Biomass-based chalcone photoinitiator, preparation method thereof, photoinitiator system and free radical photocuring system

Abstract

The invention relates to the technical field of photoinitiators, in particular to a biomass-based chalcone photoinitiator and a preparation method thereof, a photoinitiator system and a free radical photocuring system.The preparation method comprises the steps that acetone, biomass aldehyde and absolute ethyl alcohol are added into a round-bottom flask, stirring treatment is conducted in an ice-water bath for 15-30 min, then a sodium hydroxide aqueous solution is dropwise added into the round-bottom flask, stirring treatment is conducted in an ice-water bath for 15-30 min, and a free radical photocuring system is obtained; the preparation method comprises the following steps: adding the raw materials into a reaction kettle, stirring and reacting at 25-50 DEG C, adding water and dichloromethane into the reacted mixture for extraction, then drying to obtain a photoinitiator crude product, and purifying by adopting column chromatography to obtain the biomass-based chalcone photoinitiator. The biomass aldehyde raw material used in the invention is green, environment-friendly, cheap and easily available, the prepared biomass-based chalcone photoinitiator has good biocompatibility, and the application range of the photoinitiator in the fields of food, medical treatment and the like is widened. The photoinitiator system can initiate photocuring of a free radical system under an LED light source, and has good initiation efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoinitiators, and in particular relates to a biomass-based chalcone photoinitiator and a preparation method thereof, a photoinitiator system and a free radical photocuring system. Background Art

[0002] Photopolymerization is the process by which monomers and resins cross-link to form a solid product under the influence of light. Due to its advantages such as fast reaction rate, mild reaction conditions, low energy consumption, and simple operation, it is widely used in many materials fields. Traditional photopolymerization technology uses high-pressure mercury lamps as the UV light source, but these lamps have low utilization rates, short service life, and are prone to ozone generation and mercury pollution, which limits their use. In recent years, energy-saving and soft visible light irradiation sources such as LEDs and blue light have received increasing attention. Compared with UV light polymerization, photopolymerization stimulated by light sources such as LEDs and visible light is a greener and more energy-efficient reaction process.

[0003] Photoinitiators are key components in photopolymerization systems, and their absorption characteristics directly affect polymerization efficiency, material properties, and application scenarios. Commercial LED light source photoinitiators, such as TPO, produce free radicals that are harmful to the human body during the photopolymerization process and have been banned by EU regulations. Currently, there are relatively few types of photoinitiators for LED, visible light, and other light sources that can be used efficiently in commercial applications, and they generally have disadvantages such as poor solubility in photopolymerization systems, low initiation efficiency, poor biocompatibility, and high price. Therefore, it is of great significance to develop a photoinitiator with low cost, high biocompatibility, and high initiation activity. Summary of the Invention

[0004] The present invention provides a biomass-based chalcone photoinitiator, a preparation method thereof, a photoinitiator system, and a free radical photocuring system. The biomass-based chalcone photoinitiator is synthesized using a simple method using biomass aldehyde as a raw material. The biomass aldehyde is environmentally friendly, inexpensive, readily available, and produces a high yield of the target product. The prepared biomass-based chalcone photoinitiator exhibits excellent biocompatibility, effectively addressing the poor biocompatibility of existing photoinitiators and broadening the application of photoinitiators in fields such as food and medical treatment.

[0005] The present invention is specifically achieved through the following technical solutions. According to the present invention, a biomass-based chalcone photoinitiator is proposed, and its molecular structure is shown below: , , , , , .

[0006] The present invention also provides a preparation method of a biomass-based chalcone photoinitiator, comprising the following steps: adding acetone, biomass aldehyde, and anhydrous ethanol into a round-bottom flask, wherein the molar ratio of acetone to biomass aldehyde is 1:1-1:2; stirring in an ice-water bath for 15-30 minutes; adding a sodium hydroxide aqueous solution dropwise thereto; stirring and reacting at room temperature or under heating conditions, wherein the heating reaction temperature is 35-50°C; monitoring the reaction process by thin-layer chromatography until the raw material point disappears; adding water and dichloromethane to the reaction mixture for extraction; drying after extraction to obtain a crude photoinitiator product; and purifying the crude product by column chromatography to obtain the biomass-based chalcone photoinitiator.

[0007] In the preparation method of the aforementioned biomass-based chalcone photoinitiator, the biomass aldehyde is one of p-hydroxybenzaldehyde, syringaldehyde, vanillin, veratraldehyde, anisaldehyde, and protocatechualdehyde.

[0008] In the aforementioned method for preparing the biomass-based chalcone photoinitiator, the ratio of the volume of anhydrous ethanol to the molar number of acetone is 25 mL: 2.2 mmol.

[0009] In the aforementioned method for preparing the biomass-based chalcone photoinitiator, the mass percentage of the sodium hydroxide aqueous solution is 6-12%, and the amount thereof is 2-3 mL of sodium hydroxide aqueous solution per millimole of biomass aldehyde.

[0010] In the aforementioned method for preparing the biomass-based chalcone photoinitiator, the volume ratio of water added to the reaction mixture to the anhydrous ethanol is 2:1, and the volume ratio of dichloromethane to water is 1:1.

[0011] On the basis of the above photoinitiators, the present invention further provides a three-component photoinitiator system, which includes a diaryliodonium salt compound, an amine compound and the biomass-based chalcone photoinitiator.

[0012] Preferably, the diaryl iodonium salt compound is selected from one of diphenyl iodonium hexafluorophosphate, bis(p-tolyl) iodonium hexafluorophosphate, and cyclic diaryl iodonium salts, and the amine compound is selected from one of triethylamine, triethanolamine, and methyldiethanolamine.

[0013] The present invention also provides a free radical photocuring system, which comprises a diaryliodonium salt compound, an amine compound, an olefinic bond-containing compound and the biomass-based chalcone photoinitiator.

[0014] Preferably, the mass ratio of the diaryliodonium salt compound, the amine compound, the olefinic bond-containing compound, and the biomass-based chalcone photoinitiator is (1-2): (1-2): (95.9-97.9): 0.1.

[0015] Preferably, the diaryl iodonium salt compound is selected from one of diphenyl iodonium hexafluorophosphate, bis(p-tolyl) iodonium hexafluorophosphate, and a cyclic diaryl iodonium salt; the amine compound is selected from one of triethylamine, triethanolamine, and methyldiethanolamine; and the olefinic bond-containing compound is selected from one of hydroxyethyl methacrylate, polyethylene glycol diacrylate, and trimethylolpropane triacrylate.

[0016] Preferably, when the free radical light curing system is used, a LED light source with a wavelength of 365 nm is used for light curing.

[0017] Compared with the prior art, the present invention has obvious advantages and beneficial effects. By means of the above technical solution, the present invention can achieve considerable technological advancement and practicality, and has a wide range of utilization value. It has at least the following advantages: (1) The present invention introduces biomass aldehyde into the structure and synthesizes a biomass-based chalcone photoinitiator through a simple method. The biomass aldehyde is green and environmentally friendly, cheap and easy to obtain, and the yield of the target product is high. After experimental comparison, the biomass-based chalcone photoinitiator prepared by the present invention was co-cultured with HeLa cells at different concentrations. The survival rate of HeLa cells remained above 90%, and the cell survival rate was always higher than that of commercially available TPO photoinitiators. This shows that the biomass-based chalcone photoinitiator prepared by the present invention has no significant effect on cell viability, low cytotoxicity, and good biocompatibility. It effectively solves the problem of poor biocompatibility of existing photoinitiators and broadens the application range of photoinitiators in food, medical and other fields.

[0018] (2) The visible light initiator system composed of the biomass-based chalcone photoinitiator, diaryliodonium salt compounds and amine compounds of the present invention can initiate free radical system photocuring under LED light source. Within 30 seconds, the double bond conversion rate can reach more than 80%, which has good initiation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a biocompatibility diagram of the photoinitiator P1 prepared in Example 1.

[0020] Figure 2 This is a biocompatibility diagram of the photoinitiator P2 prepared in Example 2.

[0021] Figure 3 This is a biocompatibility diagram of the photoinitiator P3 prepared in Example 3.

[0022] Figure 4 This is a biocompatibility diagram of the photoinitiator P4 prepared in Example 4.

[0023] Figure 5 This is a biocompatibility diagram of the photoinitiator P5 prepared in Example 5.

[0024] Figure 6 This is a biocompatibility diagram of the photoinitiator P6 prepared in Example 6.

[0025] Figure 7 is the double bond conversion rate of the photoinitiators P1 to P6 prepared in Examples 1 to 6. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] The present invention is described in detail below with reference to specific examples. In the following examples, if no specific conditions are specified, the experiments were carried out according to conventional conditions or those recommended by the manufacturer. Raw materials and reagents used, if the manufacturer is not specified, are all commercially available conventional products.

[0028] Example 1 Photoinitiator P1: Synthesis of (1E, 4E)-1,5-bis(4-hydroxyphenyl)penta-1,4-dien-3-one, the reaction formula is as follows:

[0029] The preparation method comprises the following steps: 2.2 mmol acetone (0.13 g), 4.4 mmol 4-hydroxybenzaldehyde (0.54 g), and 25 mL of anhydrous ethanol were added to a round-bottom flask and stirred in an ice-water bath for 20 min. Then, 10 mL of 10% (mass percent) sodium hydroxide aqueous solution was added dropwise to the mixture. The reaction was stirred at room temperature and monitored by thin-layer chromatography until the starting material disappeared. The reaction mixture was extracted with 50 mL of water and 50 mL of dichloromethane. The extracted product was dried over anhydrous sodium sulfate to obtain a crude photoinitiator. The crude photoinitiator was purified by column chromatography using anhydrous ethanol:n-hexane (volume ratio of 1:2) to obtain biomass-based chalcone photoinitiator P1 in a yield of 65%. H NMR: 1H NMR (400 MHz, Chloroform-d) δ 7.64 (s, J = 1.0 Hz, 2H), 7.55-7.42 (m, 4H), 7.08 (s, 2H), 6.87-6.72 (m, 4H), 5.41 (s, 2H).

[0030] Testing the biocompatibility of the photoinitiator P1 prepared in this example: To evaluate its biocompatibility, the prepared photoinitiator P1 was subjected to a cytotoxicity experiment. The cell viability was observed after 24 h of incubation with HeLa cells (HeLa cells were obtained from the Clinical Medicine Research Center of Southern Medical University) at different concentrations of photoinitiator P1, thereby determining and estimating the cytotoxicity.

[0031] The cytotoxicity test method uses the MTT colorimetric method: HeLa cells were cultured at a density of 6500 cells / well in a 96-well microtiter plate in RPMI-1640 medium containing 10% fetal bovine serum, 100 U / mL penicillin, and 100 U / mL streptomycin. The culture environment was kept constant at 37°C and a CO2 concentration of 5% for 24 hours. The photoinitiator P1 prepared in Example 1 was prepared using RPMI-1640 cell culture medium to prepare photoinitiator P1 solutions with concentrations of 10 μM, 20 μM, 30 μM, 40 μM, and 50 μM, respectively. After the HeLa cells were cultured for 24 hours, the original culture medium in the 96-well microtiter plate was removed, and the prepared photoinitiator P1 solutions were then inoculated into the cells. Two replicates were set for each concentration of photoinitiator P1 solution, and the cells were incubated at 37°C for 24 hours. After the incubation was completed, the excess culture medium was removed and the 96-well microtiter plate was placed on a microwell reader to obtain the number of surviving HeLa cells and calculate the cell survival rate after incubation of the biomass-based chalcone photoinitiator P1 with HeLa cells for 24 h.

[0032] The photoinitiator P1 was replaced with the commercially available TPO photoinitiator. Following the same experimental method as above, the cell viability of HeLa cells after 24 hours of incubation with different concentrations of TPO photoinitiator was tested. A bar graph was drawn with the concentration of photoinitiator as the horizontal axis and the cell viability as the vertical axis, as shown in the figure below. Figure 1 As shown. Figure 1 As shown, when the concentration of photoinitiator P1 co-cultured with HeLa cells increased from 10 μM to 50 μM, the cell viability remained above 90%. Compared with the TPO photoinitiator, photoinitiator P1 had no significant effect on cell viability, and cell viability was consistently higher than that of TPO, indicating that photoinitiator P1 has low cytotoxicity and good biocompatibility.

[0033] Example 2 Photoinitiator P2: Synthesis of (1E, 4E)-1,5-bis(4-methoxyphenyl)penta-1,4-dien-3-one, the reaction formula is as follows:

[0034] The preparation method comprises the following steps: 2.2 mmol acetone (0.13 g), 4.4 mmol anisaldehyde (0.60 g), and 25 mL of anhydrous ethanol were added to a round-bottom flask and stirred in an ice-water bath for 20 min. Then, 10 mL of 10% (mass percent) sodium hydroxide aqueous solution was added dropwise to the mixture. The reaction was stirred at 35°C and monitored by thin-layer chromatography until the starting material disappeared. The reaction mixture was extracted with 50 mL of water and 50 mL of dichloromethane. The extracted product was dried over anhydrous sodium sulfate to obtain a crude photoinitiator. The crude photoinitiator was purified by column chromatography using anhydrous ethanol:n-hexane (volume ratio of 1:2) to obtain biomass-based chalcone photoinitiator P2 in a yield of 68.2%. H NMR: 1H NMR (400 MHz, Chloroform-d) δ 7.64 (s, J = 1.0 Hz, 2H), 7.55-7.42 (m, 4H), 7.08 (s, 2H), 6.87-6.72 (m, 4H), 3.85 (s, 6H).

[0035] Testing the biocompatibility of the photoinitiator P2 prepared in this example: To evaluate its biocompatibility, the prepared photoinitiator P2 was subjected to a cytotoxicity experiment. The cell viability was observed after 24 hours of incubation with HeLa cells (HeLa cells were obtained from the Clinical Medicine Research Center of Southern Medical University) at different concentrations of photoinitiator P2, thereby determining and estimating the cytotoxicity.

[0036] The cytotoxicity test method uses the MTT colorimetric method: HeLa cells were cultured at a density of 6500 cells / well in a 96-well microtiter plate in RPMI-1640 medium containing 10% fetal bovine serum, 100 U / mL penicillin, and 100 U / mL streptomycin. The culture environment was kept constant at 37°C and a CO2 concentration of 5% for 24 hours. The photoinitiator P2 prepared in Example 2 was prepared using RPMI-1640 cell culture medium to prepare photoinitiator P2 solutions with concentrations of 10 μM, 20 μM, 30 μM, 40 μM, and 50 μM, respectively. After the HeLa cells were cultured for 24 hours, the original culture medium in the 96-well microtiter plate was removed, and the prepared photoinitiator P2 solutions were then inoculated into the cells. Two replicates were set for each concentration of photoinitiator P2 solution, and the cells were incubated at 37°C for 24 hours. After the incubation was completed, the excess culture medium was removed and the 96-well microtiter plate was placed on a microwell reader to obtain the number of surviving HeLa cells and calculate the cell survival rate after incubation of the biomass-based chalcone photoinitiator P2 with HeLa cells for 24 h.

[0037] The photoinitiator P2 was replaced with the commercially available TPO photoinitiator. Following the same experimental method as above, the cell viability of HeLa cells after 24 hours of incubation with different concentrations of TPO photoinitiator was tested. A bar graph was drawn with the concentration of photoinitiator as the horizontal axis and the cell viability as the vertical axis, as shown in the figure below. Figure 2 As shown. Figure 2 As can be seen, when the concentration of photoinitiator P2 co-cultured with HeLa cells increased from 10 μM to 50 μM, the cell viability remained above 90%. Compared with the TPO photoinitiator, the photoinitiator P2 prepared in Example 2 had no significant effect on cell viability and consistently maintained higher cell viability than TPO, indicating that photoinitiator P2 has low cytotoxicity and good biocompatibility.

[0038] Example 3 Photoinitiator P3: Synthesis of (1E, 4E)-1,5-bis(3,4-dihydroxyphenyl)penta-1,4-dien-3-one, the reaction formula is as follows:

[0039] The preparation method comprises the following steps: A mixture of 2.2 mmol acetone (0.13 g), 4.4 mmol protocatechualdehyde (0.61 g), and 25 mL of anhydrous ethanol was added to a round-bottom flask and stirred in an ice-water bath for 20 min. Then, 10 mL of 10% (mass percent) sodium hydroxide aqueous solution was added dropwise to the mixture. The reaction was stirred at 40°C and monitored by thin-layer chromatography until the starting material disappeared. The reaction mixture was extracted with 50 mL of water and 50 mL of dichloromethane. The extracted product was dried over anhydrous sodium sulfate to obtain a crude photoinitiator. The crude photoinitiator was purified by column chromatography using anhydrous ethanol:n-hexane (volume ratio of 1:2) to obtain biomass-based chalcone photoinitiator P3 in a yield of 66.3%. H NMR: 1H NMR (400 MHz, Chloroform-d) δ 7.60 (s, J = 1.0 Hz, 2H), 7.2 (s, 2H), 7.0-7.12 (m, 4H), 6.87-6.72 (m, 2H), 5.44 (s, 2H), 4.67 (s, 2H).

[0040] Testing the biocompatibility of the photoinitiator P3 prepared in this example: To evaluate its biocompatibility, the prepared photoinitiator P3 was subjected to a cytotoxicity experiment. The cell viability was observed after 24 h of incubation with HeLa cells (HeLa cells were obtained from the Clinical Medicine Research Center of Southern Medical University) at different concentrations of photoinitiator P3, thereby determining and estimating the cytotoxicity.

[0041] The cytotoxicity test method used the MTT colorimetric method: HeLa cells were cultured at a density of 6500 cells / well in 96-well microtiter plates in RPMI-1640 medium containing 10% fetal bovine serum, 100 U / mL penicillin, and 100 U / mL streptomycin. The culture environment was maintained at 37°C with a CO2 concentration of 5% for 24 hours. The photoinitiator P3 prepared in Example 3 was added to the RPMI-1640 cell culture medium to prepare photoinitiator P3 solutions with concentrations of 10 μM, 20 μM, 30 μM, 40 μM, and 50 μM, respectively. After the HeLa cells were cultured for 24 hours, the original culture medium was removed from the 96-well microtiter plate, and the prepared photoinitiator P3 solutions were then inoculated into the cells. Two replicates were set for each concentration of photoinitiator P3 solution, and the cells were incubated at 37°C for 24 hours. After the incubation was completed, the excess culture medium was removed and the 96-well microtiter plate was placed on a microwell reader to obtain the number of surviving HeLa cells and calculate the cell survival rate after incubation of the biomass-based chalcone photoinitiator P3 with HeLa cells for 24 h.

[0042] The photoinitiator P3 was replaced with the commercially available TPO photoinitiator. Following the same experimental method as above, the cell viability of HeLa cells after 24 hours of incubation with different concentrations of TPO photoinitiator was tested. A bar graph was drawn with the concentration of photoinitiator as the horizontal axis and the cell viability as the vertical axis, as shown in the figure below. Figure 3 As shown. Figure 3 As can be seen, when the concentration of photoinitiator P3 co-cultured with HeLa cells increased from 10 μM to 50 μM, the cell viability remained above 90%. Compared with the TPO photoinitiator, the photoinitiator P3 prepared in Example 3 had no significant effect on cell viability, and the cell viability was consistently higher than that of TPO, indicating that photoinitiator P3 has low cytotoxicity and good biocompatibility.

[0043] Example 4 Photoinitiator P4: Synthesis of (1E, 4E)-1,5-bis(4-hydroxy-3-methoxyphenyl)penta-1,4-dien-3-one, the reaction formula is as follows:

[0044] The preparation method comprises the following steps: A mixture of 2.2 mmol acetone (0.13 g), 4.4 mmol vanillin (0.67 g), and 25 mL of anhydrous ethanol was added to a round-bottom flask and stirred in an ice-water bath for 20 min. Then, 10 mL of 10% (mass percent) sodium hydroxide aqueous solution was added dropwise to the mixture. The reaction was stirred at 40°C and monitored by thin-layer chromatography until the starting material disappeared. The reaction mixture was extracted with 50 mL of water and 50 mL of dichloromethane. The extracted product was dried over anhydrous sodium sulfate to obtain a crude photoinitiator. The crude photoinitiator was purified by column chromatography using anhydrous ethanol:n-hexane (volume ratio of 1:2) to obtain biomass-based chalcone photoinitiator P4 in a yield of 71.4%. H NMR (400 MHz, Chloroform- d ) δ 7.59-7.64 (m, 2H), 7.34 (s, 2H), 7.21-7.16 (m, 4H), 7.06-7.1 (d, 2H), 6.81-6.84 (d, 2H), 3.83 (s, 6H).

[0045] Testing the biocompatibility of the photoinitiator P4 prepared in this example: To evaluate its biocompatibility, the prepared photoinitiator P4 was subjected to a cytotoxicity experiment. The cell viability was observed after incubation of HeLa cells (HeLa cells were obtained from the Clinical Medicine Research Center of Southern Medical University) with different concentrations of photoinitiator P4 for 24 hours, thereby determining and estimating the cytotoxicity.

[0046] The cytotoxicity test method uses the MTT colorimetric method: HeLa cells were cultured at a density of 6500 cells / well in a 96-well microtiter plate in RPMI-1640 medium containing 10% fetal bovine serum, 100 U / mL penicillin, and 100 U / mL streptomycin. The culture environment was kept constant at 37°C with a CO2 concentration of 5% for 24 hours. The photoinitiator P4 prepared in Example 4 was prepared using RPMI-1640 cell culture medium to prepare photoinitiator P4 solutions with concentrations of 10 μM, 20 μM, 30 μM, 40 μM, and 50 μM, respectively. After the HeLa cells were cultured for 24 hours, the original culture medium in the 96-well microtiter plate was removed, and the prepared photoinitiator P4 solutions were then inoculated into the cells. Two replicates were set for each concentration of photoinitiator P4 solution, and the cells were incubated at 37°C for 24 hours. After the incubation was completed, the excess culture medium was removed and the 96-well microtiter plate was placed on a microwell reader to obtain the number of surviving HeLa cells and calculate the cell survival rate after incubation of the biomass-based chalcone photoinitiator P4 with HeLa cells for 24 h.

[0047] The photoinitiator P4 was replaced with the commercially available TPO photoinitiator. Following the same experimental method as above, the cell viability of HeLa cells after 24 hours of incubation with different concentrations of TPO photoinitiator was tested. A bar graph was drawn with the concentration of photoinitiator as the horizontal axis and the cell viability as the vertical axis, as shown in the figure below. Figure 4 As shown. Figure 4 As can be seen, when the concentration of photoinitiator P4 co-cultured with HeLa cells increased from 10 μM to 50 μM, the cell viability remained above 90%. Compared with the TPO photoinitiator, the photoinitiator P4 prepared in Example 4 had no significant effect on cell viability and consistently maintained higher cell viability than TPO, indicating that photoinitiator P4 has low cytotoxicity and good biocompatibility.

[0048] Example 5 Photoinitiator P5: Synthesis of (1E, 4E)-1,5-bis(3,4-dimethoxyphenyl)penta-1,4-dien-3-one, the reaction formula is as follows:

[0049] The preparation method comprises the following steps: A mixture of 2.2 mmol acetone (0.13 g), 4.4 mmol veratraldehyde (0.73 g), and 25 mL of anhydrous ethanol was added to a round-bottom flask and stirred in an ice-water bath for 20 min. Then, 10 mL of 10% (mass percent) sodium hydroxide aqueous solution was added dropwise to the mixture. The reaction was stirred at 50°C and monitored by thin-layer chromatography until the starting material disappeared. The reaction mixture was extracted with 50 mL of water and 50 mL of dichloromethane. The extracted product was dried over anhydrous sodium sulfate to obtain a crude photoinitiator. The crude photoinitiator was purified by column chromatography using anhydrous ethanol:n-hexane (volume ratio of 1:2) to obtain biomass-based chalcone photoinitiator P5 in a yield of 69%. H NMR: 1H NMR (400MHz, Chloroform-d) δ 7.61 (t, J = 1.0 Hz, 2H), 7.14-7.20 (m, 6H), 6.90-6.94 (m, 2H), 3.82-3.85 (d, 12H).

[0050] Testing the biocompatibility of the photoinitiator P5 prepared in this example: To evaluate its biocompatibility, the prepared photoinitiator P5 was subjected to a cytotoxicity experiment. The cell viability was observed after 24 h of incubation with HeLa cells (HeLa cells were obtained from the Clinical Medicine Research Center of Southern Medical University) at different concentrations of photoinitiator P5, thereby determining and estimating the cytotoxicity.

[0051] The cytotoxicity test method uses the MTT colorimetric method: HeLa cells were cultured at a density of 6500 cells / well in a 96-well microtiter plate in RPMI-1640 medium containing 10% fetal bovine serum, 100 U / mL penicillin, and 100 U / mL streptomycin. The culture environment was kept constant at 37°C with a CO2 concentration of 5% for 24 hours. The photoinitiator P5 prepared in Example 5 was prepared using RPMI-1640 cell culture medium to prepare photoinitiator P5 solutions with concentrations of 10 μM, 20 μM, 30 μM, 40 μM, and 50 μM, respectively. After the HeLa cells were cultured for 24 hours, the original culture medium in the 96-well microtiter plate was removed, and the prepared photoinitiator P5 solutions were then inoculated into the cells. Two replicates were set for each concentration of photoinitiator P5 solution, and the cells were incubated at 37°C for 24 hours. After the incubation was completed, the excess culture medium was removed and the 96-well microtiter plate was placed on a microwell reader to obtain the number of surviving HeLa cells and calculate the cell survival rate after incubation of the biomass-based chalcone photoinitiator P5 with HeLa cells for 24 h.

[0052] The photoinitiator P5 was replaced with the commercially available TPO photoinitiator. Following the same experimental method as above, the cell viability of HeLa cells after 24 hours of incubation with different concentrations of TPO photoinitiator was tested. A bar graph was drawn with the concentration of photoinitiator as the horizontal axis and the cell viability as the vertical axis, as shown in the figure below. Figure 5 As shown. Figure 5 As can be seen, when the concentration of photoinitiator P5 co-cultured with HeLa cells increased from 10 μM to 50 μM, the cell viability remained above 90%. Compared with the TPO photoinitiator, the photoinitiator P5 prepared in Example 5 had no significant effect on cell viability, and the cell viability was consistently higher than that of TPO, indicating that photoinitiator P5 has low cytotoxicity and good biocompatibility.

[0053] Example 6 Photoinitiator P6: Synthesis of (1E, 4E)-1,5-bis(4-hydroxy-3,5-dimethoxyphenyl)penta-1,4-dien-3-one, the reaction formula is as follows:

[0054] The preparation method comprises the following steps: A mixture of 2.2 mmol acetone (0.13 g), 4.4 mmol syringaldehyde (0.80 g), and 25 mL of anhydrous ethanol was added to a round-bottom flask and stirred in an ice-water bath for 20 min. Then, 10 mL of 10% (mass percent) sodium hydroxide aqueous solution was added dropwise to the mixture. The reaction was stirred at 50°C and monitored by thin-layer chromatography until the starting material disappeared. The reaction mixture was extracted with 50 mL of water and 50 mL of dichloromethane. The extracted product was dried over anhydrous sodium sulfate to obtain a crude photoinitiator. The crude photoinitiator was purified by column chromatography using anhydrous ethanol:n-hexane (volume ratio of 1:2) to obtain biomass-based chalcone photoinitiator P6 in a yield of 73.2%. H NMR spectroscopy: 1H NMR (400 MHz, Chloroform- d ) δ 8.32(s, 2H), 7.60-7.62(t, 2H), 7.21 (s, 2H), 6.94(s, 4H), 3.82-3.85 (s, 12H).

[0055] Testing the biocompatibility of the photoinitiator P6 prepared in this example: To evaluate its biocompatibility, the prepared photoinitiator P6 was subjected to a cytotoxicity experiment. The cell viability was observed after incubation of HeLa cells (HeLa cells were obtained from the Clinical Medicine Research Center of Southern Medical University) with different concentrations of photoinitiator P6 for 24 hours, thereby determining and estimating the cytotoxicity.

[0056] The cytotoxicity test method uses the MTT colorimetric method: HeLa cells were cultured at a density of 6500 cells / well in a 96-well microtiter plate in RPMI-1640 medium containing 10% fetal bovine serum, 100 U / mL penicillin, and 100 U / mL streptomycin. The culture environment was kept constant at 37°C and a CO2 concentration of 5% for 24 hours. The photoinitiator P6 prepared in Example 6 was prepared using RPMI-1640 cell culture medium to prepare photoinitiator P6 solutions with concentrations of 10 μM, 20 μM, 30 μM, 40 μM, and 50 μM, respectively. After the HeLa cells were cultured for 24 hours, the original culture medium in the 96-well microtiter plate was removed, and the prepared photoinitiator P6 solutions were then inoculated into the cells. Two replicates were set for each concentration of photoinitiator P6 solution, and the cells were incubated at 37°C for 24 hours. After the incubation was completed, the excess culture medium was removed and the 96-well microtiter plate was placed on a microwell reader to obtain the number of surviving HeLa cells and calculate the cell survival rate after incubation of the biomass-based chalcone photoinitiator P6 with HeLa cells for 24 h.

[0057] The photoinitiator P6 was replaced with the commercially available TPO photoinitiator. Following the same experimental method as above, the cell viability of HeLa cells after 24 hours of incubation with different concentrations of TPO photoinitiator was tested. A bar graph was drawn with the concentration of photoinitiator as the horizontal axis and the cell viability as the vertical axis, as shown in the figure below. Figure 6 As shown. Figure 6 As can be seen, when the concentration of photoinitiator P6 co-cultured with HeLa cells increased from 10 μM to 50 μM, the cell viability remained above 90%. Compared with the TPO photoinitiator, the photoinitiator P6 prepared in Example 6 had no significant effect on cell viability, and the cell viability was consistently higher than that of TPO, indicating that the photoinitiator P6 has low cytotoxicity and good biocompatibility.

[0058] The present invention also provides a photoinitiator system comprising a diaryliodonium salt compound, an amine compound, and a photoinitiator, wherein the photoinitiator is one of the biomass-based chalcone photoinitiators prepared in Examples 1 to 6. The diaryliodonium salt compound is selected from diphenyliodonium hexafluorophosphate, bis(p-tolyl)iodonium hexafluorophosphate, and a cyclic diaryliodonium salt, and the amine compound is selected from triethylamine, triethanolamine, and methyldiethanolamine.

[0059] Based on the above-mentioned photoinitiator system, the present invention also provides a free radical photocuring system, which includes a diaryliodonium salt compound, an amine compound, an olefinic compound, and a photoinitiator. The photoinitiator is one of the biomass-based chalcone photoinitiators prepared in Examples 1 to 6. The mass ratio of the diaryliodonium salt compound, the amine compound, the olefinic compound, and the biomass-based chalcone photoinitiator is preferably (1-2): (1-2): (95.9-97.9): 0.1. The diaryliodonium salt compound is selected from diphenyliodonium hexafluorophosphate, bis(p-tolyl)iodonium hexafluorophosphate, and a cyclic diaryliodonium salt; the amine compound is selected from triethylamine, triethanolamine, and methyldiethanolamine; and the olefinic compound is selected from hydroxyethyl methacrylate, polyethylene glycol diacrylate, and trimethylolpropane triacrylate. When the free radical light curing system is used, a LED light source with an emission wavelength of 365 nm is used for light curing.

[0060] The photopolymerization performance of the photoinitiators P1 to P6 synthesized in Examples 1 to 6 was detected in situ using a real-time infrared spectrometer. The infrared spectrum was recorded in the range of 4000 to 600 cm -1, the test time is set to 500 s. The light source for photopolymerization uses an LED light source with an emission wavelength of 365 nm. The test system consists of diphenyliodonium hexafluorophosphate, triethanolamine, polyethylene glycol diacrylate (monomer), and a photoinitiator (one of P1~P6). According to weight percentage, the addition amount of diphenyliodonium hexafluorophosphate is 2.0 wt%, the addition amount of triethanolamine is 2.0 wt%, the addition amount of polyethylene glycol diacrylate (monomer) is 95.9 wt%, and the addition amount of photoinitiator is 0.1 wt%. According to the above ratio, 6 parts of the test system consisting of photoinitiators prepared in different embodiments and diphenyliodonium hexafluorophosphate, triethanolamine, and polyethylene glycol diacrylate were obtained. The test system was evenly coated on a polyvinyl chloride (PVC) film, and then covered with a layer of PVC film to prevent oxygen inhibition during the test. The absorption peak change of the sample with the increase of illumination time was tested by infrared spectroscopy, and the absorption peak at 810 cm was measured. -1 The stretching vibration of the carbon-carbon double bond at 1720 cm -1 The C=O bond is used as a reference. The conversion rate of carbon-carbon double bonds is calculated as follows: DC (%) = [1-(A 810 / A 1720 ) t / (A 810 / A 1720 )0]×100%, DC(%) represents the carbon-carbon double bond conversion rate, (A 810 / A 1720 )0 represents the peak area ratio of C=C bond to C=O bond before curing, (A 810 / A 1720 ) t Represents the peak area ratio of C=C bond to C=O bond at curing time t. Plot the graph with test time as the horizontal axis and carbon-carbon double bond conversion rate as the vertical axis, as shown in Figure 7 As shown, it is shown that the visible light initiator system composed of the biomass-based chalcone photoinitiator, diaryliodonium salt compounds and amine compounds prepared by the present invention can initiate free radical system photocuring under LED light source. Within 30 seconds, the double bond conversion rate initiated by the photoinitiator system containing P3, P5 or P6 can reach more than 80%, which has good initiation efficiency.

[0061] The above description is merely an embodiment of the present invention and does not constitute any form of limitation to the present invention. The present invention may also have other forms of embodiments based on the above structures and functions, which are not listed here one by one. Therefore, any simple modification, equivalent changes, and modifications made to the above embodiments by any person skilled in the art in accordance with the technical essence of the present invention without departing from the scope of the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A biomass-based chalcone photoinitiator, characterized in that The molecular structure is shown below: ， ， ， ， ， 。 2. A method for preparing a biomass-based chalcone photoinitiator, characterized in that: The following steps are involved: Acetone, biomass aldehyde, and anhydrous ethanol are added to a round-bottom flask with a molar ratio of acetone to biomass aldehyde of 1:1 to 1:

2. After stirring in an ice-water bath for 15 to 30 minutes, a sodium hydroxide aqueous solution is added dropwise thereto. The mixture is stirred and reacted at room temperature or under heating conditions. The heating reaction temperature is 35 to 50° C. The reaction process is monitored by thin-layer chromatography until the raw material point disappears. Water and dichloromethane are added to the reaction mixture for extraction. After extraction, the mixture is dried to obtain a crude photoinitiator product. The crude photoinitiator product is purified by column chromatography to obtain a biomass-based chalcone photoinitiator.

3. The method for preparing a biomass-based chalcone photoinitiator according to claim 2, wherein The biomass aldehyde is one of p-hydroxybenzaldehyde, syringaldehyde, vanillin, veratraldehyde, anisaldehyde and protocatechualdehyde.

4. The method for preparing a biomass-based chalcone photoinitiator according to claim 2, wherein: The mass percentage of the sodium hydroxide aqueous solution is 6-12%, and the amount thereof is 2-3 mL of the sodium hydroxide aqueous solution per millimole of biomass aldehyde.

5. The method for preparing a biomass-based chalcone photoinitiator according to claim 2, wherein: The volume ratio of water added to the mixture after the reaction to the anhydrous ethanol was 2:1, and the volume ratio of water to dichloromethane was 1:

1.

6. A photoinitiator system, characterized in that The invention comprises a diaryliodonium salt compound, an amine compound and the biomass-based chalcone photoinitiator according to claim 1.

7. The photoinitiator system according to claim 6, characterized in that The diaryl iodonium salt compound is selected from one of diphenyl iodonium hexafluorophosphate, bis(p-tolyl) iodonium hexafluorophosphate, and cyclic diaryl iodonium salts; and the amine compound is selected from one of triethylamine, triethanolamine, and methyldiethanolamine.

8. A free radical photocuring system, characterized in that: The invention comprises a diaryliodonium salt compound, an amine compound, an olefinic bond-containing compound and the biomass-based chalcone photoinitiator according to claim 1.

9. The free radical photocuring system according to claim 8, wherein: The mass ratio of the diaryl iodonium salt compound, the amine compound, the olefinic bond-containing compound, and the biomass-based chalcone photoinitiator is (1-2): (1-2): (95.9-97.9): 0.1; the diaryl iodonium salt compound is selected from one of diphenyl iodonium hexafluorophosphate, bis(p-tolyl) iodonium hexafluorophosphate, and a cyclic diaryl iodonium salt; the amine compound is selected from one of triethylamine, triethanolamine, and methyldiethanolamine; and the olefinic bond-containing compound is selected from one of hydroxyethyl methacrylate, polyethylene glycol diacrylate, and trimethylolpropane triacrylate.

10. The free radical photocuring system according to claim 8 or 9, characterized in that: Light curing is performed using an LED light source with a wavelength of 365nm.

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