors have isoelectric points which differ from one another by at least one pH unit.
1. A detection system comprising:
a substrate having a surface;
a plurality of receptors configured to produce a detectable signal when the plurality of receptors physiochemically interacts with at least one volatile compound of a plurality of volatile compounds in a gaseous sample;
three or more sensors having cross-reactivities relative to one or more volatile compounds of the plurality of volatile compounds, each sensor of the three or more sensors comprising a sensitive part disposed on the substrate and functionalised by a receptor of the plurality of receptors and wherein
each receptor of the plurality of receptors has a formula
X-(Esp) m -Z wherein
X is either a functional group for immobilizing a respective receptor onto the surface of the substrate or is a residue of a compound comprising the functional group for immobilizing the respective receptor onto the surface of the substrate,
m is 0 or 1,
Esp is a spacer arm, and
Z is a sequence comprising two or more α-amino acids;
wherein the three or more sensors comprise a first series of sensors and a second series of sensors wherein the first series of sensors comprises a first sensor comprising a first receptor having a first α-amino acid wherein the first α-amino acid is hydrophilic α-amino acid and a second sensor comprising a second receptor comprising a second α-amino acid wherein the second-amino acid is a hydrophobic α-amino acid; and
the second series of sensors comprises a third sensor comprising a third receptor comprising a third α-amino acid having a first isoelectric point and a fourth sensor comprising a fourth receptor comprising a fourth α-amino acid having a second isoelectric point wherein the first isoelectric point differs from the second isoelectric point by one or more pH units.
2. The detection system of claim 1 , wherein the first isoelectric point differs from the second isoelectric point by two or more pH units.
3. The detection system of claim 1 , wherein the two or more α-amino acids are alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine or valine.
4. The detection system of claim 1 , wherein the two or more α-amino acids are less than 19 α-amino acids.
5. The detection system of claim 4 , wherein X is a thiol, an amine, a hydroxyl, a carboxyl, a nitrile, a selenol, a phosphate, a sulphonate, a silanol, an epoxy, a vinyl, an alkyne or a triazide functional group; or wherein X is a residue of a compound comprising at least one thiol, one amine, one hydroxyl, one carboxyl, one nitrile, one selenol, one phosphate, one sulphonate, one silanol, one epoxy, one vinyl, one alkyne or one triazide group.
6. The detection system of claim 1 , wherein m is 1 and the spacer arm is a linear hydrocarbon group or a branched hydrocarbon group, and a saturated hydrocarbon group or an unsaturated hydrocarbon group comprising 1 to 20 carbon atoms and optionally one or more heteroatoms.
7. The detection system of claim 1 , wherein X is a residue of an α-amino acid, m is 1, the spacer arm comprises a residue of an α-amino acid or a chain of residues of an α-amino acid, and Z is an α-peptide sequence.
8. The detection system of claim 7 , wherein X is a residue of a cysteine and Z is a hexapeptide sequence.
9. The detection system of claim 1 , wherein the first α-amino acid and the second α-amino acid have hydrophobicity indices such that a sum of absolute values is 1 or more.
10. The detection system of claim 1 , wherein the three of more sensors further comprise a third series of sensors comprising a fifth sensor and sixth sensor, the fifth sensor comprising a fifth receptor comprising a fifth α-amino acid wherein the fifth α-amino acid is an aromatic α-amino acid, the sixth sensor comprising a sixth receptor comprising a sixth α-amino acid wherein the sixth α-amino acid is aliphatic α-amino acid.
11. The detection system of claim 1 , wherein the three or more sensors comprise a fourth series of sensors comprising a seventh sensor and eight sensor wherein the seventh sensor comprises a seventh receptor comprising a seventh α-amino acid having a first molecular weight and the eight sensor comprises an eighth receptor comprising an eighth α-amino acid having a second molecular weight wherein the first molecular weight differ from the second molecular weight by 25 g/mol or more.
12. The detection system of claim 1 , wherein the three or more sensors are resistive, piezoelectric, mechanical, acoustic or optical sensors.
13. The detection system of claim 12 , wherein the three or more sensors are surface plasmon resonance or interferometric optical sensors.
14. The detection system of claim 13 , wherein the three or more sensors are micromachined ultrasonic transducer sensors.
15. An electronic nose configured to detect and identify a plurality of volatile compounds in a gaseous sample, the electronic nose comprising the detection system of claim 1 .
16. The electronic nose of claim 15 , further configured to detect and identify hydrogen sulphide and ammonia.
17. The detection system of claim 4 , wherein the two or more α-amino range from 3 to 15 α-amino acids.
18. The detection system of claim 4 , wherein the two or more α-amino range from 5 to 9 α-amino acids.