CN111879707B - Sensor, system and method of gold nanoparticle and quantum dot composite structure - Google Patents
Sensor, system and method of gold nanoparticle and quantum dot composite structure Download PDFInfo
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- CN111879707B CN111879707B CN202010715577.6A CN202010715577A CN111879707B CN 111879707 B CN111879707 B CN 111879707B CN 202010715577 A CN202010715577 A CN 202010715577A CN 111879707 B CN111879707 B CN 111879707B
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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
- G01N21/21—Polarisation-affecting properties
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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
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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
- G01N21/21—Polarisation-affecting properties
- G01N2021/216—Polarisation-affecting properties using circular polarised light
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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
- G01N2021/555—Measuring total reflection power, i.e. scattering and specular
Abstract
The invention discloses a sensor with a gold nanoparticle and quantum dot composite structure, a system and a method. The method is based on the local surface plasmon resonance characteristic of gold nanoparticles under total internal reflection, and combines a microfluidics technology to directly obtain the combination of gold nanoparticles and a transparent substrate, so that the gold nanoparticles have strong binding force, accurate and controllable thickness, good continuity and no pollution, and in addition, the gold film has excellent optical properties and good sensitivity and accuracy; the gold nanoparticle-quantum dot composite structure is obtained by inserting quantum dots into gaps among gold nanoparticles, so that the surface plasmon resonance effect of the gold nanoparticles is enhanced, the composite structure and the nearby medium are more sensitive to the change of parameters such as refractive index, thickness and the like, and research substances attached to the surface of the structure are easier to detect; the invention has the advantages of high sensitivity, high stability, no damage caused by marking, strong accuracy, real-time rapid detection, wide application range and the like; will have far-reaching development prospect and wide potential application value.
Description
Technical Field
The invention relates to an optical sensing technology, in particular to a gold nanoparticle and quantum dot composite structure sensor, a sensor system and a sensor method thereof.
Background
Surface plasmon resonance is an inherent property of gold nanoparticles, and the dielectric constant of the surrounding environment and the size and shape of the metal all have an effect on their oscillation frequency. In addition, the special color, photo-thermal effect and special electromagnetic field enhancement effect generated by the unique surface plasmon resonance effect of the gold nanoparticles forming the film can be applied to the fields of physics, chemistry, materials, biology, medicine and the like. Most of the current refractive index sensors stay in theoretical research, few people propose a truly practical structure, and most of the sensors are combined with optical fibers, so that the sensitivity of the sensors to detect the refractive index of liquid needs to be improved although the miniaturization is realized in the size of the device. Therefore, there is an urgent need to propose a refractive index sensor with high sensitivity that can be realized.
Quantum dots are a cluster structure consisting of a limited number of atoms, at the nanoscale, and are generally spherical or spheroidal in shape, typically between 2 and 20nm in diameter. The quantum dot has the advantages of wide excitation spectrum, continuous distribution, narrow and symmetrical emission spectrum, adjustable color, high photochemical stability, long fluorescence life and the like, and is an ideal material for various aspects such as a nano laser, a sensitive sensor, an optical memory and the like. The quantum dots have wide Stokes shift, so that the overlapping of an emission spectrum and an excitation spectrum is effectively avoided, and the detection of spectrum signals is facilitated. In addition, the quantum dot has good light stability and biocompatibility, is small in harm to organisms and can observe marked objects for a long time. Due to the structural specificity of the quantum dot, the quantum dot has the characteristic of a plurality of unusual substances, and is widely applied.
Disclosure of Invention
In order to solve the problems of poor signal, poor repeatability, high cost and the like caused by the defect of the nano structure of the traditional nano metal sensor, the invention provides a gold nanoparticle and quantum dot composite structure sensor, a sensor system and a method thereof, which have the advantages of high sensitivity, large detection limit, no need of marking, no pollution, no damage to a detection sample, high repetition rate, real-time rapid monitoring and the like, and are applied to a plurality of detection fields such as physical chemistry, biomedicine and the like.
One object of the invention is to provide a sensor with a gold nanoparticle and quantum dot composite structure.
The sensor of the present invention can be used not only as an optical refractive index sensor but also as a biosensor.
The refractive index sensor of the gold nanoparticle and quantum dot composite structure of the present invention comprises: transparent substrates, gold nanoparticles, quantum dots, microfluidic channels, triangular prisms, and fluid conduits; depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles; spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure; forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure; the microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel; the refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid; the fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the fluid conduit; the sample to be tested enters the microfluidic channel through the fluid inlet by the fluid conduit; the circularly polarized light is incident from one right-angle side of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, generates total reflection, and enhances the surface plasmon resonance effect of the gold nanoparticle due to coupling interaction of plasmon generated by the gold nanoparticle and exciton generated by the quantum dot, wherein the resonance causes P polarized light to be greatly absorbed under total reflection, so that a sharp resonance peak is formed; and receiving the reflected light, dividing the reflected light into P polarized light and S polarized light which are perpendicular to each other, and then performing differential processing to obtain corresponding voltage values, and obtaining the refractive index of the sample to be detected according to the relationship between the calibrated refractive index and the voltage.
The biosensor of the gold nanoparticle and quantum dot composite structure of the present invention includes: transparent substrates, gold nanoparticles, quantum dots, microfluidic channels, triangular prisms, and fluid conduits; depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles; spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure; the gold nanoparticle and quantum dot composite structure is soaked in buffer solution of biological molecules, and functional groups of the gold nanoparticle and quantum dot composite structure are coupled with the biological molecules to form biological target molecules; forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure; the microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel; the refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid; the fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the fluid conduit; a sample to be detected enters the microfluidic channel through the fluid inlet by the fluid conduit, biomolecules to be detected in the sample to be detected are combined with biological target molecules on the gold nanoparticle and quantum dot composite structure, and the refractive index of the biological target molecules is changed; the circularly polarized light is incident from one right-angle side of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, generates total reflection, and enhances the surface plasmon resonance effect of the gold nanoparticle due to coupling interaction of plasmon generated by the gold nanoparticle and exciton generated by the quantum dot, wherein the resonance causes P polarized light to be greatly absorbed under total reflection, so that a sharp resonance peak is formed; and receiving the reflected light, dividing the reflected light into P polarized light and S polarized light which are perpendicular to each other, performing differential processing to obtain corresponding voltage values, comparing the voltage values with the voltage values when the calibration liquid is introduced, and indicating that the sample to be detected contains biomolecules to be detected if the voltage values are changed.
The biosensor of the present invention is used to monitor specific antigen-antibody binding or signal changes to which two biomolecules can bind. When the biological molecules in the sample to be detected are combined with the biological target molecules on the composite structure, the refractive index of the biological target molecules is changed, and the refractive index on the composite structure is changed based on an optical principle, so that reflected light is changed, and the reflected light is converted to a computer through a balance detector to reflect the change of voltage before and after combination, thereby proving that the sensor can accurately monitor in real time.
The size of the gold nano-particles is 10-20 nm; the gap between adjacent gold nanoparticles is 18-26 nm; the size of the quantum dots is 9-15 nm, and the distance between adjacent quantum dots is 12-23 nm; the ratio of the gold nanoparticles to the quantum dots is 2:1-4:1.
The wavelength of the incident light is in the visible light band.
The sample to be measured is a fluid, a gas or a liquid.
The buffer solution of the biological molecules is a mixed solution of NaCl and deionized water containing specific biological target molecules. The specific biological target molecule only interacts with the biological molecule to be detected.
The calibration liquid does not contain biomolecules to be detected. The calibration liquid for biomolecule detection is a mixed liquid of deionized water, sodium bicarbonate, amino acid and antibiotics in a ratio of 10:4:2:1-10:6:3:1.
The solution to be detected containing the biomolecules to be detected is a mixed solution of deionized water, sodium bicarbonate, amino acid and antibiotics in a ratio of 10:4:2:1-10:6:3:1.
It is still another object of the present invention to provide a sensing system of a gold nanoparticle and quantum dot composite structure.
The sensing system of the gold nanoparticle and quantum dot composite structure comprises: the device comprises a laser, an attenuation sheet, a polaroid, a lambda/4 wave plate, a polarization beam splitter prism, a balance detector, a computer and a refractive index sensor or a biological sensor of a gold nanoparticle and quantum dot composite structure; wherein, the sample to be measured enters the micro-fluid channel through the fluid inlet by the fluid conduit; the laser emits laser, the intensity of the laser is regulated by the attenuation sheet, the laser is changed into linearly polarized light by the polaroid, and the linearly polarized light is changed into circularly polarized light by the lambda/4 wave plate; the circularly polarized light is incident from one right-angle side of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, generates total reflection, and enhances the surface plasmon resonance effect of the gold nanoparticle due to coupling interaction of plasmon generated by the gold nanoparticle and exciton generated by the quantum dot, wherein the resonance causes P polarized light to be greatly absorbed under total reflection, so that a sharp resonance peak is formed; the reflected light is divided into P polarized light and S polarized light which are perpendicular to each other through a polarization beam splitter prism, and the P polarized light and the S polarized light are respectively received by different channels of a balance detector and subjected to differential processing; transmitting the refractive index value to a computer, and obtaining the refractive index of the sample to be measured according to the relationship between the calibrated refractive index and the voltage by the computer; or comparing the voltage value with the voltage value when the calibration liquid is introduced, and if the voltage value is changed, indicating that the sample to be detected contains the biomolecules to be detected.
The invention further aims at providing a sensing method of the gold nanoparticle and quantum dot composite structure.
The refractive index sensing method of the gold nanoparticle and quantum dot composite structure comprises the following steps:
1) Preparing a sensor system of a gold nanoparticle and quantum dot composite structure:
a) Depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles;
b) Spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure;
c) Forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure;
d) The microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel;
e) The refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid;
f) The fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the fluid conduit;
2) Constructing a sensing system of a gold nanoparticle and quantum dot composite structure:
a) The laser emits laser;
b) The intensity of the laser is regulated by an attenuation sheet;
c) Changing the light into linear polarized light through a polaroid and changing the light into circular polarized light through a lambda/4 wave plate;
d) The circularly polarized light is incident from one right-angle side surface of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, and generates total reflection;
e) The reflected light is divided into P polarized light and S polarized light which are perpendicular to each other through a polarization beam splitter prism, and the P polarized light and the S polarized light are respectively received by different channels of a balance detector and subjected to differential processing; transmitting the voltage value to a computer to obtain a voltage value;
3) Relationship between index of refraction and voltage:
a) When a sample is not injected into the microfluidic channel, air is filled in the microfluidic channel, circularly polarized light is incident from one right-angle side surface of the triangular prism, and is irradiated onto the gold nanoparticle and quantum dot composite structure at a total reflection angle to generate total reflection, S and P polarized light in the reflected light is subjected to differential treatment by a balance detector and is transmitted to a computer, so that a voltage value corresponding to the air is obtained;
b) Injecting a first sample with known refractive index into a microfluidic channel, enabling circularly polarized light to enter from a right-angle side surface of a triangular prism, irradiating the gold nanoparticle and quantum dot composite structure with a total reflection angle to generate total reflection, carrying out differential treatment on S and P polarized light in the reflected light through a balance detector, and transmitting the S and P polarized light to a computer to obtain a voltage value corresponding to the first sample;
c) Injecting a second sample with known refractive index into the microfluidic channel, wherein the refractive index is different from that of the first sample, and repeating the step b) until N samples with known refractive indexes and corresponding voltage values are obtained, wherein N is more than or equal to 2;
d) Fitting according to the obtained N refractive indexes and the voltage values corresponding to the N refractive indexes to obtain a relation curve of the refractive indexes and the voltage values;
4) Detecting a sample to be detected:
a) The sample to be tested enters the microfluidic channel through the fluid inlet by the fluid conduit;
b) Circularly polarized light is incident from one right-angle side surface of the triangular prism and irradiates on the gold nanoparticle and quantum dot composite structure at a total reflection angle;
c) Plasmon generated by the gold nanoparticles and exciton generated by the quantum dots are coupled and interacted to enhance the surface plasmon resonance effect of the gold nanoparticles, and the resonance causes P polarized light to be greatly absorbed under total reflection to form a sharp formant;
d) The reflected light is divided into P polarized light and S polarized light which are perpendicular to each other through a polarization beam splitter prism, and the P polarized light and the S polarized light are respectively received by different channels of a balance detector and subjected to differential processing;
e) Transmitting the refractive index to a computer, obtaining a voltage value by the computer, and obtaining the refractive index of the sample to be detected by sensing according to the relation between the calibrated refractive index and the voltage.
The invention relates to a biological sensing method of a gold nanoparticle and quantum dot composite structure, which comprises the following steps:
1) Preparing a sensor system of a gold nanoparticle and quantum dot composite structure:
a) Depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles;
b) Spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure;
c) The gold nanoparticle and quantum dot composite structure is soaked in buffer solution of biological molecules, and functional groups of the gold nanoparticle and quantum dot composite structure are coupled with the biological molecules to form biological target molecules;
d) Forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure;
e) The microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel;
f) The refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid;
g) The fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the fluid conduit;
2) Constructing a sensing system of a gold nanoparticle and quantum dot composite structure:
a) The laser emits laser;
b) The intensity of the laser is regulated by an attenuation sheet;
c) Changing the light into linear polarized light through a polaroid and changing the light into circular polarized light through a lambda/4 wave plate;
d) The circularly polarized light is incident from one right-angle side surface of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, and generates total reflection;
e) The reflected light is divided into P polarized light and S polarized light which are perpendicular to each other by a polarization beam splitter prism, and the P polarized light and the S polarized light are respectively received by different channels of a balance detector; the balance detector transmits the P polarized light to the computer;
3) Calibrating the biosensor:
when the calibration liquid without the biomolecules to be detected is used as a reference in the microfluidic channel, the microfluidic channel is filled with the calibration liquid, circularly polarized light is incident from one right-angle side surface of the triangular prism, is irradiated onto the gold nanoparticle and quantum dot composite structure at a total reflection angle to generate total reflection, S and P polarized light in the reflected light is subjected to differential treatment by the balance detector and is transmitted to a computer, and a voltage value corresponding to the calibration liquid is obtained;
4) Detecting a sample to be detected:
a) The sample to be tested enters the microfluidic channel through the fluid inlet by the fluid conduit;
b) The biological molecules in the sample to be detected are combined with biological target molecules on the gold nanoparticle and quantum dot composite structure;
c) The circularly polarized light is incident from one right-angle side surface of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, and generates total reflection;
d) Plasmon generated by the gold nanoparticles and exciton generated by the quantum dots are coupled and interacted to enhance the surface plasmon resonance effect of the gold nanoparticles, and the resonance causes P polarized light to be greatly absorbed under total reflection to form a sharp formant;
e) Receiving reflected light, dividing the reflected light into P polarized light and S polarized light which are perpendicular to each other, respectively receiving the P polarized light and the S polarized light by different channels of the balance detector, and performing differential processing;
f) Transmitting the voltage value to a computer, comparing the voltage value with the voltage value when the calibration liquid is introduced, and indicating that the sample to be detected contains biomolecules to be detected if the voltage value is changed;
5) After the measurement is completed, in order to ensure the repeated use of the biosensor, the biological target molecules on the gold nanoparticle and quantum dot composite structure are separated from the sample to be measured, the sample to be measured is thoroughly washed away, and the activity of the biological target molecules is recovered.
The invention has the advantages that:
the refractive index sensor is based on the local surface plasmon resonance characteristic of gold nanoparticles under total internal reflection and combines a microfluidic technology; the gold nano particles are directly obtained and combined with the transparent substrate, the bonding force is strong, the gold nano particles are not easy to peel off, the service life is long, the thickness is accurate and controllable, the continuity is good, no pollution is caused, in addition, the optical property of the gold film is excellent, and the gold film has good sensitivity and accuracy; the gold nanoparticle-quantum dot composite structure is designed by inserting quantum dots into gaps among gold nanoparticles, so that the surface plasmon resonance effect of the gold nanoparticles is enhanced, the composite structure and the nearby medium are more sensitive to the change of parameters such as refractive index, thickness and the like, and research substances attached to the surface of the structure are easier to detect; the invention has the advantages of high sensitivity, high stability, no marking or damage, strong accuracy, less material consumption, real-time rapid detection, wide application range and the like; the method brings larger and more distant development to the research and refractive index sensing in the field of microfluidics, and also shows wide potential application value in the fields of biology, chemistry, drug transport and the like.
Drawings
FIG. 1 is a flow chart of a method of preparing one embodiment of a sensor of the gold nanoparticle and quantum dot composite structure of the present invention;
FIG. 2 is a schematic diagram of a sensor with a composite structure of gold nanoparticles and quantum dots according to an embodiment of the present invention;
FIG. 3 is a schematic view of an optical path of an embodiment of a sensing system of the gold nanoparticle and quantum dot composite structure of the present invention.
Detailed Description
The invention will be further elucidated by means of specific embodiments in conjunction with the accompanying drawings.
Example 1
As shown in fig. 1, the method for manufacturing the refractive index sensor according to the present embodiment includes the following steps:
1) Preparing a sensor system of a gold nanoparticle and quantum dot composite structure:
a) Selecting a glass sheet or a quartz sheet, sequentially placing the glass sheet or the quartz sheet into isopropanol, acetone and ultrapure water for ultrasonic cleaning for 5min as shown in 101 in fig. 1, blowing the glass sheet or the quartz sheet by inert gas nitrogen, placing the glass sheet or the quartz sheet into a film plating chamber of low vacuum sputtering equipment, determining the sputtering distance to be 4-5cm, namely the distance between the substrate and a target, ensuring good tightness of the whole system by a cover top, setting sputtering time to be 10s, vacuumizing the pressure of the film plating chamber to be less than 2Pa, twisting a needle valve to enable the vacuum degree of the film plating chamber to be maintained at 3-4Pa, discharging current to be 10mA, starting sputtering, obtaining gold film of 6nm after the sputtering time is reached, closing a switch, depositing and stacking gold nano-particles on the front surface of the transparent substrate to form nano-gold discs, taking out the gold nano-particles, and taking out the gold nano-particles according to the size of a detection window of a designed sensor to be 6mm x 4mm x 0.5mm in 102 in fig. 1, protecting the gold nano-particles in the front surface area of the transparent substrate, taking out the gold nano-particles from the periphery of the front surface area by using a cleaning machine for 2min after the gold is processed; if the periphery of the upper surface of the gold film glass sample still has an excessive nano gold film, repeating the step for a plurality of times to clean, and reserving gold nano particles in the central area of the front surface, as shown by 103 in fig. 1;
b) Fixing the sample obtained in the step a) on a base of a spin coater, dropping 0.5ml of quantum dots on gold nanoparticles, uniformly spin-coating the quantum dots, covering a cover slip, taking down the cover slip after naturally airing, and uniformly inserting the quantum dots into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure, as shown in 104 in fig. 1;
c) Weighing 25ml of liquid silica gel and 2.5ml of curing agent, mixing the liquid silica gel and the curing agent in a beaker according to the proportion of 10:1, stirring with force until small bubbles in the liquid silica gel are uniformly distributed, completely discharging the small bubbles until the liquid silica gel is bubble-free and transparent by using a vacuum drying box for 30min, pouring the liquid silica gel into a culture dish containing a fluid channel die, horizontally placing the culture dish into the drying box, solidifying and taking out the culture dish, thereby forming a groove on the surface of the solid silica gel 206, and forming a fluid inlet and a fluid outlet on a pair of opposite side walls of the groove, so as to form a micro-fluid channel 207, wherein the surface area of the groove is not smaller than the area of a gold nanoparticle and quantum dot composite structure, as shown by 105 in fig. 1;
d) The microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structure such that the gold nanoparticle and quantum dot composite structure is located within the grooves of the microfluidic channel, as shown at 106 in fig. 1;
e) The refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate 203 is attached to the hypotenuse surface of the triangular prism 202 through the refractive index matching liquid 208;
f) The fluid inlet and the fluid outlet of the microfluidic channel are respectively connected to the fluid conduit 205;
2) Constructing a sensing system of a gold nanoparticle and quantum dot composite structure:
a) Helium-neon laser 301 emits 632.8nm laser light;
b) The intensity of the laser is adjusted via the attenuator 302;
c) Becomes linearly polarized light through the polarizing plate 303 and becomes circularly polarized light through the lambda/4 wave plate 304;
d) Circularly polarized light 201 is incident from one right-angle side of the triangular prism 202, irradiates on the gold nanoparticle and quantum dot composite structure 204 at a total reflection angle, and generates total reflection;
e) The reflected light 209 is reflected by the first reflecting mirror 305, enters the polarization splitting prism 307 and is divided into P polarized light and S polarized light which are perpendicular to each other, and is received by different channels of the balance detector 308 respectively, and 306 is a second reflecting mirror; the balance detector transmits P-polarized light to computer 309;
3) Relationship between index of refraction and voltage:
a) Air with known refractive index is used as calibration, the refractive index of the air is 1.0000, the operation and the subsequent voltage change observation are convenient, the error is reduced, and the authenticity is ensured; when a sample is not injected into the microfluidic channel, the microfluidic channel is filled with air, circularly polarized light is incident from one right-angle side surface of the triangular prism, and irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle to generate total reflection, S and P polarized light in the reflected light is subjected to differential treatment by a balance detector and is transmitted to a computer, so that a voltage value corresponding to the air is obtained;
b) Deionized water is injected into the microfluidic channel, the refractive index is 1.3309, circularly polarized light is incident from one right-angle side surface of the triangular prism, the circularly polarized light irradiates on the gold nanoparticle and quantum dot composite structure at a total reflection angle to generate total reflection, S polarized light and P polarized light in the reflected light are subjected to differential treatment through the balance detector and are transmitted to a computer, and a voltage value corresponding to a first sample is obtained;
c) Injecting 10% NaCl solution with a refractive index of 1.3506 and absolute ethyl alcohol with a refractive index of 1.3660 into the microfluidic channel respectively, and repeating the step b) to obtain voltage values corresponding to the 10% NaCl solution and the absolute ethyl alcohol respectively;
d) Fitting according to the obtained refractive index and the voltage value corresponding to the refractive index to obtain a relation curve of the refractive index and the voltage value;
4) Detecting a sample to be detected:
a) The sample to be tested enters the microfluidic channel through the fluid inlet by the fluid conduit;
b) Circularly polarized light 201 is incident from one right-angle side of the triangular prism 202, irradiates on the gold nanoparticle and quantum dot composite structure 204 at a total reflection angle, and generates total reflection;
c) Plasmon generated by the gold nanoparticles and exciton generated by the quantum dots are coupled and interacted to enhance the surface plasmon resonance effect of the gold nanoparticles, and the resonance causes P polarized light to be greatly absorbed under total reflection to form a sharp formant;
d) The reflected light 209 is divided into P polarized light and S polarized light which are perpendicular to each other by a polarization splitting prism, and is received by different channels of a balance detector respectively, and subjected to differential processing;
e) Transmitting the refractive index to a computer, obtaining a voltage value by the computer, and obtaining the refractive index of the sample to be detected by sensing according to the relation between the calibrated refractive index and the voltage.
Example two
In this embodiment, necrotic cells are detected, which release a biomolecule, and precisely a specific target molecule that binds to the biomolecule, so that blood is passed through the device, and binding of the biomolecule to the specific target molecule ultimately causes a change in the detected voltage, which can be considered to be necrotic cells in the blood.
Placing the gold nanoparticle and quantum dot composite structure obtained in the first embodiment in an oxygen plasma cleaning machine for 15s, opening functional groups of the gold nanoparticle and quantum dot composite structure on the front surface of a transparent substrate, soaking the gold nanoparticle and quantum dot composite structure in buffer solution containing biomolecules for 8 hours, and using a mixed solution of NaCl and deionized water with the pH value of 7 as the buffer solution containing specific biomolecules to couple the surfaces of the gold nanoparticle and quantum dot composite structure with the biomolecules to form biological target molecules; then a sensor is formed according to the first embodiment, and a sensing system is formed, wherein a biological molecule is generated in necrotic cells and permeates out of damaged cell membranes, the biological molecule is a degrading enzyme, belongs to protein, and is combined with the specific biological target molecule, so that the refractive index on a composite structure is changed, the voltage signal of reflected light subjected to differential treatment by a balance detector is changed with the voltage signal corresponding to the calibration liquid introduced before, and whether necrotic cells exist in blood can be detected.
Finally, it should be noted that the examples are disclosed for the purpose of aiding in the further understanding of the present invention, but those skilled in the art will appreciate that: various alternatives and modifications are possible without departing from the spirit and scope of the invention and the appended claims. Therefore, the invention should not be limited to the disclosed embodiments, but rather the scope of the invention is defined by the appended claims.
Claims (8)
1. The refractive index sensor of the gold nanoparticle and quantum dot composite structure is characterized by comprising: transparent substrates, gold nanoparticles, quantum dots, microfluidic channels, triangular prisms, and fluid conduits; depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles; spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure; forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure; the microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel; the refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid; the fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the fluid conduit; the sample to be tested enters the microfluidic channel through the fluid inlet by the fluid conduit; the circularly polarized light is incident from one right-angle side of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, generates total reflection, and enhances the surface plasmon resonance effect of the gold nanoparticle due to coupling interaction of plasmon generated by the gold nanoparticle and exciton generated by the quantum dot, wherein the resonance causes P polarized light to be greatly absorbed under total reflection, so that a sharp resonance peak is formed; and receiving the reflected light, dividing the reflected light into P polarized light and S polarized light which are perpendicular to each other, and then performing differential processing to obtain corresponding voltage values, and obtaining the refractive index of the sample to be detected according to the relationship between the calibrated refractive index and the voltage.
2. The refractive index sensor according to claim 1, wherein the gold nanoparticles have a size of 10 to 20nm; the gap between adjacent gold nanoparticles is 18-26 nm; the size of the quantum dots is 9-15 nm, and the distance between adjacent quantum dots is 12-23 nm; the ratio of the gold nanoparticles to the quantum dots is 2:1-4:1.
3. A biosensor of a gold nanoparticle and quantum dot composite structure, characterized in that the biosensor of a gold nanoparticle and quantum dot composite structure comprises: transparent substrates, gold nanoparticles, quantum dots, microfluidic channels, triangular prisms, and fluid conduits; depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles; spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure; the gold nanoparticle and quantum dot composite structure is soaked in buffer solution of biological molecules, and functional groups of the gold nanoparticle and quantum dot composite structure are coupled with the biological molecules to form biological target molecules; forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure; the microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel; the refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid; the fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the fluid conduit; a sample to be detected enters the microfluidic channel through the fluid inlet by the fluid conduit, biomolecules to be detected in the sample to be detected are combined with biological target molecules on the gold nanoparticle and quantum dot composite structure, and the refractive index of the biological target molecules is changed; the circularly polarized light is incident from one right-angle side of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, generates total reflection, and enhances the surface plasmon resonance effect of the gold nanoparticle due to coupling interaction of plasmon generated by the gold nanoparticle and exciton generated by the quantum dot, wherein the resonance causes P polarized light to be greatly absorbed under total reflection, so that a sharp resonance peak is formed; and receiving the reflected light, dividing the reflected light into P polarized light and S polarized light which are perpendicular to each other, performing differential processing to obtain corresponding voltage values, comparing the voltage values with the voltage values when the calibration liquid is introduced, and indicating that the sample to be detected contains biomolecules to be detected if the voltage values are changed.
4. A biosensor according to claim 3, wherein the gold nanoparticles have a size of 10 to 20nm; the gap between adjacent gold nanoparticles is 18-26 nm; the size of the quantum dots is 9-15 nm, and the distance between adjacent quantum dots is 12-23 nm; the ratio of the gold nanoparticles to the quantum dots is 2:1-4:1.
5. The sensing system of the gold nanoparticle and quantum dot composite structure is characterized by comprising the following components: the device comprises a laser, an attenuation sheet, a polaroid, a lambda/4 wave plate, a polarization beam splitter prism, a balance detector, a computer and a refractive index sensor or a biological sensor of a gold nanoparticle and quantum dot composite structure; the refractive index sensor adopting the gold nanoparticle and quantum dot composite structure comprises a transparent substrate, gold nanoparticles, quantum dots, a microfluidic channel, a triangular prism and a fluid conduit; depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles; spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure; forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure; the microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel; the refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid; the fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the catheter; the sample to be measured enters the micro-fluid channel through the fluid inlet by the guide pipe; or alternatively, the process may be performed,
The biosensor adopting the gold nanoparticle and quantum dot composite structure comprises a transparent substrate, gold nanoparticles, quantum dots, a microfluidic channel, a triangular prism and a fluid conduit; depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles; spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure; the gold nanoparticle and quantum dot composite structure is soaked in buffer solution of biological molecules, and functional groups of the gold nanoparticle and quantum dot composite structure are coupled with the biological molecules to form biological target molecules; forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure; the microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel; the refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid; the fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the fluid conduit; a sample to be detected enters the microfluidic channel through the fluid inlet by the fluid conduit, biomolecules to be detected in the sample to be detected are combined with biological target molecules on the gold nanoparticle and quantum dot composite structure, and the refractive index of the biological target molecules is changed; the laser emits laser, the intensity of the laser is regulated by the attenuation sheet, the laser is changed into linearly polarized light by the polaroid, and the linearly polarized light is changed into circularly polarized light by the lambda/4 wave plate; the circularly polarized light is incident from one right-angle side of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, generates total reflection, and enhances the surface plasmon resonance effect of the gold nanoparticle due to coupling interaction of plasmon generated by the gold nanoparticle and exciton generated by the quantum dot, wherein the resonance causes P polarized light to be greatly absorbed under total reflection, so that a sharp resonance peak is formed; the reflected light is divided into P polarized light and S polarized light which are perpendicular to each other through a polarization beam splitter prism, and the P polarized light and the S polarized light are respectively received by different channels of a balance detector and subjected to differential processing; transmitting the refractive index value to a computer, and obtaining the refractive index of the sample to be measured by the sensing according to the relationship between the calibrated refractive index and the voltage by the computer; or comparing the voltage value with the voltage value when the calibration liquid is introduced, and if the voltage value is changed, indicating that the sample to be detected contains the biomolecules to be detected.
6. The sensing system of claim 5, wherein the gold nanoparticles have a size of 10-20 nm; the gap between adjacent gold nanoparticles is 18-26 nm; the size of the quantum dots is 9-15 nm, and the distance between adjacent quantum dots is 12-23 nm; the ratio of the gold nanoparticles to the quantum dots is 2:1-4:1.
7. A refractive index sensing method of a refractive index sensor of a gold nanoparticle and quantum dot composite structure according to claim 1, characterized in that the refractive index sensing method comprises the steps of:
1) Preparing a sensor system of a gold nanoparticle and quantum dot composite structure:
a) Depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles;
b) Spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure;
c) Forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure;
d) The microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel;
e) The refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid;
f) The fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the fluid conduit;
2) Constructing a sensing system of a gold nanoparticle and quantum dot composite structure:
a) The laser emits laser;
b) The intensity of the laser is regulated by an attenuation sheet;
c) Changing the light into linear polarized light through a polaroid and changing the light into circular polarized light through a lambda/4 wave plate;
d) The circularly polarized light is incident from one right-angle side surface of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, and generates total reflection;
e) The reflected light is divided into P polarized light and S polarized light which are perpendicular to each other through a polarization beam splitter prism, and the P polarized light and the S polarized light are respectively received by different channels of a balance detector and subjected to differential processing; transmitting the voltage value to a computer to obtain a voltage value;
3) Relationship between index of refraction and voltage:
a) When a sample is not injected into the microfluidic channel, air is filled in the microfluidic channel, circularly polarized light is incident from one right-angle side surface of the triangular prism, and is irradiated onto the gold nanoparticle and quantum dot composite structure at a total reflection angle to generate total reflection, S and P polarized light in the reflected light is subjected to differential treatment by a balance detector and is transmitted to a computer, so that a voltage value corresponding to the air is obtained;
b) Injecting a first sample with known refractive index into a microfluidic channel, enabling circularly polarized light to enter from a right-angle side surface of a triangular prism, irradiating the gold nanoparticle and quantum dot composite structure with a total reflection angle to generate total reflection, carrying out differential treatment on S and P polarized light in the reflected light through a balance detector, and transmitting the S and P polarized light to a computer to obtain a voltage value corresponding to the first sample;
c) Injecting a second sample with known refractive index into the microfluidic channel, wherein the refractive index is different from that of the first sample, and repeating the step b) until N samples with known refractive indexes and corresponding voltage values are obtained, wherein N is more than or equal to 2;
d) Fitting according to the obtained N refractive indexes and the voltage values corresponding to the N refractive indexes to obtain a relation curve of the refractive indexes and the voltage values;
4) Detecting a sample to be detected:
a) The sample to be tested enters the microfluidic channel through the fluid inlet by the fluid conduit;
b) Circularly polarized light is incident from one right-angle side surface of the triangular prism and irradiates on the gold nanoparticle and quantum dot composite structure at a total reflection angle;
c) Plasmon generated by the gold nanoparticles and exciton generated by the quantum dots are coupled and interacted to enhance the surface plasmon resonance effect of the gold nanoparticles, and the resonance causes P polarized light to be greatly absorbed under total reflection to form a sharp formant;
d) The reflected light is divided into P polarized light and S polarized light which are perpendicular to each other through a polarization beam splitter prism, and the P polarized light and the S polarized light are respectively received by different channels of a balance detector and subjected to differential processing;
e) Transmitting the refractive index to a computer, obtaining a voltage value by the computer, and obtaining the refractive index of the sample to be detected by sensing according to the relation between the calibrated refractive index and the voltage.
8. A method of biosensing a biosensor of gold nanoparticle and quantum dot composite structure according to claim 3, characterized in that the biosensing method comprises the steps of:
1) Preparing a sensor system of a gold nanoparticle and quantum dot composite structure:
a) Depositing stacked gold nanoparticles in the front central area of the transparent substrate, wherein gaps are reserved among the gold nanoparticles;
b) Spin-coating quantum dots on the gold nanoparticles, wherein the quantum dots are uniformly inserted into gaps of the gold nanoparticles to form a gold nanoparticle and quantum dot composite structure;
c) The gold nanoparticle and quantum dot composite structure is soaked in buffer solution of biological molecules, and functional groups of the gold nanoparticle and quantum dot composite structure are coupled with the biological molecules to form biological target molecules;
d) Forming a groove on the surface of the solid glue, forming through holes on a pair of opposite side walls of the groove, and respectively forming a fluid inlet and a fluid outlet to form a micro-fluid channel, wherein the surface area of the groove is not smaller than the area of the gold nanoparticle and quantum dot composite structure;
e) The microfluidic channel and the transparent substrate are both placed in a plasma cleaning machine, so that functional groups on the surfaces of the solid glue and the transparent substrate are opened, and the grooves of the microfluidic channel are faced to the front surface of the transparent substrate to tightly adhere the two together at the moment of taking out, and the edges of the microfluidic channel and the front surface of the transparent substrate are connected together through chemical bonds; the grooves of the microfluidic channel correspond to the positions of the gold nanoparticle and quantum dot composite structures, so that the gold nanoparticle and quantum dot composite structures are positioned in the grooves of the microfluidic channel;
f) The refractive index of the transparent substrate is the same as that of the triangular prism, and the back surface of the transparent substrate is attached to the hypotenuse surface of the triangular prism through the refractive index matching liquid;
g) The fluid inlet and the fluid outlet of the microfluidic channel are respectively connected with the fluid conduit;
2) Constructing a sensing system of a gold nanoparticle and quantum dot composite structure:
a) The laser emits laser;
b) The intensity of the laser is regulated by an attenuation sheet;
c) Changing the light into linear polarized light through a polaroid and changing the light into circular polarized light through a lambda/4 wave plate;
d) The circularly polarized light is incident from one right-angle side surface of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, and generates total reflection;
e) The reflected light is divided into P polarized light and S polarized light which are perpendicular to each other by a polarization beam splitter prism, and the P polarized light and the S polarized light are respectively received by different channels of a balance detector; the balance detector transmits the P polarized light to the computer;
3) Calibrating the biosensor:
when the calibration liquid without the biomolecules to be detected is used as a reference in the microfluidic channel, the microfluidic channel is filled with the calibration liquid, circularly polarized light is incident from one right-angle side surface of the triangular prism, is irradiated onto the gold nanoparticle and quantum dot composite structure at a total reflection angle to generate total reflection, S and P polarized light in the reflected light is subjected to differential treatment by the balance detector and is transmitted to a computer, and a voltage value corresponding to the calibration liquid is obtained;
4) Detecting a sample to be detected:
a) The sample to be tested enters the microfluidic channel through the fluid inlet by the fluid conduit;
b) The biological molecules in the sample to be detected are combined with biological target molecules on the gold nanoparticle and quantum dot composite structure;
c) The circularly polarized light is incident from one right-angle side surface of the triangular prism, irradiates onto the gold nanoparticle and quantum dot composite structure at a total reflection angle, and generates total reflection;
d) Plasmon generated by the gold nanoparticles and exciton generated by the quantum dots are coupled and interacted to enhance the surface plasmon resonance effect of the gold nanoparticles, and the resonance causes P polarized light to be greatly absorbed under total reflection to form a sharp formant;
e) Receiving reflected light, dividing the reflected light into P polarized light and S polarized light which are perpendicular to each other, respectively receiving the P polarized light and the S polarized light by different channels of the balance detector, and performing differential processing;
f) Transmitting the voltage value to a computer, comparing the voltage value with the voltage value when the calibration liquid is introduced, and indicating that the sample to be detected contains biomolecules to be detected if the voltage value is changed;
5) After the measurement is completed, in order to ensure the repeated use of the biosensor, the biological target molecules on the gold nanoparticle and quantum dot composite structure are separated from the sample to be measured, the sample to be measured is thoroughly washed away, and the activity of the biological target molecules is recovered.
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