Acoustic suspension droplet concentration method and method for realizing multi-component and multi-phase trace detection

Abstract

The present invention discloses a method for concentrating acoustically suspended droplets and a method for realizing multi-component and multi-phase trace detection. The method comprises suspending droplets on an acoustically suspended platform and evaporating the droplets to achieve concentration. The droplets contain one or more solvents and a substance to be concentrated. The substance to be concentrated contains at least one component, and each component can be dispersed or dissolved by at least one solvent. By utilizing the acoustically suspended platform, molecules in any volatile liquid, solid surface, and gas phase can be non-destructively enriched. Surface plasmon metal nanoparticles can be concentrated together with the analyte in different phases, thereby achieving attomolar (10 ‑ 18 The present invention is versatile and simple to prepare. It can enrich trace molecules from liquids, solid surfaces, and gas phases and localize them to a tiny area, enabling trace detection. It can enhance the performance of various microsensing analytical technologies and has applications in fields such as biomedicine, environmental science, and food safety.

Description

Technical Field

[0001] The present invention relates to an analytical detection technology that utilizes an acoustic levitation platform to non-destructively enrich molecules in any volatile liquid, solid surface, or gas phase. Surface plasmon metal nanoparticles can be concentrated with the analyte in different phases, thereby achieving attomolar (10 -18 mol / l) level surface-enhanced Raman scattering (SERS) trace detection. Background Art

[0002] Trace analyte detection is crucial in numerous fields, including analytical chemistry, disease diagnostics, biomedicine, environmental science, and national security. In these applications, trace analytes are dispersed in water or organic liquids, attached to solid surfaces, or present as gaseous mixtures. Surface-enhanced Raman scattering (SERS) holds great promise for trace analyte detection due to its high sensitivity, label-free detection, and miniaturization. Currently, a range of SERS substrates have been developed, featuring densely and evenly distributed ultrasensitive sites (called "hotspots," typically located at the interfaces between adjacent nanoparticles). The effective area of ​​a SERS sensor is determined by the spot size of the excitation laser, typically on the order of square micrometers. Therefore, concentrating and converging analytes from different phases into small, localized hotspots is crucial and challenging for practical trace analyte SERS detection. Ideally, the hotspots are hundreds of square micrometers in size, allowing for addressing during SERS detection. However, pinning at the solid / liquid / gas three-phase contact line results in the accumulation of analyte molecules around the pinning ring, a phenomenon known as the "coffee ring" effect. Water-repellent surfaces (such as superhydrophobic and superoleophobic surfaces, molecularly smooth surfaces, etc.) can delay the appearance of contact lines, but they are unavoidable. By injecting liquids into smooth porous surfaces, the "coffee ring" effect can be avoided and analytes can be enriched from common liquids. However, lubricants often wrap around droplets, affecting SERS detection. In fact, due to wetting defects and / or evaporation processes, some analytes are not losslessly enriched into final aggregates on any smooth surface. All surfaces can only enrich non-viscous liquids, and the enrichment efficiency for viscous liquid analytes is limited. Optical capture and other concentration methods have been developed to concentrate analytes / nanoparticles in solutions, but it is difficult to concentrate all analytes and nanoparticles from solutions. Methods that can enrich analytes in any volatile liquid, solid and air have not yet been studied and used.

[0003] Acoustic levitation, the use of acoustic radiation forces to suspend objects in various media (such as air), has been studied for decades in applications such as metal solidification, contactless transport of materials, droplet dynamics, and analytical chemistry. SERS has also been used to monitor chemical reactions and crystallization processes within suspended droplets. However, it still has certain limitations in the field of trace detection. Summary of the Invention

[0004] The purpose of the present invention is to address the shortcomings of existing detection methods and provide a method for realizing multi-component and multi-phase trace detection through acoustic levitation droplet concentration.

[0005] The technical solutions adopted in the present invention are as follows:

[0006] A method for concentrating acoustically suspended droplets, specifically comprising: suspending droplets through an acoustically suspended platform and evaporating them to achieve concentration, wherein the droplets contain one or more solvents and a substance to be concentrated, wherein the substance to be concentrated contains at least one component, and each component can be dispersed or dissolved by at least one solvent.

[0007] The method of the present invention can enrich molecules in any volatile liquid, solid surface and gas phase without loss by utilizing the acoustic levitation platform.

[0008] Furthermore, when the droplet is suspended by the acoustic levitation platform, the droplet is kept in an ellipsoidal shape.

[0009] Furthermore, when the concentration ratio is reached, the substrate / container is placed under the acoustic levitation platform and the droplet, and the droplet is transferred; whether the concentration ratio is reached can be determined by observing the change in the droplet volume in real time through a camera device, thereby determining whether the concentration ratio is reached.

[0010] A method for realizing multi-component and multi-phase trace detection, specifically:

[0011] Liquid droplets are suspended and evaporated using an acoustic levitation platform, wherein the droplets contain one or more solvents, surface plasmon metal nanoparticles, and an analyte, wherein the analyte contains at least one component, each component can be dispersed or dissolved by at least one solvent, and at least one solvent can disperse the surface plasmon metal nanoparticles. After the solvent in the droplets evaporates, the analyte is concentrated and enriched on the surface plasmon metal nanoparticles to form aggregates, and trace detection of the aggregates can achieve trace detection of the analyte.

[0012] Surface plasmon metal nanoparticles can be concentrated with analytes in different phases to achieve attomolar (10 -18 mol / l) level trace detection.

[0013] This method utilizes the droplet suspension enrichment (DLE) platform to enrich the final analyte in any phase. Metal nanoparticles are introduced as SERS enhancers into the suspended analyte solution droplets and enriched simultaneously with the analyte, achieving ultrasensitive SERS detection. By increasing the starting volume of the suspended droplets, the detection limit can be lowered. The DLE platform can be combined with almost all sensing technologies to collect signals from microscale (or microsensing) methods (such as photoluminescence, near-infrared absorption, etc.), showing great application potential in the field of trace analyte detection.

[0014] Furthermore, when the droplet is suspended by the acoustic levitation platform, the droplet is kept in an ellipsoidal shape.

[0015] Furthermore, when the concentration multiple is reached, the substrate is quickly moved into the acoustic levitation platform and under the droplets, and the droplets are transferred to the substrate to facilitate trace detection of aggregates. The volume changes of the suspended droplets can be detected in real time by a camera device to select a suitable termination volume.

[0016] Furthermore, the analyte is a molecule in the gas phase, and the method of suspending the droplet by the acoustic levitation platform is specifically as follows:

[0017] A solvent containing surface plasmon metal nanoparticles is added dropwise to the acoustic levitation platform for suspension, and then the analyte dispersed in the gas phase is diffused into the solvent. Preferably, a solvent that can disperse both the analyte and the surface plasmon metal nanoparticles is used.

[0018] Furthermore, the analyte is a molecule attached to a solid surface, and the method of suspending droplets using an acoustic levitation platform is specifically as follows: a solid to which the analyte is attached and one or more solvents are successively added to the acoustic levitation platform for suspension to form droplets, wherein surface plasmon metal nanoparticles are dispersed in at least one solvent.

[0019] For example, a solid with an analyte attached is first added to the acoustic levitation platform for suspension, and then one or more solvents are added to form droplets on the solid surface; or one or more solvents are first added to the acoustic levitation platform for suspension, and then the solid with an analyte attached is added to the solvent to form droplets.

[0020] Furthermore, the analyte is a molecule in a liquid phase, and the method for suspending the droplet by the acoustic levitation platform is specifically as follows:

[0021] A solvent containing the analyte and plasmonic metal nanoparticles is injected at the node locations of the ultrasonic levitation platform. When the solvents containing at least two components are mutually immiscible, the surface plasmonic metal nanoparticles are dispersed in the solvent with the greater dispersibility. The mutually immiscible solvents are injected sequentially at the node locations of the ultrasonic levitation platform.

[0022] Furthermore, the trace detection includes surface enhanced Raman scattering, photoluminescence, and near-infrared absorption spectroscopy detection.

[0023] Furthermore, the multi-component assay refers to the ability to simultaneously detect two or more different analyte molecules.

[0024] Furthermore, the multiphase method refers to the ability to simultaneously suspend liquid solvents with different surface tensions in liquid detection, and to detect different analyte molecules in multiple solvents.

[0025] Furthermore, the acoustic levitation platform refers to a platform that can suspend an object in the air using ultrasonic waves.

[0026] Furthermore, the surface plasmon metal nanoparticles refer to all metal nanoparticles that can be excited by specific lasers, thereby enhancing the surrounding local electromagnetic field.

[0027] Furthermore, the surface enhanced Raman scattering trace detection refers to a method of analyzing the Raman spectrum obtained by Raman spectrometer testing.

[0028] Compared with the existing technology, the beneficial effects of the present invention are embodied in:

[0029] The method is universal and simple to prepare. It can enrich trace molecules from liquids, solid surfaces, and gas phases and localize them to a tiny area, enabling trace detection. By integrating it with an acoustic levitation enrichment analysis platform, it can enhance the performance of various microsensing analytical techniques (such as photoluminescence and near-infrared absorption), with potential applications in fields such as biomedicine, environmental science, and food safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the method of the present invention using the DLE platform for multi-component and multi-phase detection. a) Schematic diagram of the principle of multi-component and multi-phase detection using the DLE platform; b) shows the enrichment process of a 10μl ethanolic solution of crystal violet (CV); c) shows the aggregates formed by enriching and concentrating 10μl of 500nm polystyrene spheres, 300nm ZIF-8 octahedra and UIO-66 truncated dodecahedrons, 50nm gold nanospheres, aqueous solutions of copper sulfate (CuSO4) and rhodamine 6G (R6G), and hydroxypropyl cellulose (HPC) in ethanol.

[0031] Figure 2Figure 1 shows the results of sensitive SERS detection of various liquids using the DLE platform. a is a transmission electron microscope image of gold nanospheres. Inset: Photo of gold nanosphere colloids; b is a microscopic image of gold nanospheres and CV molecules simultaneously enriched. Inset: Microscope image of gold nanosphere / CV aggregates. Scale bar: 100 μm; c is the electromagnetic field distribution on the gold nanosphere aggregate simulated by the finite difference time domain method (FDTD); d and e are the SERS spectra of CV molecules after concentration in ethanol solutions and aqueous solutions with different starting concentrations, respectively; f is a 1616 cm -1 The relationship between the SERS peak intensity and the concentration of CV molecules in ethanol and water, the error bars are obtained based on at least 10 spectra; g is the SERS detection of 1 pM CV molecules in methanol, toluene and acetone solutions; h is the simultaneous detection of R6G and 4-methoxy-α-toluenethiol (MATT) molecules at different concentration ratios; i is the SERS intensity ratio (1647 cm in R6G) -1 The peak of 1226 cm in MATT -1 Peak value) and concentration ratio (C R6G / C MATT ). Error bars are based on at least 10 spectra.

[0032] Figure 3 Figure 2 is a diagram of multiphase and multicomponent SERS detection results. Among them, a is the introduction of water into the suspended toluene droplets, and vice versa. Toluene wraps one end of the ellipsoidal water droplet. For multiphase and multiple SERS detection, gold nanoparticles well dispersed in water are conducive to the entry of the analyte into the gold nanoparticle aggregates after the solvent evaporates. Otherwise, the gold nanoparticles pre-aggregated in the organic phase will hinder the entry of the analyte, especially the analyte in the aqueous phase (see the schematic diagram on the right); b is a 50nM MATT toluene solution and a 50nM R6G aqueous solution, and the SERS spectrum of gold nanoparticles dispersed in the aqueous solution (curve I), and the SERS spectrum of gold nanoparticles when aggregated in toluene (curve II); c is the SERS spectrum of R6G and MATT at 1647cm in curves I and II in Figure b, respectively. -1 and 1226cm -1 The SERS peak intensity and intensity ratio of MATT and R6G are shown in Figure 2. d is the SERS spectra of MATT and R6G at different concentration ratios; e is the SERS intensity ratio (1647 cm in R6G) -1 The peak of 1226 cm in MATT -1 The peak value of the R6G spectrum is plotted against the concentration ratio of R6G to MATT in different liquids. Error bars are based on at least 10 spectra.

[0033] Figure 4Figures show the results of SERS detection of solid and airborne analytes using the DLE platform. (a) and (b) are the principle diagram and experimental schematic diagram of direct SERS detection of pesticides on sesame slices using the DLE platform. Step 1: Suspend gold nanoparticle colloids on suspended sesame slices. Step 2: SERS measurement after solvent evaporation. (c) SERS spectra of sesame seeds contaminated with different concentrations of the pesticide TMTD using the DLE platform. (d) SERS spectra of ethanol solutions of TMTD with different concentrations using the DLE platform. (e) and (f) SERS spectra of direct SERS detection of environmental pollutants on sand using the DLE platform. Scale bar: 1 mm. (g) SERS spectra of decachlorobiphenyl (PCB 209) and oxytetracycline (OTC) directly on sand using the DLE platform. (h) Schematic diagram of capture, enrichment, and SERS detection of airborne molecules using the DLE platform. (i) SERS spectra of ethanol droplets composed of gold nanoparticles capturing and enriching MATT molecules from air. MATT molecules of varying sizes in the air are created by heating the MATT liquid.

[0034] Figure 5 is the saturation concentration of the DLE sensing platform. CV ethanol solution 1616cm -1 The SERS intensity at the molecule changes with concentration. When the CV molecule concentration is greater than 100 nM, the SERS intensity does not increase with further concentration increases (shaded area), indicating that the analyte near the surface hotspot has reached saturation. Error bars are based on at least 10 spectra.

[0035] Figure 6 SERS detection of biomolecules using the DLE platform. (a) SERS spectra of adenosine at different concentrations; (b) SERS spectra of adenine at different concentrations.

[0036] Figure 7 Figure 1 shows the photoluminescence enhancement of R6G molecules using the DLE platform. (a) Fluorescence spectra of a 1 fM R6G ethanol solution before and after enrichment using the DLE platform. R6G excitation wavelength is 532 nm, and emission wavelength is 555 nm. (b) Fluorescence image of R6G aggregates after enrichment using the DLE platform under 488 nm excitation light. DETAILED DESCRIPTION

[0037] The present invention provides a method for concentrating acoustically suspended droplets, specifically comprising: suspending droplets through an acoustically suspended platform and evaporating them to achieve concentration, wherein the droplets contain one or more solvents and a substance to be concentrated, wherein the substance to be concentrated contains at least one component, and each component can be dispersed by at least one solvent.

[0038] Among them, evaporation can be achieved quickly by heating with a ceramic heater or the like.

[0039] like Figure 1 As shown in Figure b, during the experiment, the droplet is squeezed into an ellipsoidal shape to provide sufficient force to balance gravity. This is because in an acoustic field, the levitation force per unit volume of an ellipsoidal droplet is greater than that of a sphere of the same volume. As the solution evaporates, the ellipsoidal droplet gradually becomes quasi-spherical. At this point, the distance between the acoustic emitter and reflector can be reduced to squeeze the quasi-spherical droplet back into an ellipsoidal shape, maintaining the droplet's ellipsoidal shape throughout the concentration process. When the desired concentration factor is reached, a substrate / container is placed under the acoustic levitation platform and the droplet is transferred. The determination of whether the desired concentration factor has been reached is determined by observing the initial droplet volume and the concentration factor using a camera to calculate the final volume. When the droplet is very small (e.g., 2 nl), it oscillates frequently, hindering transfer. The transfer success rate for 10 nl droplets is 100%, and for 2 nl droplets, it is 70%. A 10μl transparent droplet composed of 10μM crystal violet (CV) dye molecules is enriched to ~100μM violet droplets (volume ~0.5nl) after solvent evaporation, easily increasing the concentration by nearly 20,000-fold. The device can suspend water / ethanol droplets up to 180μl / 30μl, corresponding to approximately 360,000 / 60,000-fold increases in concentration. Furthermore, increasing the power of the acoustic levitation platform and adjusting the acoustic frequency can expand the range of suspendable droplet sizes, further improving analyte enrichment capabilities.

[0040] The components of the present invention can be particles, nanoparticles, ions, molecules, etc. in different shapes, such as Figure 1 As shown in Figure c, 500-nanometer polystyrene spheres dispersed in ethanol aggregate into a large sphere after ethanol evaporation. The outermost layer of polystyrene spheres exhibits a hexagonal arrangement. In contrast, 300-nanometer octahedral and truncated dodecahedral metal-organic framework (MOF) particles assemble into a concave pancake shape after water evaporation. After acoustic levitation enrichment, droplets composed of 50-nanometer gold nanoparticles are barely visible, but the concentration increases significantly, with a film of densely packed gold nanoparticles appearing. Single-crystalline copper sulfate spheres form after complete water evaporation. The weight of the crystals is identical to that of the dissolved water, demonstrating lossless enrichment. Aggregates of the rhodamine 6G (R6G) analyte form after complete water evaporation. Importantly, ethanolic solutions of hydroxypropyl cellulose (HPC) are very viscous, lacking a solid surface to enrich the HPC molecules into small aggregates. In contrast, HPC enrichment forms spheres after ethanol evaporation using the acoustic levitation platform.

[0041] The present invention also provides a method for realizing multi-component and multi-phase trace detection by acoustic suspension droplet concentration, such as Figure 1As shown, a solvent containing analytes and plasmon metal nanoparticles is injected into the node position of the ultrasonic levitation platform. Then, the solvent is evaporated quickly by a ceramic heater, and a SERS substrate composed of nanoparticles is prepared during evaporation. When it is necessary to detect analytes in two mutually soluble / immiscible liquid phases, multiphase detection can be achieved by injecting the solution multiple times. The present invention can non-destructively enrich molecules in any volatile liquid, solid surface and gas phase by utilizing an acoustic levitation platform. Among them, surface plasmon metal nanoparticles can be concentrated together with the analyte in different phases, thereby achieving a range of concentrations including attomolar (10 -18 mol / l) level. In addition, it can also be used in trace analyte detection fields such as photoluminescence and near-infrared absorption.

[0042] The acoustic levitation platform described in the present invention is a platform that can suspend objects in the air using ultrasonic waves. Figure 1 The acoustic levitation platform shown in the figure includes a transmitter and a reflector arranged relative to each other, wherein the sound wave (frequency: 20.7kHz) is generated by the piezoelectric transducer in the transmitter. The sound pressure generated by the sound wave can balance the gravity of the droplet and achieve droplet levitation, as shown in the figure. Figure 1 As shown in a. The non-destructive, multi-component and multi-phase analyte enrichment of solid-state SERS substrates becomes simple and straightforward for the DLE platform. Figure 1 (a) During solvent evaporation, multiple analytes can be simultaneously enriched with gold nanoparticles for SERS detection. Multiphase analyte enrichment is achieved by introducing the aqueous solution into the organic phase (e.g., toluene) using a pipette tip.

[0043] The surface plasmon metal nanoparticles described in the present invention refer to all metal nanoparticles that can be excited by a specific laser, thereby enhancing the surrounding local electromagnetic field, such as precious metals such as gold, silver, and platinum.

[0044] Below, in conjunction with the accompanying drawings, the present invention is further described by taking gold nanospheres as plasmonic metals and constructing an aggregation containing hot spots and molecules to be detected in a DLE platform as an example.

[0045] Example 1

[0046] The SERS sensitivity of the DLE platform was evaluated using CV molecules. Using too few gold nanoparticles would make it difficult to form complete aggregates, while too many gold nanoparticles would reduce the number density of analytes within the aggregates. Figure 2In ac, Figure a is a transmission electron microscope image of 50nm gold nanoparticles, and the inset in the upper right corner is an optical microscope image of a colloidal solution of gold nanoparticles. Figure b is a scanning electron microscope image of aggregates formed by suspended enriched gold nanoparticles, and the inset in the upper right corner is an optical microscope image of the aggregates. Figure c is the established FDTD model and the result of the simulated electric field enhancement. The specific addition ratio is set according to experimental optimization. In this embodiment, 10pM gold nanoparticles are added to 10μl of CV ethanol solution. Through the DLE platform, after enriching CV molecules in an ethanol solution with a starting concentration range of 10nM to 10fM composed of 10pM gold nanospheres, obvious SERS peaks can be observed, such as Figure 2 d. When the starting concentration is 100 aM or below, it is necessary to perform interval multi-point detection of the position of CV molecules in the gold nanoparticle / CV molecule aggregate. At the starting concentration of 100 aM, the SERS enhancement factor (EF) of the DLE platform is estimated to be approximately 5.55×10 13 When the concentration is higher than 100 nM, the SERS signal intensity reaches saturation because all the SERS hotspots are occupied by the analytes, e.g. Figure 5 Similarly, after 40 pM gold nanoparticles were enriched on the DLE platform, CV molecules in aqueous solution with a concentration range of 10 nM-100 fM could be detected, as shown in Figure 2 e. CV concentration and 1616 cm in ethanol / water -1 The relationship between the SERS intensities of the peaks can be described by log I = 0.28log C + 6.87 / log I = 0.36log C + 7.76, and the goodness of fit (R 2 ) is ~0.989 / 0.9996, such as Figure 2 f. The LOD calculated using Student's t distribution is 7.05 aM, which is at least four orders of magnitude better than that of traditional SERS substrates without DLE technology.

[0047] In other organic solvents, CV molecules can be easily detected when the starting concentration is 1 pM, such as Figure 2 In principle, the DLE platform can be used for ultrasensitive SERS detection in any volatile solvent.

[0048] Figure 6 The figure shows the concentration and trace detection of adenosine / adenine in aqueous solutions of different concentrations. It can be seen that the SERS in the aqueous solution after concentration using the method of the present invention can easily detect adenosine and adenine related to life processes. The method of the present invention can be used for the detection of biological molecules in the liquid phase.

[0049] Example 2

[0050] Multi-component SERS detection was performed using the DLE platform. Figure 2 As shown in Figure 3, 40pM gold nanoparticles, R6G, and 4-methoxy-α-toluenethiol (MATT) molecules were dissolved in ethanol at four different concentration ratios (50nM:50nM, 5nM:50nM, 500pM:50nM, and 50nM:5nM). 5μl of each solvent was then injected into the node of the ultrasonic levitation platform. The SERS spectrum was measured after enrichment by 10,000 to 20,000 times using the DLE platform. The SERS spectrum of the mixture is the superposition of the SERS spectra of the two molecules, and its intensity depends on the concentration. Figure 2 As shown in FIG, the relationship between the concentration ratio and the SERS intensity ratio can be expressed as log(I R6G / I MATT )=0.68log(C R6G / C MATT )+0.80, indicating that it has good quantitative ability in multiple SERS detection.

[0051] Multiphase SERS detection is performed using the DLE platform. The aqueous solution can be introduced into the suspended organic liquid droplets (such as toluene), that is, the organic droplets are first injected into the node position of the ultrasonic levitation platform for suspension, and then the aqueous solution is injected into the node position of the ultrasonic levitation platform, and the two are mixed into a droplet; vice versa, Figure 3 a. Toluene will wrap one end of the ellipsoidal water droplet. When gold nanospheres are dispersed in water, the analyte molecules dispersed in toluene and water will be trapped in the gold nanosphere aggregates after the solvent evaporates. However, when gold nanospheres are dispersed in toluene, they will immediately aggregate due to poor dispersion, making it difficult for analyte molecules, whether dispersed in water or toluene, to enter the gold nanosphere aggregates after the solvent evaporates. Therefore, when gold nanoparticles are dispersed in water, strong SERS signals can be observed simultaneously for R6G dispersed in water and MATT dispersed in toluene, as shown in Figure 2. Figure 3 b Curve II. In contrast, the intensity of MATT dispersed in toluene decreased by about 2 times, while the intensity of R6G dispersed in water decreased by about 10 times. Figure 3 As shown in Figure c, the SERS intensity ratio of R6G to MATT further confirms that it is difficult for analyte molecules to enter the gold nanoparticle aggregates. Gold nanoparticles (40pM) were introduced into the aqueous phase via the DLE platform, and the SERS spectra of R6G in water (5μl volume) and MATT in toluene (5μl volume) at different concentration ratios (50nM:50nM, 10nM:50nM, 5nM:50nM, 1nM:50nM) after concentration 10,000-20,000 times were measured. Figure 3 d. The relationship between the concentration ratio of R6G and MATT and the SERS intensity ratio can be expressed as log(I R6G / I MATT)=0.92log(C R6G / C MATT )+0.93 to describe, R 2 is 0.998, such as Figure 3 As shown in e.

[0052] Example 3

[0053] Detecting analytes attached to tiny solid objects (such as pesticide residues and environmental pollution) is a common trace detection scenario. Before detection, a tedious pretreatment process is usually required to separate the analytes from the solid. In the method of the present invention, the DLE platform can be used to directly detect the analytes on tiny solids through SERS technology, such as Figure 4 shown.

[0054] Taking the detection of pesticide residues on sesame slices as an example, the sesame slices are first subjected to acoustic suspension. Figure 4 Then, 10 μl of ethanol containing 40 pM gold nanospheres (as shown in Figure 4 In process I) of a and b, the gold nanoparticles are dropped onto the sesame slices, and the pesticide molecules are peeled off from the sesame slices by the action of sound waves. As the solvent evaporates, the gold nanoparticles and the pesticide molecules are assembled on the surface of the sesame slices ( Figure 4 Process II in a and b). Tetramethylthiuram disulfide (TMTD) is a pesticide widely used around the world. Using the method of the present invention, without any pretreatment, the detection sensitivity of TMTD can easily reach 7.6 pg / cm 2 ,like Figure 4 c. Using the method of the present invention, SERS detection of TMTD ethanol solution with a concentration as low as 100 pM can be achieved, as shown in FIG. Figure 4 As shown in d.

[0055] The method of the present invention can also be used for detecting environmental pollutants and antibiotics in SERS detection. Decachlorobiphenyl 209 (PCB209) is a type of polychlorinated biphenyl (PCB) that can cause serious health problems even at very low concentrations. Unlike crops, the diameter of sand contaminated by PCB209 is usually less than 0.2mm. Due to its small size, high density and low power, it is difficult for an acoustic levitator to directly and stably suspend. Therefore, it is necessary to first suspend a 10μl droplet of ethanol containing 40pM gold nanoparticles. Then, 4-5 grains of sand are added to the droplet, such as Figure 4 After ethanol evaporates, the SERS signal of PCB 209 is observed by detecting sand particles, as shown in e and f. Figure 4 Oxytetracycline (OTC) is a commonly used antibiotic. Similar to the detection process of PCB 209, OTC was also analyzed by direct SERS measurement of sand particles using the DLE platform, as shown in Figure 2. Figure 4 As shown in g.

[0056] The method of the present invention can also be applied to SERS of gas phase analytes. Usually, gas phase detection requires a complex process to capture analytes in the air. However, using the method of the present invention, analytes in the air can be efficiently captured, enriched and detected by SERS without any peripheral equipment, such as Figure 4 As shown in h, i. Considering that MATT molecules prefer to dissolve in ethanol, 10 μl of ethanol droplets containing 40 pM gold nanoparticles were suspended to capture MATT molecules diffused in the air, as shown in Figure 4 As shown in h. Once the MATT molecules diffuse into the ethanol droplet, they are fixed on the surface of the gold nanoparticles. Figure 4 As shown in Figure 1, after ethanol evaporation, MATT molecules were enriched and captured between adjacent gold nanoparticles, achieving sensitive SERS detection of MATT molecules in the air. Figure 7 Figure a shows the fluorescence spectra of a 1 fM R6G alcohol solution containing 40 pM gold nanoparticles, before and after enrichment by 10,000-20,000-fold using the DLE platform, excited by a 532 nm laser. Figure b shows the aggregates formed by R6G suspension enrichment, and Figure c shows fluorescence microscopy imaging under 488 nm laser excitation. This demonstrates that the method of the present invention can also be combined with photoluminescence methods to significantly enhance its sensing capabilities.

[0057] Finally, it should be noted that the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for realizing multi-component and multi-phase trace detection, characterized in that: Specifically: Liquid droplets are suspended and evaporated using an acoustic levitation platform, wherein the droplets contain one or more solvents, surface plasmon metal nanoparticles, and an analyte, wherein the analyte contains at least one component, each component can be dispersed or dissolved by at least one solvent, and at least one solvent can disperse the surface plasmon metal nanoparticles. After the solvent in the droplet evaporates, the analyte is concentrated and enriched on the surface plasmon metal nanoparticles to form aggregates, and trace detection of the aggregates can achieve trace detection of the analyte. The surface plasmon metal nanoparticles are all metal nanoparticles that can be excited by a specific laser, thereby enhancing the surrounding local electromagnetic field. When the droplet is suspended by the acoustic levitation platform, the droplet is maintained in an ellipsoidal shape. The trace detection is surface-enhanced Raman scattering detection.

2. The method according to claim 1, wherein: The analyte is a molecule in the gas phase, and the method of suspending the droplet by the acoustic levitation platform is specifically as follows: A solvent containing dispersed surface plasmon metal nanoparticles is dropped onto the acoustic levitation platform for suspension, and then the analyte is diffused into the solvent.

3. The method according to claim 1, wherein: The analyte is a molecule attached to a solid surface, and the method for suspending a droplet using an acoustic levitation platform is as follows: A solid with an analyte attached and one or more solvents are added to an acoustic levitation platform in sequence for suspension to form droplets, wherein surface plasmon metal nanoparticles are dispersed in at least one solvent.

4. The method according to claim 1, wherein: The analyte is a molecule in a liquid phase, comprising at least two components, and when the solvents in which the at least two components are dispersed are mutually immiscible, the surface plasmon metal nanoparticles are dispersed in a solvent with greater dispersibility.

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