CN111380837A - SPR sensing chip and sensing system based on hydrogel - Google Patents
SPR sensing chip and sensing system based on hydrogel Download PDFInfo
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- CN111380837A CN111380837A CN202010160526.1A CN202010160526A CN111380837A CN 111380837 A CN111380837 A CN 111380837A CN 202010160526 A CN202010160526 A CN 202010160526A CN 111380837 A CN111380837 A CN 111380837A
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- hydrogel
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/55—Specular reflectivity
- G01N21/552—Attenuated total reflection
- G01N21/553—Attenuated total reflection and using surface plasmons
- G01N21/554—Attenuated total reflection and using surface plasmons detecting the surface plasmon resonance of nanostructured metals, e.g. localised surface plasmon resonance
Abstract
The invention discloses a hydrogel-based SPR sensing chip and a sensing system, wherein the chip comprises a flat glass sheet, a chromium film arranged on the flat glass sheet, a silver film arranged on the surface of the chromium film, silicon dioxide arranged on the surface of the silver film, gelatin hydrogel covering the surface of the silicon dioxide, and gold nanoparticles fixed on an interface where the gelatin hydrogel and the silicon dioxide are in contact, wherein the diameter of the gold nanoparticles is less than 200 nm. The invention doubly enhances the sensitivity of the SPR sensor, and enlarges the detection range of the SPR sensor by using the cylindrical lens of the array.
Description
Technical Field
The invention belongs to the field of optical biochemical sensing, and particularly relates to a hydrogel-based SPR sensing chip and a sensing system.
Background
The SPR sensor uses evanescent waves generated by total reflection of light on a medium and a metal interface to trigger collective oscillation of free electrons on the metal surface so as to generate surface plasma waves, when the wavelength or the incident angle of incident light is a certain proper value, the wave vector component of the incident light along the interface is equal to the wave vector of the surface plasma waves, the incident light and the surface plasma waves resonate, the energy of the incident light is absorbed, the energy of the reflected light is rapidly reduced, a lowest intensity value, namely an SPR resonance peak, appears on the intensity spectrum of the reflected light, the resonance angle changes along with the change of the refractive index of the medium on the surface of the metal film, and the change of the refractive index is in direct proportion to the mass of molecules combined on the metal surface. Thus, by analyzing the resonance angle, information on the intermolecular interaction can be obtained. Currently, the current practice is. The main research directions of the SPR sensor technology are miniaturization, high throughput, and improvement of sensitivity of the SPR sensor, and the sensitivity is a primary factor inhibiting the development of the SPR sensor, so how to improve the sensitivity of the SPR sensor becomes one of the research hotspots of the SPR sensing technology at present.
The theoretical value of the sensitivity of the current angle type SPR sensing system can reach 10-6-10-7RIU, however, the actual sensitivity is difficult to reach 10 due to limitations in the processing level of the system components (light source, lens, etc.) and the sensor chip-7RIU. In addition, for the angle-type SPR sensing system, the detection range of the SPR sensing system is also limited due to the limitation of the angle of the incident light. The existing system scans the angle by designing a mechanical part, but the scheme has high requirements on the precision and the stability of the mechanical part, and is not beneficial to practical application. There are also ways to focus beams of different angles using cylindrical mirrors, but a single cylindrical mirror has a limited angle to focus the beam.
Disclosure of Invention
The invention provides an SPR sensing chip based on hydrogel.
The technical scheme for realizing the purpose of the invention is as follows: a hydrogel-based SPR sensing chip comprises a flat glass sheet, a chromium film arranged on the flat glass sheet, a silver film arranged on the surface of the chromium film, silicon dioxide arranged on the surface of the silver film, gelatin hydrogel covering the surface of the silicon dioxide, and gold nanoparticles fixed on an interface where the gelatin hydrogel and the silicon dioxide are in contact.
Preferably, the plate glass sheet has a thickness of 3mm to 10mm and a refractive index of 1.52 to 1.53.
Preferably, the thickness of the chromium film is 1-5 nm.
Preferably, the silver film has a thickness of 40 to 50 nm.
Preferably, the thickness of the silicon dioxide film is 50-60 nm.
Preferably, the gelatin hydrogel is less than 100um thick.
The present invention also provides a sensing system comprising:
the sensor comprises a light source, a collimation beam expander, a polaroid, a diaphragm, an array cylindrical lens, a coupling prism, and the sensor chip, the array cylindrical lens, a first imaging lens, a second imaging lens and a CCD/CMOS according to any one of claims 1 to 5, wherein the light source, the collimation beam expander, the polaroid, the diaphragm and the array cylindrical lens are sequentially arranged on a first straight line, light emitted by the light source sequentially passes through the collimation beam expander, the polaroid, the diaphragm, the array cylindrical lens, the coupling prism and the sensor chip and is incident on the coupling prism and the sensor chip, the array cylindrical lens, the first imaging lens, the second imaging lens and the CCD/CMOS are sequentially arranged on a second straight line, and the light reflected by the sensor chip and the coupling prism sequentially passes through the array cylindrical lens, the first imaging lens and the second imaging lens and is received by the CCD/CMOS.
Compared with the prior art, the invention has the following remarkable advantages: the SPR sensing chip based on the hydrogel performs double enhancement on the sensitivity of SPR sensing, and is characterized in that: the coupling of SPR and LSPR enhances the electromagnetic field, thereby improving the sensitivity of SPR sensing; on the other hand, the change of the resonance angle is increased by amplifying the change of the refractive index through the hydrogel, and the sensitivity of SPR sensing is also improved; the SPR sensing chip based on the hydrogel utilizes the cylindrical lens of the array to enlarge the detection range of the SPR sensor.
Drawings
FIG. 1 is a schematic diagram of an SPR chip based on hydrogel of the present invention.
FIG. 2 is an SPR sensing experiment system of the present invention
Fig. 3 is a schematic diagram of enhancement of an electromagnetic field by spherical gold nanoparticles.
FIG. 4 is a schematic diagram of an electromagnetic field at the interface of spherical gold nanoparticles and a silver film.
FIG. 5 is a schematic diagram of the electromagnetic field of a flat silver film.
Detailed Description
The present invention is described in further detail below with reference to the attached drawing figures.
As shown in fig. 1, a hydrogel-based SPR sensing chip includes:
a flat glass sheet 1;
a chromium film 2 provided on the plate glass sheet;
a silver film 3 provided on the surface of the chromium film 2;
the silicon dioxide 4 arranged on the surface of the silver film 3 protects the silver film by utilizing the compactness of the silicon dioxide, so that the silver film is prevented from being oxidized, and the stability of the silver film is enhanced;
the gelatin hydrogel 5 coated on the surface of the silica 4 amplifies the change in concentration of the sample solution to be detected by utilizing the adsorption effect of the hydrogel on the particles and water. When the concentration of the sample solution is high, the hydrogel absorbs more particles and absorbs less water, and when the concentration of the sample solution is low, the hydrogel absorbs less particles and absorbs more water. The refractive index of the sample solution is related to the concentration, the change of the concentration reflects the change of the refractive index, the hydrogel amplifies the change of the refractive index of the sample, the change of the resonance angle corresponding to SPR is increased, and the sensitivity of SPR sensing is effectively improved;
and the gold nanoparticles 6 are fixed on an interface where the gelatin hydrogel 5 and the silicon dioxide 4 are in contact, the diameter of the gold nanoparticles 6 is less than 200nm, and under the condition that evanescent waves meet resonance conditions, the surfaces of the gold nanoparticles can generate stronger LSPR.
Preferably, the chromium film 2 is used to enhance the adhesion of the silver film to the flat glass sheet.
The invention utilizes the flat silver film to generate the traditional SPR and utilizes the gold nanoparticles 6 to generate the Local Surface Plasmon Resonance (LSPR). On one hand, the local surface plasmon resonance has a strong local electromagnetic field enhancement effect, the penetration depth of SPR can be improved, and the sensitivity of SPR sensing is further improved. On the other hand, SPR generated by the flat silver film and LSPR generated by the gold nanoparticles can generate coupling, so that the generated electromagnetic field is enhanced, and the sensitivity of SPR is further improved.
In a further embodiment, the plate glass sheet 1 has a thickness of 3mm to 10mm, a refractive index of 1.52 to 1.53, and good light transmittance.
In a further embodiment, the chromium film 2 has a thickness of 1-5nm, and the chromium film of 1-5nm has almost negligible effect on the generation of SPR.
In a further embodiment, the silver film 3 has a thickness of 40-50nm, which ensures stable SPR on the top surface of the silver film.
In a further embodiment, the thickness of the silicon dioxide film 4 is 50-60nm, and the influence on the peak value and half-peak width of a resonance peak is minimum under the condition that a silver film can be effectively protected.
In a further embodiment, the thickness of the gelatin hydrogel 5 is less than 100um, the gelatin hydrogel 5 can absorb particles in a solution, absorb water in the solution, and amplify the change of the refractive index of the sample, so that the change of the resonance angle is increased, and the sensitivity of SPR sensing is improved. In the case of satisfying the function of amplifying the change in refractive index, the less the sample consumption, the better.
As shown in fig. 2, a sensing system includes:
a light source 8, a collimating beam expander 9, a polarizer 10, a diaphragm 11, an array cylindrical mirror 12, a coupling prism 13, a sensor chip 14 according to any one of claims 1 to 5, an array cylindrical mirror 15, a first imaging lens 16, a second imaging lens 17, and a CCD/CMOS18, the light source 8, the collimation and beam expanding lens 9, the polaroid 10, the diaphragm 11 and the array cylindrical mirror 12 are sequentially arranged on a first straight line, light emitted by the light source 8 sequentially passes through the collimation and beam expanding lens 9, the polaroid 10, the diaphragm 11, the array cylindrical mirror 12, is incident on the coupling prism 13 and the sensing chip 14, the array cylindrical lens 15, the first imaging lens 16, the second imaging lens 17 and the CCD/CMOS18 are sequentially arranged on a second straight line, and the light reflected by the sensing chip 14 and the coupling prism 13 is received by the CCD/CMOS18 through the array cylindrical lens 15, the first imaging lens 16 and the second imaging lens 17 in sequence.
The light source 8 is used for providing single-wavelength light beams, and the wavelength is about 630 nm;
the collimation beam expanding lens 9 is used for expanding the single-wavelength light beam and then collimating the single-wavelength light beam;
a polarizing plate 10 for polarizing the single-wavelength collimated light beam to obtain a polarization state;
the array cylindrical mirror 12 is used for performing unidirectional focusing on the polarized single-wavelength collimated light beam and providing unidirectional focusing light beams containing angle information, namely, providing light rays with different angles to be incident on the coupling prism, so that the detection range of the experimental system is greatly improved;
the coupling prism 13 is used for increasing the wave vector of incident light, exciting plasma resonance on the surface of the metal film by using evanescent waves generated by total reflection of the incident light, has a refractive index of about 1.5, and is connected with the flat glass sheet by using refractive index matching fluid;
the sensor chip 14 of any one of claims 1-5;
the array cylindrical mirror 15 is used for restoring the light beam carrying the angle information into parallel light;
and the first imaging lens 16 and the second imaging lens 17 are used for reducing the light spot of the parallel light to the size of a CCD/CMOS18 target surface.
The system adopts prism coupling angle modulation, the refractive index of the coupling prism is about 1.5, and the SPR sensing chip based on hydrogel is coupled with the coupling prism through refractive index matching fluid. The light source adopts an LED light source.
The working principle of the invention is as follows: divergent light emitted by an LED light source 8 is collimated by a collimating lens 9, passes through a polarizing film 10 to obtain polarized light, passes through a diaphragm 11 to obtain a required light spot size, reaches an array cylindrical mirror 12, the light spots are compressed into a line by the array cylindrical mirror 12, the light ray contains light information of different angles, reaches a sensing chip 14 through a coupling prism 13, and an SPR phenomenon is generated on the sensing chip 14, specifically: on one hand, local surface plasmas LSPR are generated around the gold nanoparticles, and the LSPR is mainly concentrated near the surfaces of the gold nanoparticles, so that each gold nanoparticle can cause the enhancement of a local electromagnetic field. Secondly, SPR generated by the flat silver film is coupled with LSPR generated by the gold nanoparticles, so that the electromagnetic field is further enhanced, and as can be seen from figures 3 and 4, the gold nanoparticles have an obvious local enhancement effect on the electromagnetic field, while the flat silver film has no enhancement effect, as shown in figure 5. Since the electromagnetic field generated by surface plasmon resonance is very sensitive to changes in the medium, the enhancement of the electromagnetic field is beneficial to improve the sensitivity of SPR sensing. On the other hand, the hydrogel, which is a matrix in contact with the sample, amplifies the change in the refractive index of the sample, and the change in the refractive index of the sample becomes large, and the change in the corresponding resonance angle becomes large, thereby improving the sensitivity of SPR sensing. The detection range of the SPR sensor is greatly improved by adopting a cylindrical mirror array mode. The light reflected from the coupling prism 13 is restored to a circular light spot through the cylindrical mirror array 16, the light spot is proportionally reduced to the target surface of the CCD/CMOS19 through the first imaging lens 17 and the second imaging lens 18, the light intensity at the resonance angle is reduced, the pixel values of a certain row and a certain column on the CCD/CMOS19 are reduced, and the obtained image is analyzed to obtain the information related to the refractive index of the sample.
The invention utilizes the cylindrical mirror array to enlarge the detection angle of the sensing system so as to enlarge the detection range of the SPR sensing system, and can realize multi-channel measurement.
The invention improves the sensitivity of the sensor by combining the sensing chip with other materials, and can stably detect.
Claims (7)
1. The SPR sensing chip based on the hydrogel is characterized by comprising a flat glass sheet (1), a chromium film (2) arranged on the flat glass sheet, a silver film (3) arranged on the surface of the chromium film (2), silicon dioxide (4) arranged on the surface of the silver film (3), gelatin hydrogel (5) covering the surface of the silicon dioxide (4), and gold nanoparticles (6) fixed on an interface where the gelatin hydrogel (5) is contacted with the silicon dioxide (4), wherein the diameter of the gold nanoparticles (6) is less than 200 nm.
2. The hydrogel-based SPR sensing chip according to claim 1, wherein said flat glass sheet (1) has a thickness of 3mm to 10mm and a refractive index of 1.52 to 1.53.
3. The hydrogel-based SPR sensing chip according to claim 1, wherein said chrome film (2) has a thickness of 1-5 nm.
4. The hydrogel-based SPR sensing chip according to claim 1, wherein said silver film (3) has a thickness of 40-50 nm.
5. The hydrogel-based SPR sensing chip according to claim 1, wherein said silica membrane (4) has a thickness of 50-60 nm.
6. The hydrogel-based SPR sensing chip of claim 1, wherein said gelatin hydrogel (5) is less than 100um thick.
7. A sensing system, comprising:
a light source (8), a collimation beam expander (9), a polarizer (10), a diaphragm (11), an array cylindrical mirror (12), a coupling prism (13), and the sensor chip (14), the array cylindrical mirror (15), a first imaging lens (16), a second imaging lens (17) and a CCD/CMOS (18) according to any one of claims 1-5, wherein the light source (8), the collimation beam expander (9), the polarizer (10), the diaphragm (11) and the array cylindrical mirror (12) are sequentially arranged on a first straight line, light emitted by the light source (8) is sequentially incident on the coupling prism (13) and the sensor chip (14) through the collimation beam expander (9), the polarizer (10), the diaphragm (11), the array cylindrical mirror (12), the first imaging lens (16), the second imaging lens (17) and the CCD/CMOS (18), and the light reflected by the sensing chip (14) and the coupling prism (13) is received by the CCD/CMOS (18) through the array cylindrical mirror (15), the first imaging lens (16) and the second imaging lens (17) in sequence.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112304905A (en) * | 2020-10-22 | 2021-02-02 | 济南橘子智能科技有限公司 | High-performance waveguide sensing system and preparation method thereof |
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| CN102735653A (en) * | 2011-04-14 | 2012-10-17 | 国家纳米科学中心 | Biological detection method by utilization of surface plasma resonance biosensor |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112304905A (en) * | 2020-10-22 | 2021-02-02 | 济南橘子智能科技有限公司 | High-performance waveguide sensing system and preparation method thereof |
| CN112304905B (en) * | 2020-10-22 | 2022-11-04 | 吉林省兜率龙源实业集团有限公司 | High-performance waveguide sensing system and preparation method thereof |
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