The present invention relates a high-sensitivity molecular detecting device using metal ion encapsulated fullerene
Early detection of cancer is desired. For example, it is known that the exhaled breath of a cancer patient contains a substance, which is not contained in the exhaled breath of a person who is not a cancer patient.
For example, patients with esophageal cancer are known to be rich in four types of molecules: 2-butanone, acetic acid, acetone, and acetonitrile. For other cancers, other molecules are contained. In addition, it is expected that many molecules will be found in clinical practice in the future.
The molecules shown in
And, it is attempted to detect cancer at an early stage by utilizing the detection of such a substance. Currently, for example, the following techniques are being attempted as detection techniques. (1) A technology, in which gas is adsorbed on a functional film applied to a Si diaphragm formed by MEM, and then the mechanical strain of the functional film generated by the adsorption is detected as an electric current (cantilever method). (2) A technology for detecting changes in resistance due to adsorption of gas molecules (semiconductor sensor method). (3) A technology, which detects fluorescence by passing odors through molecules to the olfactory receptors of genetically engineered mice (biochip method). (4) A technology, which utilizes the fact that when a dilute gas is passed through a fluctuating electric field, only molecules with a specific mass cross-sectional area ratio reach the detector (symmetric field ion transfer analysis method).
On the other hand, as a technique using the encapsulated fullerene, the present inventors provide a photoelectric conversion device using the encapsulated fullerene described in Patent Document 1. The device is a photoelectric conversion device using an encapsulated fullerene containing supramolecular complex composed of alkaline ion-encapsulating fullerene and anionic dye.
PATENT DOCUMENT 1 JP 2015-69731 A
According to the detection techniques (1) to (4) described above, the detection concentration is at the ppb level at best. In addition, the technology of (4) requires a large-scale device.
In the early stage of cancer, a more sensitive detection technique is desired considering that the concentration of substances contained in exhaled breath is also very small.
An object of the present invention is to provide a high-sensitivity molecular detecting device using a metal ion encapsulated fullerene in order to be able to detect substances even at a concentration of ppt level.
The invention according to claim 1 is a high-sensitivity molecular detecting device using metal ion encapsulated fullerene;
including
a container with an introduction port for introducing detected molecule into the main body of the container,
complex of dye and metal ion encapsulated fullerene contained inside the container.
a pair of electrodes,
a light radiating means for irradiating the inside of the container with light, and
an ammeter for measuring a current flowing between the electrodes;
wherein an electron orbit energy level is set such that there is no electron movement in a ground state without light irradiation, and electron separated from the detected molecule moves into vacancy generated by means of an excitation in an excited state resulting from light irradiation.
The invention according to claim 2 is the high-sensitivity molecular detecting device using metal ion encapsulated fullerene according to claim 1, wherein the metal is alkali metal.
The invention according to claim 3 is the high-sensitivity molecular detecting device using metal ion encapsulated fullerene according to claim 2, wherein the alkali is Li.
The invention according to claim 4 is the high-sensitivity molecular detecting device using metal ion encapsulated fullerene according to any on of claims 1 to 3, the fullerene is C60.
The invention according to claim 5 is the high-sensitivity molecular detecting device using metal ion encapsulated fullerene according to claim 3, wherein the ion encapsulated fullerene is Li+@C60.
The invention according to claim 6 is the high-sensitivity molecular detecting device using metal ion encapsulated fullerene according to any one of claims 1 to 5, wherein the dye is a macromolecular polymer such as polythiophene poly-3-hexylthiophene (P3HT) and so on, poly p-phenylene, poly p-phenylene vinylene, polyaniline, polypyrrole, PEDOT, P3OT, POPT, MDMO-PPV, or MEH-PPV; or their derivatives.
Despite its extremely simple structure, for example, molecules specifically contained in the exhaled breath of a cancer patient can be detected even at a concentration of ppt level.
The detection target is not limited to molecules specifically contained in the exhaled breath of cancer patients, but can be any gas, solid, or liquid.
1 main body
2 dye
3 metal ion encapsulated fullerene
5, 6 electrode
7 exhaled breath containing molecule to be detected
8 introduction port
Complex of electron donor and metal ion encapsulated fullerene constitute donor acceptors, and by light irradiation they generate charge-separated state and possess oxidizing power. In Patent Document 1, a photoelectric conversion device is configured by using this oxidizing power.
The present inventors examined an use of such characteristics in other devices, and found that it is possible to detect molecules by designing an energy level. That is, as shown in
In the example shown in
In
(d)<(HOMO of dye)<(HOMO of molecule to be detected)
(LUMO of metal ion encapsulated fullerene)<(LUMO of dye)<(LUMO of molecule to be detected)
(LUMO of metal ion encapsulated fullerene)>(HOMO of dye)
(LUMO of dye)>(HOMO of molecule to be detected)
In such a setting, in the ground state (upper part of
On the other hand, in the excited state, that is, in the state of being irradiated with light as shown in the lower part of
In the photoexcited state, if the molecule to be detected is ionized, the separated electron moves to the vacancy of the dye. On the other hand, the electron excited in the dye moves to the LUMO of the metal ion encapsulated fullerene, and an electric current flows.
It is assumed that 500 cc of exhaled breath contains only 1 ppt of the molecule to be detected. The number of molecules contained in the exhaled breath of 500 cc is
5 L/25.36 L×6.02×1023÷1.19×1022
If it is assumed that only 1 ppt contains the molecule to be detected, the number of molecules is
1.19×1022×10−12÷1.19×1010
The amount of charge released by one-electron oxidation is
6×10−19 C×1.19×1010÷1.9×10−9 C
If this amount of electric charge is passed in 1 second, 1.9 nA=10 pA.
Whereas other detection techniques indirectly convert (for example, from distortion) into an electrical signal, the present invention steals electrons from the molecule to be detected and directly converts them into electrical signals without changing to mechanical quantities. Due to the change, an extremely sensitive detector is achieved.
Examples of the dye include π-electron compounds, for example, porphyrins, metal chelate compounds, polyaniline compounds, aromatic polycyclic compounds, and compounds having a polyacene-based skeleton structure.
These energy levels can be easily determined by a molecular orbital method. The energy level of the molecule shown in
In the molecular orbital method, the atomic orbitals of each atom are combined to create a one-electron molecular orbital, and it is optimized to obtain the one-electron molecular orbital with the highest approximation. And, two molecules (with their spins reversed) are stored in order from the one-electron molecular orbital with the lowest energy, and all the electrons of that molecule are stored. Further, the spatial distribution of the establishment of the existence of electrons is calculated, and how the electrons are spread around the molecule is clarified. In this way, the electronic state of the molecule can be known. However, the excitation energy of the molecule and the HOMO-LUMO gap do not always match. The HOMO and the LUMO are qualitatively determined by the molecular orbital method, and more exactly, it can be confirmed whether the energy level relationship shown in
The complex of the dye and the metal ion encapsulated fullerene may be retained in the container main body 1 together with the appropriate solvent. Further, it is preferable that the metal ion encapsulated fullerene is on the electrode 5 side.
Although the present invention is optimally applied to a medical field, it can be applied not only in the field but also in any field where substance detection is required.
Number | Date | Country | Kind |
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2018-071188 | Apr 2018 | JP | national |
Filing Document | Filing Date | Country | Kind |
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PCT/JP2019/014552 | 4/1/2019 | WO | 00 |