TWI841105B - Graphene-based surface plasmon resonance prism coupler sensor, dual-retarder mueller polarimetry system and use thereof - Google Patents

Abstract

The present disclosure provides a graphene-based surface plasmon resonance prism coupler sensor, which includes a glass substrate, a tantalum pentoxide thin film layer, a chromium-gold thin film layer and a graphene layer in sequence from bottom to top. Thus, the graphene-based surface plasmon resonance prism coupler sensor of the present disclosure can be applied to a dual-retarder Mueller polarimetry system, and equipped with a differential Mueller matrix to rapidly detect immunoglobulin G antibody.

Description

Graphene surface plasmon resonance prism coupled sensor, double delay Mueller polarization system and its application

The present invention relates to a surface plasmon resonance sensor, and in particular to a graphene surface plasmon resonance prism coupling sensor, a double delay device Mueller polarization system and uses thereof.

Nowadays, infectious viral diseases such as dengue fever, typhoid, hepatitis B, SARS-CoV-2 or COVID-19 have become a major threat to human life, and their diagnosis method is usually real-time reverse transcription polymerase chain reaction (RT-qPCR). However, the success of RT-qPCR depends on the accuracy of the sample collection process, and RT-qPCR often has false negative cases, causing infectious individuals to continue to spread, causing serious impacts on public health.

Currently, many diagnostic methods have been proposed and are feasible for the detection of specific antibodies and antigens such as immunoglobulin G (Immunoglobulin G), but a rapid, reliable and accurate method for detecting immunoglobulin G is still needed, and surface plasmon resonance sensor is one of the potential alternatives.

In addition, according to past studies, the characteristics of polarized optics are related to the state of biological tissues and cells, so polarization measurement technology can be applied to the detection of viral infectious diseases or the analysis of biological tissues. The more common method is Mueller matrix polarimetry to analyze optical parameters.

In view of this, how to develop a new surface plasmon resonance sensor based on Mueller matrix polarization measurement and use it for the detection of immunoglobulin G and make it feasible has become the goal of relevant scholars and practitioners.

One of the purposes of the present invention is to provide a graphene surface plasmon resonance prism coupled sensor, a double-retarder Mueller polarization system and its use, and to calculate the optical parameters of immunoglobulin G antibodies by differential Mueller matrix to quickly detect immunoglobulin G antibodies.

One embodiment of the present invention is to provide a graphene surface plasmon resonance prism coupled sensor, which includes a glass substrate, a tantalum pentoxide thin film layer, a chromium-gold thin film layer and a graphene layer. The glass substrate has a surface, the tantalum pentoxide thin film layer is disposed on the surface of the glass substrate, the chromium-gold thin film layer is disposed on the tantalum pentoxide thin film layer, and the graphene layer is disposed on the chromium-gold thin film layer.

Another embodiment of the present invention is to provide a double-retarder Mueller polarization system for measuring an optical parameter of a sample, and the double-retarder Mueller polarization system includes the aforementioned GSPR CPSS, a light source, a linear polarizer, a liquid crystal phase delay element set (liquid-crystal variable retarder, LCVR) and a Stokes polarimeter. The GSPR CPSS is in contact with the sample, the light source generates an incident light and is incident on the GSPR CPSS along an optical path, and the linear polarizer is located on the optical path and is disposed between the light source and the GSPR CPSS. The liquid crystal phase delay element set is located on the optical path and is arranged between the linear polarizer and the graphene surface plasmon resonance prism coupling sensor, and makes the incident light form a polarized light, and the polarized light forms a reflected light after passing through the graphene surface plasmon resonance prism coupling sensor and is received by the Stokes polarizer.

Yet another embodiment of the present invention is to provide a use of the aforementioned double-delay Mueller polarization system for detecting an immunoglobulin G antibody.

Thus, the present invention designs a graphene surface plasmon resonance prism coupled sensor and applies it to a double-delay Mueller polarization system to calculate the relationship between the optical parameters and concentration of immunoglobulin G antibodies, which can prove the feasibility of the graphene surface plasmon resonance prism coupled sensor.

The following will describe the implementation of the present invention with reference to the drawings. For the sake of clarity, many practical details will be described together in the following description. However, the reader should understand that these practical details should not be used to limit the present invention. In other words, in some implementations of the present invention, these practical details are not necessary. In addition, in order to simplify the drawings, some commonly used structures and components will be shown in the drawings in a simple schematic manner; and repeated components may be represented by the same number.

＜Graphene surface plasmon resonance prism coupled sensor＞

Please refer to FIG. 1, which is a schematic diagram of a graphene surface plasmon resonance prism coupled sensor 100 according to an embodiment of the present invention. As can be seen from FIG. 1, the graphene surface plasmon resonance prism coupled sensor 100 includes a glass substrate 110, a tantalum pentoxide thin film layer 120, a chromium-gold thin film layer 130 and a graphene layer 140 in order from bottom to top.

In detail, the glass substrate 110 has a surface 111 and can be a hemispherical glass lens. The tantalum pentoxide film layer 120 is disposed on the surface 111 of the glass substrate 110, and the chromium-gold film layer 130 is disposed on the tantalum pentoxide film layer 120, and the thickness of the chromium-gold film layer 130 can be greater than the thickness of the tantalum pentoxide film layer 120. The graphene layer 140 is disposed on the chromium-gold film layer 130, and the graphene layer 140 can be composed of a single layer of graphene. In this way, based on the excellent optical properties of graphene, the performance of the surface plasmon resonance prism coupled sensor can be enhanced, and the single layer of graphene can provide four times the electric field strength in the response value of the sensor.

＜Double-delay Mueller polarization system＞

Please refer to FIG. 2, which is a schematic diagram of a double-delay Mueller polarization system 200 according to another embodiment of the present invention. As shown in FIG. 2, the double-delay Mueller polarization system 200 includes a graphene surface plasmon resonance prism coupled sensor 100, a light source 210, a linear polarizer 220, a liquid crystal phase delay element set 230 and a Stokes polarizer 240, and the double-delay Mueller polarization system 200 is used to measure the optical parameters of a sample (not shown).

Specifically, the light source 210 generates an incident light and incidents on the GSPR 100 along an optical path 250, and the light source 210 of the present invention may be but is not limited to a He-Ne laser. The linear polarizer 220 is located on the optical path 250 and disposed between the light source 210 and the GSPR 100, wherein the principal axis angle of the linear polarizer 220 is 45 ^° . The liquid crystal phase delay element set 230 is located on the optical path 250 and is disposed between the linear polarizer 220 and the GSPR 100, and makes the incident light form a polarized light, and the polarized light forms a reflected light after passing through the GSPR 100, and is received by the Stokes polarizer 240, and then calculated and analyzed to obtain the optical parameters of the sample. Specifically, the liquid crystal phase delay element set 230 includes a first liquid crystal phase delay element 231 and a second liquid crystal phase delay element 232, and the second liquid crystal phase delay element 232 is closer to the graphene surface plasmon resonance prism coupled sensor 100 than the first liquid crystal phase delay element 231, and the slow axis angle of the first liquid crystal phase delay element 231 is 90 ^degrees , and the slow axis angle of the second liquid crystal phase delay element 232 is 45 ^degrees .

In addition, the double-retarder Mueller polarization system 200 further includes a cuvette 260, which is connected to the GSPRPS sensor 100 and used to store samples. The cuvette 260 is provided with a hole (not shown) to allow the sample to directly contact the GSPRPS sensor 100, thereby avoiding optical interference generated by the cuvette 260.

The present invention utilizes the graphene surface plasmon resonance prism coupled sensor 100 to generate total reflection in the double-delay Mueller polarization system 200 and uses the differential Mueller matrix to obtain the optical properties of the sample. The Stokes vector of the polarized light emitted by the linear polarizer 220 and the liquid crystal phase delay element set 230 in the double-delay Mueller polarization system 200 can be described as the following formula (1): S _out =LCVR(δ ₂ ,45 ^o )LCVR(δ ₁ ,90 ^o )S _in Formula 1), Wherein, δ ₁ and δ ₂ are the adjustable phase delays of the first liquid crystal phase delay element 231 and the second liquid crystal phase delay element 232, respectively, S _in is the Stokes vector of the incident light, and S _out is the Stokes vector of the reflected light. In the present invention, four different polarization states can be formed through the combination of the first liquid crystal phase delay element 231 and the second liquid crystal phase delay element 232, which are linear polarization light of 0 ^° , 45 ^° , and 90 ^° and circular polarization light, respectively. Then, δ ₁ and δ ₂ are specified by the values shown in Table 1 to construct the incident light corresponding to the linear polarization light of 0 ^° , 45 ^° , 90 ^° and circular polarization light required by the Mueller matrix of the sample, and the incident angle of the light source 210 is equal to the resonance angle 60 ^° of the graphene surface plasmon resonance prism coupled sensor 100. In addition, the present invention can change the polarization state of the incident light once every 2 seconds, so that the average time required to complete the measurement process is about 3 minutes, thereby reducing the detection time. Table I Polarization state δ ₁ δ ₂ 0 ^o linear polarization 90 ^o 270 ^{o 45o} linear polarized light 0 ^o 0 ^{o 90o} linear polarized light 90 ^o 90 ^o Circularly polarized light 90 ^o 180 ^o

Based on the above, the relationship between the Stokes vector and the Mueller matrix of the sample can be expressed as follows (2): S _out =MS _in Formula (2): Where M is the Mueller matrix, and the differential Mueller matrix can be obtained by performing matrix analysis on formula (2) as follows (3): Formula (3), Where m is the differential Mueller matrix, ν is the eigenvalue of the Mueller matrix, λ is the eigenvector of the Mueller matrix, and z is the coordinate axis. In addition, the principal fast axis angle (α) of the circular dichroism (R) and the linear birefringence property can be obtained by the following equations (4) and (5), respectively: Formula (4), Formula (5). Wherein, _mij is an element of the differential Mueller matrix. The above equations (4) and (5) are well known in the art and will not be further described here.

＜Application of Double Delay Detector Mueller Polarization System＞

The present invention provides a use of the aforementioned double-retarder Mueller polarization system 200, which is used to detect an immunoglobulin G (IgG) antibody, and the concentration of the immunoglobulin G antibody can be 0 ng/mL to 250 ng/mL. Specifically, the immunoglobulin G antibody is used as a sample in the double-retarder Mueller polarization system 200, and the circular dichroism (R) and the fast axis principal angle (α) of the linear birefringence of the immunoglobulin G antibody are obtained by using the differential Mueller matrix and the graphene surface plasmon resonance prism coupled sensor 100 to prove the feasibility of the graphene surface plasmon resonance prism coupled sensor 100 of the present invention.

The present invention is further illustrated by the following specific embodiments, which are used to facilitate those skilled in the art to which the present invention belongs, so that the present invention can be fully utilized and practiced without excessive interpretation. These embodiments should not be regarded as limiting the scope of the present invention, but are used to illustrate the materials and methods for implementing the present invention.

<Example>

In the graphene surface plasmon resonance prism coupled sensor of one embodiment of the present invention, the thickness of the tantalum pentoxide film layer is 12 nm, the thickness of the chromium-gold film layer is 20 nm, and the thickness of the graphene layer is 0.34 nm. Please refer to Figure 3, which shows the Raman spectrum of a single-layer graphene. From the results of Figure 3, it can be seen that two characteristic peaks are observed at 1600 cm ^-1 and 2700 cm ^-1 , respectively, proving that the graphene layer is composed of a single-layer graphene on the surface of the chromium-gold film layer.

＜IgG antibody detection＞

Example 1: 2 μL of IgG buffer solution extracted from mouse serum was added to 20 mL of deionized water to prepare a 1000 ng/mL mouse IgG stock solution, and the mouse IgG stock solution was diluted with an appropriate amount of deionized water to prepare a mouse IgG aqueous solution with a concentration range of 0 ng/mL to 250 ng/mL.

Example 2: 140 mg/dL of D-glucose and 2% lipofundin were added to 0 ng/mL to 250 ng/mL mouse IgG aqueous solutions to simulate real-world plasma containing glucose and fatty acid components.

Example 3: 20 mg of human IgG freeze-dried powder was dissolved in 20 mL of deionized water to prepare a 1 mg/mL human IgG aqueous solution, and then the 1 mg/mL human IgG aqueous solution was diluted with 20 mL of deionized water to prepare a 1000 ng/mL human IgG stock solution. Then, the human IgG stock solution was diluted with an appropriate amount of deionized water to prepare a human IgG aqueous solution with a concentration range of 0 ng/mL to 250 ng/mL, and 140 mg/dL of D-glucose and 2% fat emulsion were added.

Please refer to Figures 4A and 4B, wherein Figure 4A shows the relationship between the circular dichroism (R) and the mouse IgG concentration of Examples 1 and 2. Figure 4B shows the relationship between the fast axis principal angle (α) and the mouse IgG concentration of Examples 1 and 2. From the results of Figure 4A, it can be seen that within the concentration range of 0 ng/mL to 250 ng/mL, the R value increases with the increase of the mouse IgG concentration, and the R value of Example 1 is less than that of Example 2, which can explain that the correlation between the circular dichroism and the IgG concentration of Example 2 is stronger than that of Example 1, that is, the addition of glucose and fat emulsion to the mouse IgG aqueous solution will increase the absorbance of circular dichroism. In addition, in five repeated tests, the average standard deviations of the R values of Example 1 and Example 2 were 2.9×10 ^-4 and 4.1×10 ^-4 , respectively. Based on the R value of Example 2, it was found that the sensitivity of the measurement result was S=∆R/∆C=5.6×10 ^-5 , where ∆R is the change in circular dichroism, ∆C is the change in IgG concentration, and the resolution of Example 2 was T=δR/S=5 ng/mL, where δR is the average standard deviation of the R value.

As shown in the results of FIG. 4B, within the concentration range of 0 ng/mL to 250 ng/mL, the α value increases with the increase of the mouse IgG concentration, and the α value of Example 1 is less than that of Example 2, which indicates that the addition of glucose and fat emulsion to the mouse IgG aqueous solution increases the fast-axis principal angle due to the greater linear polarization refraction effect. In addition, in five repeated tests, the average standard deviations of the α values of Example 1 and Example 2 were 2.8×10 ^-4 and 3.3×10 ^-4 , respectively, and according to the α value of Example 2, it can be found that the sensitivity of the measurement result is S=∆α/∆C=3.2×10 ^-5 , where ∆α is the variation of the fast-axis principal angle, and the resolution of Example 2 is T=δα/S=10 ng/mL, where δα is the average standard deviation of the α value.

From the above results, it can be seen that the resolution of linear birefringence (LB) measurement is lower than that of circular dichroism (CD) measurement. Under total internal reflection, graphene shows significant absorption in the transverse electric mode. This result is very sensitive to the refractive index change of the medium that graphene contacts. The refractive index change caused by the interaction between antigen and antibody leads to the change of polarization absorption. Therefore, the graphene surface plasmon resonance prism coupled sensor of the present invention improves the resolution of circular dichroism measurement based on polarization absorption.

In general, the results of FIG. 4A and FIG. 4B indicate that the circular dichroism and linear birefringence properties are capable of reliably measuring the mouse IgG concentration with a fine resolution of 5 ng/mL and 10 ng/mL, respectively, thereby demonstrating the feasibility of the graphene surface plasmon resonance prism coupled sensor of the present invention for detecting the IgG concentration in mouse serum.

Please refer to Figures 5A and 5B, wherein Figure 5A shows the relationship between the circular dichroism and the human IgG concentration of Example 3. Figure 5B shows the relationship between the fast axis main angle and the human IgG concentration of Example 3. From the results of Figures 5A and 5B, it can be seen that in the concentration range of 0 ng/mL to 250 ng/mL, the R value increases with the increase of the human IgG concentration, and the α value also increases with the increase of the human IgG concentration. In addition, in five repeated tests, the average standard deviations of the R value and the α value of Example 3 are 3.6×10 ^-4 and 4.6×10 ^-4 respectively. According to the R value of Example 3, it can be found that the sensitivity of the measurement result is S=∆R/∆C=5×10 ^-5 and the resolution is T=δR/S=7.2 ng/mL, and according to the α value of Example 3, it can be found that the sensitivity of the measurement result is S=∆α/∆C=4.8×10 ^-5 and the resolution is T=δα/S=9.5 ng/mL. Therefore, similar to the results of Examples 1 and 2, since the graphene surface plasmon resonance prism coupled sensor of the present invention increases polarization absorption, the resolution of the linear birefringence measurement of Example 3 is also lower than the resolution of the circular dichroism measurement.

In summary, the present invention measures the circular dichroism and fast axis principal angle of mouse and human IgG antibodies with concentrations ranging from 0 ng/mL to 250 ng/mL through a combination of a differential Mueller matrix and a graphene surface plasmon resonance prism coupled sensor, and the overall detection time is about 3 minutes. This proves that the graphene surface plasmon resonance prism coupled sensor of the present invention can quickly detect IgG antibodies and is feasible.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of the attached patent application.

100: Graphene surface plasmon resonance prism coupled sensor

110: Glass substrate

111: Surface

120:TiO2 thin film layer

130: Chromium-gold thin film layer

140: Graphene layer

200:Double delay Mueller polarization system

210: Light source

220: Linear polarizer

230: Liquid crystal phase delay element set

231: first liquid crystal phase retardation element

232: Second liquid crystal phase retardation element

240: Stokes polarimeter

250: Light path

260: Cuvette

In order to make the above and other purposes, features, advantages and embodiments of the present invention more clearly understandable, the attached figures are described as follows: Figure 1 is a schematic diagram of a graphene surface plasmon resonance prism coupled sensor according to one embodiment of the present invention; Figure 2 is a schematic diagram of a double delayer Mueller polarization system according to another embodiment of the present invention; Figure 3 is a Raman spectrum of a single layer of graphene; Figure 4A is a graph showing the relationship between the circular dichroism (R) and the mouse IgG concentration of Examples 1 and 2; Figure 4B is a graph showing the relationship between the fast axis principal angle (α) and the mouse IgG concentration of Examples 1 and 2; Figure 5A is a graph showing the relationship between the circular dichroism and the human IgG concentration of Example 3; and Figure 5B is a graph showing the relationship between the fast axis main axis and the human IgG concentration of Example 3.

100: Graphene surface plasmon resonance prism coupled sensor

110: Glass substrate

111: Surface

120: Titanium pentoxide thin film layer

130: Chromium-gold thin film layer

140: Graphene layer

Claims (9)

A graphene surface plasmon resonance prism coupled sensor comprises: a glass substrate having a surface; a tantalum pentoxide thin film layer disposed on the surface of the glass substrate; a chromium-gold thin film layer disposed on the tantalum pentoxide thin film layer; and a graphene layer disposed on the chromium-gold thin film layer; wherein the thickness of the chromium-gold thin film layer is greater than the thickness of the tantalum pentoxide thin film layer. The graphene surface plasmon resonance prism coupled sensor as described in claim 1, wherein the glass substrate is a hemispherical glass lens. A graphene surface plasmon resonance prism coupled sensor as described in claim 1, wherein the graphene layer is composed of a single layer of graphene. A double-delay Mueller polarization system is used to measure an optical parameter of a sample, the double-delay Mueller polarization system comprising: a graphene surface plasmon resonance prism coupled sensor as described in any one of claim 1 to claim 3, which is in contact with the sample; a light source, which generates an incident light and is incident on the graphene surface plasmon resonance prism coupled sensor along an optical path; a linear polarizer, which is located on the optical path and disposed on the between the light source and the graphene surface plasmon resonance prism coupling sensor; a liquid crystal phase delay element set, which is located on the optical path and disposed between the linear polarizer and the graphene surface plasmon resonance prism coupling sensor, and makes the incident light form a polarized light; and a Stokes polarizer, the polarized light forms a reflected light after passing through the graphene surface plasmon resonance prism coupling sensor, and is received by the Stokes polarizer. A dual-retarder Mueller polarization system as described in claim 4, wherein the liquid crystal phase delay element set includes a first liquid crystal phase delay element and a second liquid crystal phase delay element, and the second liquid crystal phase delay element is closer to the graphene surface plasmon resonance prism coupled sensor than the first liquid crystal phase delay element. A double-retarder Mueller polarization system as described in claim 5, wherein the slow axis angle of the first liquid crystal phase retardation element is 90°, and the slow axis angle of the second liquid crystal phase retardation element is 45°. The double-retarder Mueller polarization system as described in claim 6 further comprises: a cuvette connected to the graphene surface plasmon resonance prism coupled sensor and used to store the sample, and having a hole to allow the sample to contact the graphene surface plasmon resonance prism coupled sensor. A use of a double-delay Mueller polarization system as described in claim 4, which is used to detect an immunoglobulin G antibody. Use of a double delay device Mueller polarization system as described in claim 8, wherein the concentration of the immunoglobulin G antibody is 0 ng/mL to 250 ng/mL.

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