Double-near-sine gold grating microstructure with photo-thermal heating and fluorescence polarization detection enhancement functions, and preparation method and application of double-near-sine gold grating microstructure

Abstract

The invention discloses a double-near-sine gold grating microstructure with photo-thermal heating and fluorescence polarization detection enhancement functions and a preparation method and application thereof, and the double-near-sine gold grating microstructure comprises a substrate and a double-near-sine type gold grating periodic array structure arranged on the substrate in an array mode. The minimum repetitive unit of the double-nearly-sinusoidal gold grating periodic array structure is a double-nearly-sinusoidal gold grating unit, and the double-nearly-sinusoidal gold grating unit comprises two parallel nearly-sinusoidal gold strips with sinusoidal waveform or quasi-sinusoidal waveform and different amplitudes. The double near-sine gold grating microstructure provided by the invention has the advantages of high integration (a heat source and a detection substrate are combined into one, the system structure is greatly simplified, and implementation of a chip laboratory is facilitated), rapidness and high efficiency (the photothermal conversion efficiency is high, the thermal response is fast, and the heating / cooling rate far exceeding that of a traditional PCR instrument), high sensitivity, low cost, low power consumption, good compatibility and the like.

Description

Technical Field

[0001] This invention relates to the field of optical fiber technology, and particularly to a dual near-sinusoidal gold grating microstructure that combines photothermal heating and fluorescence polarization detection enhancement functions, its preparation method, and its application. Background Technology

[0002] In recent years, with the increasing demand for point-of-care (POC) diagnostics, polymerase chain reaction (PCR) technology has played a crucial role in pathogen detection, gene analysis, and other fields. However, traditional real-time PCR equipment typically suffers from problems such as large size, complex operation, high cost, and slow thermal cycling, limiting its widespread application in POC scenarios. To overcome these limitations, researchers have begun exploring photothermal conversion technology based on the plasmon effect to achieve rapid, small-scale on-chip PCR systems.

[0003] Gold nanoparticles (AuNPs) are used in photonic PCR due to their excellent photothermal conversion efficiency, enabling non-contact volumetric heating at the femtosecond level and significantly shortening amplification time. However, this method still has a series of problems: for example, high-power laser sources are expensive, system energy consumption is high, optical configuration is complex, and high concentrations of AuNPs may inhibit PCR reaction efficiency, thus affecting the reliability and practicality of detection. As an improvement, planar plasmonic structures such as gold thin films can achieve large-area uniform heating under LED excitation, possessing advantages such as compact structure and fast thermal response, making them more suitable for integrated and miniaturized POC detection platforms.

[0004] In signal detection, fluorescence reading is currently the mainstream method for detecting PCR products, but it is susceptible to external interference such as ambient light and electronic noise, affecting the sensitivity and stability of the detection. Fluorescence polarization immunoassay (FPIA) technology has gradually gained attention due to its strong anti-interference ability, lack of washing steps, and suitability for real-time kinetic monitoring. This technology reflects the molecular binding state by measuring changes in fluorescence polarization signals, possessing the inherent advantage of ratiometric measurement and effectively suppressing common-mode noise. However, existing FPIA systems still have shortcomings in integration, miniaturization, and synergy with plasmon thermal cycling modules, and their potential in POC diagnostics has not yet been fully realized.

[0005] In summary, the existing technology mainly has the following problems:

[0006] 1. Functional separation problem: In existing technologies, the thermal cycling module and the fluorescence detection module are usually separated, resulting in a complex, bulky and costly system.

[0007] 2. Excitation efficiency issues: The excitation light field intensity of traditional fluorescence detection is limited and easily affected by background noise, which affects the signal-to-noise ratio and detection sensitivity.

[0008] 3. Thermal management issues: Photothermal conversion based on gold nanoparticles has problems such as local overheating, PCR inhibition, and the need for complex laser light sources.

[0009] 4. Integration and cost issues: It is difficult to achieve efficient and rapid thermal cycling and high-sensitivity, interference-resistant detection on a single chip.

[0010] Therefore, there is an urgent need to develop a novel plasmonic microstructure that can balance rapid photothermal cycling with high signal-to-noise ratio fluorescence polarization detection, thereby achieving breakthroughs in structural simplification, cost reduction, detection efficiency improvement, and system integration, and meeting the comprehensive requirements of modern POC diagnostics for sensitivity, speed, and reliability. Summary of the Invention

[0011] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a dual near-sinusoidal gold grating microstructure that combines photothermal heating and fluorescence polarization detection enhancement functions, its preparation method, and its application.

[0012] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: In the first aspect of the present invention, a dual near-sinusoidal gold grating microstructure with photothermal heating and fluorescence polarization detection enhancement functions is provided, including a substrate and a periodic array structure of dual near-sinusoidal gold gratings arranged on the substrate. The smallest repeating unit of the periodic array structure of dual near-sinusoidal gold gratings is a dual near-sinusoidal gold grating unit. The dual near-sinusoidal gold grating unit includes two parallel near-sinusoidal gold strips, both of which have sinusoidal or quasi-sinusoidal waveforms but different amplitudes.

[0013] Preferably, the two near-sinusoidal gold strips in the dual near-sinusoidal gold grating unit are spatially adjacent but separated from each other, and there is a nanometer-scale gap between the two near-sinusoidal gold strips;

[0014] The cross-sectional profiles of the two near-sinusoidal gold bars are sinusoidal or quasi-sinusoidal.

[0015] Preferably, the two near-sinusoidal gold strips in the dual near-sinusoidal gold grating unit are respectively designated as a high-amplitude near-sinusoidal gold grating strip and a low-amplitude near-sinusoidal gold grating strip. The amplitude of the high-amplitude near-sinusoidal gold grating strip is greater than that of the low-amplitude near-sinusoidal gold grating strip, and the periods of the high-amplitude near-sinusoidal gold grating strip and the low-amplitude near-sinusoidal gold grating strip are the same.

[0016] Preferably, the period and amplitude of the high-amplitude near-sinusoidal gold grating strip are denoted as P1 and h1, respectively, where P1 = 250-1000nm and the height h1 = 125-500nm;

[0017] The period and amplitude of the low-amplitude near-sinusoidal gold grating strip are denoted as P2 and h2, respectively, where P2 = 250-1000nm, the height h2 = 75-300nm, and h2 < h1.

[0018] Preferably, the period and amplitude of the high-amplitude near-sinusoidal gold grating strip are denoted as P1 and h1, respectively, where P1 = 500 nm and the height h1 = 250 nm;

[0019] The period and amplitude of the low-amplitude near-sinusoidal gold grating strip are denoted as P2 and h2, respectively, where P2 = 500 nm and the height h2 = 150 nm.

[0020] Preferably, the thickness of both near-sinusoidal gold strips is d, where d = 75-300 nm.

[0021] Preferably, it comprises, from bottom to top, a substrate, an optical adhesive layer, a double near-sinusoidal gold grating periodic array structure, and a hydrosilyl sesquioxane layer.

[0022] Preferably, the substrate is a silicon dioxide substrate, and the thickness of the hydrosilsesquioxane layer is 250-1000 nm.

[0023] Preferably, d = 150 nm and the thickness of the hydrosilyl sesquioxane layer is 500 nm.

[0024] Preferably, under illumination by a light source, the surface of the double near-sinusoidal gold grating periodic array structure is excited to generate plasma polaritons, which convert light energy into heat energy, thereby producing a photothermal effect.

[0025] When linearly polarized excitation light is used as incident light, the surface of the double near-sinusoidal gold grating periodic array structure has a field enhancement effect on incident light with a specific polarization direction, providing enhanced fluorescence polarization detection.

[0026] In a first aspect, the present invention provides a method for fabricating a double near-sinusoidal gold grating microstructure as described above, comprising the following steps:

[0027] S1. Spin-coat photoresist onto a substrate, and then use electron beam lithography, nanoimprint lithography or laser interference lithography to process a template structure of a near-sinusoidal gold grating periodic array structure formed by photoresist.

[0028] The template structure is a photoresist layer, which has the same structural shape as the near-sinusoidal gold grating periodic array structure;

[0029] S2. A gold plating layer with a thickness of d is deposited on the surface of the photoresist grating using a vacuum thermal evaporation process. This gold plating layer forms the double near-sinusoidal gold grating microstructure.

[0030] S3. Hydrosiloxane resin is spin-coated onto a double near-sinusoidal gold grating microstructure to obtain a hydrosilicon silsesquioxane layer.

[0031] A third aspect of the present invention provides an application of the double near-sinusoidal gold grating microstructure described above in PCR.

[0032] Preferably, the application method is as follows:

[0033] 1) Place the double near-sinusoidal gold grating microstructure in the PCR reaction solution. During the thermal cycling phase of PCR, irradiate the double near-sinusoidal gold grating microstructure with a light source and use the photothermal effect of the light source to heat the PCR reaction solution.

[0034] 2) In the fluorescence detection stage of PCR amplification products, linearly polarized excitation light is used to irradiate the double near-sinusoidal gold grating microstructure to collect fluorescence signals and realize the detection of PCR amplification products.

[0035] The beneficial effects of this invention are:

[0036] This invention provides a dual near-sinusoidal gold grating microstructure that combines photothermal heating and fluorescence polarization detection enhancement functions, its preparation method, and its application in PCR. The dual near-sinusoidal gold grating microstructure provided by this invention has at least the following advantages:

[0037] (1) High integration: The heat source and the detection substrate are combined into one, which greatly simplifies the system structure and facilitates the realization of a chip laboratory.

[0038] (2) Fast and efficient: High photothermal conversion efficiency and fast thermal response, which can achieve a heating / cooling rate far exceeding that of traditional PCR instruments.

[0039] (3) High sensitivity: Plasmon enhancement effect greatly improves fluorescence excitation efficiency. Combined with the inherent anti-interference ability of FPIA, it makes the detection limit lower and the results more reliable.

[0040] (4) Low cost and low power consumption: When this double near-sinusoidal gold grating microstructure is applied to PCR amplification, LEDs can be used instead of expensive lasers, while simplifying the optical system and reducing manufacturing costs and operating energy consumption.

[0041] (5) Good compatibility: This structure can be seamlessly integrated with standard microfluidic technology and is suitable for various POC diagnostic scenarios. Attached Figure Description

[0042] Figure 1 This is a cross-sectional view of the dual near-sinusoidal gold grating microstructure of the present invention;

[0043] Figure 2 This is a schematic diagram of the overall structure of the dual near-sinusoidal gold grating microstructure of the present invention;

[0044] Figure 3 The absorption spectrum of Ex light incident at a 30° angle during the testing of the double near-sinusoidal gold grating microstructure in Example 1;

[0045] Figure 4 The reflection spectra of Ez and Ex polarized light during the testing of the double near-sinusoidal gold grating microstructure in Example 1.

[0046] Figure 5 The results of polarization degree testing are shown in the test of the double near-sinusoidal gold grating microstructure in Example 1.

[0047] Figure 6 The photothermal performance test results of the dual near-sinusoidal gold grating microstructure of Example 1 are presented. Detailed Implementation

[0048] The present invention will be further described in detail below with reference to embodiments, so that those skilled in the art can implement it based on the description.

[0049] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0050] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available. For examples where specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer are followed. For reagents or instruments whose manufacturers are not specified, they are all commercially available products.

[0051] This invention provides a dual near-sinusoidal gold grating microstructure that combines photothermal heating and fluorescence polarization detection enhancement functions, with reference to... Figure 1 and Figure 2 From bottom to top, it includes a substrate, an optical adhesive layer, a double near-sinusoidal gold grating periodic array structure, and a hydrogen-silicon silsesquioxane layer. The smallest repeating unit of the double near-sinusoidal gold grating periodic array structure is the double near-sinusoidal gold grating unit, which includes two parallel near-sinusoidal gold strips with waveforms that are both sinusoidal or quasi-sinusoidal but have different amplitudes.

[0052] Among them, the two near-sinusoidal gold strips in the dual near-sinusoidal gold grating unit are spatially adjacent but separated from each other, and there is a nanometer-scale gap between the two near-sinusoidal gold strips;

[0053] The cross-sectional profiles of the two near-sinusoidal gold bars are sinusoidal or quasi-sinusoidal.

[0054] Among them, the two near-sinusoidal gold strips in the double near-sinusoidal gold grating unit are denoted as the high-amplitude near-sinusoidal gold grating strip and the low-amplitude near-sinusoidal gold grating strip, respectively. The amplitude of the high-amplitude near-sinusoidal gold grating strip is greater than that of the low-amplitude near-sinusoidal gold grating strip, and the periods of the high-amplitude near-sinusoidal gold grating strip and the low-amplitude near-sinusoidal gold grating strip are the same.

[0055] In a preferred embodiment, refer to Figure 1 The period and amplitude of the high-amplitude near-sinusoidal gold grating strip are denoted as P1 and h1, respectively, where P1 = 250-1000nm and h1 = 125-500nm.

[0056] The period and amplitude of the low-amplitude near-sinusoidal gold grating strip are denoted as P2 and h2, respectively, where P2 = 250-1000nm, the height h2 = 75-300nm, and h2 < h1.

[0057] In a preferred embodiment, the thickness of both near-sinusoidal gold strips is d, where d = 75-300 nm.

[0058] In a preferred embodiment, the substrate is a silicon dioxide substrate, and the thickness of the hydrosilsesquioxane layer is 250-1000 nm.

[0059] Figure 1 and Figure 2 The structure used in the preferred embodiment is shown in the figure. SiO2 represents silicon dioxide substrate, PMMA represents optical adhesive layer (PMMA polymethyl methacrylate photoresist is used in the preferred embodiment), Au represents double near-sinusoidal gold grating periodic array structure, and HSQ represents hydrosilyl sesquioxane layer.

[0060] In this invention, under illumination by a light source, the surface of the double near-sinusoidal gold grating periodic array structure is excited to generate plasma polaritons, which convert light energy into heat energy, thereby producing a photothermal effect.

[0061] When linearly polarized excitation light is used as incident light, the surface of the double near-sinusoidal gold grating periodic array structure has a field enhancement effect on incident light with a specific polarization direction, providing enhanced fluorescence polarization detection.

[0062] When in use, the double near-sinusoidal gold grating microstructure covers the entire reaction area (such as the bottom or sidewall of a microfluidic PCR reaction chamber).

[0063] 1. In the dual near-sinusoidal gold grating periodic array structure of the present invention:

[0064] "Double" structure: This refers to a structure in which each smallest repeating unit contains two parallel, near-sinusoidal gold strips with similar waveforms but different amplitudes. These two strips are spatially separated, but the gap between them is much smaller than the optical diffraction limit, thus producing a strong near-field coupling effect in optics.

[0065] The dual near-sinusoidal gold grating unit comprises two parallel near-sinusoidal gold strips, both with sinusoidal or sinusoidal waveforms but different amplitudes.

[0066] These are respectively denoted as high-amplitude near-sinusoidal gold grating strips and low-amplitude near-sinusoidal gold grating strips.

[0067] "Near-sinusoidal" morphology: The cross-sectional profile of the gold strip is a smooth sine wave or a near-sinusoidal wave. Compared with a rectangular grating, this smooth morphology without sharp corners can effectively reduce discharge loss at the electric field tip, provide more uniform electromagnetic field enhancement, and is beneficial for manufacturing.

[0068] Periodic arrangement: Multiple such "double near-sinusoidal" units are repeatedly arranged on a two-dimensional plane at a fixed interval (i.e., grating period P1+P2) to form a macroscopic isofunctional region.

[0069] 2. Mechanism of the double near-sinusoidal gold grating periodic array structure:

[0070] A. Principle of photothermal conversion and heat cycle:

[0071] When a linearly polarized light-emitting diode (LED) beam illuminates the structure obliquely above the substrate, the light interacts with the gold grating, exciting surface plasmon polaritons. The "double near-sinusoidal" structure design, particularly the nanoscale gap between two adjacent strips (a high-amplitude near-sinusoidal gold grating strip and a low-amplitude near-sinusoidal gold grating strip in a double near-sinusoidal gold grating unit), constitutes a hotspot region, efficiently localizing and converting incident light energy into heat. Due to the high thermal conductivity and uniform structure of the gold film, the generated heat can be rapidly and uniformly transferred to the sample solution (PCR reaction system) covering it, achieving volumetric heating of the solution. By controlling the switching of the LED light source (pulse modulation), rapid heating and cooling of the sample solution can be achieved, completing the heating cycle. The low heat capacity and high photothermal conversion efficiency of this structure ensure an extremely high thermal cycling rate.

[0072] B. Fluorescence polarization detection enhancement principle:

[0073] In the fluorescence detection phase, linearly polarized excitation light (typically green light, with wavelengths near the plasmon resonance peak of the gold grating) irradiates the structure. This "double near-sinusoidal" structure exhibits a strong field enhancement effect for incident light with specific polarization directions. Simultaneously, the structure itself acts as a polarization-sensitive element, maintaining the polarization information of the emitted fluorescence. The fluorescence emitted by the excited fluorescent molecules contains information about molecular rotational dynamics in its polarization state. The detection system measures the parallel (I0) polarization of the emitted fluorescence. ∥ ) and vertical (I ⊥The fluorescence polarization degree is calculated based on the fluorescence intensity along the polarization direction of the excitation light. The plasmon structure in this invention significantly improves the signal-to-noise ratio and sensitivity of fluorescence polarization detection by enhancing the excitation field and potentially increasing fluorescence collection efficiency.

[0074] This invention also provides a method for fabricating the above-mentioned double near-sinusoidal gold grating microstructure. The main process is as follows: the grating shape of the double near-sinusoidal gold grating microstructure is formed on the substrate surface using micro-nano fabrication techniques (such as electron beam lithography, nanoimprinting, or laser interference lithography). Then, gold is deposited on the grating structure by means of vapor deposition to form a periodic array structure of double near-sinusoidal gold grating. Finally, HSQ (hydrosilyl sesquioxane) is deposited on the periodic array structure of double near-sinusoidal gold grating to form a hydrosilyl sesquioxane layer, thereby obtaining the double near-sinusoidal gold grating microstructure. This method prevents the physical adsorption of the PCR master mixture on the AuNIs surface and also promotes the strong bonding between the microstructure and the polydimethylsiloxane (PDMS) microfluidic chip.

[0075] In a preferred embodiment, the method specifically includes the following steps:

[0076] S1. Spin-coat photoresist onto a substrate, and then use electron beam lithography, nanoimprint lithography or laser interference lithography to process a template structure of a near-sinusoidal gold grating periodic array structure formed by photoresist.

[0077] The template structure is a photoresist layer, which has the same structural shape as the near-sinusoidal gold grating periodic array structure;

[0078] S2. A gold coating with a thickness of d is deposited on the surface of the photoresist grating using a vacuum thermal evaporation process. This gold coating forms a double near-sinusoidal gold grating microstructure.

[0079] S3. Hydrosiloxane resin is spin-coated onto a double near-sinusoidal gold grating microstructure to obtain a hydrosilicon silsesquioxane layer.

[0080] The present invention also provides an application of the above-mentioned near-sinusoidal gold grating microstructure in PCR.

[0081] In a preferred embodiment, the application method is as follows:

[0082] 1) Place the double near-sinusoidal gold grating microstructure in the PCR reaction solution. During the thermal cycling phase of PCR, irradiate the double near-sinusoidal gold grating microstructure with a light source and use the photothermal effect of the light source to heat the PCR reaction solution.

[0083] 2) In the fluorescence detection stage of PCR amplification products, linearly polarized excitation light is used to irradiate the double near-sinusoidal gold grating microstructure to collect fluorescence signals and realize the detection of PCR amplification products.

[0084] The above is the general concept of the present invention. Based on this, detailed embodiments and comparative examples are provided below to further illustrate the present invention.

[0085] Example 1

[0086] A dual near-sinusoidal gold grating microstructure that combines photothermal heating and fluorescence polarization detection enhancement functions comprises, from bottom to top, a substrate, an optical adhesive layer, a periodic array structure of dual near-sinusoidal gold gratings, and a hydrosilyl sesquioxane layer.

[0087] In this dual near-sinusoidal gold grating unit, the two near-sinusoidal gold strips are spatially adjacent but separated from each other, and there is a nanometer-level gap between the two near-sinusoidal gold strips (in this embodiment, the gap is 10nm); the cross-sectional profiles of the two near-sinusoidal gold strips are both sinusoidal waveforms.

[0088] The two near-sinusoidal gold strips in the double near-sinusoidal gold grating unit are denoted as the high-amplitude near-sinusoidal gold grating strip and the low-amplitude near-sinusoidal gold grating strip, respectively.

[0089] In this embodiment, the period and amplitude of the high-amplitude near-sinusoidal gold grating strip are denoted as P1 and h1, respectively, where P1 = 500nm and the height h1 = 250nm; the period and amplitude of the low-amplitude near-sinusoidal gold grating strip are denoted as P2 and h2, respectively, where P2 = 500nm and the height h2 = 150nm.

[0090] In this embodiment, the substrate is a silicon dioxide substrate, and the optical adhesive layer is made of PMMA (polymethyl methacrylate) photoresist. The thickness of the two near-sinusoidal gold strips (i.e., the thickness of the double near-sinusoidal gold grating periodic array structure) is d = 150 nm, and the thickness of the hydrosilyl silsesquioxane layer is 500 nm.

[0091] The fabrication method of the dual near-sinusoidal gold grating microstructure provided in this embodiment is as follows:

[0092] S1. Photoresist is spin-coated onto a silicon dioxide substrate, and then a template structure with a near-sinusoidal gold grating periodic array structure formed by photoresist is fabricated using an electron beam exposure process.

[0093] The template structure is a photoresist layer, which has the same structural shape as the near-sinusoidal gold grating periodic array structure;

[0094] S2. A gold coating with a thickness of 150 nm is deposited on the surface of the photoresist grating using a vacuum thermal evaporation process. This gold coating forms a double near-sinusoidal gold grating microstructure.

[0095] S3. A 500 nm thick hydrosiloxane resin is spin-coated onto a double near-sinusoidal gold grating microstructure to obtain a hydrosilicon sesquioxane layer.

[0096] Performance testing

[0097] 1. The fluorescence polarization detection enhancement performance of the dual near-sinusoidal gold grating microstructure using the structure of Example 1 was analyzed:

[0098] 1-1. Taking linearly polarized light as the incident light, Ez is defined as the polarization direction of the light parallel to the grating lines (z-direction) of the gold grating, and Ex is defined as the polarization direction of the light perpendicular to the grating lines (x-direction). The incident light is obliquely incident on the structure from above at θ = 30°. The incident light passes through the HSQ layer sequentially, illuminating the bottom gold grating and generating a thermal effect due to localized plasmon resonance. Simultaneously, the incident light can also be used as excitation light for fluorescent materials, with fluorescence collection occurring at a 30° diagonal angle. The absorption rate when Ex light is obliquely incident on the structure at 30° is as follows: Figure 3 As shown, it has a significantly wide high absorption rate in the range of 450-610 nm. Light in this wide wavelength range can generate surface plasmons (SPR) in the structure to produce a photothermal effect. This rapidly generated heat can be used to heat the sample to be tested.

[0099] 1-2. Furthermore, this structure is selective in its reflection of two types of polarized light; that is, the reflectivities of Ex and Ez light are significantly different. This characteristic enables the structure to perform polarization detection, greatly reducing the complexity of the instrument during detection. The reflectivities of Ex and Ey light are as follows: Figure 4 As shown, significant differences exist in the reflection spectra of these two polarized lights. For instance, near 580 nm, the reflectivity of the Ez light is significantly higher than that of the Ex light, making polarization detection possible in this wavelength range. To more intuitively compare the reflection differences between the two polarized lights, the degree of polarization P was calculated. The degree of polarization is extremely high near 580 nm, exceeding 0.9. Figure 5 As shown, the formula for calculating the degree of polarization is as follows:

[0100] P = (R) Ez -R Ex ) / (R Ez +R Ex )

[0101] Where P represents the degree of polarization, R Ez R represents the reflectivity of Ez light. Ex This represents the reflectivity of the Ex light.

[0102] Analysis of Ex light and Ez light shows that when the designed structure is irradiated with Ex light at a 30° angle, heating and polarization detection functions can be achieved. When the excitation light and fluorescence bands of the fluorescent material used to detect the sample are close to 550nm and 580nm respectively, the use of polarizers and other components in the detection instrument will be greatly reduced, which is beneficial to the miniaturization of the detection equipment.

[0103] 2. The photothermal performance of the double near-sinusoidal gold grating microstructure was analyzed using the structure of Example 1:

[0104] When the Ex light is incident on the structure at a 30° angle, it illuminates the underlying gold grating and induces a localized plasmon thermal effect. The total power density distribution is as follows: Figure 6 As shown, there is a significant photothermal effect on the upper layer of the gold grating, and the distribution is relatively uniform. The heat generated can be uniformly and quickly conducted to the sample under test.

[0105] Figure: Total power consumption density distribution

[0106] Example 2

[0107] The application of the near-sinusoidal gold grating microstructure in PCR in Example 1 is as follows:

[0108] The double near-sinusoidal gold grating microstructure was placed in the PCR reaction solution, and the double near-sinusoidal gold grating microstructure covered the entire PCR reaction area.

[0109] Thermal cycling stage: High-power LEDs are turned on as a light source to illuminate the dual near-sinusoidal gold grating microstructure. The structure absorbs light energy and instantly converts it into heat energy, causing the PCR reaction solution to rise to the denaturation temperature within tens of seconds.

[0110] Annealing / Extension Stage: The LED light source is turned off, and the temperature is rapidly reduced to the annealing / extension temperature through microfluidic passive heat dissipation or active cooling.

[0111] Detection phase: During the annealing / extension temperature plateau of each cycle, a low-power, linearly polarized detection LED is turned on as a light source. The light source illuminates the dual near-sinusoidal gold grating microstructure in the same area, exciting the fluorescently labeled probe that has bound the target DNA.

[0112] Signal acquisition and processing: The fluorescence detector simultaneously acquires fluorescence intensity in both parallel and perpendicular directions and calculates the degree of polarization (P-value or mP-value). As PCR amplification proceeds, the proportion of fluorescent probes bound to macromolecules increases, leading to an increase in fluorescence polarization, thereby enabling real-time and quantitative detection.

[0113] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. A dual near-sinusoidal gold grating microstructure with both photothermal heating and fluorescence polarization detection enhancement functions, characterized in that, The invention includes a substrate and a periodic array structure of double near-sinusoidal gold gratings arranged on the substrate. The smallest repeating unit of the periodic array structure of double near-sinusoidal gold gratings is a double near-sinusoidal gold grating unit. The double near-sinusoidal gold grating unit includes two parallel near-sinusoidal gold strips, both of which have sinusoidal or quasi-sinusoidal waveforms but different amplitudes.

2. The dual-nearly-sinusoidal gold grating microstructure of claim 1, wherein, The two near-sinusoidal gold strips in the dual near-sinusoidal gold grating unit are spatially adjacent but separated from each other, with a nanometer-scale gap between the two near-sinusoidal gold strips; The cross-sectional profiles of the two near-sinusoidal gold bars are sinusoidal or quasi-sinusoidal.

3. The bi- close-to-sine gold grating microstructure according to claim 2, characterized in that, The two near-sinusoidal gold strips in the dual near-sinusoidal gold grating unit are denoted as the high-amplitude near-sinusoidal gold grating strip and the low-amplitude near-sinusoidal gold grating strip, respectively. The amplitude of the high-amplitude near-sinusoidal gold grating strip is greater than that of the low-amplitude near-sinusoidal gold grating strip, and the periods of the high-amplitude near-sinusoidal gold grating strip and the low-amplitude near-sinusoidal gold grating strip are the same.

4. The bi- close-to-sine gold grating microstructure according to claim 3, characterized in that, The period and amplitude of the high-amplitude near-sinusoidal gold grating strip are denoted as P1 and h1, respectively, where P1 = 250-1000nm and h1 = 125-500nm; The period and amplitude of the low-amplitude near-sinusoidal gold grating strip are denoted as P2 and h2, respectively, where P2 = 250-1000nm, the height h2 = 75-300nm, and h2 < h1.

5. The bi- close-to-sine gold grating microstructure according to claim 4, characterized in that, The period and amplitude of the high-amplitude near-sinusoidal gold grating strip are denoted as P1 and h1, respectively, where P1 = 500 nm and the height h1 = 250 nm. The period and amplitude of the low-amplitude near-sinusoidal gold grating strip are denoted as P2 and h2, respectively, where P2 = 500 nm and the height h2 = 150 nm.

6. The dual-near-sinusoidal gold grating microstructure of claim 1, wherein, The thickness of both near-sinusoidal gold strips is d, where d = 75-300 nm.

7. The bi- close-to-sine gold grating microstructure according to claim 6, characterized in that, From bottom to top, it consists of a substrate, an optical adhesive layer, a double near-sinusoidal gold grating periodic array structure, and a hydrogen-silsesquioxane layer.

8. The bi- close-to-sine gold grating microstructure according to claim 7, characterized in that, The substrate is a silicon dioxide substrate, and the thickness of the hydrosilsesquioxane layer is 250-1000 nm.

9. The dual-eosin-gold grating microstructure of claim 8, wherein, in, d = 150 nm, and the thickness of the hydrosilyl sesquioxane layer is 500 nm.

10. The dual-near-sinusoidal gold grating microstructure of claim 1, wherein, Under illumination, the surface of the double near-sinusoidal gold grating periodic array structure is excited to generate plasma polaritons, which convert light energy into heat energy, thereby producing a photothermal effect. When linearly polarized excitation light is used as incident light, the surface of the double near-sinusoidal gold grating periodic array structure has a field enhancement effect on incident light with a specific polarization direction, providing enhanced fluorescence polarization detection.

11. A method of producing a bi- close-to-sine gold grating microstructure according to any one of claims 1 to 10, characterized by, Includes the following steps: S1. Spin-coat photoresist onto a substrate, and then use electron beam lithography, nanoimprint lithography or laser interference lithography to process a template structure of a near-sinusoidal gold grating periodic array structure formed by photoresist. The template structure is a photoresist layer, which has the same structural shape as the near-sinusoidal gold grating periodic array structure; S2. A gold plating layer with a thickness of d is deposited on the surface of the photoresist grating using a vacuum thermal evaporation process. This gold plating layer forms the double near-sinusoidal gold grating microstructure. S3. Hydrosiloxane resin is spin-coated onto a double near-sinusoidal gold grating microstructure to obtain a hydrosilicon silsesquioxane layer.

12. The use of the double near-sine gold grating microstructure according to any one of claims 1-10 in PCR.

13. Use according to claim 12, characterized in that, The application method is: 1) The double near-sine gold grating microstructure is placed in the PCR reaction solution, and in the thermal cycling stage of PCR, the double near-sine gold grating microstructure is irradiated by a light source, and the photothermal effect of the light source irradiating the double near-sine gold grating microstructure is used to heat the PCR reaction solution; 2) In the fluorescence detection stage of the PCR amplification product, linearly polarized excitation light is used to irradiate the double near-sine gold grating microstructure, the fluorescence signal is collected, and the detection of the PCR amplification product is realized.

Images