阅读说明：本技术 检测水溶液中4-溴甲卡西酮的表面增强拉曼材料及其制备方法 (Surface enhanced Raman material for detecting 4-bromomethcathinone in aqueous solution and preparation method thereof ) 是由 邹芸 杨飞宇 刘文斌 袁晓亮 赵雪珺 曹芳琦 陈伟 蔡能斌 黄晓春 于 2018-05-31 设计创作，主要内容包括：一种检测水溶液中4-溴甲卡西酮的表面增强拉曼材料及其制备方法,通过合成金纳米颗粒作为金种后在其外部包裹介孔二氧化硅(Au@mesoSiO<Sub>2</Sub>),然后进一步在介孔二氧化硅包裹的金纳米颗粒表面长出树状金枝结构(bAu@mesoSiO<Sub>2</Sub>)。本发明能够有效防止SERS增强材料在使用时发生团簇的同时,采用树状金枝结构提高对目标物检测的灵敏度。本发明制备方法简单、成本低廉,能有效增强目标物的拉曼信号,且重复性好。(A surface enhanced Raman material for detecting 4-bromomethcathinone in aqueous solution and a preparation method thereof are disclosed, wherein gold nanoparticles are synthesized to serve as gold seeds, mesoporous silica (Au @ mesoSiO 2 ) is wrapped outside the gold nanoparticles, and then a dendritic gold branch structure (bAu @ mesoSiO 2 ) is further grown on the surface of the gold nanoparticles wrapped by the mesoporous silica.)

1. A preparation method of a composite mesoporous arborescent gold branch nanometer material with SERS activity is characterized in that gold nanoparticles are synthesized to serve as gold seeds, mesoporous silica is wrapped outside the gold nanoparticles, and then arborescent gold branch structures are further grown on the surfaces of the gold nanoparticles wrapped by the mesoporous silica.

2. The method as claimed in claim 1, wherein the step of synthesizing gold nanoparticles comprises: adding sodium citrate into boiling chloroauric acid solution for reaction.

3. The method as claimed in claim 1, wherein the mesoporous silica is wrapped with gold nanoparticles, and the synthesis steps are as follows: adding gold nanoparticles into a mixed solution of CTAB and ethanol, uniformly stirring, then sequentially adding ammonia water and Tetraethoxysilane (TEOS), and stirring and reacting in a warm water bath to obtain the gold nanoparticles.

4. The method of claim 1, wherein said dendritic golgi structures are of different lengths; the generation steps are as follows: reducing chloroauric acid on the surface of the gold nanoparticle coated by the mesoporous silica.

5. The method as claimed in claim 4, wherein the reduction is obtained by preparing mixed solutions of hydrochloric acid and chloroauric acid with different concentrations, respectively adding aqueous solutions of mesoporous silica-coated gold nanoparticles, and then respectively further reacting silver nitrate and ascorbic acid.

6. A composite mesoporous tree-like gold branch nano material with SERS activity is characterized in that gold nanoparticles are used as an inner core, a tree-like gold branch structure is grown on the surface of the inner core, and the outermost layer is coated by mesoporous silicon dioxide.

7. The composite mesoporous dendritic gold branch nanomaterial of claim 6, wherein the dendritic gold branch structure has a length of: 9nm to 50 nm.

8. The application of the composite mesoporous arborescent gold-branch nanomaterial with SERS activity in any claim is characterized in that the composite mesoporous arborescent gold-branch nanomaterial is used for Raman detection, and specifically comprises the following steps: mixing a 4-bromomethcathinone aqueous solution sample to be detected with the composite mesoporous dendritic gold branch nano material, naturally drying the mixture, and then placing the mixture under a microscope lens of a micro-Raman spectrometer for Raman signal detection.

Technical Field

The invention relates to a technology in the field of chemical detection, in particular to a surface enhanced Raman material for detecting 4-bromomethcathinone in aqueous solution and a preparation method thereof.

Background

The trace detection of the new mental active substance has important significance in the field of forensic science, and the detection of the new mental active substance mainly adopts liquid phase and gas chromatography at present, and has the defects of complicated pretreatment, time consumption and inconvenience for carrying. Optical raman has the advantages of non-contact, nondestructive and rapid detection, however, due to weak raman signal, many researchers are working on the research of Surface Enhanced Raman (SERS) material, and the combination of raman effect and noble metal can generate considerable raman signal enhancement.

Disclosure of Invention

Aiming at the defects of the existing surface Raman enhancing material, the invention provides the surface Raman enhancing material for detecting the 4-bromomethcathinone in the aqueous solution and the preparation method thereof, and the sensitivity of the SERS enhancing material for detecting the target object is improved by adopting a tree-like gold branch structure while cluster is prevented from occurring in the SERS enhancing material in use. The preparation method is simple, low in cost, capable of effectively enhancing the Raman signal of the target and good in repeatability.

The invention is realized by the following technical scheme:

the invention relates to a preparation method of a composite mesoporous arborescent gold branch nano material with SERS activity, which comprises the steps of synthesizing gold nanoparticles serving as gold seeds, wrapping mesoporous silica (Au @ mesoSiO ₂) outside the gold nanoparticles, and further growing arborescent gold branch structures (bAu @ mesoSiO ₂) on the surfaces of the gold nanoparticles wrapped by the mesoporous silica.

The method for synthesizing the gold nanoparticles comprises the following specific steps: adding sodium citrate into a boiling chloroauric acid solution for full reaction to obtain the product; preferably, after sufficient reaction, the reaction is filtered and mixed in cetyltrimethylammonium bromide (CTAB) solution and finally concentrated by centrifugation.

The mesoporous silica-coated gold nanoparticle comprises the following synthetic steps: adding gold nanoparticles into a mixed solution of CTAB and ethanol, uniformly stirring, then sequentially adding ammonia water and Tetraethoxysilane (TEOS), and stirring and reacting in a warm water bath to obtain the gold nanoparticles; it is preferable that the reactant is centrifuged and the supernatant is removed after completion of the reaction, and then the resulting precipitate is ultrasonically washed with alcohol to remove the CTAB template.

The dendritic golden branch structure preferably has different lengths; the generation steps are as follows: reducing chloroauric acid on the surface of the gold nanoparticle coated by the mesoporous silica.

The reduction is carried out by preparing mixed solutions of hydrochloric acid and chloroauric acid with different concentrations, adding gold nanoparticle aqueous solution wrapped by mesoporous silica into the mixed solutions, respectively, fully reacting silver nitrate and ascorbic acid, centrifuging after the reaction is finished, removing supernatant, and cleaning obtained precipitate with alcohol to obtain bAu @ meso SiO ₂ with different gold branch lengths.

The invention relates to a composite mesoporous dendritic gold branch nano material (bAu @ meso SiO ₂) with SERS activity, which takes gold nanoparticles as an inner core, a dendritic gold branch structure is grown on the surface of the inner core, and the outermost layer is coated by mesoporous silicon dioxide.

The length of the tree-shaped golden branch structure is as follows: 9nm to 50 nm.

The invention relates to an application of the composite mesoporous arborescent gold branch nano material with SERS activity, which is used for Raman detection and specifically comprises the following steps: mixing a 4-bromomethcathinone aqueous solution sample to be detected with the composite mesoporous dendritic gold branch nano material, naturally drying the mixture, and then placing the mixture under a microscope lens of a micro-Raman spectrometer for Raman signal detection.

The concentration of the 4-bromomethcathinone aqueous solution sample to be detected is 1.5mg/mL, the 4-bromomethcathinone aqueous solution sample is mixed with bAu @ mesoSiO ₂ with different lengths of gold branches in an ultrasonic mode, the 4-bromomethcathinone aqueous solution sample and the four mixed solutions are respectively dripped on a silicon chip, and Raman detection is performed after natural drying.

The Raman signal detection adopts a Raman spectrometer with the model of LabRAM HR Evolution, the excitation wavelength of 473nm, 100 times of objective focusing, the integration time of each measurement is 10s, the integration times are 3 times, the recording range is 1000cm ^-1 -4000cm ^-1, the Raman spectrum carries out multi-point measurement on each sample to be measured, and finally the average value is obtained.

the Raman signal detection adopts an infrared spectrometer and an ultraviolet-visible spectrometer to perform spectral absorption characterization on the synthesized bAu @ meso SiO ₂, and utilizes a scanning lens to perform characterization on the synthesized material.

the model of the infrared spectrometer iS Nicolet iS50(Thermo Scientific), when in characterization, the infrared spectrometer adopts an attenuated total reflection accessory for measurement, the wave number range iS 500cm ^-1 -4000cm ^-1, the resolution iS 0.4cm ^-1, and each sample iS subjected to accumulative measurement for 3 times to obtain an average value.

The model of the ultraviolet-visible spectrometer is AQUALOG (horiba), and the measurement wavelength range is 250nm-800 nm.

The scanning lens is used for detecting a scanning lens sample after a sample to be detected is dispersed in an alcohol solution and is dripped on a copper net and is dried in vacuum.

The model of the scanning lens is FEI (Tecnai G ² F20S-Twin), and the accelerating voltage is 200 kV.

Technical effects

Compared with the prior art, the method solves the problem of the traditional gold particle cluster by mesoporous silica package, and further improves the sensitivity of SERS detection by constructing a tree-shaped gold branch structure. By detecting the 4-bromomethcathinone aqueous solution sample, the longer the hairpin length is, the more the hairpin number is, and the higher the SERS detection sensitivity is. For drugs which do not have corresponding detection plates at present, the material can be used for optical rapid detection of case-involved sites.

Drawings

FIG. 1 shows the dendritic gold branch structure coated with mesoporous silica synthesized by the present invention in different proportions;

FIG. 2 shows that mesoporous silica-coated dendritic gold-branched structures with different proportions are used for detecting Raman signals of a 4-bromomethcathinone aqueous solution sample;

FIG. 3 is an infrared and visible spectrum of gold particles coated with mesoporous silica;

FIG. 4 is an infrared spectrum of a gold-dendritic structure coated with mesoporous silica.

Detailed Description

This example prepares bAu @ mesoSiO ₂ by:

The method is characterized in that the synthesized gold nanoparticles are used as gold seeds to be synthesized and used in the next step (AuNPs), and the method specifically comprises the following steps: 37.5mL of 1% sodium citrate was added to 250mL of a boiling 1mM chloroauric acid solution, stirred for 15 minutes, and then allowed to stand for cooling. Filtering the cooled gold nanoparticle solution by using a 0.22 mu M filter head, mixing the filtered gold nanoparticle solution in a 0.1M Cetyl Trimethyl Ammonium Bromide (CTAB) solution, and finally centrifuging and concentrating at the room temperature at the speed of 7000 rpm/min;

Wrapping mesoporous silica (Au @ meso SiO ₂) on the surface of the gold nanoparticle, specifically, preparing 170mL of 6mM CTAB solution and 75mL of ethanol, stirring and mixing uniformly at 35 ℃, adding 5mL of 5mM gold nanoparticle, after stirring uniformly and stabilizing the temperature, adding 100 mu L of 25% ammonia water into the solution, after 5min, dropwise adding 180 mu L of Tetraethoxysilane (TEOS), reacting the final mixed solution in 45 ℃ warm water bath at the rotating speed of 600rpm/min for 24h under stirring, after the reaction is finished, pouring the solution into a centrifuge tube, centrifuging at the temperature of 25 ℃, the rotating speed of 9000rpm/min, removing the supernatant, performing ultrasonic centrifugal cleaning on the precipitate by using alcohol, repeating twice to remove the CTAB template, and obtaining the mesoporous silica wrapped gold nanoparticle;

Thirdly, growing a tree-shaped gold branch structure (bAu @ meso SiO ₂) on the surface of the gold nanoparticle on the basis of the gold nanoparticle coated by the mesoporous silica, specifically, growing the tree-shaped gold branch structure on the gold core coated by the mesoporous silica, namely, Au @ meso SiO ₂ is adopted as a gold seed, chloroauric acid is reduced on the surface of the gold core, in order to compare the target effect in SERS (surface enhanced Raman scattering) detection by comparing the lengths of different gold branches, the specific process is that four groups of 50 muL hydrochloric acid with the concentration of 1M and 50mL chloroauric acid with the concentration of 0.25mM are prepared, stirred and mixed for 5min, then, 500 muL silver nitrate with the concentration of 3mM and 1.389mL Au @ meso SiO ₂ solutions with the volume of 1.5mM are added into the four groups of solutions respectively, and the four groups of solutions react for 10min, the four groups of solutions are respectively removed, supernatant is obtained, the obtained, and the obtained precipitate is centrifuged to obtain final gold branches of which are washed twice by alcohol @ 46 ₂.

As shown in fig. 1, the transmission electron microscope pictures of the dendritic gold branch structures with different proportions in this embodiment prove that the mesoporous silica is coated on the surface of the gold particles, and the dendritic gold branch structures grow on the surface of the gold particles.

The different proportions are as follows: the proportions of the trivalent gold ions and the zero-valent gold are respectively 2, 2.5, 4 and 6, and the lengths of the gold branches are respectively: 14.5 +/-5 nm, 35 +/-10 nm, 50 +/-10 nm and 40 +/-10 nm.

As shown in FIG. 2, based on the synthesized dendritic gold-branched structure with different ratios, 4-bromomethcathinone aqueous solution samples with the concentration of 1.5mg/mL are detected, and the enhancement effect of bAu @ meso SiO ₂ -3 is best seen from Raman spectral lines, and then bAu @ meso SiO ₂ -2 and bAu @ meso SiO ₂ -4 are the second, while bAu @ meso SiO ₂ -1 has no enhancement effect, and black spectral lines represent Raman signals measured without enhancement materials, so that Raman signals of 4-bromomethcathinone aqueous solution samples with the concentration of 1.5mg/mL cannot be detected under the condition without enhancement materials, and three Raman peak signals appear under the enhancement effect of bAu @ meso SiO ₂ -3 materials, wherein the peak positions are respectively 1cm ^-1, 1585cm ^-1 and 1689cm ^-1.

By analyzing the peak positions of corresponding Raman signals, 1071cm ^-1 and 1689cm ^-1 can be attributed to the symmetric stretching vibration of C ═ O bonds, and 1585cm ^-1 is attributed to the cyclic C-C bond stretching vibration, and the peak positions are completely coincided with the chemical structure of 4-bromomethcathinone.

As shown in FIG. 3, a) shows the absorption curve of Au @ meso SiO ₂ in the visible light band, the absorption peak is located at about 550nm, b) is an infrared spectrum of Au @ meso SiO ₂, the infrared fingerprint peaks are 795cm ^-1, 950cm ^-1, 1076cm ^-1, 2851cm ^-1 and 2924cm ^-1, by carrying out corresponding peak position analysis on the infrared fingerprint peaks, the 795cm ^-1 and 950cm ^-1 are respectively derived from Si-O bond symmetric swing and Si-OH bond asymmetric swing, the 1076cm ^-1 is derived from Si-O-Si bond asymmetric stretching swing, and the infrared peak is enough to indicate that gold particles are wrapped by mesoporous silica, and the two infrared peaks of 2851cm ^-1 and 2924cm ^-1 are caused by CH symmetric stretching vibration and CH asymmetric stretching vibration in CTAB.

As shown in FIG. 4, the infrared peaks of bAu @ meso SiO ₂, of which two peaks 2851cm ^-1 and 2924cm ^-1 disappeared, indicated that CTAB was gradually removed during repeated washing with alcohol, and no CTAB remained in the final bAu @ meso SiO ₂ product.

the foregoing embodiments may be modified in many different ways by those skilled in the art without departing from the spirit and scope of the invention, which is defined by the appended claims and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.