A method for modifying a soy protein-based hydrogel with metal ions

Abstract

This invention discloses a method for modifying soybean protein-based hydrogels using metal ions, belonging to the field of soybean functional protein material application technology. The method includes: mixing a soybean protein isolate solution with an epigallocatechin-3-gallate solution, adjusting the pH to 9.0, stirring in the dark, and freeze-drying to obtain an SPI-EGCG complex; oxidizing guar gum with sodium periodate, terminating the reaction with ethylene glycol, dialysis, and freeze-drying to obtain oxidized guar gum; reconstituted SPI-EGCG and adding AgNO₃, MgCl₂, or FeCl₃·6H₂O metal salt solutions respectively, adjusting and maintaining an alkaline pH to allow the metal ions to coordinate with EGCG, then adding oxidized guar gum, and stirring and allowing to stand to form an SPI-EGCG / metal ion-OGG hydrogel. This method constructs a multi-linked network through metal-polyphenol coordination and Schiff base dynamic crosslinking, which can improve the network crosslinking degree, elastic properties and antibacterial properties of soybean protein-based hydrogels. The preparation process is simple and suitable for the modification and preparation of soybean protein-based functional hydrogel materials.

Description

Technical Field

[0001] This invention belongs to the field of application technology of soybean functional protein materials, and mainly relates to a method for modifying soybean protein-based hydrogels using metal ions. Background Technology

[0002] In recent years, soybean protein-based hydrogels have shown great potential in high-value applications. The main preparation methods for these hydrogels are physical crosslinking and chemical crosslinking. While physical crosslinking is relatively simple, it generally suffers from poor mechanical properties and insufficient stability. A hydrogel prepared by modifying soybean protein isolate with polyphenols and then combining it with oxidized guar gum requires no heating or other chemical crosslinking agents; it can be completed with only simple stirring.

[0003] Metal-phenolic interactions are supramolecular network structures formed by the combination of metal ions or metalloid ligands with phenolic substances. Due to the excellent bioactivity and chemical reactivity of polyphenols and the wide range of metal ion selectivity, metal-phenolic interactions have been endowed with rich properties and functions. Therefore, metal-phenolic interactions have been assembled into a series of materials. The preparation process of metal-phenolic networks is simple, rapid, and green chemistry-based. Its most unique advantage is that it can combine the properties of polyphenols and metal ions, mutually modifying or synergistically enhancing each other's functions, thus achieving better performance compared to single materials.

[0004] Schiff base bonds can be generated in situ with cells, tissues, and bioactive molecules under physiological conditions, forming hydrogel networks. Dynamic cross-linked networks can also endow hydrogels with self-healing properties. The Schiff base reaction, as a powerful chemical tool, has shown great potential in improving the mechanical properties, thermal stability, and functionality of polysaccharide and protein-based hydrogel materials. Furthermore, exploring novel, environmentally friendly cross-linking agents, and combining Schiff base chemistry with other cross-linking strategies, may yield innovative hydrogel systems with unique properties and functions. Summary of the Invention

[0005] The purpose of this invention is to address the common problems of poor mechanical properties and insufficient stability in soybean protein-based hydrogels. It provides a method for preparing soybean protein-based hydrogels by modifying soybean protein isolate using metal-polyphenol linkages and then compounding it with oxidized guar gum. This process requires no heating or other chemical cross-linking agents, only simple stirring. Furthermore, by introducing a non-toxic metal-phenol interaction system and dynamic chemical bonds such as Schiff bases, a multi-crosslinked network system is constructed. This further explores how to regulate the network structure, macroscopic mechanical properties, protein structural changes, and in vitro physiological and biochemical functions of the hydrogel by altering the intermolecular cross-linking density.

[0006] The technical problem to be solved by the present invention is achieved through the following technical solution: 1. A method for modifying soybean protein-based hydrogels using metal ions, characterized in that the method steps are as follows: (1) Preparation of soybean protein-EGCG complex (SPI-EGCG): Soybean protein isolate is dissolved in deionized water with a protein concentration of 2% (w / v). After stirring for 2 h, it is hydrated overnight at 4 ℃. An equal volume of EGCG solution (0.3%, w / v) is added to the SPI solution, mixed evenly, and the pH value is adjusted to 9.0. After stirring continuously in the dark for 24 h, it is freeze-dried to obtain SPI-EGCG; (2) Preparation of oxidized guar gum (OGG): Guar gum is dissolved in deionized water and heated at 70 ℃ and stirred continuously for 1 h to obtain a 0.5% guar gum solution. NaIO4 aqueous solution (25 mg / mL) is slowly added dropwise to the guar gum solution. The mixture is stirred at 800 r / min at 25 ℃ in the dark for 24 h. 3 mL of ethylene glycol is added to terminate the reaction, and the mixture is dialyzed for 4 days. Replace the deionized water once per h, and freeze-dry the dialysis solution to obtain oxidized guar gum (OGG); (3) Method for metal ion interaction with soybean protein-based hydrogel: Dissolve SPI-EGCG in deionized water and stir for 2 h to obtain a 12% (w / v) SPI-EGCG solution. Prepare 10 mg / mL solutions of AgNO3, MgCl2, and FeCl3·6 H2O respectively. Take 500 µL of metal ion solution and add it to the SPI-EGCG solution. Adjust the pH to 9.0 with 2 mol / L NaOH solution. Stir the SPI-EGCG / metal ion mixed solution for 3 h to allow for full reaction and maintain the pH at 9.5 to obtain the SPI-EGCG / metal ion complex. Add 0.1 g OGG to each group of SPI-EGCG / metal ion complex solutions, stir vigorously for 30 min and let stand for 1 hour. h, hydrogels (SPI-EGCG / metal ion-OGG hydrogels) were obtained, which were labeled as SE-OGG, SE / Ag-OGG, SE / Mg-OGG and SE / Fe-OGG, respectively.

[0007] 2. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that (1) soybean protein isolate is dissolved in deionized water at a protein concentration of 2% (w / v), stirred for 2 h, and then hydrated overnight at 4°C.

[0008] 3. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that (1) an equal volume of EGCG solution (0.3%, w / v) is added to the SPI solution, mixed evenly, and the pH value is adjusted to 9.0. After continuous stirring in the dark for 24 h, SPI-EGCG is freeze-dried.

[0009] 4. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that (2) guar gum is dissolved in deionized water and heated at 70 °C and continuously stirred for 1 h to obtain a 0.5% guar gum solution.

[0010] 5. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that (2) the aqueous solution of NaIO4 (25 mg / mL) is slowly added dropwise to the guar gum solution, and the mixture is stirred at 800 r / min at 25°C for 24 h in the dark, and 3 mL of ethylene glycol is added to terminate the reaction.

[0011] 6. The method for modifying soybean protein-based hydrogels with metal ions according to claim 1, characterized in that (2) the dialysis is performed for 4 days, the deionized water is replaced every 24 hours, and the lyophilized dialysis solution is used to obtain oxidized guar gum (OGG).

[0012] 7. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that (3) SPI-EGCG is dissolved in deionized water and stirred for 2 h to obtain a 12% (w / v) SPI-EGCG solution, and 10 mg / mL solutions of AgNO3, MgCl2, and FeCl3·6 H2O are prepared respectively. 500 µL of metal ion solution is added to the SPI-EGCG solution, and the pH is adjusted to 9.0 with 2 mol / L NaOH solution.

[0013] 8. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that (3) the SPI-EGCG / metal ion mixed solution is stirred for 3 h to allow for full reaction, and the pH is maintained at 9.5 to obtain the SPI-EGCG / metal ion complex.

[0014] 9. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that (3) 0.1 g OGG is added to each group of SPI-EGCG / metal ion composite solutions, and after vigorous stirring for 30 min and standing for 1 h, hydrogels (SPI-EGCG / metal ion-OGG hydrogels) are obtained. These hydrogels are respectively labeled as SE-OGG, SE / Ag-OGG, SE / Mg-OGG and SE / Fe-OGG. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the present invention; Figure 2 The effect of adding metal ions on the rheological properties of soybean protein-based hydrogels; Figure 3 The effect of adding metal ions on the antibacterial properties of soybean protein-based hydrogels; Detailed Implementation

[0016] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0017] A method for modifying soybean protein-based hydrogels using metal ions, characterized by the following steps: (1) Preparation of soybean protein-EGCG complex (SPI-EGCG): Soybean protein isolate is dissolved in deionized water with a protein concentration of 2% (w / v). After stirring for 2 h, it is hydrated overnight at 4 ℃. An equal volume of EGCG solution (0.3%, w / v) is added to the SPI solution, mixed evenly, and the pH value is adjusted to 9.0. After stirring continuously in the dark for 24 h, it is freeze-dried to obtain SPI-EGCG; (2) Preparation of oxidized guar gum (OGG): Guar gum is dissolved in deionized water and heated at 70 ℃ with continuous stirring for 1 h to obtain a 0.5% guar gum solution. NaIO4 aqueous solution (25 mg / mL) is slowly added dropwise to the guar gum solution. The mixture is stirred at 800 r / min at 25 ℃ in the dark for 24 h. 3 mL of ethylene glycol is added to terminate the reaction, and the mixture is dialyzed for 4 days. Replace the deionized water once per h, and freeze-dry the dialysis solution to obtain oxidized guar gum (OGG); (3) Method for metal ion interaction with soybean protein-based hydrogel: Dissolve SPI-EGCG in deionized water and stir for 2 h to obtain a 12% (w / v) SPI-EGCG solution. Add 0.1 g OGG to the above SPI-EGCG solution, stir vigorously for 30 min and let stand for 1 h to obtain hydrogel SE-OGG. Prepare 10 mg / mL solutions of AgNO3, MgCl2, and FeCl3·6 H2O respectively. Take 500 µL of metal ion solution and add it to the SPI-EGCG solution. Adjust the pH to 9.0 with 2 mol / L NaOH solution. Stir the SPI-EGCG / metal ion mixed solution for 3 h to fully react and maintain the pH at 9.5 to obtain the SPI-EGCG / metal ion complex. Add 0.1 g OGG to each group of SPI-EGCG / metal ion complex solutions, stir vigorously for 30 min and let stand for 1 h. h, hydrogels (SPI-EGCG / metal ion-OGG hydrogels) were obtained, which were labeled SE-OGG, SE / Ag-OGG, SE / Mg-OGG and SE / Fe-OGG, respectively. Example 1

[0018] Soy protein isolate was dissolved in deionized water to a protein concentration of 2% (w / v). After stirring for 2 h, it was hydrated overnight at 4 °C. An equal volume of EGCG solution (0.3%, w / v) was added to the SPI solution, mixed thoroughly, and the pH was adjusted to 9.0. After stirring continuously in the dark for 24 h, the mixture was freeze-dried to obtain SPI-EGCG. Guar gum was dissolved in deionized water and heated at 70 °C with continuous stirring for 1 h to obtain a 0.5% guar gum solution. A NaIO4 aqueous solution (25 mg / mL) was slowly added dropwise to the guar gum solution, and the mixture was stirred at 800 r / min at 25 °C for 24 h in the dark. The reaction was terminated by adding 3 mL of ethylene glycol, and the mixture was dialyzed for 4 days, with the deionized water changed every 24 h. The dialysate was freeze-dried to obtain oxidized guar gum. SPI-EGCG was dissolved in deionized water and stirred for 2 h to obtain a 12% (w / v) SPI-EGCG solution. The pH was maintained at 9.5, and 0.1 g of EGCG solution was added. OGG was vigorously stirred for 30 min and allowed to stand for 1 h to obtain the hydrogel SE-OGG. Example 2

[0019] Soy protein isolate was dissolved in deionized water to a protein concentration of 2% (w / v). After stirring for 2 h, it was hydrated overnight at 4 °C. An equal volume of EGCG solution (0.3%, w / v) was added to the SPI solution, mixed thoroughly, and the pH was adjusted to 9.0. After stirring continuously in the dark for 24 h, the mixture was freeze-dried to obtain SPI-EGCG. Guar gum was dissolved in deionized water and heated at 70 °C with continuous stirring for 1 h to obtain a 0.5% guar gum solution. A NaIO4 aqueous solution (25 mg / mL) was slowly added dropwise to the guar gum solution, and the mixture was stirred at 800 r / min at 25 °C for 24 h in the dark. The reaction was terminated by adding 3 mL of ethylene glycol, and the mixture was dialyzed for 4 days, with the deionized water changed every 24 h. The dialysate was freeze-dried to obtain oxidized guar gum. SPI-EGCG was dissolved in deionized water and stirred for 2 h to obtain a 12% (w / v) SPI-EGCG solution. 10 Add 500 µL of AgNO3 solution to the SPI-EGCG solution and adjust the pH to 9.0 with 2 mol / L NaOH solution. Stir the SPI-EGCG / AgNO3 mixture for 3 h to allow for complete reaction and maintain the pH at 9.5 to obtain the SPI-EGCG / Ag complex. Add 0.1 g of OGG to each group of SPI-EGCG / Ag complex solutions, stir vigorously for 30 min and let stand for 1 h to obtain the hydrogel SE / Ag-OGG. Example 3

[0020] Soy protein isolate was dissolved in deionized water to a protein concentration of 2% (w / v). After stirring for 2 h, it was hydrated overnight at 4 °C. An equal volume of EGCG solution (0.3%, w / v) was added to the SPI solution, mixed thoroughly, and the pH was adjusted to 9.0. After stirring continuously in the dark for 24 h, the mixture was freeze-dried to obtain SPI-EGCG. Guar gum was dissolved in deionized water and heated at 70 °C with continuous stirring for 1 h to obtain a 0.5% guar gum solution. A NaIO4 aqueous solution (25 mg / mL) was slowly added dropwise to the guar gum solution, and the mixture was stirred at 800 r / min at 25 °C for 24 h in the dark. The reaction was terminated by adding 3 mL of ethylene glycol, and the mixture was dialyzed for 4 days, with the deionized water changed every 24 h. The dialysate was freeze-dried to obtain oxidized guar gum. SPI-EGCG was dissolved in deionized water and stirred for 2 h to obtain a 12% (w / v) SPI-EGCG solution. 10 500 µL of MgCl2 solution was added to the SPI-EGCG solution, and the pH was adjusted to 9.0 with 2 mol / L NaOH solution. The SPI-EGCG / MgCl2 mixture was stirred for 3 h to allow for a complete reaction, and the pH was maintained at 9.5 to obtain the SPI-EGCG / Mg complex. 0.1 g of OGG was added to each group of SPI-EGCG / Mg complex solutions, and the mixture was stirred vigorously for 30 min and allowed to stand for 1 h to obtain the hydrogel SE / Mg-OGG. Example 4

[0021] Soy protein isolate was dissolved in deionized water to a protein concentration of 2% (w / v). After stirring for 2 h, it was hydrated overnight at 4 °C. An equal volume of EGCG solution (0.3%, w / v) was added to the SPI solution, mixed thoroughly, and the pH was adjusted to 9.0. After stirring continuously in the dark for 24 h, the mixture was freeze-dried to obtain SPI-EGCG. Guar gum was dissolved in deionized water and heated at 70 °C with continuous stirring for 1 h to obtain a 0.5% guar gum solution. A NaIO4 aqueous solution (25 mg / mL) was slowly added dropwise to the guar gum solution, and the mixture was stirred at 800 r / min at 25 °C for 24 h in the dark. The reaction was terminated by adding 3 mL of ethylene glycol, and the mixture was dialyzed for 4 days, with the deionized water changed every 24 h. The dialysate was freeze-dried to obtain oxidized guar gum. SPI-EGCG was dissolved in deionized water and stirred for 2 h to obtain a 12% (w / v) SPI-EGCG solution. 10 500 µL of FeCl3·6 H2O solution was added to SPI-EGCG solution, and the pH was adjusted to 9.0 with 2 mol / L NaOH solution. The SPI-EGCG / FeCl3·6 H2O mixed solution was stirred for 3 h to allow for complete reaction, and the pH was maintained at 9.5 to obtain the SPI-EGCG / Fe complex. 0.1 g of OGG was added to each group of SPI-EGCG / Fe complex solutions, and after vigorous stirring for 30 min and standing for 1 h, the hydrogel SE / Fe-OGG was obtained.

[0022] Comparative analysis of the above examples revealed enhanced rheological properties of soybean protein-based hydrogels under different metal-polyphenol interactions, indicating that hydrogels incorporating metal-phenol interactions possess stronger elastic properties and network cross-linking. In particular, Ag-ion-guided SE / Ag-OGG exhibited the highest storage modulus. (See...) Figure 2 The determination of antibacterial properties showed that the antibacterial effect of hydrogels with added metal ions was significantly higher than that of SE-OGG (see [link to study]). Figure 3 It significantly improved the antibacterial properties.

Claims

1. A method for modifying soybean protein-based hydrogels using metal ions, characterized in that... The method steps are as follows: (1) Preparation of soybean protein-EGCG complex (SPI-EGCG): Soybean protein isolate is dissolved in deionized water with a protein concentration of 2% (w / v). After stirring for 2 h, it is hydrated overnight at 4 ℃. An equal volume of EGCG solution (0.3%, w / v) is added to the SPI solution, mixed evenly, and the pH value is adjusted to 9.

0. After stirring continuously in the dark for 24 h, it is freeze-dried to obtain SPI-EGCG; (2) Preparation of oxidized guar gum (OGG): Guar gum is dissolved in deionized water and heated at 70 ℃ and stirred continuously for 1 h to obtain a 0.5% guar gum solution. NaIO4 aqueous solution (25 mg / mL) is slowly added dropwise to the guar gum solution. It is stirred at 800 r / min at 25 ℃ in the dark for 24 h. 3 mL of ethylene glycol is added to terminate the reaction, and the mixture is dialyzed for 4 days. Replace the deionized water once per h, and freeze-dry the dialysis solution to obtain oxidized guar gum (OGG); (3) Method for metal ion interaction with soybean protein-based hydrogel: Dissolve SPI-EGCG in deionized water and stir for 2 h to obtain a 12% (w / v) SPI-EGCG solution. Prepare 10 mg / mL solutions of AgNO3, MgCl2, and FeCl3·6 H2O respectively. Take 500 µL of metal ion solution and add it to the SPI-EGCG solution. Adjust the pH to 9.0 with 2 mol / L NaOH solution. Stir the SPI-EGCG / metal ion mixed solution for 3 h to allow for full reaction and maintain the pH at 9.5 to obtain the SPI-EGCG / metal ion complex. Add 0.1 g OGG to each group of SPI-EGCG / metal ion complex solutions, stir vigorously for 30 min and let stand for 1 hour. h, hydrogels (SPI-EGCG / metal ion-OGG hydrogels) were obtained, which were labeled SE-OGG, SE / Ag-OGG, SE / Mg-OGG and SE / Fe-OGG, respectively.

2. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that... (1) describes dissolving soy protein isolate in deionized water at a protein concentration of 2% (w / v), stirring for 2 h, and then hydrating overnight at 4 ℃.

3. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that... (1) As described above, an equal volume of EGCG solution (0.3%, w / v) is added to the SPI solution, mixed evenly, and the pH value is adjusted to 9.

0. After stirring continuously in the dark for 24 h, the mixture is freeze-dried to obtain SPI-EGCG.

4. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that... (2) describes dissolving guar gum in deionized water and heating it at 70 °C while stirring continuously for 1 h to obtain a 0.5% guar gum solution.

5. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that... (2) The aqueous solution of NaIO4 (25 mg / mL) was slowly added dropwise to the guar gum solution, and the mixture was stirred at 800 r / min at 25 °C for 24 h in the dark. Then, 3 mL of ethylene glycol was added to terminate the reaction.

6. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that... (2) The dialysis was performed for 4 days, with the deionized water changed every 24 hours. The lyophilized dialysis solution was then used to obtain oxidized guar gum (OGG).

7. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that... (3) The SPI-EGCG solution was obtained by dissolving SPI-EGCG in deionized water and stirring for 2 h. 10 mg / mL solutions of AgNO3, MgCl2 and FeCl3·6 H2O were prepared respectively. 500 µL of metal ion solution was added to the SPI-EGCG solution and the pH was adjusted to 9.0 with 2 mol / L NaOH solution.

8. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that... (3) The SPI-EGCG / metal ion mixed solution was stirred for 3 h to allow for full reaction, and the pH was maintained at 9.5 to obtain the SPI-EGCG / metal ion complex.

9. The method for modifying soybean protein-based hydrogels using metal ions according to claim 1, characterized in that... (3) 0.1 g OGG was added to each group of SPI-EGCG / metal ion composite solutions, and after vigorous stirring for 30 min and standing for 1 h, hydrogels (SPI-EGCG / metal ion-OGG hydrogels) were obtained. These hydrogels were labeled as SE-OGG, SE / Ag-OGG, SE / Mg-OGG and SE / Fe-OGG, respectively.

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