JP4149872B2 - Nanoelectronic devices using BZ transition of DNA - Google Patents

Description

  The present invention relates to a nanoelectronic device material that utilizes differences in physical properties between right-handed (B-type) and left-handed (Z-type) DNA. DNA usually has a right-handed helical structure, but part or all of it is transferred to a left-handed helical structure. This transition may be reversible or irreversible. Since the physical or chemical physical property of DNA changes depending on how the DNA is wound, the present invention provides a novel nanoelectronic device material that utilizes this physical property difference. Is.

DNA is considered to be an important substance in the field of life science as a molecular species having genetic information, but at the same time, DNA is a molecular species having a large number of π-electron systems in the base and has a unique chemical structure. It is also attracting attention as a molecular species. DNA is a linear polymer compound belonging to a polysaccharide and has characteristics as a material. For example, material properties are attracting attention also in the field of nanotechnology such as nanowire technology focusing on the point of being a linear polymer compound and nanoelectronic device technology based on charge transfer focusing on π-electron systems.
A number of techniques that apply to electronic devices using such characteristics of DNA have been reported. For example, inventions related to structures containing inorganic molecules that bind to selected positions of DNA, such as structures that are AND gates or OR gates (see Patent Documents 1 and 2), conductive organics in which a charge supply material is bound to DNA There are an invention related to a polymer (see Patent Document 3), an invention related to an optical device containing an organic photonic crystal having a plurality of layers in which rod-like organic molecules such as DNA are arranged in parallel (see Patent Document 4), and the like.

DNA is usually a double helix with a right-handed helical structure. Along the spiral, the base π-electron system also extends like a spiral staircase. On the other hand, it was discovered about 30 years ago that left-handed DNA was also present. As a result of X-ray analysis of the crystal state, it was proved that it was left-handed, but its biological role is still unclear. Although it has been discussed that some DNA may exist in the left-handed manner in nature, it has not been demonstrated yet. Possibility is that a part of the binding site such as transcription factor is left-handed, and the base is exposed, and transcription factor or the like binds to it or when right-handed DNA is replicated. Although some have been left-handed to loosen the twist of the winding, none have been demonstrated yet.
However, it has already been demonstrated that left-handed DNA exists in the crystalline state, and its structure has also been analyzed. Hereinafter, left-handed DNA is referred to as Z-type DNA, and normal right-handed DNA is referred to as B-type DNA. Research on left-handed DNA (Z-DNA) is also underway, but it is difficult for Z-DNA to exist stably in solution at a length of about 6-20 mer used for research, Modifications are required to allow DNA to exist stably in solution. The present inventors have already reported about such modification (refer patent document 5).
In addition, the present inventors have previously found that Z-type DNA is stabilized by deoxy-type 8-methylguanosine (MeG), and reported it in the literature (for example, see Non-Patent Document 1). ). Various studies have been conducted so far using this deoxy-type 8-methylguanosine. Furthermore, it has been shown that hydrogen abstraction of the C1 ′ and C2′β positions of the 5 ′ sugar by uracil radicals occurs in halouracil in B-type DNA depending on the structure and sequence (for example, non-patent literature) 1-4.)
In these reports, we have identified 5′-d (CGCG ^I UGCG) -3 ′ / 5′-d (C ^m GCAC ^m GCG) -3 ′ containing 6-iodouracil ( ^I U). (m ^G represents methyl grayed guanine.) is, B type and stably can be present in Z-type, and examined photoreaction each type of DNA, the light reaction is dependent on the structure of DNA It is reported that ribonolactone and erythrose can be produced in the B type, and rG can be produced in the Z type. The reaction formula of the 5′-G ^I U-3 ′ part of this photoreaction is shown below.

In right-handed DNA (type B), uracil iodine is dissociated by light irradiation, and the generated radicals extract sugar hydrogen to produce ribonolactone (see Non-Patent Documents 3 and 5). In left-handed (Z-type) DNA, radicals are similarly generated, but the adjacent purine ring is not affected, and the 2′-position of the sugar is oxidized to a hydroxyl group. That is, an RNA sugar chain (rG) is used (see Non-Patent Documents 2 and 4).
As described above, research on the reactivity and behavior of left-handed DNA (Z-DNA) has been advanced, but there is almost no research on the function and application of Z-DNA.

JP 2000-101167 A JP 2003-37313 A JP 2003-183400 A JP 2003-195002 A Japanese Patent Application No. 2003-52817 Sugiyama, H .; Kawai, K .; et al., Nucleic Acids Res., 1996, 24, 1272. Kawai, K .; Saito, I .; et al., J. Am. Chem. Soc. 1999, 121, 1391-1392. Sugiyama, H .; et al., Tetrahedron Letters 1996, 37, 1805-1808. Oyoshi, T .; Kawai, K .; et al., J. Am. Chem. Soc., 2003, 125, 1526-1531. Sugiyama, H .; Tsutsumi, Y .; et al., J. Am. Chem. Soc., 1990, 112, 6720-6721.

  The present invention elucidates the form of the π-electron system of each base in the right-handed (B-type) and left-handed (Z-type) states of DNA, and clarifies the movement of electrons or charges by the π-electron system. The present invention provides a novel applied technology of DNA using electron or charge transfer. More specifically, the present invention provides a novel nanoelectronic device material that utilizes changes in the helical structure of DNA.

The present invention relates to a nanoelectronic device material that utilizes differences in physical properties between right-handed (B-type) and left-handed (Z-type) DNA. Specifically, the difference in physical properties between the right-handed (B-type) and left-handed (Z-type) DNAs having a base sequence in which bases having purine rings and bases having pyrimidine rings are alternately arranged, preferably Relates to a nanoelectronic device material utilizing the difference in electrical conductivity. Further, the present invention relates to a nanoelectronic device material that utilizes the difference in physical properties between right-handed (B-type) and left-handed (Z-type) DNA containing aminopurine or a derivative thereof as a base, preferably using the presence or absence of fluorescence. .
The present invention also relates to an electronic device material such as a memory element material, a sensor element material, a logic element material, and an arithmetic element material using the above-described nanoelectronic device material.

The present inventors have provided nucleotides such as 8-alkylguanine that can form relatively stable left-handed DNA.
Unlike iodouracil, bromouracil ( ^Br U) is said to depend on the sequence and the reaction does not proceed due to the reverse electron transfer reaction to G in the G ^Br U sequence. Actually, 5′-d (CGCG ^Br UGCG) -3 ′ / 5′-d (C ^m GCAC ^m GCG) -3 ′ (hereinafter, this oligonucleotide is referred to as ODN1-2) in the B-type structure is light. Almost no photoreaction occurs even when irradiated. However, when this ODN1-2 is converted to the Z-type in the presence of 2M NaCl, the reaction proceeds rapidly, and 5′-d (CGC) rGd (UGCG) -3 ′ is 35% of ODN1 lost by the photoreaction. It was revealed that it was produced in a yield. It was confirmed by CD spectrum that the DNA oligomer had a Z-type structure. FIG. 1 shows these results. The upper part of FIG. 1 shows the case of B-type DNA, and the lower part shows the case of Z-type DNA. The left side of FIG. 1 shows the HPLC results after light irradiation, and the right side shows the CD results. In the B type, there are only two peaks of ODN1 and ODN2 after light irradiation, but in the Z type, the peak of the RNA-type guanine (rG) and the substance (Iz) containing imidazole or imidazolone generated by decomposition appear. is doing. These results indicate that DNA structural changes based on the BZ transition dramatically caused ODN1-2 reactivity.

The present inventors predicted that the structure is responsible for the dramatic increase in photoreactivity of ^Br U in the Z-type, and when the overlap between the bases of the B-type DNA and the Z-type DNA was examined, it was very interesting. I was able to find. That is, the bases of the B-type DNA are spirally overlapped in the same strand, whereas the Z-type has a 4-base π-stack structure consisting of two bases from both strands. This structure is schematically shown in FIG. 2, and its molecular model is shown in FIG. 3 as a color diagram by computer graphics instead of the drawing. FIG. 2 schematically shows the structure of a B-type DNA and the structure of a Z-type DNA, and FIG. 3 shows each of them in a molecular model. In the schematic diagram of FIG. 2, in the right-handed B-type DNA, one base sequence and the base sequence of its complementary strand are regularly arranged in a spiral, but in the left-handed Z-type DNA, it is left-handed. For this reason, the bases are located in a staircase shape and cannot take a continuous spiral structure. However, each base is not located irregularly, but two bases of one strand are shifted in position, and more interestingly, 2 bases of one strand and 2 of the complementary strand This is a structure in which bases overlap. That is, in this ODN1-2, 4 guanine (G4) and the fifth bromouracil ^(Br U5), and 11th cytosine its complement (C11) and 10 No. 8-methylguanine ^(m G10) The four bases of G4- ^Br U5-C11- ^m G10 with four bases have a π-stack structure. FIG. 3 shows the overlap of the four bases using a molecular model. The left side of the molecular model shows a B-type right-handed pattern, and the right-hand side is a Z-type left-handed case. Guanine (G4) (light blue) and the fifth bromouracil ( ^Br U5) from one chain (blue and green) are overlapped in isolation, it has become more structures its complementary strand cytosine (C11) (yellow) and 10 No. 8-methylguanine ^(m G10) (yellow and red) overlap I understand.
In addition, it was found that the peak appearing at a retention time of 30.5 minutes was an octamer 5′-d (CIzCAC ^m GCG) -3 ′ containing imidazolone. It is known that imidazolone is produced by oxidation of guanine (Kino, K., Saito, I., Sugiyama, H., J. Am. Chem. Soc., 1998, 120 , 7373-7374). 5′-d (CIzCAC ^m GCG) -3 ′ is generated together with the generation of 5′-d (CGC) rGd (UGCG) -3 ′ and ^m G10 in the π-stack structure of G4- ^Br U5-C11- ^m G10. that is progressing electron transfer to ^{Br U5} from showed.

The following experiment was conducted to confirm this hypothesis. Since 8-methoxyguanine ( ^mo G) has a low oxidation potential and is known to be Iz when it becomes a cation radical by one-electron oxidation (Ikeda, H., Saito, IJ Am. Chem. Soc. 1999, 121 , 10836-10837.), 5′-d (CGCG ^Br UGCG) -3 ′ / 5′-d (C ^mo GCAC ^m GCG) -3 ′ (hereinafter referred to as “ ^mo G”), the 10th position where charge transfer is expected This oligonucleotide was referred to as ODN1-3) and was photoreacted in B-type and Z-type DNA. As a result of light irradiation, none of these oligomers showed photoreactivity at all in the B type, but in the Z type, 5′-d (CGC) rGd (UGCG) -3 ′ was produced by 80% and 5′- It was confirmed that 73% of d (CIzCAC ^m GCG) -3 ′ was produced. The resulting HPLC chart is shown in FIG. The upper part of FIG. 4 shows the case of B-type DNA (B-DNA), and the lower part shows the case of Z-type DNA (Z-DNA). As a result, it was shown that the electron transfer from ^mo G10 to ^Br U5 is progressing.

^However, the ^mo G 4-position, 6-position, 14-position brewed ^{5'-d (CGC mo G Br} UGCG) -3 '/ 5'-d (C m GCAC m GCG) -3' ( hereinafter, this oligo The nucleotide is referred to as ODN5-2).
5′-d (CGCG ^Br U ^mo GCG) -3 ′ / 5′-d (C ^m GCAC ^m GCG) -3 ′ (hereinafter, this oligonucleotide is referred to as ODN6-2), and 5′-d (CGCG) ^Br UGCG) -3 ′ / 5′-d (C ^m GCAC ^mo GCG) -3 ′ (hereinafter, this oligonucleotide is referred to as ODN1-4) did not promote the reaction.

The results and the base sequence of each ODN are shown in FIG. The upper part of FIG. 5 shows the nucleotide sequence of each oligonucleotide (ODN), and the lower part shows the yield of imidazolones (Iz) as a result of the photoreaction of double-stranded DNA comprising these ODNs (the back side of the lower part of FIG. 5). ) And the yield of RNA-type guanine (rG) (the lower front side of FIG. 5). The scale in the yield graph in the lower part of FIG. 5 is every 20%. The bromouracil ( ^Br U) portion in the six types of double-stranded DNA is green, methoxyguanine ( ^mo G) is orange, and guanine (G), which is assumed to be involved in the reaction, is shown in light blue.
Next, FIG. 6 shows the reaction formula of the photochemical reaction in the π-stack structure of the Z-type DNA of ODN1-3 with 4 bases of G4- ^Br U5-C11- ^mo G10. The result of the photochemical reaction shown in FIG. 5 is that, as shown in FIG. 6, the electrons move from the ^mo G base at position 10 to ^Br U to become a ^Br U ^{− ·} radical state, from which Br ⁻ is desorbed. By releasing hydrogen, rG in which ribose is hydroxylated is produced. Further, Iz is generated from ^mo G ^{+ ·} that has given electrons. For this reason, the generation efficiency of Iz increases according to the generation efficiency of rG. The 14th position is also present in the complementary strand and is the same as the 10th position in terms of the complementary strand side 2 bases away from the ^Br U position, but no increase in reaction is observed. This is because the 14th position exists in a cluster different in π-stack from ^Br U in the Z-type structure, and electrons cannot be given to ^Br U. From this, it is considered that charge transfer between the clusters hardly occurs.

  FIG. 7 schematically shows the movement of electrons between these bases. FIG. 7 is similar to FIG. The left side of FIG. 7 shows right-handed B-type DNA, and the right side shows left-handed Z-type DNA. In FIG. 7, the portion shown in orange is the position of No. 10 guanine, and the portion shown in green is the position of No. 5 bromouracil. In the B type, since the bases are regularly arranged in a spiral shape, no π-electron system overlaps between No. 10 guanine and No. 5 uracil, and no electron transfer occurs. In the left-handed Z-type, 4 bases of No. 4, No. 5, No. 11, and No. 10 form a π-stack. This π-stack cluster is shown surrounded by a frame. Since the 10th guanine is present in the same cluster as the 5th uracil, the electron transfer occurs, but since the 7th cytosine belongs to a cluster different from the π-stack, the electron transfer does not occur. Absent. Similarly, since the 14th guanine belongs to a cluster different from the above-mentioned π-stack, no electron transfer occurs. As a result, it is considered that the yield of rG and Iz is different as shown in FIG.

  Such a 4-base π-stack structure in left-handed DNA (Z-DNA) has been recognized for the first time by the present invention, and it is also possible to cause movement of electrons in a range belonging to the same π-stack. It was confirmed for the first time. FIG. 8 schematically shows such a π-stacked molecular model. In FIG. 8, the left side shows a case of right-handed B type, and the right side shows a case of left-handed Z type. In FIG. 8, yellow indicates a base supplied from one strand, and blue indicates a base supplied from its complementary strand. In the right-handed B type, the bases from the respective chains have a beautiful spiral structure, whereas in the left-handed Z type, four bases overlap each other to form a π-stack, and each of these π -It can be seen that the stacks (clusters) are isolated and have a structure in which the π-electron system is disconnected. It can be seen that this structure is a structure in which electrons move within one π-stack consisting of 4 bases, but do not move between other clusters. That is, the right-handed B-type is slightly shifted due to the helical structure, but the π-electron system is continuous from the 5 ′ end to the 3′-end of DNA, whereas the left-handed Z-type is continuous. Not every four bases, indicating that the electrical conductivity from the 5 ′ end to the 3 ′ end of DNA differs between the B type and the Z type. That is, it is shown that the electrical conductivity between the 5 'end and the 3' end of the DNA can be switched by transferring the DNA from right-handed to left-handed (BZ transition). This indicates that the DNA itself can be used as a switch for controlling the circuit on and off.

Schuster et al. Examined the oxidation reaction of cation radicals by excitation of anthraquinone using hairpin structure DNA having a 5′-GG sequence, and found that there was no significant difference in electron transfer between B-type and Z-type. (Abdou, IM, Schuster, GB, et al., J. Am. Chem. Soc., 2001, 123 , 6696-6697.). However, the guanine-continuous structure used in this report (-G-G-) is difficult to transfer to the left-handed Z-type structure, and it is not clear whether it is a complete Z-type. In addition, this report lacks consideration of the cluster structure of the present invention, and further detailed examination is required.
According to the above experimental results of the present invention, the Z-type DNA has a unique π-stack structure with four bases not found in the B-type, and the structural B-type and Z-type of the base π-electron system. It is obvious that it will occur during

In the above example, an oxidation reaction by a guanine derivative has been observed, but the oxidation of natural guanine was examined next. 8-methyl-guanine ^{(m G),} the oxidation reaction in the cluster seen here for easily oxidized than guanine (G) was confirmed whether occurring in natural guanine (G). Therefore, 5′-d (CGCG ^Br UGCG) -3 ′ / 5′-d (CGCAC ^m GCG) -3 ′ in which ^m G that stabilizes the Z-type structure is replaced with G
The photoreactivity of this oligonucleotide (hereinafter referred to as ODN1-7) was examined. ODN1-7 is less likely to be Z-shaped than ODN1-2, and 2M NaCl takes only 50% of the Z-shaped structure. Even when the photoreaction was carried out under these conditions, the formation of 2′OH form was observed, and 9.0% of 5′-d (CGC) rGd (UGCG) -3 ′ and 3.5% of 5′-d ( The production of CIzCAC ^m GCG) -3 ′ was confirmed. Electron transfer of this type was confirmed that occurs generally in the Z-type DNA containing ^{Br U.} The quantitative results are summarized in FIG. From the results of the above photoreaction of bromouracil, it was found that the 4-base cluster structure in Z-type DNA restricts the charge transfer to the inside of the cluster and can control the on / off of the reaction. The π stacking mode like the cluster structure of this time is not seen except for the Z-type structure.

Next, the possibility of a device was investigated by utilizing the fact that charge transfer can be controlled by clusters. By using aminopurine to output the difference in charge transfer between the cluster structures as fluorescence, the nature of Z-type DNA was considered as an application to molecular devices. Aminopurine has been used as a charge transfer probe by Barton et al., And it can be confirmed that the electron transfer has been observed by quenching the fluorescence. It has been reported that when the base is G or A, an electron is given to aminopurine, and when C or T, the electron is received. First, Ap-containing DNA oligomer 5′-CGCApCGCGCG-3 ′ / 5′-CGCGCGTGCG-3 ′
(Hereinafter, this oligonucleotide is referred to as ODN8-9). As a comparative experiment, DNA having a sequence that does not become Z-shaped
5′-CGCApCG A GCG-3 ′ / 5′-CGC T CTGTGCG-3 ′
(Hereinafter, this oligonucleotide is referred to as ODN10-11).
The fluorescence of each DNA was measured while measuring the Z-type amount of each DNA by CD spectrum. First, the DNA oligomer was changed from B to Z according to the salt concentration, and each fluorescence was measured. The results are shown in FIG. 9a (left side of FIG. 9) is the case of ODN 8-9, and FIG. 9b (right side of FIG. 9) is the case of ODN 10-11. In each graph, the horizontal axis represents NaCl concentration (M), the vertical axis represents fluorescence intensity on the left side, and the abundance (%) of Z-type DNA on the right side. Square marks (orange) in each graph indicate the amount (%) of Z-type DNA measured by CD spectrum, and diamond marks (blue) indicate fluorescence intensity.
As a result, most of the 1M NaCl is B-type DNA (95% or more), and aminopurine is quenched. This is probably because aminopurine is sandwiched between C on the 5 ′ side and C on the 3 ′ side and it is possible to give electrons to both. Furthermore, the 4-base cluster structure not only controls the charge transfer path within the structure, but also affects the charge transfer by changing the overlapping sequence of the cluster becoming ApCCG. As the salt concentration increased and became Z-type, the fluorescence increased to the same intensity as the single strand. This is because charge transfer is maintained in the cluster structure in the Z-type structure, and C on the 5 ′ side exists in another cluster in the Z-type, and there is a base for exchanging electrons on the 5 ′ side of Ap. It seems to be because it disappears. Bromouracil has shown that charge transfer is less likely to occur between cluster structures, and the same reason is thought to be that aminopurine quenching is less likely to occur. Furthermore, it seems that it is important for the fluorescence intensity that the bases in the B-type and the Z-type are overlapped and the position of the base belonging to the complementary strand is also changed. However, the important point here is that the charge transfer is greatly influenced by the cluster structure of 4 bases.

Moreover, it is known that Z type and B type change with temperature. That is, it changes from B type to Z type as the temperature decreases. Therefore, using ODN8-9, the change in BZ and the change in fluorescence due to CD were examined by changing the salt concentration of 3M, which is 50% Z-type, from 2 ° C to 32 ° C every 10 ° C. As a result, it was found that the fluorescence decreased as the temperature changed from Z-type to B-type. As a comparative experiment, when DNA oligomer ODN10-11 that does not have a Z-shape was used, no fluorescence was observed regardless of temperature changes. The results are shown in FIG. FIG. 10a (upper left of FIG. 10) is a case where ODN8-9 is used, the horizontal axis of the graph indicates temperature (° C.), and the vertical axis indicates fluorescence intensity. FIG. 10b (upper right side of FIG. 10) is a case where ODN10-11 is used, the horizontal axis of the graph indicates temperature (° C.), and the vertical axis indicates fluorescence intensity. FIG. 10c (lower left side of FIG. 10) shows the case where the temperature is changed alternately between 2 ° C. and 32 ° C. using ODN8-9 or ODN10-11, and the horizontal axis of the graph indicates the temperature (° C.). The vertical axis indicates the fluorescence intensity. The oval mark (pink) in the graph indicates the case of ODN8-9, and the rhombus mark (blue) indicates the case of ODN10-11. FIG. 10d (lower right side of FIG. 10) schematically shows the fluorescence of ODN8-9 due to the temperature-dependent BZ transition.
From these results, it can be seen that the charge transfer path can be controlled depending on the temperature and output as fluorescence is possible, and it can be used as an unprecedented unique molecular thermometer and temperature sensor (FIG. 10d). reference).

  Furthermore, each Z-B state can be used as a molecular device. Fluorescence was measured by changing the temperature of the oligomer in 3M NaCl alternately between 2-32 ° C. As a result, the fluorescence was low at 32 ° C. and increased at 2 ° C., and a BZ structure change and an output corresponding to the change were obtained in response to repeated temperature changes (see FIG. 10c). Therefore, it is easy to control, and the two states can be easily distinguished by fluorescence. Therefore, it can be expected as a functional molecule such as a molecular device.

As described above, the present invention provides a nanoelectronic device material that utilizes the difference in physical properties between right-handed (B-type) and left-handed (Z-type) DNA. The DNA of the present invention may be any DNA as long as it can be transferred into a right-handed (B-type) or left-handed (Z-type) state depending on the salt concentration, temperature, etc. Or non-natural type DNA may be sufficient. Preferred DNAs are 5 to 200 bp, 5 to 150 bp, 5 to 100 bp, 5 to 80 bp, 5 to 50 bp, 5 to 30 bp, 5 to 20 bp, or 8 to 200 bp, 8 to 150 bp, 8 to 100 bp, 8 ˜80 bp, 8-50 bp, 8-30 bp, 8-20 bp, and 8-15 bp. The base sequence generally has a base sequence in which bases having a purine ring and bases having a pyrimidine ring are alternately arranged. For example, those having a GCGC sequence and those having an ATAT sequence are preferable. Examples of the base having a purine ring include adenine, guanine, and derivatives thereof. Examples of the base having a pyrimidine ring include those having pyrimidine-dione or a derivative thereof such as thymine or uracil or a derivative thereof, cytosine or a derivative thereof. For example, as shown in the above-mentioned examples, those containing a sequence such as GCGXGCGC (X represents a pyrimidine ring or a derivative thereof, for example, a base having a substituted or unsubstituted pyrimidine-dione or a derivative thereof). preferable.
Non-natural bases include halocils such as uracil, bromouracil and iodouracil, 8-alkylguanines such as halocytosine, 8-methylguanine and 8-ethylguanine, 8-methyl-2-acetylguanine and 8-ethyl-2. There may be mentioned 8-alkyl-2-acylguanine such as acetylguanine, 8-alkoxyguanine such as 8-methoxyguanine, 8-ethoxyguanine, 8-aminopurine, 2-aminopurine and the like.
Further, the right-handed (B-type) and left-handed (Z-type) states of DNA in the present invention may be reversible or irreversible. As described above, the BZ transition can occur reversibly or irreversibly, and in any case, it can be used as the DNA of the present invention. For example, a reversible BZ transition is preferable when used as an element such as switching or a sensor element, and an irreversible BZ transition when used as a fixed storage element. Can also be used.

The difference in physical properties between the right-handed (B-type) and left-handed (Z-type) states of the DNA of the present invention is due to the fact that it takes a π-stack structure consisting of four bases by becoming Z-type as described above. Differences in physical properties based on electrons or charge transfer can be mentioned. Any difference in physical properties is not particularly limited. For example, the electrical conductivity of DNA, the presence or absence of fluorescence based on electron transfer, the change in fluorescence wavelength, or the change in fluorescence intensity.
The nanoelectronic device material of the present invention includes various electronic devices such as memory device elements, temperature sensing sensors, sensor device elements such as sensor elements for detecting the presence of organic molecules, and logic circuit switching elements. Can be used as such. Since the DNA of the present invention functions in principle as a molecule, it can be a nano-order element.
For example, the DNA of the present invention can be connected to a gold or silicone substrate or an electrode to form a device. For these connection techniques, DNA immobilization techniques such as a DNA chip can be applied.

Changes in the right-handed (B-type) and left-handed (Z-type) states of the DNA of the present invention include salt concentration change, temperature change, light irradiation, binding to organic molecules such as small molecules and proteins, and specific forms. Can be caused by the presence of molecules. For example, the right-handed state (B type) of the DNA of the present invention is turned on or bit 1 and the left-handed state (Z type) is turned off or bit 0 to be a switching element or a memory element. it can. In addition, by utilizing irreversible BZ transition, ROM-type memory is used in which only DNA at a specific position in a B-type DNA sequence is irreversibly transferred to Z-type by light irradiation or the like. A device is also conceivable.
In addition, when there is a temperature sensor using temperature change or a substance that induces BZ transition in the analyte substance by contacting the analyte substance with the DNA portion of the present invention, such as a small molecule or protein When a molecule having a specific character is present, BZ transition occurs. Therefore, a sensor element for detecting the presence of an organic molecule or the like can be used.

  The present invention relates to a novel nanoelectronic device using electron or charge transfer focusing on the fact that left-handed Z-shaped DNA has a 4-base π-stack structure, and these 4 bases form isolated clusters. The material is provided. The present invention utilizes the BZ transfer reaction of DNA, and in principle can be used as a nanoelectronic device material in molecular units, and DNA is a molecule in which sugar chains are bound relatively firmly. Seed and natural DNA has replication ability, has excellent mechanical strength, is easily mass-produced, and can be made into a minute device material.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited at all by these Examples.

5′-d (CGCG ^Br UGCG) -3 ′ / 5′-d (C ^m GCAC ^m GCG) -3 ′ (ODN1-2) is determined according to the method of a previously reported (see Non-Patent Documents 1, 2 and 5). Synthesized.
36 μM of ODN1-2 was taken in 20 mM phosphate buffer (pH 7.0) so that the total amount was 100 μL, and 20 mM or 2.0 M NaCl in each solution was added. A 20 mM NaCl solution is B-type ODN1-2, and a 2.0 M NaCl solution is Z-type ODN1-2. Each solution was irradiated with 302 nm ultraviolet light (HM-5 hypermonochromator (Jasco)) at 0 ° C. for 30 minutes.
The CD spectrum of each reaction mixture was measured according to the method reported previously (see Non-Patent Document 1).
In addition, each reaction mixture was subjected to HPLC with Chemcobond 5ODS-H column (4.6 × 150 mm) at 40 ° C. and 0.05 M ammonium formate containing acetonitrile with a concentration change of 2 to 7% linear gradient. The solution was analyzed by eluting for 40 minutes at a flow rate of 1 mL / min.
The results of each HPLC and CD spectrum are shown in FIG.
The structures of rG and Iz were analyzed with an ionization electrospray mass spectrometer (ESI-MS, negative) after digesting them with enzymes.
5′-d (CGC) rGd (UGCG) -3 ′ calculated value: 2428.6
Actual value: 2428.2
5′-d (CIzCAC ^m GCG) -3 ′ calculated value: 2369.4
Actual value: 2369.8

5′-d (CGCG ^Br UGCG) -3 ′ / 5′-d (C ^mo GCAC ^m GCG) -3 ′ (ODN1-3) is applied in accordance with the method of the previous report (see Non-Patent Documents 1, 2 and 5). And synthesized.
This was treated in the same manner as described in Example 1 and each reaction mixture was measured by HPLC as in Example 1.
The results are shown in FIG.

5′-d (CGCG ^Br UGCG) -3 ′ / 5′-d (C ^m GCAC ^mo GCG) -3 ′ (ODN1-4),
5′-d (CGC ^mo G ^Br UGCG) -3 ′ / 5′-d (C ^m GCAC ^m GCG) -3 ′ (ODN5-2),
5′-d (CGCG ^Br U ^mo GCG) -3 ′ / 5′-d (C ^m GCAC ^m GCG) -3 ′ (ODN6-2), and 5′-d (CGCG ^Br UGCG) -3 ′ / 5 '-D (CGCAC ^m GCG) -3'
(ODN1-7) was synthesized according to the method of the previous report (see Non-Patent Documents 1, 2 and 5).
This was treated in the same manner as described in Example 1 and each reaction mixture was measured by HPLC as in Example 1.
The results are shown in FIG.

5′-CGCApCGCGCG-3 ′ / 5′-CGCGCGTGCG-3 ′
(ODN8-9) and
5′-CGCApCG A GCG-3 ′ / 5′-CGC T CTGTGCG-3 ′
(ODN10-11) was synthesized according to the method of the previous report (see Non-Patent Documents 1, 2 and 5).
Each 30 μM was taken in 20 mM phosphate buffer (pH 7.0), and the NaCl concentration of each solution was changed to 1 to 5 M, and the fluorescence intensity was measured. The measurement was excited at 317 nm and the emission spectrum at 360 nm was monitored.
The amount of Z-type was determined by a CD spectrum at 10 ° C. in a 1 cm cell in accordance with a previously reported method (see Non-Patent Document 1). The solution was hybridized by heating to 90 ° C. and slowly cooling to room temperature. The ratio of the B-type and Z-type amounts was determined by the CD ellipticity at 295 nm.
The results are shown in FIG.

ODN8-9 and ODN10-11 used in Example 4 were each taken at 30 μM in 20 mM phosphate buffer (pH 7.0), and the NaCl concentration of each solution was adjusted to 3M.
The fluorescence intensity was measured in the same manner as in Example 4 by changing the temperature of each solution from 2 ° C. to 32 ° C. every 10 ° C. The results are shown in FIGS. 10a and b.
Further, FIG. 10c shows the result of measuring the fluorescence intensity in the same manner while changing the temperature between 2 ° C. and 32 ° C.

  The present invention provides a nanoelectronic device material that utilizes the difference in physical properties between right-handed (B-type) and left-handed (Z-type) DNA, and is a novel material that can function in molecular units. It can be used as a switching element, memory element, sensor element, detection element, and the like.

FIG. 1 shows the results of HPLC and CD spectra of the right-handed (B-DNA) (upper part of FIG. 1) and the left-handed (Z-DNA) (lower part of FIG. 1) of ODN1-2 of the present invention. Is. FIG. 2 schematically shows the sequence state of each base of right-handed (B-DNA) (left side of FIG. 2) and left-handed (Z-DNA) (right side of FIG. 2) of ODN1-2 of the present invention. It is a thing. FIG. 3 is a graphic representation of the sequence state of each base of the right-handed (B-DNA) (left side of FIG. 3) and left-handed (Z-DNA) (right side of FIG. 3) of ODN1-2 of the present invention. It is a color drawing of computer graphics instead of a generalized drawing. FIG. 4 shows the HPLC results of right-handed (B-DNA) (upper part of FIG. 4) and left-handed (Z-DNA) (lower part of FIG. 4) of ODN1-3 of the present invention. . FIG. 5 shows the nucleotide sequence of the oligonucleotide of the present invention (the upper part of FIG. 5) and the respective photochemical reactions of ODN1-2, ODN1-3, ODN1-4, ODN5-2, ODN6-2, and ODN1-7. The graph shows the yield of rG and Iz. FIG. 6 shows a chemical reaction formula showing the reaction mechanism of the photochemical reaction of ODN1-3 of the present invention. FIG. 7 schematically shows the movement of electrons in the photochemical reaction of ODN1-2 of the present invention. FIG. 8 is a drawing schematically showing a molecular model of the base sequence of each of right-handed DNA (B-DNA) (left side of FIG. 8) and left-handed (Z-DNA) (right side of FIG. 8). It is an alternative color photograph. In Z-DNA, a π-stack structure with 4 bases is formed. FIG. 9 shows the ratio of the amount of B-type and Z-type at each salt concentration (orange color) of ODN8-9 of the present invention (left side of FIG. 9) and ODN10-11 (right side of FIG. 9) to be compared. 4 is a graph showing the square marks) and the fluorescence intensity (blue diamond marks). FIG. 10 is a graph showing the fluorescence intensity at each temperature of the ODN8-9 (FIG. 10a) of the present invention and the ODN 10-11 (FIG. 10b) to be compared. FIG. 10c shows the fluorescence intensity when each of ODN8-9 (pink ellipse mark) and ODN10-11 (blue rhombus mark) for comparison are changed to 2 ° C. and 32 ° C. 10d schematically shows the color development of fluorescence in the BZ transition between the B type and the Z type.

N in SEQ ID NO: 1 represents 5-bromouracil.
The second n in SEQ ID NO: 2 represents 5-bromouracil, and the first n represents 8-methoxyguanine.
The first n in SEQ ID NO: 3 represents 8-methoxyguanine, and the second n represents 5-bromouracil.
N in SEQ ID NOs: 4 and 5 represents 8-aminopurine.

Claims (13)

  Nanoelectronics utilizing the difference in physical properties based on the movement of electrons or charges by taking a π-stack structure consisting of four bases by changing the DNA from right-handed (B-type) to left-handed (Z-type) A nanoelectronic device material, which is a device material, wherein the DNA is 8 to 200 bp in length and has a base sequence in which bases having purine rings and bases having pyrimidine rings are alternately arranged.   The nanoelectronic device material according to claim 1, wherein the difference in physical properties based on the movement of electrons or charges is a difference in electrical conductivity.   The nanoelectronic device material according to claim 2, wherein the difference in electrical conductivity is used as a switch for controlling a circuit on and off.   The nanoelectronic device material according to claim 1, wherein the difference in physical properties based on the movement of electrons or charges is the presence or absence of fluorescence, a change in fluorescence wavelength, and / or a change in fluorescence intensity.   The nanoelectronic device material according to claim 1, wherein the difference in physical properties based on the movement of electrons or charges is a difference in photoreactivity in a photoreaction.   The change in the state of DNA from right-handed (B type) to left-handed (Z type) is a reversible transfer reaction caused by changes in temperature and / or salt concentration. Nanoelectronic device materials.   The nanoelectronic device material according to any one of claims 1 to 6, wherein the DNA has a pyrimidine-dione ring or a ring made of a derivative thereof as a base moiety.   The nanoelectronic device material according to any one of claims 1 to 7, wherein the DNA is of a natural type. The nanoelectronic device material according to any one of claims 1 to 7 , wherein the DNA contains aminopurine or a derivative thereof as a base.   An element for a memory device, characterized by using the nanoelectronic device material according to claim 1.   11. The element for a storage device according to claim 10, wherein a difference in electrical conductivity between the B-type and the Z-type of DNA is used as a switch for controlling the circuit on and off.   A sensor element for a sensor device, wherein the nanoelectronic device material according to any one of claims 1 to 4 and 6 to 9 is used.   The sensor element for a sensor device according to claim 12, wherein the sensor element is a sensor for temperature detection.

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