Optical sensor based on rare earth doped microbubble cavity

Abstract

The invention belongs to the technical field of optical sensing, and discloses an optical sensor based on a rare earth doped microbubble cavity, which is characterized in that when the optical sensor is used for predicting the concentration, the rare earth doped microbubble cavity is pumped by utilizing pumping source laser; then injecting an immunoglobulin G solution to be detected into the microfluidic channel of the rare earth doped microbubble cavity, and recording to obtain a changed signal laser spectrum; and comparing the signal laser power with a standard curve of the relationship between the concentration and the signal laser power to find a concentration value corresponding to the same signal laser power, so as to obtain the concentration of the immunoglobulin G solution to be detected. Biomolecules are detected by using an active cavity structure of the rare earth doped microbubble cavity, so that a high-precision biosensor can be realized, the concentration of an immune globulin solution can be predicted, and whether specific binding occurs among various immune globulins can also be predicted.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical sensing, and more specifically, relates to an optical sensor based on a rare earth doped microbubble cavity. Background Art

[0002] With the development of modern science and technology, especially the development of emerging disciplines such as life sciences, the topics of biomolecule analysis and drug analysis are constantly emerging, and the requirements for analysis results are getting higher and higher. Optical sensors are becoming more and more popular due to their non-contact and non-destructive measurement, almost no interference, high-speed transmission, and remote sensing and remote control, and have become a current research hotspot.

[0003] Whispering gallery mode optical microcavity is an optical resonant cavity that localizes the light field in a micrometer-scale region. It has an ultra-high quality factor and a small mode volume, can significantly enhance the interaction between light and matter, and has great application potential in the fields of microlasers, optical sensing, nonlinear optics, quantum optics, etc. The optical microbubble cavity is a thin shell structure with a hollow interior and a natural microfluidic channel. It is an excellent platform for realizing biosensors, with advantages such as high sensitivity, low detection limit, and fast detection speed. The sensing mechanism based on optical microcavity includes mode shift, mode splitting, and mode broadening (all of which belong to passive cavities), and their detection limit and sensitivity are affected by the mode linewidth. On the other hand, rare earth elements have high conversion efficiency and long upper energy level lifetime. The working wavelength is determined only by their own energy level structure and does not depend on the host material. The emission spectrum covers the ultraviolet to mid-infrared band, and is a commonly used gain medium for solid lasers.

[0004] The research group of the inventor of the present invention has previously reported a rare earth doped optical microcavity and its preparation method (see Chinese invention patent application CN113497401A). The obtained rare earth doped microcavity can be used for ultra-high sensitivity molecular detection and ultra-long photon lifetime optical storage. If the application in the field of biological molecules can be explored, it will undoubtedly greatly expand the application prospects of rare earth doped optical microcavities. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the purpose of the present invention is to provide an optical sensor based on a rare earth doped microbubble cavity, wherein a high-precision biosensor can be realized by using the rare earth doped microbubble cavity as an active cavity structure to detect biomolecules (i.e., immunoglobulin G). On the one hand, the present invention uses a rare earth doped microbubble cavity laser for biomolecule concentration analysis, which can predict the concentration of an immunoglobulin solution and, on the other hand, whether specific binding occurs between multiple immunoglobulins.

[0006] To achieve the above object, according to one aspect of the present invention, a method for predicting the concentration of an immunoglobulin G solution based on an optical sensor of a rare earth-doped microbubble cavity is provided, characterized in that it comprises the following steps:

[0007] S1: Prepare clean rare earth ion doped optical microbubble cavity;

[0008] S2: using a pump source laser to pump the rare earth doped microbubble cavity to generate a signal laser; wherein the pump source laser wavelength is within the absorption band of the rare earth element contained in the rare earth doped microbubble cavity;

[0009] S3: injecting an immunoglobulin G solution to be detected, the type of immunoglobulin being known but the concentration being unknown, into the microfluidic channel of the rare earth-doped microbubble cavity, and after stabilization, recording the signal laser spectrum at this time as the signal laser spectrum after the change;

[0010] According to the signal laser power of the changed signal laser spectrum, the concentration of the immunoglobulin G solution to be tested can be obtained by comparing it with the standard curve of the relationship between concentration and signal laser power and finding the concentration value corresponding to the same signal laser power;

[0011] Among them, the standard curve of the relationship between concentration and signal laser power is prepared according to the type of immunoglobulin contained in the immunoglobulin G solution to be detected, and multiple standard solutions with known concentration values ​​are prepared, and the concentrations of these standard solutions are different from each other; using the same rare earth ion-doped optical microbubble cavity and the same pump source as step S2, and under the same relative position conditions, for each standard solution, one standard solution is injected each time into the microfluidic channel of the rare earth-doped microbubble cavity after being rinsed with phosphate buffer (PBS), so that the original solution in the microfluidic channel is discharged, and after stabilization, the signal laser spectrum is recorded to obtain a data point of the relationship between concentration value and signal laser power; thus, based on the multiple data points of the relationship between concentration value and signal laser power obtained from multiple standard solutions, a fitting curve of the relationship between concentration and signal laser power can be obtained, and the fitting curve is the standard curve.

[0012] As a further preferred embodiment of the present invention, in the process of obtaining the standard curve, before the standard solution is injected for the first time, it also includes: injecting phosphate buffer (PBS) into the microfluidic channel of the rare earth-doped microbubble cavity, and after stabilization, recording the signal laser spectrum at this time as the initial state signal laser spectrum;

[0013] Accordingly, each time phosphate buffer (PBS) is used to flush the inside of the microfluidic channel of the rare earth-doped microbubble cavity, specifically, phosphate buffer (PBS) is injected into the microfluidic channel of the rare earth-doped microbubble cavity to discharge the original solution inside the microfluidic channel. After stabilization, the signal laser spectrum at this time is recorded, and it is compared with the initial state signal laser spectrum to make the signal laser spectrum consistent with the initial state signal laser spectrum to ensure clean flushing.

[0014] As a further preferred embodiment of the present invention, in step S3, the immunoglobulin G solution to be detected is obtained by mixing two immunoglobulin solutions in a preset volume ratio and reacting for a preset time;

[0015] Accordingly, in the process of obtaining the standard curve, the standard solution used is obtained by mixing two immunoglobulin solutions designed with different concentrations in a preset volume ratio and reacting them for a preset time.

[0016] As a further preferred embodiment of the present invention, in step S1, the rare earth ion-doped optical microbubble cavity is obtained by treating a quartz capillary tube using a polymer-assisted melt thermal diffusion method;

[0017] The polymer-assisted melt heat diffusion method utilizes the film-forming property of the polymer to uniformly dope the rare earth element into the microbubble cavity, and the polymer is one of polymethyl methacrylate, polyethylene and polypropylene.

[0018] As a further preferred embodiment of the present invention, the rare earth ion is specifically at least one of erbium ion, ytterbium ion and thulium ion.

[0019] According to another aspect of the present invention, the present invention provides a method for predicting whether two immunoglobulin G solutions specifically bind to each other based on an optical sensor of a rare earth-doped microbubble cavity, characterized in that it comprises the following steps:

[0020] (1) preparing a clean rare earth ion-doped optical microbubble cavity;

[0021] (2) using a pump source laser to pump the rare earth-doped microbubble cavity to generate a signal laser, wherein the wavelength of the pump source laser is within the absorption band of the rare earth element contained in the rare earth-doped microbubble cavity;

[0022] (3) For two immunoglobulin G solutions, one of the immunoglobulin G solutions is selected to design samples of different concentrations, and the immunoglobulin contained in the immunoglobulin G solution is recorded as component A to obtain a group of component A immunoglobulin G solutions of different concentrations; the immunoglobulin contained in the other immunoglobulin G solution is recorded as component B, and the concentration of the component B immunoglobulin G solution is kept fixed; the component A immunoglobulin G solutions of different concentrations are mixed with the component B immunoglobulin G solutions according to a preset volume ratio and reacted for a preset time to obtain a group of test solutions of different concentrations; for each test solution, one test solution is injected into the microfluidic channel of the rare earth-doped microbubble cavity after being rinsed with phosphate buffer (PBS) each time, so that the original solution in the microfluidic channel is discharged, and after stabilization, the signal laser spectrum is recorded to obtain a data point of the relationship between the concentration value and the signal laser power; thus, according to the multiple data points of the relationship between the concentration value and the signal laser power obtained for multiple test solutions, a fitting curve of the relationship between the concentration and the signal laser power can be obtained;

[0023] According to the degree of change of the signal laser power with concentration in the fitting curve, it can be judged whether specific binding can occur between component A and component B; if a specific binding reaction can occur, the signal laser power changes more dramatically with concentration than if a specific binding reaction cannot occur.

[0024] As a further preference of the present invention, the fitting curve is a linear fitting curve in a two-dimensional coordinate system, and the two-dimensional coordinate system has concentration and signal laser power as coordinate axes, wherein the concentration axis is a logarithmic coordinate axis and the signal laser power axis is a linear coordinate axis in dBm.

[0025] As a further preferred embodiment of the present invention, after step (2) and before step (3), the method further includes: injecting phosphate buffer solution (PBS) into the microfluidic channel of the rare earth-doped microbubble cavity, and after stabilization, recording the signal laser spectrum at this time as the initial state signal laser spectrum;

[0026] Correspondingly, in step (3), each time phosphate buffer (PBS) is used to flush the inside of the microfluidic channel of the rare earth-doped microbubble cavity, specifically, phosphate buffer (PBS) is injected into the microfluidic channel of the rare earth-doped microbubble cavity to discharge the original solution inside the microfluidic channel. After stabilization, the signal laser spectrum at this time is recorded, and it is compared with the initial state signal laser spectrum to make the signal laser spectrum consistent with the initial state signal laser spectrum to ensure that it is flushed clean.

[0027] Compared with the prior art, the above technical solutions conceived by the present invention can achieve the following

[0028] Beneficial effects:

[0029] (1) The present invention proposes for the first time the use of rare earth doped microbubble cavity lasers for biomolecule sensing, which significantly reduces the laser mode linewidth, improves detection sensitivity and reduces the detection limit.

[0030] (2) The present invention uses laser signals for sensing. Compared with the existing schemes based on mode shift, mode splitting and mode broadening, it does not require complex equipment such as tunable lasers, thus saving costs. The present invention uses an active microbubble cavity (rare earth elements can be used as gain media and belong to the active layer) structure for the first time, proving that compared with a passive cavity, the optical gain in the active cavity can partially compensate for the intracavity loss, narrow the mode linewidth, and significantly improve the response of the microcavity to external signals, thereby improving the sensing sensitivity and reducing the detection limit.

[0031] (3) The present invention achieves high-precision detection of biomolecule concentration by combining an optical microcavity laser with a biosensor. Taking Example 1 as an example, the absolute value of the sensitivity can reach 3.095 dB / (fg / mL).

[0032] (4) In addition, the present invention can also be used to detect whether specific binding can occur between multiple immunoglobulins. In the fitting curve of the relationship between concentration and signal laser power obtained under the same detection conditions, the signal laser power of the immunoglobulins that can undergo specific binding reaction changes more dramatically with concentration than that of the immunoglobulins that cannot undergo specific binding reaction. As described later Figure 4 and Figure 5 As exemplified, Figure 4 The corresponding mixed reaction in Example 1 undergoes specific binding. Figure 5 The mixed reaction in Example 2 does not specifically bind, obviously Figure 4 The fitted curve is steeper and has a higher absolute value of slope (that is, Figure 4 The power of the medium signal laser changes more dramatically with concentration).

[0033] In summary, the present invention uses rare earth doped microbubble cavity lasers for biosensors, which has the advantages of low cost, simple operation, high sensitivity, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic top view of the working platform of the microbubble cavity laser used for biomolecule detection in the present invention.

[0035] Figure 2 This is the output spectrum of the microbubble cavity laser when there is no filler in it (the inset is a microscopic image of the microbubble cavity).

[0036] Figure 3 This is the initial state spectrum when phosphate buffer (PBS) is injected into the microbubble cavity laser.

[0037] Figure 4 This is the signal laser spectrum change obtained in Example 1.

[0038] Figure 5 This is the signal laser spectrum change obtained in Example 2.

[0039] Figure 1 In the figure, the meanings of the respective reference numerals are as follows: 1 is a pump laser; 2 is a rare earth-doped microbubble cavity; 3 is an immunoglobulin G solution to be tested. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0041] Based on the present invention, the implementation may include the following steps: first, a rare earth-doped optical microbubble cavity is prepared from a quartz capillary by a polymer-assisted melt thermal diffusion method; then, the rare earth-doped microbubble cavity is pumped by a resonant pumping method to generate a signal laser; finally, biomolecule solutions of different concentrations are injected into the microfluidic channel of the rare earth-doped microbubble cavity laser, thereby changing the effective refractive index of the optical mode of the microbubble cavity, resulting in a change in the signal laser power, and achieving high-sensitivity detection.

[0042] The rare earth doped optical microbubble cavity used in the following examples is prepared by using a polymer-assisted melt thermal diffusion method to prepare a quartz capillary, which is prepared by a carbon dioxide laser processing platform. The detailed preparation method of the rare earth doped optical microcavity can be directly referred to CN113497401A.

[0043] Example 1

[0044] A biosensor based on microbubble cavity laser, the specific implementation steps are as follows:

[0045] (1) A quartz capillary was prepared by a polymer-assisted melt thermal diffusion method to obtain an optical microbubble cavity 2 doped with rare earth ions erbium, the diameter of the microbubble cavity was 101 μm, and the wall thickness was 1.8 μm. Figure 2 The inset is an optical microscopic image of the microbubble cavity.

[0046] (2) Figure 1 As shown, a 980nm laser 1 is used as a pump source, and the pump laser is injected into the rare earth doped optical microbubble cavity 2 to obtain Figure 2 The laser output spectrum is shown.

[0047] (3) Phosphate buffered saline (PBS) is injected into the microfluidic channel to flush the microfluidic channel, and the signal laser spectrum at this time is recorded as the initial state.

[0048] (4) Inject the immunoglobulin G solution 3 to be tested into the microfluidic channel of the microbubble cavity (after the new solution is injected, the original solution in the microfluidic channel will be discharged). After stabilization (in this embodiment, the laser spectrum is collected 1 minute after passing into the microfluidic channel), record the signal laser power after the change.

[0049] (5) Inject phosphate buffer solution into the microfluidic channel to flush the microfluidic channel (PBS solution is used to flush the immunoglobulin solution remaining in the microfluidic channel) to return the signal laser to the initial state. Whether the initial state is restored after flushing in this step, it is necessary to compare the obtained signal laser spectrum with the signal laser spectrum recorded in step (3) to ensure that the flushing is complete.

[0050] (6) Repeat steps (3) and (4) to record the changes in signal laser power caused by different concentrations of IgG solutions.

[0051] The immunoglobulin G solutions of different concentrations to be detected used in this example were obtained by mixing mouse IgG solutions with concentrations of 100 ng / mL, 10 ng / mL, 1 ng / mL, 100 pg / mL, 10 pg / mL, 1 pg / mL, 100 fg / mL, 10 fg / mL and 1 fg / mL and a sheep anti-mouse IgG solution with a concentration of 100 ng / mL in a volume ratio of 1:1 for 5 hours.

[0052] The logarithm of the mouse IgG concentration (unit: fg / mL) in the mouse IgG solution used to prepare the immunoglobulin G solution to be tested is used as the abscissa, and the signal laser power (unit: dBm) is used as the ordinate to plot the results. Figure 4 As shown, it can be seen that the signal laser power changes with the concentration of the immunoglobulin G solution, and the laser sensor has a sensitivity of -3.095dB / (fg / mL).

[0053] Example 2

[0054] The difference between this embodiment and embodiment 1 is that the immunoglobulin G solutions to be detected of different concentrations used in embodiment 2 are obtained by mixing 100 ng / mL, 10 ng / mL, 1 ng / mL, 100 pg / mL, 10 pg / mL, 1 pg / mL, 100 fg / mL, 10 fg / mL and 1 fg / mL human IgG and 100 ng / mL goat anti-mouse IgG solution in a volume ratio of 1:1 for 5 hours for comparison of specific detection (it is known in the prior art that the mouse IgG used in embodiment 1 can specifically bind to the goat anti-mouse IgG; while the human IgG used in embodiment 2 cannot specifically bind to the goat anti-mouse IgG). Figure 5 As shown in FIG. 1 , the signal laser power finally changes with the concentration of the immunoglobulin G solution. Compared with Example 1, the maximum response of the laser power is only 6.22 dB (as shown in FIG. 1 ). Figure 5 Among the data points shown, the difference between the maximum value and the minimum value of the ordinate is 6.22 dB).

[0055] It can be seen from Examples 1 and 2 that in Example 1, the mouse IgG and goat anti-mouse IgG molecules in the immunoglobulin G solution specifically bind to each other, causing the refractive index of immunoglobulin G solutions of different concentrations to change greatly, and the laser power to change greatly; while in Example 2, the human IgG and goat anti-mouse IgG molecules in the immunoglobulin G solution cannot specifically bind to each other, causing the refractive index of immunoglobulin G solutions of different concentrations to change little, and the laser power to change little. It can be seen that the laser sensor in the present invention has a good specific detection effect.

[0056] The above embodiments are only examples. For example, in addition to using two solutions to mix and react to obtain the immunoglobulin G solution to be detected, one of the solutions can also be used directly as the solution to be detected to detect the solution concentration. In addition, the rare earth element used in the above embodiments is erbium, and the pump laser wavelength is 980nm, which satisfies the pump source laser wavelength within the absorption band of the rare earth element; of course, other rare earth ions can also be used, and at the same time, the pump source laser wavelength is within the absorption band of the rare earth element.

[0057] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for predicting the concentration of immunoglobulin G solution based on an optical sensor of a rare earth-doped microbubble cavity, characterized in that: The steps include: S1: Prepare clean rare earth ion doped optical microbubble cavity; S2: using a pump source laser to pump the rare earth doped microbubble cavity to generate a signal laser; wherein the pump source laser wavelength is within the absorption band of the rare earth element contained in the rare earth doped microbubble cavity; S3: injecting an immunoglobulin G solution to be detected, the type of immunoglobulin being known but the concentration being unknown, into the microfluidic channel of the rare earth-doped microbubble cavity, and after stabilization, recording the signal laser spectrum at this time as the signal laser spectrum after the change; According to the signal laser power of the changed signal laser spectrum, the concentration of the immunoglobulin G solution to be tested can be obtained by comparing it with the standard curve of the relationship between concentration and signal laser power and finding the concentration value corresponding to the same signal laser power; Among them, the standard curve of the relationship between concentration and signal laser power is prepared according to the type of immunoglobulin contained in the immunoglobulin G solution to be detected, and multiple standard solutions with known concentration values ​​are prepared, and the concentrations of these standard solutions are different from each other; using the same rare earth ion-doped optical microbubble cavity and the same pump source as step S2, and under the same relative position conditions, for each standard solution, one standard solution is injected each time into the microfluidic channel of the rare earth-doped microbubble cavity after being rinsed with phosphate buffer (PBS), so that the original solution in the microfluidic channel is discharged, and after stabilization, the signal laser spectrum is recorded to obtain a data point of the relationship between concentration value and signal laser power; thus, based on the multiple data points of the relationship between concentration value and signal laser power obtained from multiple standard solutions, a fitting curve of the relationship between concentration and signal laser power can be obtained, and the fitting curve is the standard curve.

2. The method according to claim 1, characterized in that: In the process of obtaining the standard curve, before the standard solution is injected for the first time, the method further includes: injecting phosphate buffer solution (PBS) into the microfluidic channel of the rare earth-doped microbubble cavity, and recording the signal laser spectrum at this time after stabilization as the initial state signal laser spectrum; Accordingly, each time phosphate buffer (PBS) is used to flush the inside of the microfluidic channel of the rare earth-doped microbubble cavity, specifically, phosphate buffer (PBS) is injected into the microfluidic channel of the rare earth-doped microbubble cavity to discharge the original solution inside the microfluidic channel. After stabilization, the signal laser spectrum at this time is recorded, and it is compared with the initial state signal laser spectrum to make the signal laser spectrum consistent with the initial state signal laser spectrum to ensure clean flushing.

3. The method according to claim 1, characterized in that: In step S3, the immunoglobulin G solution to be detected is obtained by mixing two immunoglobulin solutions according to a preset volume ratio and reacting them for a preset time; Accordingly, in the process of obtaining the standard curve, the standard solution used is obtained by mixing two immunoglobulin solutions designed with different concentrations in a preset volume ratio and reacting them for a preset time.

4. The method according to claim 1, characterized in that: In step S1, the rare earth ion doped optical microbubble cavity is obtained by treating a quartz capillary tube using a polymer-assisted melt thermal diffusion method; The polymer-assisted melt heat diffusion method utilizes the film-forming property of the polymer to uniformly dope the rare earth element into the microbubble cavity, and the polymer is one of polymethyl methacrylate, polyethylene and polypropylene.

5. The method according to claim 1, characterized in that: The rare earth ion is specifically at least one of erbium ion, ytterbium ion and thulium ion.

6. A method for predicting whether two immunoglobulin G solutions specifically bind to each other based on an optical sensor of a rare earth-doped microbubble cavity, characterized in that: The steps include: (1) preparing a clean rare earth ion-doped optical microbubble cavity; (2) using a pump source laser to pump the rare earth-doped microbubble cavity to generate a signal laser, wherein the wavelength of the pump source laser is within the absorption band of the rare earth element contained in the rare earth-doped microbubble cavity; (3) For two immunoglobulin G solutions, one of the immunoglobulin G solutions is selected to design samples of different concentrations, and the immunoglobulin contained in the immunoglobulin G solution is recorded as component A, so as to obtain a group of component A immunoglobulin G solutions of different concentrations; the immunoglobulin contained in the other immunoglobulin G solution is recorded as component B, and the concentration of the component B immunoglobulin G solution is kept fixed; the component A immunoglobulin G solutions of different concentrations are mixed with the component B immunoglobulin G solutions according to a preset volume ratio and reacted for a preset time to obtain a group of test solutions of different concentrations; for each test solution, one test solution is injected into the microfluidic channel of the rare earth-doped microbubble cavity after being rinsed with phosphate buffer solution (PBS), so that the original solution in the microfluidic channel is discharged, and after stabilization, the signal laser spectrum is recorded to obtain a data point of the relationship between the concentration value and the signal laser power; thus, according to the multiple data points of the relationship between the concentration value and the signal laser power obtained for multiple test solutions, a fitting curve of the relationship between the concentration and the signal laser power can be obtained; According to the degree of change of the signal laser power with concentration in the fitting curve, it can be judged whether specific binding can occur between component A and component B; if a specific binding reaction can occur, the signal laser power changes more dramatically with concentration than if a specific binding reaction cannot occur.

7. The method according to claim 6, characterized in that: The fitting curve is a linear fitting curve in a two-dimensional coordinate system, and the two-dimensional coordinate system uses concentration and signal laser power as coordinate axes, wherein the concentration axis is a logarithmic coordinate axis, and the signal laser power axis is a linear coordinate axis with dBm as the unit.

8. The method according to claim 6, characterized in that: After step (2) and before step (3), the method further includes: injecting phosphate buffer solution (PBS) into the microfluidic channel of the rare earth-doped microbubble cavity, and after stabilization, recording the signal laser spectrum at this time as the initial state signal laser spectrum; Correspondingly, in step (3), each time phosphate buffer (PBS) is used to flush the inside of the microfluidic channel of the rare earth-doped microbubble cavity, specifically, phosphate buffer (PBS) is injected into the microfluidic channel of the rare earth-doped microbubble cavity to discharge the original solution inside the microfluidic channel, and after stabilization, the original solution is recorded. Record the signal laser spectrum at this time and compare it with the initial state signal laser spectrum. Make the signal laser spectrum consistent with the initial state signal laser spectrum to ensure clean flushing.

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