A method for detecting natural dyes in textiles based on laser light reduction of silver nanoparticles surface-enhanced raman technology

Abstract

This invention provides a method for detecting natural dyes in textiles using surface-enhanced Raman spectroscopy (SERS) based on laser-reduced silver nanoparticles. The method involves pretreating dyed fibers with HF vapor, focusing a laser with a wavelength of 440–480 nm onto the fiber surface to generate a fixed silver nanoparticle substrate. This substrate is then used for SERS detection of natural dyes in the textiles. The silver nanoparticle substrate provided by this invention is directly fixed to the fiber under test, significantly enhancing the Raman detection signal of natural dyes in textiles. This method offers advantages such as simple operation, low cost, high sensitivity, and high analytical efficiency.

Description

Technical Field

[0001] This invention relates to the field of textile testing, and in particular to a method for detecting natural dyes in textiles based on surface-enhanced Raman spectroscopy using laser-reduced silver nanoparticles. Background Technology

[0002] Natural dyes generally originate from plants or insects. They are used to color fabrics through direct dyeing or the use of mordants, resulting in textiles with rich and vibrant colors. Natural dyes found in cultural relics and works of art contain a wealth of information, including the era of their creation, the source of their raw materials, the dyeing process, and their preservation status. To achieve a scientific understanding of natural dyes, cultural relic scientists have employed various methods to detect and analyze them in textiles. Currently, the most commonly used detection method is high-performance liquid chromatography (HPLC) and its coupled techniques. However, this technique requires large sample volumes and has limitations in detecting natural dyes in textiles where sampling is restricted.

[0003] Surface-enhanced Raman spectroscopy (SERS) is a derivative technique of Raman spectroscopy that can detect trace amounts of chemical substances and identify them based on their unique vibrational characteristics. As a non-destructive or minimally destructive analytical technique, it is increasingly used in the field of archaeological research due to its advantages such as high sensitivity, fast detection speed, small sample requirements, and ability to overcome fluorescence. It can also be used for the ultrasensitive detection of natural dyes in textiles.

[0004] The metal type, morphology, and structure of the SERS substrate largely determine the enhancement effect of Raman scattering. In the field of natural dye analysis and detection, the most common type of SERS substrate is nanoscale silver colloid, usually prepared by chemical reduction. However, silver nanoparticles in suspension have poor stability, resulting in limited enhancement and reproducibility of the SERS signal. Furthermore, when utilizing the SERS effect to enhance the Raman scattering of analytes, the analyte must be very close to the surface of the SERS substrate (within a few nanometers) or directly adsorbed on the surface; otherwise, the SERS phenomenon will not occur. To address these technical challenges, this invention utilizes a laser photoreduction method to prepare a silver nanoparticle SERS substrate in situ on the dyed fibers to be detected, significantly enhancing the plasma effect that generates surface enhancement phenomena. Compared with conventional methods, this invention offers the advantages of speed and simplicity. Summary of the Invention

[0005] The purpose of this invention is to provide a method for detecting natural dyes in textiles based on surface-enhanced Raman spectroscopy using laser-reduced silver nanoparticles, offering a simple, rapid, sensitive, and inexpensive method for the detection and analysis of natural dyes.

[0006] The specific technical solution of this invention is: a method for detecting natural dyes in textiles based on surface-enhanced Raman spectroscopy using laser-induced reduction of silver nanoparticles, comprising the following steps:

[0007] (1) Pretreatment of modern dyed fibers with known dye composition by HF vapor to generate fixed silver nanoparticles on the fibers.

[0008] (2) SERS spectra were collected on natural dyes in modern dyed fibers to establish a natural dye spectrum library;

[0009] (3) The archaeological fiber samples to be tested were pretreated with HF vapor to generate fixed silver nanoparticles on the fibers.

[0010] (4) The natural dyes in the archaeological fiber samples were collected by SERS spectroscopy and compared with the spectrum of modern dyed fibers obtained in step (2) to obtain the dye composition.

[0011] As a preferred embodiment of the present invention, step (1) includes the following steps:

[0012] 1.1) Clean the grooved slides and coverslips with anhydrous ethanol and Milli-Q water;

[0013] 1.2) After pretreatment in the HF reaction chamber, the modern dyed fibers are removed, air-dried, and then fixed to a coverslip with tape.

[0014] 1.3) Add silver nitrate aqueous solution to the groove of the slide, and cover the slide with the coverslip from step 1.2) facing down;

[0015] 1.4) Focus the light reduction laser onto the fiber surface to generate silver nanoparticles attached to the fiber; remove the coverslip and thoroughly clean the fiber several times with Milli-Q water.

[0016] Furthermore, in step 1.2), the amount of fiber used is at least one fiber with a length of 10-15 mm; the pretreatment time is 10 min; in step 1.3), the concentration of silver nitrate is 0.1 mol / L; in step 1.4), the wavelength of the photoreduction laser is 450 nm, the power is 2-4 mW, and the irradiation time is 4-10 min.

[0017] For photoreduction lasers, blue light with a wavelength of 440–480 nm should be selected whenever possible. In experiments exploring the optimal wavelength for photoreduction lasers, our team discovered that when using lasers above 480 nm, the lower photon energy increases the irradiation time required to achieve the same SERS enhancement effect, reducing substrate preparation efficiency. Simultaneously, the laser power needs to be controlled at 2–4 mW. Below 2 mW, it is difficult to form effective silver nanoparticles, while excessively high power may cause thermal damage to the fibers, affecting the detection results. Irradiation time has a significant impact on the morphology of silver nanoparticles and needs to be controlled between 4 and 10 minutes. Irradiation time is positively correlated with the SERS enhancement effect; for blue lasers, irradiation time exceeding 10 minutes will not result in a significant further increase in SERS intensity.

[0018] As a preferred embodiment of the present invention, step (2) specifically involves: cleaning the grooved slide and coverslip with anhydrous ethanol and Milli-Q water; adding Milli-Q water to the groove of the slide; placing the coverslip with the fiber fixed in step (1) downwards onto the slide; and collecting SERS spectra of the fiber; changing the type of dyed fiber and repeating the above steps to establish a spectrum library of each natural dye.

[0019] As a preferred embodiment of the present invention, in step (3), the specific steps are as follows: cleaning the grooved glass slide and coverslip with anhydrous ethanol and Milli-Q water; placing the archaeological fiber sample to be tested in the HF reaction chamber for pretreatment and then taking it out, and generating fixed silver nanoparticles on the fiber using the same method as in step (1).

[0020] As a preferred embodiment of the present invention, the specific steps in step (4) are as follows: clean the grooved slide and coverslip with anhydrous ethanol and Milli-Q water; add Milli-Q water to the groove of the slide, place the coverslip with the fiber fixed in step (3) downward on the slide, and collect the SERS spectrum of the fiber; compare it with the spectrum of modern dyed fiber obtained in step (2) to obtain the dye composition.

[0021] As a preferred embodiment of the present invention, in steps (2) and (4), the SERS spectral acquisition parameters are set as follows: excitation wavelength 532 nm, energy 0.5 mW, and scanning range 300-1800 cm⁻¹. -1 The integration time is 10 seconds, and the average value is taken after three integrations.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] (1) This invention uses laser-induced reduction of silver nitrate solution without the use of additional reducing agents, resulting in cleaner and more stable silver nanoparticles. The silver nanoparticle substrate provided by this invention can be prepared in situ at the desired location, which is simple to operate, low in cost, highly sensitive, and highly efficient in analysis.

[0024] (2) This invention constructs a surface-enhanced Raman technology detection and analysis method for natural dyes in textiles, which directly generates a fixed silver nanoparticle substrate on the fiber to be tested, thereby significantly enhancing the Raman detection signal of natural dyes in textiles. Attached Figure Description

[0025] Figure 1 SEM image of silver nanoparticles prepared in situ on fibers using laser photoreduction method.

[0026] Figure 2 The image shows the SERS spectrum of madder dyed fibers from Xinjiang. The values ​​marked on the image are 341, 394, 419, 448, 472, 579, 629, 659, 680, 759, 813, 897, 962, 1014, 1046, 1064, 1157, 1185, 1207, 1259, 1287, 1321, 1422, 1475, 1552, 1581, and 1601 cm⁻¹. -1 These are the characteristic SERS peaks of natural dyes extracted from madder fibers dyed in Xinjiang.

[0027] Figure 3 Comparison of SERS spectra of Xinjiang madder-dyed fibers on SERS substrates prepared by two different lasers. Figure 3 (a) Substrate fabricated using a 532nm laser Figure 3 (b) The substrate was prepared using a 450nm laser.

[0028] Figure 4 The image shows the SERS spectrum of indigo-dyed fibers. The values ​​marked on the image are 484, 532, 547, 574, 611, 669, 724, 750, 935, 962, 1005, 1100, 1169, 1204, 1225, 1258, 1302, 1355, 1396, 1456, 1493, 1588, and 1604 cm⁻¹. -1 These are the characteristic peaks of SERS from natural dyes extracted from indigo-dyed fibers.

[0029] Figure 5 The image shows the SERS spectrum of dyed Phellodendron amurense fibers, with the following values ​​marked: 453, 735, 978, 1093, 1151, 1219, 1295, 1324, 1441, 1502, 1544, and 1629 cm⁻¹. -1 These are the characteristic SERS peaks of natural dyes extracted from Phellodendron amurense dyed fibers.

[0030] Figure 6The image shows the SERS spectrum of fiber from an artifact unearthed in Ruoqiang, Xinjiang (artifact number BZ:3190-red). The values ​​marked on the image are 344, 397, 424, 451, 475, 585, 633, 662, 683, 762, 818, 901, 966, 1019, 1040, 1070, 1160, 1188, 1221, 1288, 1326, 1425, 1478, 1554, 1581, and 1604 cm⁻¹. -1 The characteristic peaks of the natural dye extracted from the BZ:3190-red sample are similar to those of the BZ:3190-red sample. Figure 2 By comparing the characteristic peaks of the Xinjiang madder dyed fibers, it can be concluded that the BZ:3190-red sample was dyed with Xinjiang madder (due to the influence of dyeing method, HF treatment and other factors, a few wavenumber shifts are considered reasonable).

[0031] Figure 7 The image shows the SERS spectrum of fiber from an artifact unearthed in Ruoqiang, Xinjiang (artifact number BZ:3190-blue). The values ​​marked on the image are 645, 727, 926, 1165, 1204, 1247, 1347, 1393, and 1458 cm⁻¹. -1 The characteristic peaks of the natural dye extracted from the BZ:3190-blue sample are similar to those of the blue sample. Figure 3 By comparing the characteristic peaks of the indigo-dyed fibers, it can be concluded that the BZ:3190-blue sample was dyed with indigo (due to the influence of dyeing method, HF treatment and other factors, a few wavenumber shifts are considered reasonable).

[0032] Figure 8 The image shows the SERS spectrum of fiber from an artifact unearthed in Ruoqiang, Xinjiang (artifact number BZ:3200). The values ​​marked on the image are 456, 736, 1096, 1221, 1292, 1332, 1450, 1498, 1549, and 1626 cm⁻¹. -1 The characteristic peaks of the natural dye extracted from the BZ:3200 sample are similar to those of the BZ:3200 sample. Figure 4 By comparing the characteristic peaks of the dyed fibers of Phellodendron chinense, it can be concluded that the BZ:3200 sample was dyed with Phellodendron chinense (due to the influence of dyeing method, HF treatment and other factors, a few wavenumber shifts are considered reasonable). Detailed Implementation

[0033] This invention provides a method for detecting natural dyes in textiles based on surface-enhanced Raman spectroscopy using laser-induced reduction of silver nanoparticles. The embodiments of this invention are described in detail below, providing detailed implementation methods and specific operating procedures. However, the scope of protection of this invention is not limited to the following embodiments.

[0034] Example 1:

[0035] This embodiment tests the dyed fibers of Xinjiang madder.

[0036] A 10mm long Xinjiang madder dyed fiber was placed in an HF reaction chamber for pretreatment for 10 minutes, then removed and air-dried. The fiber was then fixed to a coverslip with tape. A 0.1mol / L silver nitrate aqueous solution was added to the groove of a glass slide. The coverslip with the fiber fixed to be tested was placed face down on the glass slide. A 450nm wavelength light-reduction laser was focused onto the fiber surface for 4 minutes at a laser power of 2.5mW, generating silver nanoparticles on the fiber surface. Figure 1 Remove the coverslip and thoroughly clean the fibers several times with Milli-Q water.

[0037] Milli-Q water was added to the groove of a glass slide. A coverslip containing madder root dyed fibers was placed face down on the slide, and SERS spectra were acquired on the fibers. The SERS spectra were set as follows: excitation wavelength 532 nm, energy 0.5 mW, and scan range 300-1800 cm⁻¹. -1 The integration time is 10 seconds, and the average value is taken after three integrations.

[0038] Figure 2 The image shows the SERS spectrum of madder dyed fibers from Xinjiang. The values ​​marked on the image are 341, 394, 419, 448, 472, 579, 629, 659, 680, 759, 813, 897, 962, 1014, 1046, 1064, 1157, 1185, 1207, 1259, 1287, 1321, 1422, 1475, 1552, 1581, and 1601 cm⁻¹. -1 These are the characteristic SERS peaks of natural dyes extracted from madder fibers dyed in Xinjiang.

[0039] Example 2:

[0040] Xinjiang madder dyed fibers were pretreated according to the method in Example 1; a light reduction laser with a wavelength of 532 nm was focused on the fiber surface for 20 min and the laser power was 2.5 mW to generate silver nanoparticles on the fiber surface; the coverslip was removed and the fibers were thoroughly washed several times with Milli-Q water; SERS spectra were acquired according to the method in Example 1.

[0041] Figure 3 Comparison of SERS spectra of Xinjiang madder dyed fibers on substrates prepared by two different lasers. The 532nm laser substrate requires a longer irradiation time (20 min) to achieve the same SERS enhancement as the 450nm laser substrate, resulting in lower preparation efficiency. Figure 3 (a) 600-900cm -1 The characteristic peaks of Xinjiang madder were lower, and the number of characteristic peaks was relatively smaller compared to other plants. Figure 3(b) Less.

[0042] Example 3:

[0043] This embodiment tests indigo-dyed fibers.

[0044] Indigo-dyed fibers were pretreated according to the method in Example 1 to prepare silver nanoparticles and SERS spectra were collected.

[0045] Figure 4 The image shows the SERS spectrum of indigo-dyed fibers. The values ​​marked on the image are 484, 532, 547, 574, 611, 669, 724, 750, 935, 962, 1005, 1100, 1169, 1204, 1225, 1258, 1302, 1355, 1396, 1456, 1493, 1588, and 1604 cm⁻¹. -1 These are the characteristic peaks of SERS from natural dyes extracted from indigo-dyed fibers.

[0046] Example 4:

[0047] This embodiment tests the dyed fibers of Phellodendron amurense.

[0048] Pretreatment of Phellodendron amurense dyed fibers was performed according to the method in Example 1 to prepare silver nanoparticles and SERS spectra were collected.

[0049] Figure 5 The image shows the SERS spectrum of dyed Phellodendron amurense fibers, with the following values ​​marked: 453, 735, 978, 1093, 1151, 1219, 1295, 1324, 1441, 1502, 1544, and 1629 cm⁻¹. -1 These are the characteristic SERS peaks of natural dyes extracted from Phellodendron amurense dyed fibers.

[0050] Example 5:

[0051] This embodiment involves the testing and analysis of archaeological fiber samples (artifact numbers BZ:3190-red, BZ:3190-blue, BZ:3200) unearthed in Ruoqiang, Xinjiang.

[0052] Four types of archaeological fiber samples were pretreated according to the method in Example 1, silver nanoparticles were prepared, and SERS spectra were collected.

[0053] Figure 6The image shows the SERS spectrum of an archaeological fiber sample (artifact number BZ:3190-red), with the following values ​​marked: 344, 397, 424, 451, 475, 585, 633, 662, 683, 762, 818, 901, 966, 1019, 1040, 1070, 1160, 1188, 1221, 1288, 1326, 1425, 1478, 1554, 1581, and 1604 cm⁻¹. -1 The characteristic peaks of the natural dye extracted from the BZ:3190-red sample are similar to the characteristic peaks of the Xinjiang madder dyed fiber in Example 1. Figure 2 By comparison, it can be concluded that the BZ:3190-red sample was stained with madder root from Xinjiang (due to the influence of staining method, HF treatment and other factors, a few wavenumber shifts are considered reasonable).

[0054] Figure 7 The image shows the SERS spectrum of an archaeological fiber sample (artifact number BZ:3190-blue), with the following values ​​marked: 645, 727, 926, 1165, 1204, 1247, 1347, 1393, and 1458 cm⁻¹. -1 The characteristic peaks of the natural dye extracted from the 1186-blue sample are similar to the characteristic peaks of the indigo-dyed fibers in Example 3. Figure 4 By comparison, it can be concluded that the BZ:3190-blue sample was stained with indigo (due to the influence of staining method, HF treatment and other factors, a few wavenumber shifts are considered reasonable).

[0055] Figure 8 The image shows the SERS spectrum of an archaeological fiber sample (artifact number BZ:3200), with the following values ​​marked: 456, 736, 1096, 1221, 1292, 1332, 1450, 1498, 1549, and 1626 cm⁻¹. -1 The characteristic peaks of the natural dye extracted from the BZ:3200 sample are similar to the characteristic peaks of the Phellodendron amurense dyed fiber in Example 4. Figure 5 By comparison, it can be concluded that the BZ:3200 sample was stained with Phellodendron bark (due to the influence of staining method, HF treatment and other factors, a few wavenumber shifts are considered reasonable).

[0056] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A method for detecting natural dyes in textiles based on surface-enhanced Raman spectroscopy using laser-reduced silver nanoparticles, characterized in that... Includes the following steps: (1) Pretreatment of modern dyed fibers with known dye compositions using HF vapor to generate fixed silver nanoparticles on the fibers; specifically including: 1.1) Clean the grooved slides and coverslips with anhydrous ethanol and Milli-Q water; 1.2) After pretreatment in the HF reaction chamber, the modern dyed fiber is removed, air-dried, and fixed to the coverslip with tape; at least one fiber is used, with a length of 10-15 mm; the pretreatment time is 8-12 min. 1.3) Add a silver nitrate aqueous solution with a concentration of 0.08~0.12 mol / L to the groove of the slide, and cover the slide with the coverslip from step 1.2) facing down; 1.4) Focus the photoreduction laser onto the fiber surface to generate silver nanoparticles attached to the fiber; remove the coverslip and thoroughly clean the fiber several times with Milli-Q water; the wavelength of the photoreduction laser is 440~480 nm, the power is 2~4 mW, and the irradiation time is 4~10 min. (2) SERS spectra were collected from natural dyes in modern dyed fibers to establish a spectral library of each natural dye; (3) The archaeological fiber samples to be tested were pretreated with HF vapor to generate fixed silver nanoparticles on the fibers. (4) The natural dyes in the archaeological fiber samples were collected by SERS spectroscopy and compared with the spectrum of modern dyed fibers obtained in step (2) to obtain the dye composition.

2. The method as described in claim 1, characterized in that: The specific steps of step (2) are as follows: Clean the grooved slide and coverslip with anhydrous ethanol and Milli-Q water; add Milli-Q water to the groove of the slide, place the coverslip with the fiber fixed in step (1) on the slide downwards, and collect the SERS spectrum of the fiber; change the type of dyed fiber and repeat the above steps to establish a spectrum library of each natural dye.

3. The method as described in claim 1, characterized in that: The specific steps of step (3) are as follows: Clean the grooved slide and coverslip with anhydrous ethanol and Milli-Q water; after pretreatment in the HF reaction chamber, the archaeological fiber sample to be tested was taken out and fixed silver nanoparticles were generated on the fiber using the same method as in step (1).

4. The method as described in claim 3, characterized in that: The specific steps of step (4) are as follows: Clean the grooved slide and coverslip with anhydrous ethanol and Milli-Q water; add Milli-Q water to the groove of the slide, place the coverslip with the fiber fixed in step (3) on the slide downwards, and collect the SERS spectrum of the fiber; compare it with the spectrum of modern dyed fiber obtained in step (2) to obtain the dye composition.

5. The method as described in claim 4, characterized in that: In steps (2) and (4), the SERS spectral acquisition parameters are set as follows: excitation wavelength 532 nm, energy 0.5 mW, and scan range 300-1800 cm⁻¹. -1 The integration time is 10 seconds, and the average value is taken after three integrations.

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