SERS substrate preparation method and SERS substrate structure

Abstract

The invention relates to the technical field of SERS (Surface Enhanced Raman Scattering) substrates, in particular to an SERS substrate preparation method and an SERS substrate structure, and the method comprises the following steps: performing reactive ion etching on a substrate with the surface coated with a single-layer microsphere array through two reaction gases; wherein one gas is used for carrying out physical bombardment on the single-layer microsphere array, and the other gas is used for carrying out chemical etching on the single-layer microsphere array; an arrayed protruding structure is formed on the substrate, a plurality of pointed protrusions are formed on the surface of the protruding structure, and the adjacent pointed protrusions are arranged at intervals. According to the technical scheme, in the detection process, the to-be-detected solution is dropwise added to the SERS substrate, in the drying process of the to-be-detected solution, due to the effect of capillary force, the to-be-detected solution between the protruding structures can be finally gathered between the sharp protrusions, the sharp protrusions play the enrichment effect, namely, the sharp protrusions provide rich electromagnetic enhancement hot spots, and in the detection process, the detection accuracy is greatly improved. Raman signals of molecules can be amplified in a high-magnification mode, and then simple and efficient SERS detection is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of SERS substrates, and in particular to a SERS substrate preparation method and a SERS substrate structure. Background Art

[0002] Molecular detection technology based on precious metal surface enhanced Raman scattering (SERS) has the advantages of rapidity, high sensitivity, non-destructiveness and fingerprint recognition, and has important application prospects in food safety, drug inspection, chemical safety, life sciences and medicine. The key to high-performance SERS detection is to design and construct precious metal micro-nanostructure substrates rich in physical electromagnetic enhancement "hot spots" and to enrich the target molecules in the test liquid in the "hot spot" area as much as possible. However, SERS detection substrates and detection methods that have both high sensitivity and enrichment effects usually have a certain degree of complexity.

[0003] For example, "A SERS substrate based on metal lattice, a preparation method thereof, and a method for Raman detection using the substrate" (patent number: 201610599623.4) uses processes such as evaporation, coating, etching, hydrophobicity and protection treatment to obtain a precious metal lattice with hydrophobic surroundings. When used for SERS detection, a precious metal nanoparticle sol mixed with the target molecule to be detected is dripped onto the surface of the substrate. Due to the hydrophobic properties of the substrate, the nanoparticle sol tends to gather around the lattice, thereby generating a "hot spot" to achieve SERS detection of the target molecule.

[0004] Although the above-mentioned SERS substrate has the effect of generating "hot spots", the structure and preparation process of the SERS substrate are complex and costly. In addition, the precious metal lattice on the surface of the substrate itself has low SERS activity and requires the help of external precious metal nanoparticles to dynamically form active areas. The detection process is complicated and the signal stability is low. Summary of the invention

[0005] In order to solve at least the above technical problems existing in the prior art, the present invention provides a SERS substrate preparation method and a SERS substrate structure.

[0006] On one hand, the present invention provides a method for preparing a SERS substrate, the method comprising: performing reactive ion etching on a substrate having a single-layer microsphere array on its surface by using two reaction gases; wherein one gas physically bombards the single-layer microsphere array, and the other gas chemically etches the single-layer microsphere array; forming an array of protrusion structures on the substrate, and forming a plurality of pointed protrusions on the surface of the protrusion structure, wherein adjacent pointed protrusions are arranged at intervals.

[0007] In some embodiments, the method further comprises: self-assembling the microsphere suspension into a single-layer close-packed array on the surface of the substrate using a gas-liquid interface self-assembly method, thereby obtaining a substrate having a single-layer microsphere array on the surface.

[0008] In some embodiments, the method further comprises: using a magnetron sputtering process to sputter a gold film or a silver film on the surface of the substrate after reactive ion etching.

[0009] In some embodiments, the microspheres in the microsphere suspension are made of one or more of polystyrene, cross-linked polystyrene / polydivinylbenzene, polymethacrylate or silicon dioxide.

[0010] In some embodiments, the outer diameter of the microspheres in the microsphere suspension is 200 nm to 2000 nm.

[0011] In some embodiments, the reaction gas is argon and oxygen, wherein the argon is used for physical bombardment and the oxygen is used for chemical etching; or the reaction gas is argon and sulfur hexafluoride gas, wherein the argon is used for physical bombardment and the sulfur hexafluoride gas is used for chemical etching.

[0012] In some embodiments, the gas flow ratio of the two reaction gases is 1:1 to 3:1, and the total flow does not exceed 80 standard cubic centimeters per minute; the working pressure is 1 Pa to 5 Pa, the etching power is 50 W to 300 W, and the etching time is 10 seconds to 120 seconds.

[0013] In some embodiments, in the magnetron sputtering process, the vacuum degree is 1 Pa to 10 Pa, the sputtering current is 10 mA to 50 mA, and the sputtering time is 30 seconds to 300 seconds; the thickness of the gold film or the silver film is 5 nm to 50 nm.

[0014] On the other hand, the present invention also provides a SERS substrate structure, including a substrate and a protrusion structure; the surface of the substrate includes a plurality of the protrusion structures, and the plurality of the protrusion structures are arranged in an array; the surface of the protrusion structure includes a plurality of pointed protrusions, and adjacent pointed protrusions are arranged at intervals.

[0015] In some embodiments, the size of the protrusion structure is 150 nanometers to 1500 nanometers, and the interval between adjacent protrusion structures is 10 nanometers to 500 nanometers.

[0016] The present invention provides a SERS substrate preparation method and a SERS substrate structure, wherein the substrate comprises a convex structure arranged in an array, and pointed protrusions are arranged on the surface of the convex structure; during a detection process, a test solution is dripped onto the SERS substrate, and during the drying process of the test solution, due to the action of capillary force, the test solution between the convex structures will eventually converge between the pointed protrusions, and the pointed protrusions play an enrichment role, that is, the pointed protrusions provide abundant electromagnetic enhancement hotspots, and during the detection process, the Raman signal of the molecule can be highly amplified, thereby realizing simple and efficient SERS detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood by reading the detailed description below with reference to the accompanying drawings. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, in which:

[0018] In the drawings, the same or corresponding reference numerals represent the same or corresponding parts.

[0019] Figure 1 A flowchart of a method for preparing a SERS substrate provided in an embodiment of the present invention;

[0020] Figure 2 An electron microscope image of a SERS substrate structure provided by an embodiment of the present invention;

[0021] Figure 3 for Figure 2 A partial enlarged view of

[0022] Figure 4 A schematic diagram of a SERS characteristic spectrum of a SERS substrate structure provided in an embodiment of the present invention;

[0023] Figure 5 This is a trace detection diagram of the SERS substrate structure provided in an embodiment of the present invention.

[0024] In the figure:

[0025] 1: substrate; 2: raised structure; 3: pointed protrusion. DETAILED DESCRIPTION

[0026] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0027] like Figure 1As shown, an embodiment of the present invention provides a method for preparing a SERS substrate, the method comprising the following steps:

[0028] Step S10: The microsphere suspension is self-assembled into a single-layer close-packed array on the surface of the substrate by using a gas-liquid interface self-assembly method, thereby obtaining a substrate with a single-layer microsphere array on the surface.

[0029] In the embodiment of the present invention, the microspheres in the microsphere suspension are made of one or more of polystyrene, cross-linked polystyrene / polydivinylbenzene, polymethacrylate or silicon dioxide. For example, the microspheres are made of polymer microspheres of polystyrene, cross-linked polystyrene / polydivinylbenzene, polymethacrylate, or inorganic microspheres of silicon dioxide.

[0030] For example, the outer diameter of the microspheres in the microsphere suspension is 200 nm to 2000 nm.

[0031] In the microsphere suspension, the suspension can be deionized water, ethanol, n-butanol, acetone, and a water / ethanol mixture, etc. For example, the suspension is a mixture of water and ethanol, wherein the mass ratio of water to ethanol in the mixture is 0.5:1 to 1:2; or for example, the suspension is a mixture of water and acetone, wherein the mass ratio of water to acetone in the mixture is 0.2:1 to 1:2.

[0032] In step S10, the microsphere suspension is self-assembled into a single-layer close-packed array on the surface of a substrate using a gas-liquid interface self-assembly method, wherein the substrate can be a silicon wafer or a polymer substrate, and the material used for the substrate needs to be complementary to the material of the microspheres. For example, when the microsphere material includes a polymer material such as polystyrene, cross-linked polystyrene / polydivinylbenzene, polymethacrylate, etc., the substrate can be a silicon wafer, and when the microsphere material is an inorganic material such as silicon dioxide, the substrate can be a polymer substrate.

[0033] Step S20: performing reactive ion etching on a substrate having a single-layer microsphere array on its surface by using two reaction gases; wherein one gas physically bombards the single-layer microsphere array, and the other gas chemically etches the single-layer microsphere array; forming a protrusion structure of the array on the substrate, and forming a plurality of pointed protrusions on the surface of the protrusion structure, with adjacent pointed protrusions spaced apart.

[0034] After reactive ion etching of a substrate covered with a single-layer microsphere array, an array-arranged protrusion structure is formed on the substrate, and a plurality of spaced pointed protrusions are formed on the surface of the protrusion structure, so that a multi-gap structure is formed on the surface of the protrusion structure, which tends to be a hollow structure.

[0035] Wherein, a plurality of protrusion structures are arranged in an array, and a plurality of pointed protrusions on the surface of the protrusion structure have different heights and different intervals, so that an irregular pointed protrusion structure can be formed on the surface of the protrusion structure.

[0036] By utilizing the sharp protrusions and the spaces between the sharp protrusions, the solution to be tested can be enriched, thereby forming hot spots during detection, thereby achieving more efficient SERS detection.

[0037] In the reactive ion etching operation step, different reactive gases are selected according to the material of the substrate with the single-layer microsphere array on the surface. For example, the reactive gases include argon and oxygen or argon and sulfur hexafluoride.

[0038] For example, for polymer microspheres of polystyrene (PS), cross-linked polystyrene / polydivinylbenzene (PS / DVB), and polymethacrylate (PMMA), the reaction gases are argon (Ar) and oxygen (O2), among which the action mechanism of argon is physical bombardment, and the action mechanism of oxygen is chemical etching; for inorganic microspheres of silicon dioxide (SiO2), argon (Ar) and sulfur hexafluoride gas (SF6) are selected, among which the action mechanism of argon is physical bombardment, and the action mechanism of sulfur hexafluoride gas is chemical etching.

[0039] For example, in the reactive ion etching operation steps, the gas flow ratio of the two reaction gases is 1:1 to 3:1, and the total flow does not exceed 80 standard cubic centimeters per minute; the working pressure is 1 Pa to 5 Pa, the etching power is 50 W to 300 W, and the etching time is 10 seconds to 120 seconds.

[0040] Step S30: using a magnetron sputtering process to sputter a gold film or a silver film on the surface of the substrate after reactive ion etching.

[0041] After the reactive ion etching step, a protrusion structure array is formed on the substrate, and the surface of the protrusion structure has pointed protrusions, and a gold film or a silver film is sputtered on the part of the structure. For example, the thickness of the sputtered gold film or the silver film is 5 nanometers to 50 nanometers.

[0042] For example, in an embodiment of the present invention, in the magnetron sputtering process, the vacuum degree is 1 Pa to 10 Pa, the sputtering current is 10 mA to 50 mA, and the sputtering time is 30 seconds to 300 seconds.

[0043] The embodiment of the present invention provides a SERS substrate structure, including a substrate and a protrusion structure. The substrate and the protrusion structure are based on Figure 1 The SERS substrate preparation method shown is prepared and formed, and sharp protrusions are formed on the surface of the protrusion structure, and the sharp protrusions are used to self-enrich the solution to be tested.

[0044] In conjunction with the accompanying drawings, various structures in the SERS substrate structure provided by the embodiments of the present invention, as well as the positional relationship and connection relationship between the various structures are described in detail below.

[0045] refer to Figure 2and Figure 3 As shown, the surface of the substrate 1 includes a plurality of protrusion structures 2, and the plurality of protrusion structures 2 are arranged in an array; the surface of the protrusion structure 2 includes a plurality of pointed protrusions 3, and adjacent pointed protrusions 3 are arranged at intervals.

[0046] When the SERS substrate is used, the test solution is dropped on the substrate 1. During the drying process of the test solution, due to the action of capillary force, the test solution between the protrusion structures 2 will eventually converge between the pointed protrusions 3 of each protrusion structure 2, playing a role of self-enrichment, thereby facilitating the trace detection of target molecules.

[0047] In the embodiment of the present invention, the size of the protrusion structure 2 is 150 nanometers to 1500 nanometers, and the interval between adjacent protrusion structures 2 is 10 nanometers to 500 nanometers.

[0048] For example, the outer diameter of the microspheres in the microsphere suspension is 200 nanometers, the size of the protrusion structure 2 that can be prepared in the reactive ion etching step is 150 nanometers to 190 nanometers, and the gap between adjacent protrusion structures 2 is 10 nanometers to 50 nanometers; or, for example, the outer diameter of the microspheres in the microsphere suspension is 500 nanometers, the size of the protrusion structure 2 that can be prepared in the reactive ion etching step is 400 nanometers to 490 nanometers, and the gap between adjacent protrusion structures 2 is 10 nanometers to 100 nanometers; or, for example, the outer diameter of the microspheres in the microsphere suspension is 1000 nanometers, the size of the protrusion structure 2 that can be prepared in the reactive ion etching step is 700 nanometers to 950 nanometers, and the gap between adjacent protrusion structures 2 is 50 nanometers to 300 nanometers.

[0049] The following takes the detection of synthetic cannabinoid drugs as an example to further illustrate the SERS substrate structure provided in the embodiments of the present invention.

[0050] A polystyrene microsphere suspension with a microsphere size of 120 nanometers was used to prepare a high-quality wafer-sized single-layer close-packed array through gas-liquid interface self-assembly, and a SERS detection substrate with ultra-sensitive detection performance for synthetic cannabinoid drug molecules and metabolites was constructed through reactive ion etching and sputtering deposition processes. The specific SERS detection substrate molding process can refer to the SERS substrate preparation method shown in the figure.

[0051] A SERS characteristic spectrum database is established for a variety of synthetic cannabinoid target drugs, and each synthetic cannabinoid target drug includes a corresponding SERS characteristic spectrum, such as Figure 4 Shown is one of the SERS characteristic spectra.

[0052] The synthetic cannabinoids on the SERS substrate were detected by Raman detection, and the detection limit reached 50 nanograms. Figure 5As shown in the reference figure, the characteristic peaks of the sample spectrum overlap / basically overlap with those of the characteristic spectrum, and the matching degree between the sample spectrum and the characteristic spectrum is 95.44%. The matching degree between the two is high. Therefore, based on this test result, it can be determined that the target drug is contained in the tested solution.

[0053] The Raman detector uses the SERS substrate structure provided by the embodiment of the present invention, and the detection accuracy and efficiency of the SERS substrate structure are higher.

[0054] The present invention provides a SERS substrate preparation method and a SERS substrate structure, wherein the substrate comprises protrusion structures 2 arranged in an array, and pointed protrusions 3 are arranged on the surface of the protrusion structures 2; during the detection process, a test solution is dripped onto the SERS substrate, and during the drying process of the test solution, due to the action of capillary force, the test solution between the protrusion structures 2 will eventually converge between the pointed protrusions 3, and the pointed protrusions 3 play an enrichment role, that is, the pointed protrusions provide abundant electromagnetic enhancement hotspots, and during the detection process, the Raman signal of the molecule can be highly amplified, thereby realizing simple and efficient SERS detection.

[0055] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0056] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0057] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a SERS substrate, characterized in that: The method comprises: Reactive ion etching is performed on a substrate having a single-layer microsphere array on its surface by using two reactive gases; wherein one gas physically bombards the single-layer microsphere array and the other gas chemically etches the single-layer microsphere array; An array of protrusion structures is formed on the substrate, and a plurality of pointed protrusions are formed on the surface of the protrusion structure, with adjacent pointed protrusions being arranged at intervals.

2. The method for preparing a SERS substrate according to claim 1, characterized in that: The method further comprises: The microsphere suspension is self-assembled into a single-layer close-packed array on the surface of the substrate by using a gas-liquid interface self-assembly method, thereby obtaining a substrate with a single-layer microsphere array on the surface.

3. The method for preparing a SERS substrate according to claim 2, characterized in that: The method further comprises: A magnetron sputtering process is adopted to sputter a gold film or a silver film on the surface of the substrate after reactive ion etching.

4. The method for preparing a SERS substrate according to claim 2, characterized in that: The microspheres in the microsphere suspension are made of one or more of polystyrene, cross-linked polystyrene / polydivinylbenzene, polymethacrylate or silicon dioxide.

5. The method for preparing a SERS substrate according to claim 4, characterized in that: The outer diameter of the microspheres in the microsphere suspension is 200 nanometers to 2000 nanometers.

6. The method for preparing a SERS substrate according to claim 4, characterized in that: The reaction gas is argon and oxygen, wherein the argon is used for physical bombardment and the oxygen is used for chemical etching; or The reaction gases are argon gas and sulfur hexafluoride gas, wherein the argon gas is used for physical bombardment, and the sulfur hexafluoride gas is used for chemical etching.

7. The method for preparing a SERS substrate according to claim 6, characterized in that: The gas flow ratio of the two reaction gases is 1:1 to 3:1, and the total flow does not exceed 80 standard cubic centimeters per minute; the working pressure is 1 Pa to 5 Pa, the etching power is 50 W to 300 W, and the etching time is 10 seconds to 120 seconds.

8. The method for preparing a SERS substrate according to claim 3, characterized in that: In the magnetron sputtering process, the vacuum degree is 1 Pa to 10 Pa, the sputtering current is 10 mA to 50 mA, and the sputtering time is 30 seconds to 300 seconds; The thickness of the gold film or silver film is 5 nanometers to 50 nanometers.

9. A SERS substrate structure, characterized in that: It comprises a substrate (1) and a protruding structure (2); The surface of the substrate (1) comprises a plurality of protruding structures (2), and the plurality of protruding structures (2) are arranged in an array; The surface of the protrusion structure (2) comprises a plurality of pointed protrusions (3), and adjacent pointed protrusions (3) are arranged at intervals.

10. The SERS substrate structure according to claim 9, characterized in that: The size of the protruding structures (2) is 150 nanometers to 1500 nanometers, and the interval between adjacent protruding structures (2) is 10 nanometers to 500 nanometers.

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