Application of MOF-818, an anti-ultraviolet material for silk fabrics

Abstract

The present invention discloses a method for preparing a silk fabric UV-blocking material, MOF-818, comprising the following steps: 1) dissolving 84.0-86.0 mg of ZrOCl₂∙8H₂O, 246.0-248.0 mg of Cu(NO₃)₂∙3H₂O, and 64.0-66.0 mg of H₂PyC in 9-11 mL of DMF, sequentially dissolving the resulting mixture into a solution containing 118-121 μL of TFA, heating the mixture to 100°C for 10 hours, cooling the mixture, and centrifuging the mixture at 10,000 rpm for 10 minutes to collect the resulting product; and 2) soaking the resulting product in DMF, solvent-exchanging the solution with DMF, and soaking it in acetone five times daily, followed by vacuum drying at room temperature to obtain MOF-818. The invention has the following beneficial effects: high operability and protective effects on silk fabrics.

Description

Technical Field

[0001] The invention relates to the technical field of silk fabric protection materials, and in particular to application of silk fabric ultraviolet protection material MOF-818. Background Art

[0002] Silk fibers are natural polymers, but their protein properties make them susceptible to degradation by ultraviolet light, causing them to turn yellow, brittle, decay, and even powder. The presence of oxygen is often the primary cause of polymer degradation, with oxidative degradation being the primary effect of polymers exposed to air. UV radiation produces free radicals that exacerbate the effects of light, heat, and other factors on polymers, leading to more complex degradation and crosslinking reactions. In recent years, the ozone layer has been severely damaged, significantly increasing the amount of ultraviolet radiation reaching the ground. Silk, a protein-based polymer, is susceptible to degradation and aging from UV light. Therefore, research on the UV protection of silk fabrics has attracted considerable attention.

[0003] Silk fibers have poor light resistance. Sunlight not only breaks hydrogen bonds within the silk fibroin but also promotes photooxidation. When silk fibroin absorbs energy from the irradiated light source, the chemical bonds within the molecules reach dissociation energy and break, disrupting the silk structure. In particular, when tertiary carbon atoms are present in the peptide chain, photochemical reactions are highly susceptible to generating free radicals under UV light. These free radicals cause discrete degradation of the peptide chains, breaking the silk fiber's peptide chains and leading to a decrease in the mechanical properties and color change of the silk fabric. This damage to the silk fibroin continues even after the light exposure ceases.

[0004] For decades, people have been committed to studying the aging mechanism of silk and looking for ways to overcome it through research. Silk cultural relics have been buried underground for a long time and are rarely exposed to sunlight. After being unearthed, they are suddenly exposed to ultraviolet rays from the sun and their damage is aggravated. Therefore, the research on UV-proof materials has become very important. Single-atom catalyst MOF-818, as a new type of nanomaterial, has a low coordination number, a special coordination environment, extremely high atomic utilization, and highly uniform catalytic sites. It is a bridge between homogeneous and traditional heterogeneous catalysts. Studies have found that single-atom catalysts exhibit excellent catalytic activity and can effectively decompose dissolved oxygen or reactive oxygen free radicals. This feature can be used in the research on antioxidant protection of silk cultural relics. Summary of the Invention

[0005] The purpose of the present invention is to provide an application of a silk fabric anti-ultraviolet material MOF-818, which has a simple operation method, low processing and manufacturing cost, strong operability, and good protective effect on silk fabrics.

[0006] The application of the silk fabric anti-ultraviolet material MOF-818 of the present invention is used for protecting silk fabrics. The preparation method of the anti-ultraviolet material MOF-818 comprises the following steps:

[0007] 1) 84.0-86.0 mg of ZrOCl2∙8H2O, 246.0-248.0 mg of Cu(NO3)2∙3H2O, and 64.0-66.0 mg of H2PyC were dissolved in 9-11 mL of DMF, followed by ultrasonication to obtain a homogeneous mixed solution. 118-121 μL of TFA was then added to the mixed solution, which was heated at 100°C for 10 h. After cooling to room temperature, the mixture was centrifuged at 10,000 rpm for 10 min to collect the resulting product.

[0008] 2) The product obtained in step 1) was soaked in DMF for 3 days, during which the solvent was exchanged 5 times per day with fresh DMF, and then soaked in acetone for 4 days, 5 times per day. Finally, the sample was vacuum dried at room temperature to obtain MOF-818.

[0009] The application of MOF-818, an anti-ultraviolet material for silk fabrics, comprises the following steps:

[0010] 1) Mix the synthesized MOF-818 material in deionized water to prepare a 5 mg / ml solution. Add the MOF-818 powder to the deionized water and mix well.

[0011] 2) Pour the solution prepared in step 1) into a spray bottle, spray the MOF-818 material aqueous solution onto the surface of the silk fabric using the spray bottle, and spread it flat to dry;

[0012] 3) The silk fabric sprayed with MOF-818 material was placed in a UV aging chamber irradiated with a 340nm ultraviolet wavelength for 20 days; at the same time, the silk fabric sample block that had not been treated was also placed in a UV aging chamber irradiated with a 340nm ultraviolet wavelength.

[0013] In step 3), the temperature and humidity of the UV aging box are set to 25°C and 65% respectively.

[0014] Beneficial effects of the present invention:

[0015] MOF-818, a novel nanomaterial, boasts a low coordination number, a unique coordination environment, extremely high atomic utilization, and highly uniform catalytic sites, serving as a bridge between homogeneous and traditional heterogeneous catalysts. Based on its excellent catalytic activity, single-atom catalysts can efficiently decompose dissolved oxygen and reactive oxygen radicals. This can eliminate free radicals generated by ultraviolet radiation on silk fabrics, inhibiting free radical chain growth reactions and effectively protecting silk fabrics. This is of great significance for the UV protection of silk fabrics in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a transmission electron microscopy (TEM) image of MOF-818 of the present invention;

[0017] Figure 2 This is the X-ray diffraction pattern of MOF-818 of the present invention;

[0018] Figure 3 This is the MOF-818HAADF-STEM image of the present invention;

[0019] Figure 4 This is a diagram of the SOD-like enzyme activity of MOF-818 of the present invention;

[0020] Figure 5 This is a graph showing the relationship between MOF-818 concentration and SOD-like enzyme activity;

[0021] Figure 6 This is a scanning electron microscope image (SEM) of MOF-818 in the present invention;

[0022] Figure 7 The XPS photoelectron spectrum of MOF-818 in the present invention;

[0023] Figure 8 is the EDX spectrum of MOF-818 in the present invention;

[0024] Figure 9 This is a high-resolution image of the C 1s XPS spectrum of MOF-818 in the present invention;

[0025] Figure 10 This is a high-resolution image of the O 1s XPS spectrum of MOF-818 in the present invention;

[0026] Figure 11 This is a high-resolution image of the N 1s XPS spectrum of MOF-818 in the present invention.

[0027] Figure 12 is the infrared absorption graph of MOF-818 in the present invention;

[0028] Figure 13This is a high-resolution image of the Cu 2p XPS spectrum of MOF-818 in the present invention;

[0029] Figure 14 This is a high-resolution image of the Zr 3d XPS spectrum of MOF-818 in the present invention;

[0030] Figure 15 is the Brunauer-Emmet-Teller (BET) surface area of ​​MOF-818 in the present invention;

[0031] Figure 16 This is the pore size distribution diagram of MOF-818 in the present invention;

[0032] Figure 17 This is a color difference diagram of the silk fabric of the present invention before and after protection with MOF-818;

[0033] Figure 18 This is a surface electron microscopy (SEM) image of the unaged silk fabric of the present invention;

[0034] Figure 19 This is a surface electron microscope (SEM) image of the silk fabric of the present invention after aging;

[0035] Figure 20 This is a surface electron microscope (SEM) image of the silk fabric of the present invention after being protected by MOF-818;

[0036] Figure 21 IR spectra of different samples in the present invention;

[0037] Figure 22 This is the X-ray diffraction pattern of the same sample in the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings.

[0039] The application of the silk fabric anti-ultraviolet material MOF-818 of the present invention is used for protecting silk fabrics. The preparation method of the anti-ultraviolet material MOF-818 comprises the following steps:

[0040] 1) 85.0 mg of ZrOCl2∙8H2O, 248.0 mg of Cu(NO3)2∙3H2O, and 65.0 mg of H2PyC were dissolved in 10 mL of DMF, followed by ultrasonication to obtain a homogeneous mixed solution. 120 μL of TFA was then added to the mixed solution, which was heated at 100°C for 10 h. After cooling to room temperature, the mixture was centrifuged at 10,000 rpm for 10 min to collect the resulting product.

[0041] 2) The product obtained in step 1) was soaked in DMF for 3 days, during which the solvent was exchanged with fresh DMF 5 times per day, and then soaked in acetone for 4 days, 5 times per day. Finally, the sample was vacuum-dried at room temperature to obtain MOF-818.

[0042] Among them: TEM image of MOF-818, Figure 1 and the corresponding element map images Figure 3 It shows that Zr, N, O, and Cu are evenly distributed in the selected area, showing an octahedral structure; the X-ray diffraction pattern, i.e. Figure 2 As shown, the peaks at 3.01, 4.91, 5.99 and 6.89 correspond to the crystal structures of 111, 220, 222 and 400 faces, respectively. This indicates that MOF-818 was successfully prepared. We further used a SOD detection kit to study the SOD-like activity of MOF-818, and detected it at about 450nm using a UV-visible spectrophotometer. When MOF-818-like was added to the system, it reacted with O2•- to produce hydrogen peroxide (H2O2) and oxygen (O2). As shown Figure 2 As shown in Figure 2, MOF-818 exhibited excellent SOD-like enzyme activity, and as the concentration of MOF-818 increased from 0.1 ug / mL to 10 ug / mL, the activity also increased. Figure 5 shown.

[0043] The application of MOF-818, an anti-ultraviolet material for silk fabrics, comprises the following steps:

[0044] 1) Mix the synthesized MOF-818 material in deionized water to prepare a 5 mg / ml solution. Add the MOF-818 powder to the deionized water and mix well.

[0045] 2) Pour the solution prepared in step 1) into a spray bottle, spray the MOF-818 material aqueous solution onto the surface of the silk fabric using the spray bottle, and spread it flat to dry;

[0046] 3) The silk fabric sprayed with MOF-818 material was placed in a UV aging chamber irradiated with a 340nm ultraviolet wavelength for 20 days; at the same time, the silk fabric sample block that had not been treated was also placed in a UV aging chamber irradiated with a 340nm ultraviolet wavelength.

[0047] In step 4), the temperature and humidity of the UV aging box are set to 25°C and 65% respectively.

[0048] The following is an evaluation of the protective effect of the single-atom catalyst MOF-818 on the color change and degradation degree of silk fabrics after ultraviolet irradiation using color difference, infrared, and diffraction methods;

[0049] 1) Color difference test

[0050] The silk fabric was tested for color difference before application (select three areas), and then the color difference test was performed (in the same area), and then ∆E was calculated. Figure 17 As shown, the calculation formula is as follows: ∆L, ∆a, and ∆b are the differences in L, a, and b before and after measurement, respectively. The color difference change in silk treated with MOF-818 is smaller than that of untreated silk, demonstrating that the protective agent plays a key role in UV protection. Silk is a natural polymer fiber, but its protein nature makes it susceptible to UV light and photochemical reactions. In particular, when tertiary carbons are present in the peptide chain, photochemical reactions can easily produce free amino acids and yellow substances, which can alter the color of silk fibers and ultimately lead to color changes. MOF-818 catalyzes free radicals such as O₂•- produced during the reaction, reducing UV damage to silk.

[0051] 2) Morphology analysis

[0052] Depend on Figure 18 It can be seen that the surface of the silk fabric sample that has not been aged is smooth. Except for a few places, the overall thickness is relatively uniform, without obvious fractures or cracks. The sample that has been light aged for 200 hours has a smooth surface. Figure 19 As shown in the figure, cracks in the same direction as the fiber axis have appeared on the surface of the sample, and some fibers have split, indicating that some silk fabrics have aged. The sample of silk fabric treated with MOF-818 and aged for 200 hours has Figure 20 As shown in the figure, there are no obvious cracks and fractures on the surface of the sample, which indicates that MOF-818 has a certain protective effect on silk fibers under ultraviolet radiation.

[0053] 3) Infrared analysis

[0054] Table 1 Infrared characteristic absorption bands of test samples

[0055]

[0056] By using infrared spectroscopy to test blank samples, aged samples after MOF-818 treatment, and pure aged samples, it was found that all samples showed characteristic absorption bands of protein fibers. Figure 21As shown, there are absorption bands at around 3270 cm-1 for -NH stretching vibration, amide I, II, and III bands at 1620 cm-1, 1512 cm-1, and 1230 cm-1, and amide IV band at 1060 cm-1. Among them, the amide I band at 1620 cm-1 belongs to β-sheets, and the amide III band at 1230 cm-1 belongs to random coils and α-helices. At the same time, strong absorption peaks appear at 2930 cm-1, 1440 cm-1, and 1160 cm-1. Overall, the sample tested meets the infrared spectral characteristics of silk fibers and is determined to be silk fiber.

[0057] As shown in Table 1, the absorption peak near 3270 cm⁻¹ of both the aged and pure MOF-818-treated samples is slightly higher than that of the blank sample. However, the absorption peak of the amide II band is slightly weakened after aging. The aging treatment of the tested samples damages the silk fibroin molecules to a certain extent, disrupting some hydrogen bonds and resulting in a decrease in the -NH peak that forms hydrogen bonds. Overall, the shift of the aged samples treated with MOF-818 is smaller than that of the pure aged samples, indicating that MOF-818 plays a certain protective role against the aging of silk fabrics, preserving the molecular structure of silk fibroin fibers.

[0058] 4) Diffraction analysis

[0059] Table 2 Correlation values ​​of X-ray diffraction patterns of different samples

[0060]

[0061] The blank sample, the aged sample after MOF-818 treatment and the pure aged sample were analyzed by X-ray diffraction. Figure 22 Comparative tests, as shown in Figure 2 and Table 2, revealed that after aging, the pure aged sample had the highest crystallinity. The crystallinity of the aged sample treated with MOF-818 increased slightly, but was lower than that of the pure aged sample. When silk fibers age and degrade, the amorphous regions degrade first, leading to an increase in crystallinity. However, with increased aging time and degradation, the crystalline regions begin to degrade, weakening their spatial arrangement and ultimately decreasing crystallinity. These results indicate that applying MOF-818 can, to a certain extent, slow the aging rate of silk when exposed to UV radiation.

[0062] 5) Amino acid analysis

[0063] Silk fabrics are primarily composed of glycine and alanine, followed by serine and tyrosine. Aspartic acid, glutamine, threonine, and isoleucine are present in smaller amounts. Comparing the amino acid content of blank samples, aged samples treated with MOF-818, and pure aged samples before and after aging revealed that glycine, located in the β-pleated region, and alanine, located in the crystalline region of silk fibers, both decrease in content after aging. Serine, primarily found in sericin, while tyrosine and phenylalanine, primarily found in the amorphous region, experience the most significant decreases in their content during aging.

[0064] Tyrosine, an aromatic substance, is easily oxidized by heat. Its side groups are sterically hindered, primarily in the amorphous region, making them more susceptible to loss. This significantly reduces tyrosine content before and after aging. The ratio of glycine to tyrosine content shows that the Gly / Tyr ratio increases from 3.603 to 3.744 before and after aging, while the ratio after MOF-818 treatment is 3.741. This increase in the ratio indicates that the content of large side amino acids in the aged samples decreases, and MOF-818 treatment can effectively slow the aging process of silk fibers.

[0065] Table 3 Amino acid content of different samples during aging

[0066]

Claims

1. The application of MOF-818, an anti-ultraviolet material for silk fabrics, is characterized by: The preparation method of MOF-818, an anti-ultraviolet material for protecting silk fabrics, comprises the following steps: 1) 84.0-86.0 mg of ZrOCl2∙8H2O, 246.0-248.0 mg of Cu(NO3)2∙3H2O, and 64.0-66.0 mg of H2PyC were dissolved in 9-11 mL of DMF, followed by ultrasonication to obtain a homogeneous mixed solution. 118-121 μL of TFA was then added to the mixed solution, which was heated at 100°C for 10 h. After cooling to room temperature, the mixture was centrifuged at 10,000 rpm for 10 min to collect the resulting product. 2) The product obtained in step 1) was soaked in DMF for 3 days, during which the solvent was exchanged 5 times per day with fresh DMF, and then soaked in acetone for 4 days, 5 times per day. Finally, the sample was vacuum dried at room temperature to obtain MOF-818.

2. The use of the silk fabric anti-ultraviolet material MOF-818 as claimed in claim 1, characterized in that: The application method comprises the following steps: 1) Mix the synthesized MOF-818 material in deionized water to prepare a 5 mg / ml solution. Add the MOF-818 powder to the deionized water and mix well. 2) Pour the solution prepared in step 1) into a spray bottle, spray the MOF-818 material aqueous solution onto the surface of the silk fabric using the spray bottle, and spread it flat to dry; 3) The silk fabric sprayed with MOF-818 was placed in a UV aging chamber irradiated with a 340nm UV wavelength for 20 days. At the same time, untreated silk fabric samples were also placed in a UV aging chamber irradiated with a 340nm UV wavelength.

3. The use of the ultraviolet protection material MOF-818 for silk fabrics according to claim 2, characterized in that: In step 3), the temperature and humidity of the UV aging box are set to 25°C and 65% respectively.

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