A corn cob-like structure of lignin-dopamine / zinc oxide hybrid particles, and a preparation method and application thereof

Abstract

The present application belongs to the technical field of chemical product preparation, and particularly relates to a corn rod-shaped structure lignin-dopamine / zinc oxide hybrid particle and a preparation method and application thereof. 2+ Dopamine-modified lignin is deposited on the surface, the antibacterial performance and SPF value are improved, a unique corn rod-shaped hybrid structure is formed, and the dispersibility of the particles is significantly improved. The hybrid particles obtained by the present application have excellent ultraviolet shielding performance, high efficient DPPH free radical scavenging activity and strong inhibition effect on malassezia, realize the synergistic effect of physical sunscreen, antioxidant and antibacterial functions, and have wide application prospect in the field of cosmetics.

Description

Technical Field

[0001] This invention belongs to the field of chemical product preparation technology, specifically relating to a corn rod-shaped lignin-dopamine / zinc oxide hybrid particle, its preparation method, and its application. Background Technology

[0002] As consumers increasingly demand higher safety and efficacy in cosmetics, naturally derived, multifunctional, and environmentally friendly cosmetic ingredients have become a hot research topic. Among these, ultraviolet (UV) protection, free radical scavenging, and antibacterial properties are important functional indicators for sunscreens, antioxidant serums, shampoos, and scalp care products.

[0003] Zinc oxide (ZnO) is a widely used physical sunscreen agent with advantages such as broad-spectrum UV shielding ability, low irritation, and low sensitivity. However, nano zinc oxide is prone to agglomeration, has poor dispersibility in formulations, and has limited ability to scavenge free radicals when used alone, lacking targeted inhibitory effects against fungi such as Malassezia.

[0004] Lignin is a naturally abundant polyphenolic polymer with excellent UV absorption, antioxidant properties, and biocompatibility, and has been regarded as a potential functional carrier in cosmetics in recent years. However, industrial lignin has high impurity content, poor water solubility, and few surface active sites, resulting in weak interfacial bonding when directly compounded with zinc oxide, which affects its dispersion and efficacy in cosmetic matrices.

[0005] Therefore, developing a technology that can simultaneously achieve high UV shielding performance, strong antioxidant activity, and efficient antibacterial properties has significant practical application value for the cosmetics industry. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments.

[0007] As one aspect of the present invention, the present invention provides a method for preparing corn rod-shaped lignin-dopamine / zinc oxide hybrid particles, which includes the following steps: (1) The enzymatic hydrolyzed lignin raw material from corn cob is crushed, sieved, dispersed in water, the pH is adjusted to alkaline to dissolve the lignin, impurities are removed by filtration, and then the pH of the filtrate is adjusted to acidic to precipitate the lignin. After washing, purified corn cob lignin particles are obtained. (2) Disperse the purified corn cob lignin particles obtained in step (1) in water, add hydroxydopamine monomer and mix evenly, adjust the pH of the system to acidic, and carry out the reaction under heating conditions under the protection of crosslinking agent and inert gas. After the reaction is completed, centrifuge and wash to obtain dopamine modified lignin. (3) Under stirring conditions, zinc acetate solution is added dropwise to the dopamine-modified lignin dispersion obtained in step (2), the pH is adjusted to alkaline, and a closed reaction is carried out under heating conditions. After the reaction is completed, the lignin-dopamine / zinc oxide hybrid particles with corn rod structure are obtained by centrifugation and washing.

[0008] As a preferred embodiment of the preparation method described in this invention: in step (1), adjusting the pH to alkaline means adjusting the pH to 11-12; adjusting the pH to acidic means adjusting the pH to 2-2.5.

[0009] As a preferred embodiment of the preparation method described in this invention: in step (2), the pH of the system is adjusted to acidity by adjusting the pH to 2.0-2.5; the crosslinking agent is glyoxal; and the inert gas is nitrogen.

[0010] As a preferred embodiment of the preparation method described in this invention: in step (2), the heating conditions are to react for 3-4 hours under constant temperature oil bath conditions of 70-75℃.

[0011] As a preferred embodiment of the preparation method described in this invention: in step (2), the mass ratio of the purified corn cob lignin particles to the hydroxydopamine monomer is 1:0.5-1.

[0012] As a preferred embodiment of the preparation method described in this invention: in step (3), adjusting the pH to alkaline means adjusting the pH to 11.5-12; the heating conditions are to react for 12-16 hours under sealed conditions at 85-90℃.

[0013] As a preferred embodiment of the preparation method described in this invention: in step (3), the mass ratio of zinc acetate to the purified corn cob lignin particles in step (2) is 1:1-1.5.

[0014] As a preferred embodiment of the preparation method described in this invention, the centrifugation speed in steps (2) and (3) is 8800~11000 r / min.

[0015] The beneficial effects of this invention: The hydroxydopamine monomer of this invention cross-links the lignin surface via the Mannich reaction, and due to its strong adsorption and reduction properties, it helps to improve Zn... 2+ Deposition on the surface of dopamine-modified lignin enhances antibacterial properties and SPF value, forming a unique corn-stick-like hybrid structure that significantly improves particle dispersibility. The hybrid particles obtained in this invention possess excellent UV shielding performance, highly efficient DPPH free radical scavenging activity, and potent inhibitory effects against Malassezia, achieving a synergistic effect of physical sun protection, antioxidant, and antibacterial functions, and have broad application prospects in the cosmetics field. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below, wherein: Figure 1 This is a scanning electron microscope image of the dopamine-modified lignin-zinc oxide hybrid particles from Example 1.

[0017] Figure 2 This is a width-direction particle size distribution diagram of dopamine-modified lignin-zinc oxide hybrid nanoparticles in Example 1.

[0018] Figure 3 To test the UV resistance of the sample from Example 1, a Labsphere UV2000S UV transmittance analyzer was used. The test sample was coated onto a PMMA sheet with a side length of 5 cm at a coating density of 1.3 mg / cm². 2 The ISO 2012 standard was selected, with a wavelength range of 250-450nm, 5 test plates, and 20 test points.

[0019] Figure 4 This is the NMR spectrum of dopamine-modified lignin from Example 1. Detailed Implementation

[0020] To make the above-mentioned objectives, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to specific examples.

[0021] The corn cob lignin was purchased from Lingyu Chemical Co., Ltd. in Jinzhou, Liaoning Province; hydroxydopamine (98% purity) was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; and glyoxal was purchased from Adamas Reagent Co., Ltd.

[0022] Example 1: (1) The corn cob lignin (enzymatic hydrolysis lignin) raw material was mechanically crushed and passed through a 140-mesh sieve to obtain corn cob lignin fine powder. At room temperature (25 ℃), 10 g of corn cob lignin fine powder was dispersed in 500 mL of deionized water, sodium hydroxide was added to adjust the pH to 12, and the mixture was stirred for 60 min. Impurities were removed by suction filtration, and 0.5 mol / L dilute hydrochloric acid was added dropwise until the pH reached 2.5. The precipitated particles were then washed with deionized water to obtain corn cob lignin particles. (2) Weigh 1.0 g of corn cob lignin particles and add 50 ml of deionized water to obtain an aqueous solution of corn cob lignin particles. Add 1.0 g of hydroxydopamine monomer and mix thoroughly under magnetic stirring. Add 0.5 mol / L dilute hydrochloric acid dropwise to adjust the pH of the system to 2.5. Then, purge with nitrogen gas and add 500 μL of glyoxal. React at a constant temperature oil bath of 70 ℃ for 4 h. Centrifuge at 8800 r / min and wash 3 times to remove the supernatant to obtain dopamine-modified lignin. (3) Under stirring conditions, 1.0 g of zinc acetate (dissolved in 10.0 mL of water) was slowly added dropwise to dopamine-modified lignin. The pH was adjusted to 11.5 with 1 mol / L NaOH. The reaction was carried out at 90 °C for 12 h. After the reaction was completed, the precipitate was collected by centrifugation at 11000 r / min. The supernatant was replaced with water. The centrifugation operation was repeated three times to obtain dopamine-modified lignin-zinc oxide hybrid particles with a "corn stick" structure.

[0023] Example 2: (1) The corn cob lignin (enzymatic hydrolysis lignin) raw material was mechanically crushed and passed through a 140-mesh sieve to obtain corn cob lignin fine powder. At room temperature (25 ℃), 10 g of corn cob lignin fine powder was dispersed in 500 mL of deionized water, sodium hydroxide was added to adjust the pH to 11.5, and the mixture was stirred for 90 min. Impurities were removed by suction filtration, and 0.5 mol / L dilute hydrochloric acid was added dropwise until the pH reached 2.0. Then, the precipitated particles were washed with deionized water to obtain corn cob lignin particles. (2) Weigh 1.0 g of corn cob lignin particles and add 50 ml of deionized water to obtain an aqueous solution of corn cob lignin particles. Add 1.0 g of hydroxydopamine monomer and mix thoroughly under magnetic stirring. Add 0.5 mol / L dilute hydrochloric acid dropwise to adjust the pH of the system to 2.0. Then, purge with nitrogen gas and add 500 μL of glyoxal. React at a constant temperature oil bath of 75 ℃ for 3 h. Centrifuge at 8800 r / min and wash 3 times to remove the supernatant to obtain dopamine-modified lignin. (3) Under stirring conditions, 1.0 g of zinc acetate (dissolved in 10.0 mL of water) was slowly added dropwise to dopamine-modified lignin. The pH was adjusted to 12 with 1 mol / L NaOH. The reaction was carried out at 90 °C for 12 h. After the reaction was completed, the precipitate was collected by centrifugation at 11000 r / min. The supernatant was replaced with water. The centrifugation operation was repeated three times to obtain dopamine-modified lignin-zinc oxide hybrid particles with a "corn stick" structure.

[0024] Comparative Example 1: (1) The corn cob lignin (enzymatic hydrolysis lignin) raw material was mechanically crushed and passed through a 140-mesh sieve to obtain corn cob lignin fine powder. At room temperature (25 ℃), 10 g of corn cob lignin fine powder was dispersed in 500 mL of deionized water, sodium hydroxide was added to adjust the pH to 12, and the mixture was stirred for 60 min. Impurities were removed by suction filtration, and 0.5 mol / L dilute hydrochloric acid was added dropwise until the pH reached 2.5. The precipitated particles were then washed with deionized water to obtain corn cob lignin particles. (2) Weigh 1.0 g of corn cob lignin particles and add 50 ml of deionized water to obtain an aqueous solution of corn cob lignin particles. Add 1.0 g of hydroxydopamine monomer and mix thoroughly under magnetic stirring. Adjust the pH to 8.5. React at a constant temperature oil bath of 70℃ for 4 h. Centrifuge at 8800 r / min and wash 3 times to remove the supernatant to obtain dopamine-modified lignin. (3) Under stirring conditions, 1.0 g of zinc acetate (dissolved in 10.0 mL of water) was slowly added dropwise to dopamine-modified lignin. The pH was adjusted to 11.5 with 1 mol / L NaOH. The reaction was carried out at 90 °C for 12 h. After the reaction was completed, the precipitate was collected by centrifugation at 11000 r / min. The supernatant was replaced with water. The centrifugation operation was repeated three times to obtain modified lignin-zinc oxide hybrid particles.

[0025] Comparative Example 2: Referring to Example 1, step (2) is omitted.

[0026] (1) The corn cob lignin (enzymatic hydrolysis lignin) raw material was mechanically crushed and passed through a 140-mesh sieve to obtain corn cob lignin fine powder. At room temperature (25 ℃), 10 g of corn cob lignin fine powder was dispersed in 500 mL of deionized water, sodium hydroxide was added to adjust the pH to 12, and the mixture was stirred for 60 min. Impurities were removed by suction filtration, and 0.5 mol / L dilute hydrochloric acid was added dropwise until the pH reached 2.5. The precipitated particles were then washed with deionized water to obtain corn cob lignin particles. (2) Under stirring conditions, 1.0 g of zinc acetate (dissolved in 10.0 mL of water) was slowly added dropwise to corn cob lignin particles. The pH was adjusted to 11.5 with 1 mol / L NaOH. The reaction was sealed at 90 °C for 12 h. After the reaction was completed, the precipitate was collected by centrifugation at 11000 r / min. The supernatant was replaced with water. The centrifugation operation was repeated three times to obtain dopamine-modified lignin-zinc oxide hybrid particles with a "corn cob" structure.

[0027] Comparative Example 3: Referring to Example 1, steps (1, 2) were modified as follows: corn cob-derived lignin (enzymatically hydrolyzed lignin) raw material was mechanically pulverized and passed through a 140-mesh sieve to obtain corn cob lignin fine powder. 1.0 g of the lignin fine powder obtained after mechanical pulverization and sieving, and 1.0 g of hydroxydopamine monomer were dispersed in 50 ml of deionized water and thoroughly mixed under magnetic stirring. 0.5 mol / L dilute hydrochloric acid was added dropwise to adjust the pH of the system to 2.5, followed by nitrogen bubbling and the addition of 500 μL of glyoxal. The reaction was carried out continuously for 4 h under a constant temperature oil bath at 70℃. After three cycles of centrifugation and washing at 8800 r / min, the supernatant was removed. The preparation method of step (3) was the same as in Example 1.

[0028] Comparative Example 4: Referring to Example 1, glyoxal was not added in step (2), and the other conditions remained unchanged.

[0029] The UV shielding performance of each group of samples was analyzed using a UV-Vis-NIR spectrophotometer (UV-3600 plus, Tsushima, Japan) in transmission mode. During the test, the scanning speed was medium, and the scanning range was 280-780 nm.

[0030] The antioxidant performance was tested by determining its free radical scavenging rate using the DPPH method. The sample and the colorimetric reagent were reacted in the dark for 30 minutes at a 1:1 volume ratio (2 mL + 2 mL), and pure solvent (ethanol) was used as a blank for calibration.

[0031] The antibacterial activity of Malassezia was characterized using colony counting. Activated Malassezia was diluted to 1 × 10⁻⁶. 3 The sample was sterilized by UV and then mixed with 1 mL of bacterial solution. The mixture was incubated at 37°C and 200 rpm for 3 h with shaking. The mixture was then spread on agar plates and incubated at 37°C for 24 h before counting the surviving colonies. An equal volume of PBS buffer (pH=7.4) was used as a control group to replace the sample solution and incubate with the bacterial solution.

[0032] Table 1

[0033] Under acidic conditions at pH 2.5, hydroxydopamine tends to covalently crosslink with enzymatically hydrolyzed lignin rather than undergo self-polymerization. Hydroxydopamine monomers crosslink the surface of enzymatically hydrolyzed lignin via the Mannich reaction. Due to its strong adsorption and reduction properties, it facilitates the crosslinking of Zn... 2+ Deposition of dopamine on the surface of lignin improves antibacterial properties and SPF value, but as the ZnO loading increases, the content of dopamine-modified lignin, which plays an antioxidant role, decreases accordingly, leading to a reduction in antioxidant efficiency. Without the participation of hydroxydopamine, the antioxidant efficiency of lignin cannot be improved, and the ZnO loading will also decrease accordingly.

[0034] 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 it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing corn-shaped lignin-dopamine / zinc oxide hybrid particles, characterized in that, Includes the following steps: (1) The enzymatic hydrolyzed lignin raw material from corn cob is crushed, sieved, dispersed in water, the pH is adjusted to alkaline to dissolve the lignin, impurities are removed by filtration, and then the pH of the filtrate is adjusted to acidic to precipitate the lignin. After washing, purified corn cob lignin particles are obtained. (2) Disperse the purified corn cob lignin particles obtained in step (1) in water, add hydroxydopamine monomer and mix evenly, adjust the pH of the system to acidic, and carry out the reaction under heating conditions under the protection of crosslinking agent and inert gas. After the reaction is completed, centrifuge and wash to obtain dopamine modified lignin. (3) Under stirring conditions, zinc acetate solution is added dropwise to the dopamine-modified lignin dispersion obtained in step (2), the pH is adjusted to alkaline, and a closed reaction is carried out under heating conditions. After the reaction is completed, the lignin-dopamine / zinc oxide hybrid particles with corn rod structure are obtained by centrifugation and washing.

2. The preparation method according to claim 1, characterized in that: In step (1), adjusting the pH to alkaline means adjusting the pH to 11-12; adjusting the pH to acidic means adjusting the pH to 2-2.

5.

3. The preparation method according to claim 1 or 2, characterized in that: In step (2), adjusting the pH of the system to acidity means adjusting the pH to 2.0-2.5; the crosslinking agent is glyoxal; and the inert gas is nitrogen.

4. The preparation method according to claim 1 or 3, characterized in that: In step (2), the heating conditions are to react for 3-4 hours under constant temperature oil bath conditions of 70-75℃.

5. The preparation method according to any one of claims 1-3, characterized in that: In step (2), the mass ratio of the purified corn cob lignin particles to hydroxydopamine monomer is 1:0.5-1.

6. The preparation method according to any one of claims 1-3, characterized in that: In step (3), adjusting the pH to alkaline means adjusting the pH to 11.5-12; the heating conditions are to react for 12-16 hours under sealed conditions at 85-90℃.

7. The preparation method according to any one of claims 1-3, characterized in that: In step (3), the mass ratio of zinc acetate to the purified corn cob lignin particles in step (2) is 1:1-1.

5.

8. The preparation method according to any one of claims 1-3, characterized in that: The centrifugation speed in steps (2) and (3) is 8800~11000 r / min.

9. The corn rod-shaped lignin-dopamine / zinc oxide hybrid particles prepared by the method according to claim 1.

10. The application of the corn rod-shaped lignin-dopamine / zinc oxide hybrid particles according to claim 9 in the preparation of cosmetics with UV protection, antioxidant and / or antibacterial functions.

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