Novel method for biomimetic synthesis of amino acid surfactant by oxidizing natural polyphenol with nano enzyme
By using nanoflowers and salt hydrates to catalyze the formation of quinone from ethyl caffeate in butyl acetate at room temperature and pressure, and then reacting it with leucine, a high-purity, biosafe amino acid surfactant was prepared. This solved the problem of low catalytic activity of tyrosinase in organic solvents, and achieved a simple and efficient preparation process with excellent surface properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SICHUAN UNIV
- Filing Date
- 2024-10-09
- Publication Date
- 2026-04-10
AI Technical Summary
In existing technologies, tyrosinase has low catalytic activity in organic solvents, which means that bisphenol substrate reactions must be carried out in organic solvents, limiting the application of nanoflowers in organic phases and resulting in long synthesis times.
A quinone was generated by catalyzing the production of ethyl caffeate dissolved in butyl acetate using nanoflowers and hydrates at room temperature and pressure. The quinone was then refluxed with leucine to prepare an amino acid surfactant. The BSA-Cu3(PO4)2 hybrid nanoflowers were used to simulate the catalytic action of tyrosinase.
It simplifies the preparation process, reduces costs, shortens time, improves the purity and biosafety of the target product, and optimizes surface properties.
Smart Images
Figure FT_1 
Figure FT_2 
Figure FT_3
Abstract
Description
Technical Field
[0001] This invention relates to the fields of nanomaterials and fine chemicals, specifically to a novel method for preparing a biomimetic amino acid surfactant by oxidizing natural polyphenols with nanoenzymes. Background Technology
[0002] Amino acid surfactants, due to their low toxicity, mild properties, and low irritation, have broad development prospects in cosmetics, daily detergents, and pharmaceuticals. Inspired by the reaction of dopaquinone with amino groups in the melanin production pathway, melanin-like amino acid surfactants, using o-benzoquinone compounds as the hydrophobic module and amino acids as the hydrophilic module, possess advantages such as novel structure, excellent performance, diverse functions, safe application, and green processing, attracting widespread attention. Due to the instability of quinones and their low abundance in nature, the synthetic reaction must begin with bisphenols. However, the water insolubility of bisphenol substrates and the instability of quinones in water necessitate that the reaction be carried out in organic solvents. This excludes the possibility of using tyrosinase as a catalyst, as the catalytic activity of tyrosinase in organic solvents is 2 to 5 orders of magnitude lower than its catalytic activity in aqueous solutions.
[0003] Studies have shown that enzyme reactions in organic solvents require a certain degree of hydration. Hydrophilic solvents strip the necessary water from the enzyme through partitioning, while hydrophobic solvents bind the necessary water to the enzyme. Therefore, organic-phase enzyme catalysis requires the selection of hydrophobic solvents, and the addition of hydrates to ensure a certain amount of water is needed for enzyme catalysis. Novel nanoflower-shaped nanozymes, compared with natural enzymes, have the advantages of high surface area, large volume ratio, and high catalytic activity. They are based on the synergistic effect of protein amides and metal ions, forming the nucleation of primary nanoparticles, ultimately forming the petal structure of nanoflowers. Several methods for synthesizing nanoflowers have been reported; these methods are simple, non-toxic, and cost-effective, but the preparation time is still relatively long. There is no precedent for using nanoflowers for bisphenol catalysis in an organic phase. Summary of the Invention
[0004] To address the problems and limitations of existing technologies, the present invention aims to provide a novel method for preparing a biomimetic amino acid surfactant by oxidizing natural polyphenols using nanoenzymes. This method innovatively employs nanoenzymes containing nanoflowers and hydrates, which are used at room temperature and pressure to catalyze the formation of quinone from ethyl caffeate (ECF) dissolved in hydrophobic solvents such as butyl acetate. The initial product, o-benzoquinone, is separated and dissolved in ethanol, and then refluxed with leucine. The resulting amino acid surfactant exhibits good surface properties.
[0005] The technical solution of the present invention is as follows: (I) Preparation method of nanoflowers: (1) Prepare a PBS solution containing 6 mg / mL BSA protein (containing 15 mM KH2PO4 and 15 mM K2HPO4).
[0006] (2) After diluting the solution in step (1) to different protein concentrations using PPB (or PBS), add a certain amount of 1 mol / L copper sulfate to ensure a total volume of 30 mL and shake to mix.
[0007] (3) The nanoflower solutions obtained by standing at 4℃ for different times were centrifuged at 10000 rpm for 5 min, washed with ultrapure water, and then vacuum dried at 60℃ for 30 min to obtain nanoflowers.
[0008] Optionally, in step (2), the final concentration of BSA protein is 0.1-1 mg / mL, the final concentration of PBS solution calculated based on KH2PO4 is 9.0-14.4 mM, and the final concentration of additional NaCl (or KCl) is 5-25 mM. More preferably, it is a PBS solution with a final concentration of 0.1 mg / mL of BSA protein containing 14.4 mM KH2PO4 and K2HPO4 and 5 mM NaCl. When the BSA concentration is less than 1 mg / mL, the nanozyme is hydrangea-shaped; when it is higher than or equal to 1 mg / mL, it is microsphere-shaped. When the final concentration of KH2PO4 is less than 6.0 mM, the nanoflowers cannot form.
[0009] Optionally, in step (2), the final concentration of copper sulfate is 10-40 mM, more preferably 40 mM. Nanoflowers cannot form if the final concentration of copper sulfate is below 10 mM.
[0010] Optionally, the settling time in step (3) is 2-72 h, more preferably 2 h. Nanoflowers cannot form if the settling time is less than 2 h.
[0011] (II) Preparation methods of quinones: (4) Use hydrophobic organic solvents such as butyl acetate to dissolve ECF(I).
[0012] (5) At room temperature, add 6 g of different types of hydrate and 50 mg of nanoflower to multiple 50 mL solutions in step (4) of the same batch and react at 500 rpm for 1 h to prepare quinone (II). The initial product will gradually precipitate butyl acetate.
[0013] (6) Filter the solutions from step (5) of the same batch, and dissolve the quinone (II) in 15 mL of ethanol. Since the nanozyme is insoluble in ethanol, filter it to remove the nanozyme and retain the quinone-containing filtrate.
[0014]
[0015] (I) (II) Optionally, in step (4), the ECF concentration is 1-15 mM, more preferably 9 mM.
[0016] Optionally, the salt hydrate used in step (5) is sodium carbonate decahydrate, potassium carbonate crystals, or trisodium phosphate dodecahydrate, more preferably sodium carbonate decahydrate.
[0017] (III) Preparation methods of amino acid surfactants: (7) Weigh 140 mg KOH and different masses of leucine (III) into a three-necked round-bottom flask and add 50 mL of the quinone (II) solution from step (5).
[0018] (8) Place the three-necked round-bottom flask with the sample completed in step (7) into a 50 ℃ reflux device, add a stir bar and seal it, and react at a stirring speed of 500 rpm for 5 h.
[0019] (9) The solution obtained by filtration after reaction is placed in a petri dish and dried naturally. The final product (IV) is dissolved in ultrapure water to prepare an amino acid surfactant.
[0020] Optionally, the final concentration of leucine used in step (7) is 15 mM-90 mM, more preferably 90 mM.
[0021]
[0022] (II) (III) (IV) In the surfactants of the present invention, ECF oxide can form the hydrophobic portion of the surfactant, and leucine can form the hydrophilic portion of the surfactant, thereby possessing surface-active properties.
[0023] The present invention has the following beneficial effects: Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The entire preparation process of the present invention is simple, the operation method is convenient, the overall cost is low, the equipment requirements are low, and the yield is relatively ideal.
[0024] (2) The present invention optimizes the preparation method of BSA-Cu3(PO4)2 hybrid nanoflowers, shortens the preparation time of static nanoflowers, and optimizes the preparation conditions of BSA-Cu3(PO4)2 hybrid nanoflowers.
[0025] (3) The preparation method of the present invention proposes for the first time that BSA-Cu3(PO4)2 hybrid nanoflower combined with salt hydrate is a nanozyme that simulates tyrosinase, and realizes for the first time that the nanozyme catalyzes bisphenol substrate in organic phase, with high purity of the target initial product.
[0026] (4) The target product amino acid surfactant obtained by the present invention has high purity and contains natural material structure, has excellent biological safety, and the obtained amino acid surfactant has excellent surface properties and good foaming properties. Attached Figure Description
[0027] Figure 1 SEM images of nanoflowers prepared in Examples 1, 2, 3, 4, 5, 6, and 7.
[0028] Figure 2 TEM and XPS images of the nanoflowers prepared in Examples 1 and 2 are shown.
[0029] Figure 3 XRD patterns of nanoflowers prepared in Examples 1 and 2 and the control.
[0030] Figure 4 FTIR images of nanoflowers prepared in Examples 1 and 2 and the control.
[0031] Figure 5 The images show the UV absorption spectra of the amino acid surfactants prepared in Examples 1, 12, 13, and 14 after dilution.
[0032] Figure 6 The surface tension diagram is for the amino acid surfactant prepared in Example 1.
[0033] Figure 7 The foam volume diagrams are for the amino acid surfactants prepared in Examples 1, 12, 13, and 14.
[0034] Figure 8 The graph shows the yield and conversion of quinones prepared in Examples 8, 9, 10, and 11. Detailed Implementation
[0035] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention. Example 1
[0036] Prepare a PBS solution containing 6 mg / mL BSA protein (containing 15 mM KH2PO4 and 15 mM K2HPO4). Take 0.5 mL of the solution and add it to 28.3 mL of PPB solution (containing 15 mM KH2PO4 and 15 mM K2HPO4, and 5 mM NaCl). Add 1.2 mL of 1 mol / L copper sulfate solution. Place the solution in a refrigerator at 4 °C for 2 h, remove the supernatant, centrifuge at 10000 rpm for 5 min, wash with ultrapure water, and vacuum dry at 60 °C for 30 min to obtain nanoflowers.
[0037] The obtained nanoflower SEM images are as follows Figure 1 As shown, it presents a hydrangea-like shape; TEM and XPS images are as follows. Figure 2 As shown, its center is relatively thick, but the outer layer is thinner, exhibiting a disordered petal-like shape, indicating the presence of elements such as Cu, N, O, P, and S. This suggests that it is a Cu-hybridized nanoflower containing protein. XRD pattern as shown... Figure 3 As shown, it exhibits clear and sharp diffraction peaks, indicating good crystallinity. The recorded peak positions largely coincide with some peaks of the copper phosphate standard, while others show no sharp diffraction peaks compared to the standard. This suggests the formation of a Cu-protein complex on the surface of the nanoflower, which shields some of the sharp peaks of the copper phosphate standard and generates new peaks. FTIR is shown below. Figure 4 As shown, at 625 cm -1 990 cm -1 and 1050 cm -1 Strong characteristic absorptions were observed at 1640 cm⁻¹, corresponding to bending, symmetric stretching, and asymmetric stretching of the PO vibration, respectively, indicating the presence of phosphate groups. BSA, however, did not show these signals, demonstrating the corresponding similarity of functional groups between the nanoflowers and the copper phosphate standard sample. Furthermore, nanoflowers with different protein contents and BSA showed absorption at 1640 cm⁻¹. -1 and 1530 cm -1 The nanoflower exhibits strong characteristic absorption, attributed to absorption bands I and II of the amide, which implies the presence of protein compared to copper phosphate.
[0038] Quinone was prepared by reacting 50 mL of 9 mM ECF solution with butyl acetate, adding 50 mg of nanoflowers and 6 g of sodium carbonate decahydrate, and reacting at 500 rpm for 1 h. The reacted solution was filtered, and the solid was dissolved in 15 mL of ethanol. The nanozyme was removed by filtration, and the quinone-containing solution was retained. This process was repeated four times. 50 mL of this filtrate was added to a three-necked round-bottom flask, along with 140 mg of KOH and 590 mg of leucine (90 mM). The flask was then placed in a 50 °C reflux reflux apparatus and reacted with stirring at 500 rpm for 5 h. The reacted solution was filtered, and the filtrate was naturally dried in a petri dish. The final product was dissolved in ultrapure water to prepare an amino acid surfactant. Foaming performance tests were performed, detailed in the examples below. 160 mg of the obtained product was dissolved in 20 mL of ultrapure water and diluted 10 times; the resulting UV absorption spectrum is shown below. Figure 5 As shown, an absorption peak of 600-700 nm appeared, indicating that it was generated by the combination of quinone and amino acid. The resulting surface tension is as follows. Figure 6 As shown. Example 2
[0039] Prepare a PBS solution containing 6 mg / mL BSA protein (15 mM KH₂PO₄ and 15 mM K₂HPO₄). Add 5 mL of this solution to 23.8 mL of a PPB solution (15 mM KH₂PO₄ and 15 mM K₂HPO₄, 5 mM NaCl). Add 1.2 mL of a 1 mol / L copper sulfate solution. Incubate at 4 °C for 2 h. Remove the supernatant and centrifuge at 10000 rpm for 5 min. Wash with ultrapure water and vacuum dry at 60 °C for 30 min to obtain nanoflowers. The obtained nanoflowers are shown in the SEM image below. Figure 1 As shown, it presents a spherical shape; TEM and XPS images are as follows. Figure 2 As shown, both its center and outer layer are solid, and its elemental composition is similar to that of 1. The XRD pattern is as follows. Figure 3 Similar to Example 1, the obtained FTIR is as follows: Figure 4 As shown, it is similar to Example 1. Example 3
[0040] Prepare a PBS solution containing 6 mg / mL BSA protein (15 mM KH₂PO₄ and 15 mM K₂HPO₄). Add 2.5 mL of this solution to 26.3 mL of a PPB solution (15 mM KH₂PO₄ and 15 mM K₂HPO₄, 5 mM NaCl). Add 1.2 mL of a 1 mol / L copper sulfate solution. Incubate at 4 °C for 2 h. Remove the supernatant and centrifuge at 10,000 rpm for 5 min. Wash with ultrapure water and vacuum dry at 60 °C for 30 min to obtain nanoflowers. The obtained nanoflowers are shown in the SEM image below. Figure 1As shown, it resembles a hydrangea flower. Example 4
[0041] Prepare a PBS solution containing 6 mg / mL BSA protein (15 mM KH₂PO₄ and 15 mM K₂HPO₄). Add 0.5 mL of this solution to 28.3 mL of the PBS solution, along with 1.2 mL of 1 mol / L copper sulfate solution. Incubate at 4 °C for 72 h, remove the supernatant, centrifuge at 10000 rpm for 5 min, wash with ultrapure water, and vacuum dry at 60 °C for 30 min to obtain nanoflowers. The obtained nanoflowers are shown in the SEM image below. Figure 1 As shown, it resembles a hydrangea flower. Example 5
[0042] Prepare a PBS solution containing 6 mg / mL BSA protein (15 mM KH₂PO₄ and 15 mM K₂HPO₄). Add 0.5 mL of this solution to 18 mL of PBS solution, along with 10.3 mL of ultrapure water and 1.2 mL of 1 mol / L copper sulfate solution. Incubate at 4 °C for 2 h, remove the supernatant, centrifuge at 10000 rpm for 5 min, wash with ultrapure water, and vacuum dry at 60 °C for 30 min to obtain nanoflowers. The obtained nanoflowers are shown in the SEM image below. Figure 1 As shown, it resembles a hydrangea flower. Example 6
[0043] Prepare a PBS solution containing 6 mg / mL BSA protein (15 mM KH₂PO₄ and 15 mM K₂HPO₄). Add 0.5 mL of this solution to 28.3 mL of a PPB solution (15 mM KH₂PO₄ and 15 mM K₂HPO₄, 25 mM NaCl). Add 1.2 mL of a 1 mol / L copper sulfate solution. Incubate at 4 °C for 2 h. Remove the supernatant and centrifuge at 10,000 rpm for 5 min. Wash with ultrapure water and vacuum dry at 60 °C for 30 min to obtain nanoflowers. The SEM images of the obtained nanoflowers are shown below. Figure 1 As shown, it resembles a hydrangea flower. Example 7
[0044] Prepare a PBS solution containing 6 mg / mL BSA protein (15 mM KH₂PO₄ and 15 mM K₂HPO₄). Add 0.5 mL of this solution to 28.3 mL of a PPB solution (15 mM KH₂PO₄ and 15 mM K₂HPO₄, 5 mM NaCl). Add 0.3 mL of a 1 mol / L copper sulfate solution and 0.6 mL of ultrapure water. Incubate at 4 °C for 2 h. Remove the supernatant and centrifuge at 10,000 rpm for 5 min. Wash with ultrapure water and vacuum dry at 60 °C for 30 min to obtain nanoflowers. The SEM images of the obtained nanoflowers are shown below. Figure 1 As shown, it resembles a hydrangea flower. Example 8
[0045] A 50 mL ECF solution with a concentration of 9 mM was prepared using butyl acetate. 50 mg of nanoflowers and 6 g of sodium carbonate decahydrate were added, and the mixture was reacted at 500 rpm for 1 h to prepare quinones. The reaction solution was filtered, and the filtrate was analyzed by high performance liquid chromatography. The specific method is listed after the examples. The filtered solid was dissolved in 50 mL of ethanol, and the nanozyme was removed by filtration. The quinone-containing solution obtained by filtration was retained and tested for quinones. The specific method is listed after the examples. Example 9
[0046] A 50 mL ECF solution with a concentration of 9 mM was prepared using butyl acetate. 50 mg of nanoflowers and 6 g of crystalline potassium carbonate were added, and the mixture was reacted at 500 rpm for 1 h to prepare quinones. The reaction solution was filtered, and the filtrate was analyzed by high performance liquid chromatography. The specific method is listed after the examples. The filtered solid was dissolved in 50 mL of ethanol, and the nanozyme was removed by filtration. The quinone-containing solution obtained by filtration was retained and tested for quinones. The specific method is listed after the examples. Example 10
[0047] A 50 mL ECF solution with a concentration of 9 mM was prepared using butyl acetate. 50 mg of nanoflowers and 6 g of trisodium phosphate dodecahydrate were added, and the mixture was reacted at 500 rpm for 1 h to prepare quinones. The reaction solution was filtered, and the filtrate was analyzed by high performance liquid chromatography. The filtered solid was dissolved in 50 mL of ethanol to remove the quinones, and the nanozyme was removed by filtration. The quinone-containing solution obtained by filtration was retained and tested for quinones. Specific details are listed after the examples. Example 11
[0048] A 50 mL 15 mM ECF solution was prepared using butyl acetate. 50 mg of nanoflowers and 6 g of sodium carbonate decahydrate were added, and the mixture was reacted at 500 rpm for 1 h to prepare quinones. The reaction solution was filtered, and the filtrate was analyzed by high performance liquid chromatography. The filtered solid was dissolved in 50 mL of ethanol to remove the quinones, and the nanozyme was removed by filtration. The quinone-containing solution obtained by filtration was retained and tested for quinones. Specific details are listed after the examples. Example 12
[0049] Quinone was prepared by reacting 50 mL of 9 mM ECF solution with butyl acetate, adding 50 mg of nanoflowers and 6 g of sodium carbonate decahydrate, and reacting at 500 rpm for 1 h. The reacted solution was filtered, and the solid was dissolved in 15 mL of ethanol. The nanozyme was removed by filtration, and the quinone-containing solution was retained. This process was repeated four times. 50 mL of this filtrate was added to a three-necked round-bottom flask, along with 140 mg of KOH and 393 mg (15 mM) of leucine. The flask was then placed in a 50 °C reflux reflux apparatus and reacted with stirring at 500 rpm for 5 h. The reacted solution was filtered, and the filtrate was naturally dried in a petri dish. The final product was dissolved in ultrapure water to prepare an amino acid surfactant. Foaming performance tests were performed, detailed in the examples below. 160 mg of the obtained product was dissolved in 20 mL of ultrapure water and diluted 10 times; the resulting UV absorption spectrum is shown below. Figure 5 As shown, an absorption peak of 600-700 nm appeared, indicating that it was generated by the combination of quinone and amino acid. Example 13
[0050] Quinone was prepared by reacting 50 mL of 9 mM ECF solution with butyl acetate, adding 50 mg of nanoflowers and 6 g of sodium carbonate decahydrate, and reacting at 500 rpm for 1 h. The reacted solution was filtered, and the solid was dissolved in 15 mL of ethanol. The nanozyme was removed by filtration, and the quinone-containing solution was retained. This process was repeated four times. 50 mL of the filtrate was added to a three-necked round-bottom flask, along with 140 mg of KOH and 98 mg (30 mM) of leucine. The flask was then placed in a reflux reflux apparatus at 50 °C and reacted with stirring at 500 rpm for 5 h. The reacted solution was filtered, and the filtrate was naturally dried in a petri dish. The final product was dissolved in ultrapure water to prepare an amino acid surfactant. Foam performance tests were performed, detailed in the examples. The UV absorption spectrum obtained by dissolving 160 mg of the obtained product in 20 mL of ultrapure water and diluting it 10 times is shown in the figure. Figure 5 As shown, an absorption peak of 600-700 nm appeared, indicating that it was generated by the combination of quinone and amino acid. Example 14
[0051] Quinone was prepared by reacting 50 mL of 9 mM ECF solution with butyl acetate, adding 50 mg of nanoflowers and 6 g of sodium carbonate decahydrate, and reacting at 500 rpm for 1 h. The reacted solution was filtered, and the solid was dissolved in 15 mL of ethanol. The nanozyme was removed by filtration, and the quinone-containing solution was retained. This process was repeated four times. 50 mL of this filtrate was added to a three-necked round-bottom flask, along with 140 mg of KOH and 196 mg (60 mM) of leucine. The flask was then placed in a reflux reflux apparatus at 50 °C and reacted with stirring at 500 rpm for 5 h. The reacted solution was filtered, and the filtrate was dried naturally in a petri dish. The final product was dissolved in ultrapure water to prepare an amino acid surfactant. Foam performance tests were performed, detailed in the examples. The UV absorption spectrum obtained by dissolving 160 mg of the obtained product in 20 mL of ultrapure water and diluting it 10 times is shown in the figure. Figure 5 As shown, an absorption peak of 600-700 nm appeared, indicating that it was generated by the combination of quinone and amino acid.
[0052] The filtrates from the nanozyme oxidation of ECF obtained in Examples 8, 9, 10, and 11 above were analyzed as follows: (1) High performance liquid chromatography analysis ECF solutions were filtered and analyzed using an LC-16 system (Shimadzu, China) equipped with an InterSustain C18 column (4.6 × 250 mm, 5 μm), and detected using 250 nm UV. The mobile phase consisted of 65% ultrapure water and 35% acetonitrile, with a flow rate of 1 mL / min. −1 This is used to determine ECF consumption and to calculate ECF conversion rate. The results are as follows: Figure 8 The formula is as follows:
[0053] The quinone-containing solutions obtained in Examples 8, 9, 10, and 11 above were tested as follows: (2) Ultraviolet absorption test Adding 180 μL of DMSO to a quinone solution containing 36 mM MBTH and 60 μL of N,N'-dimethylformamide to a quinone solution obtained in 2740 μL produced a red complex, which was then tested under UV light in a 3.5 mL quartz cuvette for identification and quantification of quinone. The quinone solution obtained by separating 4 mg of nanoflowers and 500 mg of sodium carbonate decahydrate in 3 mL of 6 mM ECF for 1 h was used as the basis for complete quinone conversion. After establishing a standard curve through serial dilution, the quinone yield was calculated. The results are shown below. Figure 8 The formula is as follows:
[0054] The amino acid surfactants obtained in the above examples were subjected to the following tests: (3) Surface tension test: The amino acid surfactant obtained in Example 1 was prepared into aqueous solutions of different concentrations. At room temperature, the surface tension of the solutions with different amino acid surfactant concentrations was measured using a BZY-1 automatic surface tension meter. The critical micelle concentration was approximately 8.17 mM, at which point the surface tension was approximately 36.43 mN / m, indicating that the obtained surfactant has excellent surface properties. In contrast, the surface tensions of ordinary surfactants SDS and sodium cocoyl glycinate were 35.35 and 28.03 mN / m, respectively.
[0055] In addition, 15 mM aqueous solutions of the amino acid surfactants prepared in Examples 12, 13, and 14 were prepared, and the surface tension of the solutions was measured under the same conditions. The test results are shown in Table 1 below. It can be seen that the obtained surfactants can significantly reduce the surface tension of water and have excellent surface properties.
[0056] Table 1. Surface tension test results of amino acid surfactants Example 12 Example 13 Example 14 Surface tension (mN / m) 34.89 33.97 34.52 (4) Foam performance test: The amino acid surfactants prepared in Examples 1, 12, 13, and 14 at 15 mM were prepared. 10 mL of each surfactant was added to a 100 mL stoppered graduated cylinder at room temperature (25 °C). The stopper was closed, and the cylinder was vigorously shaken up and down 60 times. Foaming properties were observed, and foam heights were recorded at 0 and 20 min. The initial foam volumes for Examples 1, 12, 13, and 14 were 19, 14, 17, and 25 mL, respectively, and the foam volumes at 20 min were 18, 12, 11, and 17 mL, respectively. In contrast, the initial foam volumes of the common surfactants SDS and sodium cocoyl glycinate were 20 and 15 mL, respectively, and the foam volumes at 20 min were 15 and 5 mL, respectively. The amino acid surfactants prepared in these examples exhibit good foaming properties.
[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention should be considered as equivalent substitutions and are included within the scope of protection of the present invention.
Claims
1. A method for biomimetic synthesis of amino acid surfactants using nanoenzymes to oxidize natural polyphenols, characterized in that... The method includes the following steps: (1) Add copper sulfate to a PBS solution containing BSA (bovine serum albumin), let stand for 2 hours, centrifuge and dry to prepare BSA-Cu3(PO4)2 hybrid nanoflowers as nanozymes that mimic the structure of the binuclear copper active center of tyrosinase. (2) Dissolve natural polyphenols in an organic solvent, add the nanozyme obtained in step (1) as a catalyst, and then add solid salt hydrate to provide active water, similar to the role of cofactor in enzyme catalysis, to oxidize natural polyphenols to generate o-benzoquinone compounds, and use ethanol to separate the o-benzoquinone primary product. (3) Using the initial product of o-benzoquinone obtained in step (2) as the hydrophobic part, it is refluxed with leucine in KOH ethanol solution to carry out Michael addition reaction, simulating melanin generation, and biomimetic synthesis of amino acid surfactant. The resulting final product has excellent surface properties.
2. The method for biomimetic synthesis of amino acid surfactants using nanoenzyme oxidation of natural polyphenols according to claim 1, characterized in that... In step (1), the BSA protein content is 0.1-1 mg / mL, the final concentration of KH2PO4 in PBS is 9.0-14.4 mM, the final concentration of NaCl (or KCl) added is 5-25 mM, and the concentration of copper sulfate is 10-40 mM.
3. The method for biomimetic synthesis of amino acid surfactants using nanoenzymes to oxidize natural polyphenols according to claim 1, characterized in that... The organic solvent in step (2) is butyl acetate.
4. The method for biomimetic synthesis of amino acid surfactants using nanoenzymes to oxidize natural polyphenols according to claim 1, characterized in that... In step (2), the natural polyphenol is ethyl caffeate with a concentration of 1-15 mM.
5. The method for biomimetic synthesis of amino acid surfactants using nanoenzyme oxidation of natural polyphenols according to claim 1, characterized in that... In step (2), the solid salt hydrate is any one of sodium carbonate decahydrate, crystalline potassium carbonate, or trisodium phosphate dodecahydrate.
6. The method for biomimetic synthesis of amino acid surfactants using nanoenzymes to oxidize natural polyphenols according to claim 1, characterized in that... In step (2), the reaction time is 1 h. The initial product of o-benzoquinone will gradually precipitate out. The filtered solid is dissolved in ethanol. The initial product of o-benzoquinone is soluble in ethanol, while the nanozyme is insoluble in ethanol. The nanozyme is removed by filtration for reuse, and the ethanol solution containing o-benzoquinone is retained.
7. The method for biomimetic synthesis of amino acid surfactants using nanoenzymes to oxidize natural polyphenols according to claim 1, characterized in that... In step (3), the reflux reaction was carried out by weighing 140 mg KOH and different masses of leucine into a three-necked round-bottom flask, adding 50 mL of o-benzoquinone ethanol solution, placing it in a reflux apparatus at 50 ℃, and stirring at 500 rpm for 5 h. The solution obtained after the reaction was filtered and placed in a petri dish to dry naturally. The final product was dissolved in ultrapure water to prepare the amino acid surfactant.
8. The method for preparing the amino acid surfactant according to claim 1, characterized in that... The novel amino acid surfactant has the following structural formula: 。