An invertible chiral hollow nanotruncated cone array film, preparation method and application thereof

Abstract

An invertible chiral hollow nano-truncated cone array film, a preparation method and its application belong to the technical field of label-free identification of chiral molecules. The method relates to a colloidal microsphere interface assembly method, a mask etching method and a grazing angle deposition method. The present invention has a simple operation process, low cost and high controllability. The chiral signal of the structure can be adjusted by adjusting the morphology of the structure, and a chiral hollow nano-truncated cone array film can be prepared on a large scale. In addition, the prepared chiral array film can obtain an inverted chiral material with a strong chiral response through a simple flipping operation. Based on the unique three-dimensional cavity, the chiral hollow nano-truncated cone array film can enhance the chiral near field in a confined manner, and is used in the field of chiral sensing to achieve label-free differentiation and identification of chiral cysteine ​​molecules. The present invention provides a simple and large-area method for the preparation of chiral micro-nano structures, and provides an effective and convenient idea for label-free differentiation and identification detection of chiral molecules.

Description

Technical Field

[0001] The invention belongs to the technical field of label-free identification of chiral molecules, and specifically relates to an invertible chiral hollow nano frustum array film, a preparation method and application thereof in label-free identification of chiral molecules. Background Art

[0002] Chirality is a common phenomenon in nature, which means that a substance can be completely symmetrical with its mirror image structure but cannot completely overlap with it. [1,2] . Chirality research has important scientific significance and application value for the development of many fields such as chemistry, life sciences, materials science, optics, and pharmacy. Artificial chiral materials have great application prospects in the fields of chiral catalysis, advanced optical devices, etc. due to their strong circular dichroism and optical dispersion. [3,4] .

[0003] With the advancement of micro-nano preparation technology, the field of chiral materials has developed rapidly in recent years. Some traditional preparation methods, such as electron beam etching, focused ion beam etching, nanoprinting and other technologies, are the main methods for preparing chiral materials. [5-7] However, the preparation cost is high and the preparation area is limited, which limits its practical application. In order to better transform it into practical devices, it is necessary to develop low-cost and efficient technologies to prepare artificial chiral materials. In addition, the identification of chiral molecules usually requires the modification of other biological molecules, and the application of artificial chiral materials in label-free chiral recognition is still rare. [8,9] , which needs further exploration and development. Therefore, it is very meaningful to propose a low-cost method for large-scale preparation of invertible chiral materials and apply the material to the field of label-free chiral molecular sensing.

[0004] [1] Hentschel M.; M.; Duan XY; Giessen H.; Liu N.,Sci.Adv2017,3,1-12.

[0005] [2]Kuzyk A.; Schreiber R.; Fan Z.; Pardatscher G.; Roller EM; Hogele A.; Simmel FC; Govorov AO; Liedl T.,Nature 2012,483,311-314.

[0006] [3]Valev VK; Baumberg JJ; Sibilia C.; Verbiest T., Adv.Mater 2013, 25, 2517–2534.

[0007] [4]Chen JQ; Gao XS; Zheng Q.; Liu JB; Meng DJ; Li HY; Cai R.; FanH.Z.; Ji YL; Wu

[0008] [5] Liu ZG; Xu Y.; Ji CY; Chen SS; Li XP; Zhang XD; Yao YG; Li.JF, Adv. Mater 2020, 32, 1907077.

[0009] [6]Kim D.;Yu JY;Hwang I.;Park S.;Demmerle F.;Boehm G.;Amann MC;Belkin MA;Lee J.,Nano.Lett 2020,20,8032-8039.

[0010] [7]Rodrigues SP;Cui Y.;Lan S.;Kang L.;Cai W.,Adv.Mater 2015,27,1124-1130.

[0011] [8]Liu YR; Wu ZL; Kollipara PS; Montellano R.; Sharma K.; ZhengY.B., ACS.Nano 2021,15,6448-6456.

[0012] [9]Qu Y.; Bai Y.; Aba T.; Ullah H.; Abudukelimu A.; Huang JB; Gou T.; LiJ.; Zhang ZY,J.Phys.Chem.C 2020,124,13912-13919. Summary of the invention

[0013] The purpose of the present invention is to provide a method for preparing an inverted chiral hollow nano-truncated cone array film at low cost and on a large scale, and to apply the chiral material to label-free identification of chiral molecules. In addition, the chiral array film prepared by the method can obtain an inverted chiral material with a strong chiral response through a simple flipping operation.

[0014] This method involves a colloidal microsphere interface assembly method, a mask etching method, and a grazing angle deposition method. The whole process is simple to operate, low-cost, and highly controllable, and can prepare chiral hollow nano-truncated cone array films on a large scale. The chiral signal can be adjusted by adjusting the morphology of the structure. Based on the unique three-dimensional cavity, the chiral hollow nano-truncated cone array film can enhance the chiral near field in a confined area, which can be used in the field of chiral sensing to achieve label-free differentiation and recognition of chiral cysteine ​​molecules. In addition, through a simple flipping operation, an inverted chiral material can be prepared, which also has a strong chiral response.

[0015] The method for preparing an invertible chiral hollow nano-truncated cone array film of the present invention comprises the following steps:

[0016] 1) Spin coating a layer of forward photoresist stock solution on a hydrophilic treated substrate at a rotation speed of 1000-4000 rpm, and then placing the substrate at 80-120° C. for 1-3 hours to obtain a photoresist film with a cured thickness of 0.4-2 μm;

[0017] 2) slowly dropping a hydrophobic polystyrene microsphere deionized water ethanol dispersion onto the surface of deionized water to obtain a monolayer of polystyrene microspheres at the air-liquid interface, then dropping an anionic surfactant to obtain a monolayer of hexagonally closely arranged polystyrene microspheres at the air-liquid interface, and then transferring the monolayer onto the substrate having the photoresist film cured thereon obtained in step 1);

[0018] 3) The sample obtained in step 2) is subjected to reactive plasma etching, and the photoresist film is etched to form an array of nano-truncated cones due to the masking effect of the hydrophobic polystyrene microspheres. As the etching proceeds, the polystyrene microspheres gradually become smaller, and the etching is stopped before the microspheres completely disappear; then the obtained sample is immersed in 5-25 mL of toluene solution and ultrasonicated for 20-60 seconds to remove the residual polystyrene microspheres in the upper layer, thereby obtaining a nano-truncated cone photoresist array on the substrate;

[0019] 4) a silver film with a thickness of 15 to 80 nm is deposited on the sample prepared in step 3) by oblique thermal deposition, and the incident angle (i.e., the angle between the oblique thermal deposition direction and the substrate normal) is 15° to 40°; then the substrate with the silver film is rotated clockwise or counterclockwise by 0° to 180° (excluding 0° and 180°) along an axis perpendicular to the substrate surface, and then a gold film with a thickness of 15 to 80 nm is thermally deposited at the same incident angle as the above-described silver film deposition; the gold and silver will partially overlap, and the overlapping areas will be different when rotated at different angles;

[0020] 5) Soaking the substrate prepared in step 4) in anhydrous ethanol for 5 to 30 minutes to remove the photoresist covered by the metal film, rinsing and drying naturally, and obtaining a right-handed or left-handed chiral hollow nano-truncated cone array film on the substrate;

[0021] 6) Invert the sample obtained in step 4) on another hydrophilic glass substrate, fix the relative position relationship between the two, slowly add anhydrous ethanol until the sample is submerged, and the immersion time is 5 to 30 minutes. After the photoresist film on the previous substrate is dissolved, remove the remaining ethanol, so that the obtained film structure slowly and evenly falls on the other hydrophilic substrate, and after natural drying, slowly rinse with anhydrous ethanol for 3 to 5 times, thereby obtaining an inverted right-handed or left-handed chiral hollow nano-cone array film on the other hydrophilic substrate.

[0022] Further,

[0023] The substrate in step 1) is a glass sheet or a quartz sheet.

[0024] In step 2), the diameter of the polystyrene microspheres is 0.3 to 3 μm.

[0025] In step 2), the deionized water ethanol dispersion of hydrophobic polystyrene microspheres is prepared by adding 1 to 3 mL of deionized water to a deionized water dispersion of polystyrene microspheres having a concentration of 1 to 20 wt% and a diameter of 0.3 to 3 μm, ultrasonically treating for 10 to 20 minutes, and then centrifuging at 6000 to 11000 rpm for 10 to 30 minutes; adding 1 to 3 mL of deionized water to the polystyrene microsphere precipitate obtained after centrifugation, ultrasonically treating for 10 to 20 minutes, and then centrifuging at 6000 to 11000 rpm for 10 to 30 minutes; repeating the above steps of adding deionized water, ultrasonically treating for 10 to 20 minutes, and then centrifuging at 6000 to 11000 rpm for 10 to 30 minutes to the polystyrene microsphere precipitate obtained after centrifugation; and centrifugation process 4 to 12 times; adding 1 to 5 mL of a mixture of ethanol and deionized water in a volume ratio of 1:1 to the polystyrene microsphere precipitate obtained by centrifugation, ultrasonicating for 10 to 20 minutes, and then centrifuging at a speed of 6000 to 11000 rpm for 10 to 30 minutes; repeating the process of adding a mixture of ethanol and deionized water to the polystyrene microsphere precipitate obtained by centrifugation, ultrasonicating and centrifuging 4 to 12 times; and adding 1 to 5 mL of a mixture of ethanol and deionized water in a volume ratio of 1:1 to the polystyrene microsphere precipitate obtained by the last centrifugation, ultrasonicating for 10-60 minutes, thereby obtaining a deionized water ethanol dispersion of hydrophobic polystyrene microspheres.

[0026] The conditions of reactive plasma etching in step 3) are: etching temperature 20-30° C., oxygen flow rate 10-60 sccm, etching pressure 3-10 mTorr, etching power 100-300 W, and etching time 100-300 seconds.

[0027] The vacuum degree of both thermal depositions in step 4) is 5×10 -4 ~2×10 -4 Pa, the deposition rate is

[0028] The inverted chiral hollow nano-truncated cone array film in step 6) maintains the morphology of the original structure and has a strong chiral response.

[0029] Each step of the present invention is simple to operate, and the prepared inverted chiral hollow nano-truncated cone array film has the characteristics of large area and strong chiral response. Based on the unique three-dimensional resonant cavity of the material, the chiral near-field can be enhanced in a confined manner to achieve label-free differentiation and identification of chiral cysteine ​​molecules. In addition, through a simple flipping operation, an inverted chiral material can be prepared, which also has a strong chiral response. The inverted chiral hollow nano-truncated cone array film prepared by the present invention provides a simple and large-area method for the preparation of chiral micro-nano structures, and provides an effective and convenient idea for label-free differentiation and identification detection of chiral molecules. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the process of preparing an inverted chiral hollow nano-truncated cone array film; wherein the angle between the oblique deposition direction and the substrate normal is 30°, that is, the incident angle θ=30°; when the silver film is obliquely deposited, the photoresist truncated cone array has a 180° range covered by silver, and when the gold film is obliquely deposited after rotating 90° clockwise or counterclockwise, the photoresist truncated cone array has a 180° range covered by gold, and the range covered by both silver and gold is 90°.

[0031] Figure 2 It is a pair of scanning electron microscope (SEM) images of chiral hollow nano-truncated cone arrays; the left side is the SEM of the left-handed nano-truncated cone structure, corresponding to implementation case 6; the right side is the right-handed nano-truncated cone structure, corresponding to implementation case 7, wherein the illustration in the upper right corner is a tilted SEM photo of the corresponding structure.

[0032] Figure 3 (A) SEM photos of right-handed nanotruncated cone arrays with different opening angles. From left to right, the opening angles are 90°, 60° and 30°. During the preparation process, the arrays were rotated 90°, 120° and 150° clockwise or counterclockwise after the silver was tilted and deposited. (B) Circular dichroism spectra of left-handed and right-handed chiral nanotruncated cone arrays with three different opening angles of 90°, 60° and 30° from left to right. The black solid line is the circular dichroism line of the left-handed nanotruncated cone, and the gray dotted line is the circular dichroism line of the right-handed nanotruncated cone. As shown in the figure, the chirality intensity of the chiral nanotruncated cone is directly related to its structural morphology. As the opening angle decreases from 90° to 30°, the circular dichroism signal intensity gradually decreases, indicating that the chirality of the structure gradually weakens.

[0033] Figure 4These are the circular dichroism spectra detected by the nano-truncated cone array after adding chiral biological molecules: (A) is the circular dichroism line shift diagram before and after adding L-cysteine ​​molecular solution; (B) is the circular dichroism line shift diagram before and after adding D-cysteine ​​molecular solution; (C) is the ΔΔλ diagram of L-cysteine ​​and D-cysteine, with L-cysteine ​​being +3.51 and D-cysteine ​​being -3.12, thus achieving label-free differentiation and identification of chiral enantiomers.

[0034] Figure 5 (A) is the SEM photo of the inverted chiral nanocone array, indicating that the inverted chiral nanocone film retains its original three-dimensional structural characteristics after flipping; the illustration in the upper right corner is the cross-sectional SEM photo of the structure; (B) is the circular dichroism spectrum of the structure, which has a strong symmetrical chiral response. DETAILED DESCRIPTION

[0035] Example 1: Preparation of hydrophilic glass sheet

[0036] Use a glass cutter to cut the glass sheet into a size of 2.5 cm in length and 1.5 cm in width, then place the glass sheet in a mixed solution of hydrogen peroxide and concentrated sulfuric acid (volume ratio of 3:7), heat it in an 80°C water bath for 4 hours, then wash it with deionized water for about 5 times, and blow it dry with nitrogen to obtain a hydrophilic glass sheet.

[0037] Example 2: Preparation of photoresist film

[0038] The photoresist stock solution (BP212-37S, positive photoresist, purchased from Beijing Kehua Microelectronics Materials Co., Ltd.) was spin-coated onto a hydrophilically treated glass sheet using a desktop coating machine at a speed of 3000 rpm for 30 seconds. The glass sheet was then placed in an oven at 88°C for 2 hours, taken out and naturally cooled to room temperature to obtain a glass substrate with a 1.5 μm thick photoresist film solidified thereon.

[0039] Example 3: Preparation of polystyrene microspheres in ethanol and deionized water dispersion

[0040] At room temperature, 3 mL of deionized water was added dropwise to 2 mL of a 5 wt% polystyrene microsphere aqueous dispersion with a diameter of 700 nm, and ultrasonicated at 100% power for 15 minutes, followed by centrifugation at 8800 rpm for 15 minutes, and the upper clear liquid was removed by aspiration; 3 mL of deionized water was added to the lower polystyrene microsphere precipitate, ultrasonicated for 15 minutes, and centrifuged at 8800 rpm for 15 minutes; the above steps of adding deionized water, ultrasonicating, and centrifuging to the lower polystyrene microsphere precipitate were repeated 5 times; and then the lower polystyrene microsphere precipitate was added to the lower polystyrene microsphere precipitate. 5 mL of a mixed solution of ethanol and deionized water (volume ratio of 1:1) was added to the precipitate, and the mixture was ultrasonicated for 15 minutes, followed by centrifugation at 8800 rpm for 15 minutes. The above steps of adding anhydrous ethanol and deionized water mixed solution to the lower polystyrene microsphere precipitate, ultrasonication, and centrifugation were repeated 5 times. After the upper clear liquid was aspirated for the last time, 2.5 mL of a mixed solution of ethanol and deionized water (volume ratio of 1:1) was added to the lower polystyrene microsphere precipitate, and the mixture was ultrasonicated for 60 minutes to obtain a deionized water ethanol dispersion of polystyrene microspheres.

[0041] Example 4: Preparation of hexagonal close-packed monolayer polystyrene colloidal crystals

[0042] 0.4 mL of the deionized water-ethanol dispersion of polystyrene microspheres (700 nm in diameter) prepared in Example 3 was sucked with a 1 mL medical disposable syringe and slowly injected into the interface of deionized water and air in a plastic culture dish, and 2 drops of a 9 wt% sodium dodecyl sulfate aqueous solution were slowly dripped along the edge of the culture dish, and then the polystyrene microspheres formed a hexagonal tightly packed single layer structure. The glass sheet with the photoresist prepared in Example 2 was slowly tilted and extended below the liquid surface, and the tightly packed single layer of microspheres was horizontally picked up and placed on an inclined surface for drying, thereby obtaining a photoresist film of a single layer of tightly packed polystyrene colloidal crystals.

[0043] Example 5: Preparation of photoresist nanotruncated cone array

[0044] The sample was placed in an anisotropic reactive plasma etcher and etched for 200 seconds at an etching temperature of 20°C, an etching pressure of 10 mTorr, an oxygen flow rate of 50 sccm, and an etching power of 100 W. During the etching process, the polystyrene microspheres and the photoresist underneath were etched simultaneously. The structure was then placed in 20 mL of toluene and ultrasonicated for 60 seconds to remove the remaining polystyrene microspheres, thereby obtaining a photoresist truncated cone array structure on the substrate.

[0045] Example 6: Asymmetric double-layer metal evaporation method

[0046] The sample prepared in Example 5 was mounted on the sample stage of the vacuum evaporation coating equipment, and the incident angle (i.e., the angle between the normal line and the deposition direction) was adjusted to 30°.-4 Silver is deposited by thermal evaporation under vacuum degree of Pa, and the deposition rate After this thermal evaporation deposition, the sample stage of the vacuum evaporation coating equipment was fixed and kept stationary. The substrate was rotated 90° counterclockwise along the axis perpendicular to the substrate surface. -4 Pa vacuum thermal evaporation deposition of gold, deposition rate , deposition thickness 35nm.

[0047] Example 7: Asymmetric double-layer metal evaporation method

[0048] The sample prepared in Example 5 was mounted on the sample stage of the vacuum evaporation coating equipment, and the incident angle (i.e., the angle between the normal line and the deposition direction) was adjusted to 30°. -4 Silver is deposited by thermal evaporation under vacuum degree of Pa, and the deposition rate After this thermal evaporation deposition, the sample stage of the vacuum evaporation coating equipment was fixed and kept stationary. The substrate was rotated 90° clockwise along the axis perpendicular to the substrate surface. -4 Pa vacuum thermal evaporation deposition of gold, deposition rate , deposition thickness 35nm.

[0049] Example 8: Preparation of Chiral Nanotruncated Cone Array Film

[0050] The substrates treated in Example 6 and Example 7 were respectively immersed in anhydrous ethanol for 20 minutes to remove the photoresist layer, and then taken out and naturally dried to obtain left-handed and right-handed hollow chiral nanotruncated cone array films, respectively.

[0051] Example 9: Preparation of inverted chiral nanotruncated cone array film

[0052] The treated substrates of Example 6 and Example 7 were inverted on another hydrophilic treated glass sheet, and the two were placed horizontally in a culture dish, and anhydrous ethanol was slowly added until the structure was submerged, and the photoresist was removed by soaking for 5 minutes. Then, the upper glass was slowly removed, and the anhydrous ethanol in the culture dish was sucked off, so that the inverted chiral nanotruncated cone array film was separated from the original glass substrate, and fell flat on the target glass substrate at the same time, dried naturally, and then slowly rinsed with anhydrous ethanol for 3 times, thereby obtaining inverted left-handed and right-handed chiral hollow nanotruncated cone array films on another hydrophilic substrate.

[0053] Example 10: Label-free identification of chiral molecules

[0054] Based on Example 8, biomolecules are connected to chiral structures to perform recognition and detection of biomolecules. Figure 4As shown in A, left-handed and right-handed hollow chiral nanotruncated cone array membranes were placed in L-cysteic acid solution (concentration 10 -3 mol / L) in water and in aqueous solution, the distance of spectral line movement is different, thus identifying chiral molecules. L =6.76nm, Δλ R =3.25nm, ΔΔλ=Δλ L -Δλ R =3.51nm. Figure 4 As shown in B, left-handed and right-handed hollow nanotruncated cones were placed in a D-cysteic acid solution (concentration 10 -3 mol / L), the distance of spectral line movement is different from that in aqueous solution, Δλ L =6.11nm, Δλ R =9.23nm, ΔΔλ=Δλ L -Δλ R =-3.12nm. The chirality of the biomolecule can be determined by judging the difference in the spectral line movement distance (ΔΔλ). Figure 4 As shown in C, when ΔΔλ is positive, the molecular configuration is L; when ΔΔλ is negative, the molecular configuration is D), which is easier to detect. This structure is expected to be used for detection in the medical field and label-free differentiation and identification of other biological molecules.

[0055] The above is only a preferred embodiment of the present invention, and does not limit the method scheme of the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the essence of the method of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing an invertible chiral hollow nanotruncated cone array film, the steps of which are as follows: 1) Spin coating a layer of forward photoresist stock solution on a hydrophilic treated substrate at a rotation speed of 1000-4000 rpm, and then placing the substrate at 80-120° C. for 1-3 hours to obtain a photoresist film with a cured thickness of 0.4-2 μm; 2) slowly dropping a hydrophobic polystyrene microsphere deionized water ethanol dispersion onto the surface of deionized water to obtain a monolayer of polystyrene microspheres at the air-liquid interface, then dropping an anionic surfactant to obtain a monolayer of hexagonally closely arranged polystyrene microspheres at the air-liquid interface, and then transferring the monolayer onto the substrate having the photoresist film cured thereon obtained in step 1); 3) The sample obtained in step 2) is subjected to reactive plasma etching, and the photoresist film is etched to form an array of nano-truncated cones due to the masking effect of the hydrophobic polystyrene microspheres. As the etching proceeds, the polystyrene microspheres gradually become smaller, and the etching is stopped before the microspheres completely disappear; then the obtained sample is immersed in 5-25 mL of toluene solution and ultrasonicated for 20-60 seconds to remove the residual polystyrene microspheres in the upper layer, thereby obtaining a nano-truncated cone photoresist array on the substrate; 4) a silver film with a thickness of 15 to 80 nm is deposited on the sample prepared in step 3) by oblique thermal deposition, and the incident angle (i.e., the angle between the oblique thermal deposition direction and the substrate normal) is 15° to 40°; then the substrate with the silver film is rotated clockwise or counterclockwise by 0° to 180° (excluding 0° and 180°) along an axis perpendicular to the substrate surface, and then a gold film with a thickness of 15 to 80 nm is thermally deposited at the same incident angle as the above-described silver film deposition; the gold and silver will partially overlap, and the overlapping areas will be different when rotated at different angles; 5) Soaking the substrate prepared in step 4) in anhydrous ethanol for 5 to 30 minutes to remove the photoresist covered by the metal film, rinsing and drying naturally, and obtaining a right-handed or left-handed chiral hollow nano-truncated cone array film on the substrate; 6) Invert the sample obtained in step 4) on another hydrophilic glass substrate, fix the relative position relationship between the two, slowly add anhydrous ethanol until the sample is submerged, and the immersion time is 5 to 30 minutes. After the photoresist film on the previous substrate is dissolved, remove the remaining ethanol, so that the obtained film structure slowly and evenly falls on the other hydrophilic substrate, and after natural drying, slowly rinse with anhydrous ethanol for 3 to 5 times, thereby obtaining an inverted right-handed or left-handed chiral hollow nano-cone array film on the other hydrophilic substrate.

2. The method for preparing an invertible chiral hollow nanotruncated cone array film according to claim 1, characterized in that: The substrate in step 1) is a glass sheet or a quartz sheet.

3. The method for preparing an invertible chiral hollow nanotruncated cone array film according to claim 1, characterized in that: In step 2), the diameter of the polystyrene microspheres is 0.3 to 3 μm.

4. The method for preparing an invertible chiral hollow nanotruncated cone array film according to claim 1, characterized in that: In step 2), the deionized water ethanol dispersion of hydrophobic polystyrene microspheres is prepared by adding 1 to 3 mL of deionized water to a deionized water dispersion of polystyrene microspheres having a concentration of 1 to 20 wt% and a diameter of 0.3 to 3 μm, ultrasonically treating for 10 to 20 minutes, and then centrifuging at 6000 to 11000 rpm for 10 to 30 minutes; adding 1 to 3 mL of deionized water to the polystyrene microsphere precipitate obtained after centrifugation, ultrasonically treating for 10 to 20 minutes, and then centrifuging at 6000 to 11000 rpm for 10 to 30 minutes; repeating the above steps of adding deionized water, ultrasonically treating for 10 to 20 minutes, and then centrifuging at 6000 to 11000 rpm for 10 to 30 minutes to the polystyrene microsphere precipitate obtained after centrifugation; and centrifugation process 4 to 12 times; adding 1 to 5 mL of a mixture of ethanol and deionized water in a volume ratio of 1:1 to the polystyrene microsphere precipitate obtained by centrifugation, ultrasonicating for 10 to 20 minutes, and then centrifuging at a speed of 6000 to 11000 rpm for 10 to 30 minutes; repeating the process of adding a mixture of ethanol and deionized water to the polystyrene microsphere precipitate obtained by centrifugation, ultrasonicating and centrifuging 4 to 12 times; and adding 1 to 5 mL of a mixture of ethanol and deionized water in a volume ratio of 1:1 to the polystyrene microsphere precipitate obtained by the last centrifugation, ultrasonicating for 10-60 minutes, thereby obtaining a deionized water ethanol dispersion of hydrophobic polystyrene microspheres.

5. The method for preparing an invertible chiral hollow nanotruncated cone array film according to claim 1, characterized in that: The conditions of reactive plasma etching in step 3) are etching temperature 20-30° C., oxygen flow rate 10-60 sccm, etching pressure 3-10 mTorr, etching power 100-300 W, and etching time 100-300 seconds.

6. The method for preparing an invertible chiral hollow nanotruncated cone array film according to claim 1, characterized in that: The vacuum degree of both thermal depositions in step 4) is 5×10 -4 ~2×10 -4 Pa, the deposition rate is 7. An invertible chiral hollow nanotruncated cone array film, characterized in that: The method is prepared by any one of claims 1 to 6.

8. Application of the invertible chiral hollow nanotruncated cone array film according to claim 7 in label-free recognition of chiral molecules.

Images