JP5130517B2 - Optical waveguide type DNA sensor and DNA detection method - Google Patents

Description

  The present invention relates to an optical waveguide type DNA sensor and a DNA detection method, and more specifically, an optical waveguide type DNA sensor and a DNA detection method for performing DNA sensing using light.

  With the aging of society, the increase in medical costs has become serious, and in order to reduce medical costs, there is a need for the development of sensors that can detect minute amounts of DNA quickly and at room temperature. In recent years, a method has been reported that can detect a DNA sample rapidly and at room temperature using gold fine particles (Non-patent Document 1).

In addition, a DNA detection method using a gold colloid solution has been reported. FIG. 1 is a diagram for explaining a conventional DNA detection method using a gold colloid solution.
In FIG. 1, a colloidal gold solution 2 is placed in a container 1 made of a material that transmits light 3. In this gold colloid solution 2, single-stranded DNA (probe DNA) is dropped into the gold colloid solution to fix the probe DNA to the gold fine particles, and then the target single-stranded DNA (target DNA) is placed in the gold colloid solution. Generated by dripping.

  At this time, if the probe DNA and the target DNA are complementary, a hybridization reaction occurs and aggregation of gold fine particles occurs. The gold colloid in which the gold fine particles are dispersed is red, but when the above aggregation occurs, the absorption spectrum shifts to the long wavelength side, and the color of the solution changes from red to purple.

  Conventionally, DNA sensing is performed using this color change. That is, in FIG. 1, in the container 1, a light receiving element 4 such as a photodiode is disposed on the side opposite to the incident side of the light 3, and the colloidal gold solution 2 is irradiated with the light 3, and the transmitted light 5 is received. Light is received by the element 4. DNA sensing is performed by examining the absorption spectrum of the transmitted light 5 received by the light receiving element 4.

Yoshiko Miura, Toru Yonezawa, “Preparation of gold nanoparticles and biosensing using it” Dojin News No. 113 (2005), p. 1-7

In this way conventional, light incident on the gold colloid solution, is performed a DNA detection by analyzing the spectrum of the transmitted light, the gold colloid solution, COO with a negative charge ^- the group gold particles Surrounding, an electrical repulsive force acts between the gold fine particles, and the gold fine particles are dispersed without being aggregated. Accordingly, accurate measurement cannot be performed with a small amount of DNA specimen (probe DNA and target DNA), and a large amount of colloidal gold solution is required in order to cause a large amount of gold fine particles to exist in a region through which light passes.

  The present invention has been made in view of such problems, and an object thereof is to provide an optical waveguide type DNA sensor and a DNA detection method capable of accurately detecting DNA even with a small amount of a DNA sample. There is.

In order to achieve the above object, the present invention provides an optical waveguide, an optical coupling means for coupling light to the optical waveguide, DNA can be fixed, A colloidal gold solution in which gold particles charged with a sign are dispersed; a region on the optical waveguide to which probe DNA and target DNA are applied; and the combined light crosses at least the region. And further comprising the gold fine particles provided on the region, wherein a charge having a sign opposite to the charge is introduced into the region. And the gold microparticles are electrostatically adsorbed to each other , an optical waveguide type DNA sensor .

The invention described in claim 2 is the invention described in claim 1 , characterized in that the probe DNA is fixed to the gold fine particles.

A third aspect of the invention is characterized in that, in the invention of the first or second aspect , the wavelength band of the combined light overlaps at least partly with the absorption wavelength band of the gold fine particles.

The invention according to claim 4 is an optical waveguide capable of fixing DNA and having a region to which a colloidal gold solution in which fine gold particles charged with one sign are dispersed, a probe DNA, and a target DNA are provided. A step of preparing an optical waveguide in which a charge having a sign opposite to the charge is introduced in the region; and a step of applying the gold colloid solution, the probe DNA, and the target DNA to the region And a step of coupling light to the optical waveguide, guiding the coupled light so as to cross the region, and a step of receiving light crossing the region.

According to a fifth aspect of the present invention, in the fourth aspect of the invention, when the probe DNA and the target DNA are mismatched, the gold fine particles are electrostatically adsorbed on the surface of the region. It is characterized by that.

The invention according to claim 6 is the invention according to claim 4 or 5 , characterized in that the wavelength band of the combined light overlaps at least partly with the absorption wavelength band of the gold fine particles.

  According to the present invention, the charge opposite to the sign of the charge can be applied to a predetermined region of the optical waveguide to which DNA can be fixed and charged with one charge, the probe DNA, and the target DNA. Since it is introduced, the material can be electrostatically adsorbed to the optical waveguide. Therefore, it is possible to provide an optical waveguide type DNA sensor and a DNA detection method capable of accurately detecting DNA even with a small amount of DNA sample.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
A gold colloid solution in which gold fine particles having a particle diameter of about 15 nm are dispersed is red. In this gold colloid solution, when the gold fine particles are aggregated, the absorption spectrum shifts to the longer wavelength side, and the color of the solution changes from red to blue. The aggregation of the gold fine particles is caused by a hybridization reaction between the probe DNA fixed to the gold fine particles and the target DNA.

  DNA sensing according to an embodiment of the present invention utilizes the above-described color change or aggregation, that is, utilizing a hybridization reaction between the probe DNA and the target DNA, so that an absorption spectrum, a transmission spectrum, fluorescence, etc. This is done by measuring the light characteristic or refractive index change.

  When a colloidal solution such as a gold colloid solution is used for DNA sensing using light, since gold fine particles are dispersed, a large amount of DNA specimen and gold colloid solution are required as described above. Therefore, in one embodiment of the present invention, the gold fine particles are arranged in the sensing region at a higher density than the gold particle density in the colloidal solution.

In order to realize such an arrangement, in one embodiment of the present invention, on the sensing region of the optical waveguide, a functional group having a positive charge that is opposite to the COO ⁻ group that is a functional group surrounding the gold fine particle. (For example, NH ₂ ⁺ group) is arranged. That is, a positive charge is introduced into the region. In this way, when a colloidal gold solution is applied on the sensing region, the gold fine particles in the solution have a COO ⁻ group surrounding the gold fine particles and a positive charge (for example, NH ₂ ⁺ group) introduced on the sensing region. Is electrostatically adsorbed to the sensing area by the Coulomb force. This is shown in FIG.

In FIG. 2A, a gold colloid solution 22 is applied on the optical waveguide 21, and the gold fine particles 23 are electrostatically adsorbed on the optical waveguide 21 to which positive charges are introduced. The optical waveguide 21 is provided with NH ₂ ⁺ groups (not shown) subjected to silane coupling treatment, and coulombs acting between the NH ₂ ⁺ groups and the COO ⁻ groups around the gold fine particles 23. Due to the force, the gold fine particles 23 are electrostatically adsorbed to the optical waveguide 21.

  On the other hand, if the above-described positive charge is not introduced, even if the gold colloid solution 22 is applied on the optical waveguide 21 as shown in FIG. Dispersed in solution.

  As can be seen from FIGS. 2 (a) and 2 (b), when a positive charge is introduced into the surface of the optical waveguide, gold fine particles are adsorbed on the interface of the optical waveguide. When light is guided to P, the light guided through the waveguide by the length of the waveguide in the traveling direction of the light guided through the waveguide (also simply referred to as “the length of the waveguide”). Can act on gold fine particles. Therefore, even if the amount of the DNA specimen or the colloidal gold solution is small, the region where the light guided through the waveguide as the measurement light and the gold fine particles act can be gained by the length of the waveguide.

  That is, when a colloidal solution in which gold fine particles are dispersed is used as in the conventional method shown in FIG. 2B or FIG. 1, the number of gold fine particles to which light used for measurement acts when the amount of the sample is small is Since the gold fine particles are dispersed in the solution, the amount of the gold fine particles becomes small, and the amount of the specimen and the colloidal gold solution has to be increased in order to perform highly accurate measurement. However, as shown in FIG. 2A, gold fine particles distributed three-dimensionally by dispersion in a predetermined amount of colloidal gold solution can be two-dimensionally arranged. By guiding the light in parallel with the surface arranged in the above, the guided light can be applied to all of the two-dimensionally arranged gold fine particles. Therefore, as in the conventional case, gold fine particles that do not act on the measurement light due to dispersion can be allowed to act on the measurement light when measured in the colloid solution, so that the gold fine particles in the colloid solution are efficiently used. Therefore, it is possible to reduce the amount of specimens.

  Note that it is preferable that all of the gold fine particles contained in the gold colloid solution applied to the optical waveguide are electrostatically adsorbed to the optical waveguide, but the gold fine particles may remain in the solution without being adsorbed. One of the important things in one embodiment of the present invention is that gold fine particles contained in a given colloidal gold solution are allowed to efficiently react with light guided through a waveguide. If the part is electrostatically adsorbed to the optical waveguide, the gold fine particles included in the applied gold colloid solution can increase the number of gold fine particles acting on the light guided through the waveguide.

  As described above, it is important in one embodiment of the present invention to increase the number of gold fine particles that interact with the light guided through the waveguide as the measurement light. For this reason, the evanescent wave is stained by the guided light. It is important that more gold fine particles be present in the region to be discharged. For this purpose, gold fine particles dispersed by negative charges are electrostatically adsorbed on the sensing region of the optical waveguide.

In one embodiment of the present invention, gold fine particles are used as a material used for immobilizing the probe DNA. However, the present invention is not limited thereto, and for example, DNA such as silicon oxide (SiO ₂ ) can be immobilized. Any material may be used as long as it is a material that is charged with the charge of the above sign and is dispersed in the solution by being surrounded by a functional group having the charge of one sign. As such a material, it is preferable that the color in the case of a colloidal solution differs from the color at the time of aggregation.

(First embodiment)
FIG. 3A is a side view of the optical waveguide type DNA sensor according to the present embodiment, and FIG. 3B is a top view of the optical waveguide type DNA sensor shown in FIG.
In FIG. 3, a potassium ion exchange glass optical waveguide (400 ° C., 1 h ion exchange in molten potassium nitrate) 32 is formed on one surface of a glass substrate 31 with a thickness of about 2 microns. The optical waveguide 32 is a single mode waveguide. A light absorption layer 33 is formed on the surface of the glass substrate 31 that faces the surface on which the optical waveguide 32 is formed. Alq3 34 which is an organic EL material is formed in a predetermined region of the optical waveguide 32. A Cytop 35 is formed so as to cover the Alq3 34, and a cover glass 36 is disposed on the Cytop 35.

  A prism 37 is disposed on the optical waveguide 32 in a direction indicated by an arrow D in FIG. 3B by being separated from the Cytop 35 and the cover glass 36 by a predetermined distance. Index matching oil (not shown) is disposed between the prism 37 and the optical waveguide 32, and light guided through the optical waveguide 32 enters the prism 37. A sensing region 38, which is a region for applying the gold colloid solution, is formed on the optical waveguide 32 between the Cytop 35 and the cover glass 36 and the prism 37 and on the region where the guided light S is guided. Has been. The sensing region 38 can be formed from a Teflon (registered trademark) sheet or the like, and a gold colloid solution is applied to the sensing region 38, and a DNA specimen is also applied. That is, the sensing region 38 is formed so that the guided light S crosses.

  Further, an LED 39 for ultraviolet irradiation is arranged so that light is incident on the Alq334. The LED 39 emits ultraviolet light having a wavelength of 365 nm.

  A filter 40 and an optical sensor 41 are disposed so as to receive light emitted from the prism 37. Moreover, the filter 42 and the optical sensor 43 are formed so that the light radiate | emitted from the area | region in which the light absorption layer 33 is not formed of the glass substrate 31 may be received.

  By the way, in this embodiment, Alq3 which is an organic EL material is used in order to correspond to the absorption spectrum of gold fine particles. The emission wavelength region of Alq3 is a wide wavelength region of 500 to 600 nm. Therefore, the absorption spectrum of the gold fine particle and the emission spectrum of Alq3 are almost overlapped, that is, the emission wavelength region of Alq3 corresponds to the wavelength of the absorption peak of the gold fine particle, so that highly sensitive detection is possible.

  Therefore, it comprises like this embodiment, and ultraviolet rays (wavelength = 365 nm) are irradiated to Alq3 34 from LED39, and photoluminescence light is produced | generated in Alq334. Of the generated photoluminescence light, predetermined light is coupled to the optical waveguide 32 to become the guided light S. In this way, the guided light S having a wide spectral width is guided through the optical waveguide 32 which is a single mode waveguide. The guided light S is emitted from the prism 37, and the emitted light U emitted from the prism enters the optical sensor 41 via the filter 40. Of the generated photoluminescence light, the light T is emitted from the region of the glass substrate 31 where the light absorption layer 33 is not formed, and enters the optical sensor 43 via a filter 42 described later. To do.

Next, a method for producing an optical waveguide type DNA sensor according to this embodiment will be described.
A commercially available slide glass is cleaned by ultrasonic cleaning, rinsed sufficiently, and then immersed in a potassium nitrate solution salt at 400 ° C. for 40 minutes. In this way, the potassium ion exchange optical waveguide 32 formed on the glass substrate 31 is produced. Next, a thin film of Alq3 34 is produced in a predetermined region of the optical waveguide 32 by vacuum deposition, a Cytop 35 is formed so as to cover the produced Alq3 34, and a cover glass 36 is disposed. Next, the sensing area 38 is formed by a Teflon (registered trademark) sheet, index matching oil is applied to a predetermined region of the optical waveguide 32, and the prism 37 is disposed on the index matching oil.

Now, in the colloidal gold solution, an electrically repulsive force acts between the fine particles by the negatively charged COO ⁻ group surrounding the gold fine particles. Therefore, the colloidal gold solution is dispersed without aggregation of particles. Therefore, if an NH ₂ ⁺ group capable of having a positive charge is introduced on the substrate surface, the gold fine particles can be electrostatically adsorbed on the substrate.

Therefore, in the present embodiment, NH ₂ ⁺ groups are introduced into the optical waveguide substrate by performing a silane coupling process on the sensing region 38 of the optical waveguide. That is, a sensor having the configuration shown in FIG. 3 is prepared, and a process of introducing a charge opposite to the charge of the functional group surrounding the gold fine particles in the gold colloid solution into the sensing region 38 is performed.

Next, a colloidal gold solution (concentration 74 ppm, particle diameter 16.5 nm) is dropped onto the sensing region 38. Since NH ₂ ⁺ groups are introduced on the surface of the sensing region 38 by silane coupling treatment, the gold fine particles in the dropped gold colloid solution are fixed by being electrically adsorbed on the surface of the sensing region 38. It becomes.

  Next, Au-probe DNA, 0.5 M NaCl solution and target DNA are dropped onto the sensing region 38 where the gold fine particles are electrostatically adsorbed. In this way, the optical waveguide type DNA sensor according to the present embodiment is manufactured. In the present embodiment, Au—S bonds are used for bonding gold fine particles and DNA.

  When the dropped target DNA is a full match with the probe DNA, the probe DNA and the target DNA should undergo a hybridization reaction. That is, it is considered that the state of the charge of the DNA fixed to the gold fine particle differs depending on whether the target DNA is a full match or mismatch with the probe DNA, and the immobilization to the optical waveguide is different.

  Therefore, in the present embodiment, depending on whether the target DNA is a full match or a mismatch with the probe DNA, in order to control the fixation of the gold fine particles to which the DNA is fixed to the sensing region of the optical waveguide, A positive charge is introduced, for example, by performing a coupling process.

Next, the DNA detection method according to this embodiment will be described.
First, in FIG. 3, a gold colloid solution, a probe DNA, and a target DNA are respectively applied to the sensing region 38 into which a positive charge has been introduced. Next, ultraviolet light is emitted from the LED 39 to the Alq3 34 to generate photoluminescence light. The emission spectrum of the photoluminescence light has a peak in the wavelength band of 500 nm to 600 nm, and almost overlaps with the absorption peak of the gold fine particles. Part of the generated photoluminescence light is coupled to the optical waveguide 32 as guided light S, and the other part exits from the sensor as light T and enters the optical sensor 43 via the filter 42.

  Since the guided light S is guided through the optical waveguide 32 while being totally reflected, an evanescent wave is generated. At this time, when the probe DNA and the target DNA are mismatched, the gold microparticles on which the single-stranded DNA is immobilized (the probe DNA is immobilized) are electrostatically adsorbed (immobilized) on the surface of the sensing region. Therefore, the evanescent wave acts on the gold fine particles existing within the range, and light having a wavelength of about 530 nm is absorbed. Therefore, when the light emitted from the prism 37 and received by the optical sensor 41 via the filter 40 is analyzed, the light intensity at the wavelength of about 530 nm, which is an absorption peak, decreases with time. This is shown in FIG.

  In FIG. 4, spectrum (a) gives the transmission spectrum of light received by the optical sensor 41 before immobilization (adsorption), that is, a colloidal gold solution, probe DNA, and target DNA are applied to the sensing region 38. It is the previous transmission spectrum. The spectrum (b) is a transmission spectrum of light received by the optical sensor 41 10 minutes after the gold colloid solution, the probe DNA, and the target DNA are applied to the sensing region 38 (also referred to after fixation (after adsorption)). The spectrum (c) is the transmission spectrum of the light received by the optical sensor 41 20 minutes after fixation (after adsorption), and the spectrum (d) is 30 minutes after fixation (after adsorption). This is a transmission spectrum of light received by the optical sensor 41. As can be seen from FIG. 4, the light intensity in the vicinity of 530 nm of the transmission spectrum is weakened with time, so that it can be seen that the light in the wavelength band is absorbed. That is, it can be seen that the gold fine particles are fixed on the surface of the sensing region 38.

  On the other hand, when the probe DNA and the target DNA are in a full match, the double-stranded DNA is fixed to the gold fine particle, and the gold fine particle is not fixed (adsorbed) to the sensing region 38. Therefore, the transmission spectrum of the light received by the optical sensor 41 hardly changes regardless of the elapsed time after fixing. This is shown in FIG.

  In FIG. 5, spectrum (a) is a transmission spectrum of light received by the optical sensor 41 before immobilization (adsorption) occurs. The spectrum (b) is a transmission spectrum of light received by the optical sensor 41 10 minutes after fixation (after adsorption), and the spectrum (c) is an optical sensor 20 minutes after fixation (after adsorption). 41 is a transmission spectrum of light received at 41, and a spectrum (d) is a transmission spectrum of light received by the optical sensor 41 30 minutes after fixing (after adsorption). As can be seen from FIG. 5, even when time elapses, almost no change is observed in the light intensity in the vicinity of about 530 nm of the transmission spectrum, so that it is understood that the light in the wavelength band is hardly absorbed. That is, it can be seen that gold fine particles are not fixed to the surface of the sensing region 38.

  In the configuration of the present embodiment, in order to confirm that the gold fine particles are not fixed to the surface of the optical waveguide into which the positive charge is introduced at the time of the full match and the gold fine particles are fixed to the surface of the optical waveguide at the time of the mismatch, the absorption is performed as follows. The spectrum was measured.

  By the method described above, three optical waveguide substrates were prepared under the same manufacturing conditions. The first optical waveguide substrate is cut into two, and one of the cut optical waveguide substrates is provided with a colloidal gold solution, probe DNA, and target DNA so as to be a full match, and the other optical waveguide substrate is applied to the other optical waveguide substrate. Applies a colloidal gold solution, probe DNA, and target DNA so as to be mismatched, and the above-described application is performed 10 minutes after the application (after fixation) for each of the full-match optical waveguide substrate and the mismatch optical waveguide substrate. The absorption spectrum of light that passed through the region was measured. This absorption spectrum is shown in FIGS.

  In the same manner, the second optical waveguide substrate was also cut into two, and the absorption spectrum was measured 20 minutes after fixing, with one being a fully matched substrate and the other being a mismatched substrate. The third optical waveguide substrate was also cut into two in the same manner as described above, and the absorption spectrum 30 minutes after fixing was measured using one as a fully matched substrate and the other as a mismatched substrate. These absorption spectra are also shown in FIGS.

  As can be seen from FIG. 6, in the case of the full match, the absorption peak of the gold fine particles at about 530 nm was not seen regardless of the elapsed time after the fixation. Therefore, it can be seen that light absorption by the gold fine particles hardly occurs. Therefore, it can be seen that almost no gold fine particles are present in the range of the evanescent wave by the light guided through the optical waveguide substrate, that is, the gold fine particles are hardly fixed.

  Further, as can be seen from FIG. 7, in the case of mismatch, an absorption peak was observed at about 530 nm, which coincided with the absorption peak of the gold fine particles at any elapsed time. Therefore, it can be seen that light absorption occurs by the gold fine particles. Therefore, it can be seen that a large number of gold fine particles are present in the range of evanescent waves generated by the light guided through the optical waveguide substrate, that is, the gold fine particles are fixed to the surface of the optical waveguide substrate.

  Now, returning to the description of the detection method, the guided light S acts on the gold fine particles when the gold fine particles pass through the optical waveguide 32 and are fixed (electrostatically adsorbed) in the sensing region 38. The light is emitted from the prism 37 to become emitted light U. The emitted light U enters the optical sensor 41 through the filter 40.

  Since the transmission spectrum obtained from the light received by the optical sensor 43 functions as a reference, the calculated transmission spectrum is obtained by taking a ratio with the transmission spectrum obtained from the light received by the optical sensor 41. Looking at this transmission spectrum, when the peak at about 530 nm decreases with time, it is determined as a mismatch, and when it does not decrease and hardly changes, it is determined as a full match. In this way, DNA is detected.

  In this embodiment, Alq334 and LED39 are used to make light having a predetermined wavelength band incident on the optical waveguide. However, the present invention is not limited to this, and light having a predetermined wavelength band is incident on the optical waveguide. Any means may be used if possible. For example, a second prism may be disposed in a predetermined region of the optical waveguide 32 so as to face the prism 37, and light may be incident on the optical waveguide 32 through the prism. Further, one end of an optical fiber or an optical waveguide through which light of a predetermined wavelength band is guided is connected to an end face of the optical waveguide 32 on the side facing the prism 37 by a butt joint method or the like to guide the light. It may be incident on the waveguide 32.

  Further, in the present embodiment, it is sufficient that the transmission spectrum and the absorption spectrum can be changed by reflecting the effect of absorption of the evanescent wave on the light to be measured by the DNA fixed to the gold fine particles adsorbed on the optical waveguide at the time of mismatch. . Therefore, in the present embodiment, Alq3 is used to generate light having a wavelength band that matches the absorption wavelength band of the gold fine particles. However, even if the above-mentioned coincidence does not occur, the absorption of the above-described evanescent wave is performed. It is sufficient if the influence can be reflected in the measurement light. If the wavelength band of the guided light S overlaps at least partly with the absorption wavelength band of the fine gold particles, the influence of the absorption of the evanescent wave can be reflected in the measurement light. It is sufficient if light can be guided to the optical waveguide.

(Second Embodiment)
In the first embodiment, DNA sensing is performed by measuring a transmission spectrum obtained from the outgoing light U. However, in this embodiment, DNA sensing is performed by measuring a change in refractive index from the outgoing light U. In this case, the optical sensor 41 is a refractive index measuring sensor. Further, since the refractive index varies depending on the temperature, it is preferable to keep the temperature of the sensing region 38 constant by arranging the optical waveguide type DNA sensor shown in FIG. 3 on a temperature control such as a hot plate.

(Third embodiment)
In the first and second embodiments, since a gold colloid solution is used, positive charges are introduced into the surface of the optical waveguide. However, in the present invention, it is not essential to introduce a positive charge to the surface of the optical waveguide. In the present invention, in a solution in which a material for immobilizing DNA such as a colloidal gold solution is dispersed, it is essential that the material is electrostatically adsorbed on the surface of the optical waveguide. Therefore, it is important to introduce a charge having a sign opposite to that of the charge charged in the material into the optical waveguide. For example, when the material is surrounded by a functional group having a charge of one sign, the charge of the other sign is introduced into the optical waveguide. Therefore, if the material is surrounded by a functional group having a positive charge, a negative charge may be introduced into the surface of the optical waveguide.

It is a figure for demonstrating the conventional DAN detection method using a gold colloid solution. (A) is a figure which shows a mode that the gold fine particle which concerns on one Embodiment of this invention electrostatically adsorb | sucks to an optical waveguide, (b) is a gold fine particle not adsorb | sucking to an optical waveguide electrostatically. It is a figure which shows a mode that it has disperse | distributed in the colloidal solution. (A) is a side view of the optical waveguide type DNA sensor according to the present embodiment, and (b) is a top view of the optical waveguide type DNA sensor shown in (a). It is a figure which shows the time-dependent change of a transmission spectrum when probe DNA and target DNA mismatch according to one Embodiment of this invention. It is a figure which shows the time-dependent change of a transmission spectrum when probe DNA and target DNA fully match based on one Embodiment of this invention. It is a figure which shows the time-dependent change of the absorption spectrum at the time of the full match based on one Embodiment of this invention. It is a figure which shows the time-dependent change of the absorption spectrum at the time of mismatch based on one Embodiment of this invention.

Explanation of symbols

21 Optical Waveguide 22 Gold Colloid Solution 23 Gold Fine Particle 31 Glass Substrate 32 Potassium Ion Exchange Glass Optical Waveguide 33 Light Absorption Layer 34 Alq3
35 Cytop
36 Cover glass 37 Prism 38 Sensing area 39 LED
40, 42 Filter 41, 43 Optical sensor

Claims (6)

An optical waveguide;
Optical coupling means for coupling light to the optical waveguide;
A colloidal gold solution in which fine gold particles charged with a charge of one sign are dispersed, a region on the optical waveguide to which probe DNA and target DNA are applied;
The coupled light is guided through the optical waveguide so as to cross at least the region;
Further comprising the gold fine particles applied on the region,
In the region, a charge having a sign opposite to the charge is introduced ,
An optical waveguide type DNA sensor , wherein the surface and the gold fine particles are electrostatically adsorbed on the surface of the region . Optical waveguide DNA sensor according to claim 1 wherein the gold particles, characterized in that said probe DNA is fixed. 3. The optical waveguide type DNA sensor according to claim 1, wherein the wavelength band of the combined light overlaps at least partly with the absorption wavelength band of the gold fine particles. An optical waveguide having a region to which DNA can be fixed, a colloidal gold solution in which gold particles charged with one sign are dispersed, a probe DNA, and a target DNA are provided. Preparing an optical waveguide into which a charge having a sign opposite to that of the charge is introduced;
Applying the gold colloid solution, the probe DNA, and the target DNA to the region;
Coupling light into the optical waveguide and guiding the coupled light across the region;
And a step of receiving light crossing the region. 5. The DNA detection method according to claim 4 , wherein, when the probe DNA and the target DNA are mismatched, the gold fine particles are electrostatically adsorbed on the surface of the region. 6. The DNA detection method according to claim 4 or 5 , wherein the wavelength band of the combined light overlaps at least partly with the absorption wavelength band of the gold fine particles.

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