Full-bio-based hydrogel ball as well as preparation method and application thereof

Abstract

The invention discloses a full bio-based hydrogel ball as well as a preparation method and application thereof, and belongs to the technical field of hydrogel. According to the full-bio-based hydrogel ball provided by the invention, cellulose nanofibers (CNF), lignin nanobottles (LNBs) and sodium alginate (SA) are integrated, a three-dimensional network structure with high-density negative charge functional sites is constructed, and selective adsorption separation of target protein is realized by utilizing electrostatic interaction. CNF, SA and carboxyl groups and phenolic hydroxyl groups on the surfaces of LNBs form a high-density negative charge network, and the equilibrium adsorption capacity of protein reaches 1200 mg / g under the conditions of pH 6 and zero salt ion strength.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogels, and particularly relates to a fully biobased hydrogel sphere, a preparation method thereof, and an application thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the understanding of the overall background of the present invention, and is not necessarily to be regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] As a key macromolecule in living organisms, proteins have a wide range of applications in fields such as drug development and food processing. Studying methods to reduce the protein concentration in solutions can not only improve experimental accuracy, but also enhance drug purity and reduce side effects in pharmaceutical production, and optimize product texture and safety in the food industry. In addition, such methods are also of great significance in environmental protection. They can effectively remove proteins from wastewater and prevent water eutrophication. Therefore, the research on reducing protein concentration not only promotes technological progress, but also plays a key role in many practical application fields.

[0004] In recent years, adsorption separation technology has made remarkable progress, especially the development of renewable, green and efficient new materials has become a research hotspot. However, the currently commonly used adsorption materials mainly rely on organic synthetic polymer materials, which often have problems such as poor biocompatibility and non-biodegradability, and are difficult to meet the requirements of current green economy and low-carbon development. Although some emerging biobased adsorption materials show potential in protein separation, their adsorption performance, preparation cost, and process complexity are still difficult to meet the actual production needs, and the adsorption separation ability and efficiency also need to be improved. Therefore, developing a highly efficient fully biobased gel material with excellent separation performance for proteins, simple preparation method, and low cost has become a key problem to be solved urgently at present. Summary of the Invention

[0005] In order to solve the deficiencies of existing protein adsorption materials, the object of the present invention is to provide a fully biobased hydrogel sphere, a preparation method thereof, and an application thereof. This method innovatively integrates cellulose nanofibers (CNF), lignin nanobottles (LNBs), and sodium alginate (SA) to construct a three-dimensional network structure with high-density negatively charged functional sites, and uses electrostatic interaction to achieve selective adsorption separation of target proteins. This solution aims to break through the limitations of traditional organic synthetic materials and provide a new efficient, environmentally friendly and scalable separation technology approach for vaccine purification, biomedicine, and the food industry.

[0006] The present invention constructs a fully biobased hydrogel sphere with protein separation function by regulating the addition ratios of cellulose nanofibers, lignin nanobottles, and sodium alginate. The main steps of the method include: preparation of the hydrogel sphere colloid, crosslinking treatment, washing, and protein adsorption and separation. The method provided by the present invention does not require chemical modification of raw materials and complex preparation processes, has mild reaction conditions, easily available materials, and a simple preparation process. It can be well applied in the protein adsorption engineering, has selectivity for protein separation, and has good adsorption capacity for specific proteins. The protein adsorption capacity depends on the ratios of cellulose nanofibers, lignin nanobottles, and sodium alginate in the hydrogel sphere. The fully natural biobased hydrogel sphere has high efficiency, controllability, renewability, biocompatibility, and biodegradability. The prepared fully natural biobased hydrogel sphere has good application potential in bioengineering and separation engineering.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a fully biobased hydrogel sphere, which is composed of cellulose nanofibers, lignin nanobottles, sodium alginate, and a crosslinking agent, forming a three-dimensional network structure; wherein, the carboxyl groups and phenolic hydroxyl groups on the surfaces of cellulose nanofibers, sodium alginate, and lignin nanobottles form a negative charge network.

[0009] In the present invention, sodium alginate (SA), cellulose nanofibers, lignin, and Ca 2+ improve the performance of the composite material through synergistic effects: SA forms a three-dimensional network skeleton with Ca 2+ by the ion curing method, fixes lignin and provides a high specific surface area; nano-lignin binds to SA through functional groups such as methoxy groups and hydroxyl groups to enhance stability, and efficiently adsorbs proteins by means of negative charges, π-π, and hydrogen bond interactions. At the same time, its own antioxidant property is beneficial to protecting proteins; the combination of the three forms a "support-adsorption-regulation" system to achieve efficient protein adsorption under a degradable framework.

[0010] In one or more embodiments, the diameter of the fully biobased hydrogel sphere is 2 - 10 mm, preferably 2 - 5 mm. The specific surface area of the fully biobased hydrogel sphere is between 50–100 m 2 / g.

[0011] In one or more embodiments, the mass ratio of cellulose nanofibers (CNF), lignin nanobottles (LNBs), and sodium alginate (SA) is (1 - 3):(0 - 2):(0.1 - 2), preferably (1 - 3):(0.1 - 2):(0.1 - 2), and further preferably (1 - 2):(1 - 2):(1 - 2).

[0012] In one or more embodiments, the cellulose nanofibers are transparent jelly-like gels, with a length of 5 - 10 μm and a purity > 99%;

[0013] In one or more embodiments, the lignin nanobottles (LNBs) have a size between 50 and 500 nm, and the bottle mouth size is between 10 and 200 nm, with high size uniformity and a polydispersity index (PDI) below 0.1.

[0014] The preparation method of the lignin nanobottles (LNBs) is as follows: Ultrasonically dissolve the lignin raw material in an aqueous solution of γ-valerolactone, and filter to obtain a γ-valerolactone solution of lignin; Under the conditions of heating and stirring, slowly drop the γ-valerolactone solution of lignin into the aqueous solution of γ-valerolactone for self-assembly to obtain the product. Among them, the heating and stirring conditions are: the temperature is 40 - 60 °C. For the specific preparation method, refer to the authorized patent CN118530473B.

[0015] In one or more embodiments, the cross-linking agent is CaCl2.

[0016] In a second aspect, the present invention provides a method for preparing the above-mentioned all-bio-based hydrogel spheres, including the following steps:

[0017] Dissolve cellulose nanofibers, lignin nanobottles and sodium alginate in water, and stir to form a composite colloidal solution; Mix the composite colloidal solution with a cross-linking agent solution, and let it stand to obtain the product.

[0018] In one or more embodiments, under the conditions of 40 - 60 °C, continuously stir for 1 - 4 hours, and the stirring speed is 500 - 2000 rpm, preferably 500 - 1000 rpm, to form a homogenized colloidal solution.

[0019] In one or more embodiments, the specific steps of dissolving cellulose nanofibers, lignin nanobottles and sodium alginate in water and stirring to form a composite colloidal solution are as follows: First, prepare a cellulose nanofiber solution and a sodium alginate solution separately, stir and mix them to form a uniform and stable cellulose nanofiber solution / sodium alginate (CNF / SA) composite colloidal solution; Then add the lignin nanobottle solution, and continue to stir to form a uniform and stable cellulose nanofiber solution / sodium alginate / lignin nanobottle (CNF / SA / LNBs) composite colloidal solution.

[0020] Furthermore, the concentration of the cellulose nanofiber solution is 1.0 - 2.0 wt%.

[0021] The concentration of the sodium alginate solution is 1.0 - 2.0 wt%.

[0022] The concentration of the lignin nanobottle solution is 1.0 - 2.0 wt%.

[0023] Furthermore, the mass ratio of cellulose nanofibers, lignin nanobottles to sodium alginate is (1 - 3):(0 - 2):(0.1 - 2), preferably (1 - 3):(0.1 - 2):(0.1 - 2), and more preferably (1 - 2):(1 - 2):(1 - 2).

[0024] Furthermore, the cellulose nanofibers are dissolved in water and ultrasonically treated for 20 - 60 min.

[0025] Sodium alginate is dissolved in water and stirred at 70 - 85 °C until completely dissolved.

[0026] The mass - to - volume ratio of sodium alginate to water is (0.1 - 0.5 g):(10 - 50 ml), preferably (0.2 - 0.5 g):(20 - 50 ml).

[0027] Furthermore, after adding the lignin nanobottle solution, ultrasonic - assisted stirring is carried out at 30 - 100 kHz, 100 - 300 W for 5 - 20 minutes.

[0028] In one or more embodiments, the composite colloid solution is added dropwise to the cross - linker solution, wherein the cross - linker is CaCl2 and the concentration of the CaCl2 solution is 0.01 - 0.3 mol / L. The volume ratio of the cellulose nanofiber solution to the CaCl2 solution is 30 - 100:600, preferably 30 - 60:600.

[0029] The volume ratio of the composite colloid solution to the CaCl2 solution is 1:(5 - 10).

[0030] Furthermore, the dropping rate is 1 - 5 mL / min, preferably 1 - 3 mL / min. The height of the droplet fall is 5 - 20 cm, preferably 5 - 10 cm.

[0031] In one or more embodiments, the static temperature is 20 - 40 °C, preferably 20 - 30 °C; the static time is 3 - 15 hours, preferably 10 - 14 h, to ensure the full curing of the three - dimensional network.

[0032] In one or more embodiments, washing is also included. The gel beads are washed with water multiple times (3 - 5 times) until the washing conductivity < 50 S / cm to thoroughly remove the unreacted calcium ions and free impurities remaining on the surface, and finally obtain all - biobased hydrogel beads with a stable structure and surface functionalization.

[0033] In a preferred embodiment, the preparation method of the all - biobased hydrogel beads of the present invention comprises the following steps:

[0034] Disperse cellulose nanofibers (CNF), lignin nanobottles (LNBs) and sodium alginate (SA) in deionized water according to a specific mass ratio, and continuously stir for 1-4 hours at 40-60 °C to form a homogenized colloidal solution.

[0035] Dropwise add the above mixed solution into a CaCl2 cross-linking bath with a concentration of 0.01-0.3 mol / L through a syringe, and utilize the instantaneous ionic cross-linking effect of calcium ions and sodium alginate, etc. to realize the in-situ formation of hydrogel spheres. After the dropping is completed, let the gel spheres stand in the cross-linking bath for 3-15 hours to ensure the full curing of the three-dimensional network.

[0036] Wash the gel spheres with deionized water multiple times (3-5 times) to thoroughly remove the residual unreacted calcium ions and free impurities on the surface, and finally obtain all-bio-based hydrogel spheres with a stable structure and surface functionalization.

[0037] In a third aspect, the present invention provides the application of the above all-bio-based hydrogel spheres in bioengineering and separation engineering.

[0038] Preferably, the separation engineering includes protein adsorption separation.

[0039] The protein adsorption separation includes vaccine purification, whey protein refining, protein-containing wastewater treatment, etc.

[0040] Preferably, the protein is a protein with significantly different charge characteristics, including bovine serum albumin, lysozyme, and pepsin.

[0041] In a fourth aspect, the present invention provides a method for protein adsorption separation, including the following steps:

[0042] Add all-bio-based hydrogel spheres to the protein solution and oscillate at a constant temperature.

[0043] The protein solution is prepared by dissolving the protein in a buffer solution, and the buffer solution is a phosphate buffer solution.

[0044] The constant-temperature oscillation is carried out at 20-30 °C for 12-36 hours.

[0045] One or some of the above technical solutions have the following advantages or beneficial effects:

[0046] Compared with traditional protein adsorption separation technologies, the present invention shows significant advantages in the following aspects by constructing a ternary composite hydrogel sphere system of cellulose nanofibers (CNF), sodium alginate (SA) and lignin nanobottles (LNBs):

[0047] (1) The mild process protects the structural integrity of proteins. The whole process adopts neutral pH, normal temperature and low pressure operation, and adsorption separation conditions, avoiding the damage of strong acids / alkalis, high temperature or high shear force to the secondary structure and functional groups of proteins. It is suitable for the precise separation of proteins with significantly different charge characteristics such as bovine serum albumin, lysozyme, and pepsin.

[0048] (2) The raw materials used in the present invention are all bio-based materials, and the preparation process is green. Using cellulose nanofibers (CNF), lignin nanobottles (LNBs) and sodium alginate (SA) as the core components, it realizes 100% renewable resource substitution for petroleum-based materials. The preparation process does not require organic solvents, reducing the COD value of wastewater compared with the traditional resin method. Through the synergistic effect of CNF / LNBs, the dosage of SA is reduced by 40 - 60%.

[0049] (3) The present invention has enhanced functions and significantly improved adsorption performance. The carboxyl groups and phenolic hydroxyl groups on the surfaces of CNF, SA and LNBs form a negative charge network. Under the conditions of pH 6 and zero salt ion strength, the equilibrium adsorption capacity for proteins reaches 1200 mg / g; the natural phenolic compounds in LNBs can scavenge free radicals and inhibit the oxidative denaturation of proteins, ensuring the retention rate of the target protein activity during the adsorption process.

[0050] (4) The ternary composite system of sodium alginate / cellulose nanofiber / lignin nanobottle formed by adding lignin nanobottles (LNBs) in the present invention has a protein adsorption capacity (1100 - 1200 mg / g) much higher than that of the ternary composite system of sodium alginate / cellulose nanofiber / alkali lignin formed by adding ordinary alkali lignin (872 g / g) when applied to protein adsorption and separation. This reflects the synergistic effect of lignin nanobottles (LNBs).

[0051] (5) The present invention has the potential for efficient separation and large-scale production. In the continuous flow mode, the separation factor for proteins with different charge properties can be increased, the purity can be improved, and it can be repeatedly adsorbed-desorbed cycled with stable mechanical strength of the gel beads. It can be applied to vaccine purification, whey protein refining, and protein-containing wastewater treatment, and this technology has universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The specification drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0053] Figure 1 It is a schematic diagram of the preparation experimental process of the all-bio-based hydrogel beads in Examples 3 and 4 of the present invention;

[0054] Figure 2 It is the surface morphology of the hydrogel beads prepared in Examples 1 - 4 and Comparative Examples 1 - 2 of the present invention;

[0055] Figure 3 Protein adsorption and separation capabilities of the hydrogel spheres prepared in Comparative Examples 1-2 and Examples 1-4 of the present invention

[0056] Figure 4 Schematic diagram of the design of the fully biobased hydrogel spheres of the present invention Detailed implementation manners

[0057] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments

[0058] Example 1

[0059] Preparation of cellulose nanofiber / sodium alginate (CNF / SA = 1:1) composite hydrogel spheres: Prepare a 1.0 wt% cellulose nanofiber suspension: Disperse 1.0 g of CNF in 99 g of deionized water and sonicate for 30 minutes. Add 0.5 g of SA to 50 mL of deionized water and stir at 80 °C for 1 hour until completely dissolved. Mix the SA solution with 50 mL of the CNF suspension and stir at a constant temperature of 45 °C (800 rpm) for 3 hours to form a homogeneous and stable CNF / SA composite colloid (SA / CNF mass ratio 1:1). Drop the composite colloid into 600 ml of 0.1 mol / L CaCl2 solution at a rate of 2 mL / min and crosslink at 25 °C for 12 hours to form a network structure. Wash 5 times with deionized water until the washing conductivity < 50 S / cm to remove unreacted calcium ions and obtain CNF / SA binary composite hydrogel spheres with a diameter of 2.5 ± 0.3 mm

[0060] Example 2:

[0061] Preparation of cellulose nanofiber / sodium alginate (CNF / SA mass ratio 3:1) composite hydrogel spheres: Disperse 1.0 g of CNF in 99 g of deionized water and sonicate for 30 minutes. Add 0.25 g of SA to 25 mL of deionized water and stir at 85 °C for 2 hours until completely dissolved. Mix the SA solution with 75 mL of the CNF suspension and stir at a constant temperature of 40 °C (800 rpm) for 2 hours to form a homogeneous and stable CNF / SA composite colloid (CNF / SA mass ratio 3:1). Drop the composite colloid into 600 ml of 0.1 mol / L CaCl2 solution at a rate of 2 mL / min and crosslink at 25 °C for 12 hours to form a network structure. Wash 5 times with deionized water until the washing conductivity < 50 S / cm to remove unreacted calcium ions and obtain CNF / SA binary composite hydrogel spheres with a diameter of 2.5 ± 0.3 mm

[0062] Example 3:

[0063] Disperse 1.0 g of CNF in 99 g of deionized water and sonicate for 30 minutes. Add 0.25 g of SA to 25 mL of deionized water and stir at 85 °C for 2 hours until completely dissolved. Mix the SA solution with 50 mL of the CNF suspension and stir at a constant temperature of 40 °C (800 rpm) for 2 hours to form a homogeneous and stable CNF / SA composite colloid (CNF / SA mass ratio 2:1). Then add 25 ml of the LNBs dispersion, where the LNBs dispersion is 1 g of LNBs dissolved in 99 g of water, and continue stirring for 1 hour until the lignin is uniformly dispersed (ultrasonic assistance, 40 kHz, 200 W, 10 minutes) to form a homogeneous and stable CNF / SA / LNBs colloid (CNF / SA / LNBs mass ratio 2:1:1). Drop the composite colloid into 600 ml of 0.1 mol / L CaCl2 solution at a rate of 2 mL / min, with the droplet falling height of 10 cm. Crosslink at 25 °C for 12 hours to form a network structure. Wash with deionized water 5 times until the washing conductivity < 50 S / cm to remove unreacted calcium ions and obtain CNF / SA / LNBs ternary composite hydrogel spheres with a diameter of 2.5 ± 0.3 mm.

[0064] Example 4:

[0065] Disperse 1.0 g of CNF in 99 g of deionized water and sonicate for 30 minutes. Add 0.33 g of SA to 33 mL of deionized water and stir at 85 °C for 2 hours until completely dissolved. Mix the SA solution with 33 mL of the CNF suspension and stir at a constant temperature of 40 °C (800 rpm) for 2 hours to form a homogeneous and stable CNF / SA composite colloid. Then add 33 ml of the LNBs dispersion, where the LNBs dispersion is 1 g of LNBs dissolved in 99 g of water, and continue stirring for 1 hour until the lignin is uniformly dispersed (ultrasonic assistance, 40 kHz, 200 W, 10 minutes) to form a homogeneous and stable CNF / SA / LNBs colloid (CNF / SA / LNBs mass ratio 1:1:1). Drop the composite colloid into 600 ml of 0.1 mol / L CaCl2 solution at a rate of 2 mL / min, with the droplet falling height of 10 cm. Crosslink at 25 °C for 12 hours to form a network structure. Wash with deionized water 5 times until the washing conductivity < 50 mS / cm to remove unreacted calcium ions and obtain CNF / SA / LNBs ternary composite hydrogel spheres with a diameter of 2.5 ± 0.3 mm.

[0066] Comparative Example 1:

[0067] Preparation of pure sodium alginate hydrogel beads: Weigh 1.0 g of sodium alginate and add it to 100 mL of deionized water. Stir the mixture at a constant temperature of 80 °C in a water bath (600 rpm) for 1 hour to obtain a homogeneous and transparent 1 wt% SA solution. Load the SA solution into a 10 mL flat-tip syringe (needle inner diameter 0.8 mm) and slowly drip it into a 600 ml 0.1 mol / L CaCl2 cross-linking bath at a rate of 2 mL / min from a height of 10 cm above the liquid surface. Let it stand and cross-link at 25 °C for 120 minutes. Wash the hydrogel beads 5 times with deionized water until the washing conductivity < 50 S / cm to remove unreacted calcium ions, and obtain pure SA hydrogel beads with a diameter of 2.5 ± 0.3 mm.

[0068] Comparative Example 2

[0069] Disperse 1.0 g of CNF in 99 g of deionized water and sonicate for 30 minutes. Add 0.33 g of SA to 33 mL of deionized water and stir at 85 °C for 2 hours until completely dissolved. Mix the SA solution with 33 mL of CNF suspension and stir at a constant temperature of 40 °C (800 rpm) for 2 hours to form a homogeneous and stable CNF / SA composite colloid. Then add 33 ml of lignin dispersion (the lignin is ordinary alkali lignin, amorphous large particles), where the lignin dispersion is 1 g of lignin dissolved in 99 g of water, and continue to stir for 1 hour until the lignin is evenly dispersed (sonication-assisted, 40 kHz, 200 W, 10 minutes) to form a homogeneous and stable CNF / SA / alkali lignin colloid (the mass ratio of CNF / SA / alkali lignin is 1:1:1). Drop the composite colloid into 600 ml of 0.1 mol / L CaCl2 solution at a rate of 2 mL / min, with the liquid drop falling height of 10 cm. Cross-link at 25 °C for 12 hours to form a network structure. After washing 5 times with deionized water until the washing conductivity < 50 mS / cm to remove unreacted calcium ions, obtain ternary composite hydrogel beads of CNF / SA / alkali lignin with a diameter of 2.5 ± 0.3 mm.

[0070] Protein adsorption separation experiment and result analysis

[0071] Experimental method: Dissolve lysozyme in phosphate buffer solution (PBS, pH 6.0) respectively to prepare a solution with a concentration of 1.5 mg / mL. Take 160 mL of protein solution and add 20 g of wet gel beads (Examples 1-4 and Comparative Examples 1-2), and oscillate at a constant temperature of 25 °C for 24 hours. Use ultraviolet-visible spectrophotometry (UV-Vis, wavelength 280 nm) to measure the protein concentration in the solution before and after adsorption, and calculate the adsorption efficiency (Q, mg / g).

[0072] Experimental Results and Analysis: Through data comparison, it is found that the lysozyme adsorption capacity of Comparative Example 1 (pure SA gel beads) is 548.7 mg / g, and that of Comparative Example 2 is 872 g / g. The lysozyme adsorption capacity of Example 1 (SA / CNF) is increased to 797 mg / g. When the CNF content in Example 2 (high CNF ratio) is increased to 3 times that of SA, the lysozyme adsorption capacity further increases to 904 mg / g. Their mechanism of action includes electrostatic interaction. The CNF surface has a high carboxyl density and is strongly negatively charged at pH 6.0, and selectively adsorbs positively charged lysozyme through electrostatic attraction. The nanofiber network of CNF increases the porosity and specific surface area of the gel beads, promoting the diffusion and anchoring of protein molecules.

[0073] With the synergistic effect of lignin nanobottles (LNBs), the lysozyme adsorption capacity of Example 3 (SA / CNF / LNBs) reaches 1156 mg / g, a 45.2% increase compared to Example 1. When the LNBs content in Example 4 (high LNBs ratio) is increased to 1 time that of SA, the adsorption capacity further increases to 1200 mg / g, a 40.5% increase compared to Comparative Example 2. Its mechanism of action is hydrogen bonding and hydrophobic interaction. The phenolic hydroxyl groups of LNBs dissociate under acidic conditions, enhancing the surface negative charge, and at the same time, the hydrophobic microdomains capture the hydrophobic fragments of proteins through hydrophobic interaction.

[0074] In summary, the present invention constructs a ternary composite system of sodium alginate (SA) / cellulose nanofibers (CNF) / lignin nanobottles (LNBs), and proposes a highly efficient, controllable and environmentally friendly protein adsorption and separation method. Its core advantages are reflected in the following dimensions: (1) High-performance adsorption and structural protection. By optimizing the ratio of CNF and LNBs (SA / CNF / LNBs), the equilibrium adsorption capacity of lysozyme reaches 1200 mg / g at pH 6.0, which is 1.19 times higher than that of traditional sodium alginate gel beads, breaking through the performance bottleneck of bio-based materials. The mild adsorption conditions ensure the retention of the protein secondary structure, providing highly active raw materials for high-end applications such as vaccine carriers and biosensors. (2) Multilevel structure controllable design. By adjusting the ratio of CNF / LNBs, the charge density of the gel beads can be accurately controlled, realizing a flexible switch from spectral adsorption to targeted separation. (3) Green process and industrialization potential. Using agricultural and forestry waste (CNF, LNBs) and seaweed extract (SA) as the core, it completely replaces petroleum-based materials, and the carbon emissions are greatly reduced compared to traditional resins. The one-step ion cross-linking method does not require high temperature, high pressure or organic solvents, and the COD value of the wastewater is reduced, meeting the principles of green chemistry. It can also be produced on a large scale, further reducing the treatment cost. It can also be recycled for adsorption-desorption and is biodegradable, providing an industrial-level solution for biomedicine, food refining and environmental engineering, with clear commercial conversion value and sustainable development significance.

[0075] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A fully bio-based hydrogel ball, characterized in that: It is composed of cellulose nanofibers, lignin nanobottles, sodium alginate and a cross-linking agent to form a three-dimensional network structure; wherein the carboxyl groups and phenolic hydroxyl groups on the surfaces of the cellulose nanofibers, sodium alginate and lignin nanobottles form a negatively charged network.

2. The all-biobased hydrogel sphere according to claim 1, characterized in that: The diameter of the all-biobased hydrogel spheres is 2-10 mm; Preferably, the specific surface area of ​​the all-biobased hydrogel sphere is 50–100 m 2 / g.

3. The all-biobased hydrogel sphere according to claim 1, characterized in that: The mass ratio of cellulose nanofibers, lignin nanobottles and sodium alginate is (1-3):(0-2):(0.1-2), preferably (1-3):(0.1-2):(0.1-2), and more preferably (1-2):(1-2):(1-2); Preferably, the length of the cellulose nanofibers is 5-10 μm and the purity is >99%; Preferably, the size of the lignin nanobottle is between 50 and 500 nm, the size of the bottle mouth is between 10 and 200 nm, and the polydispersity coefficient is less than 0.

1.

4. A method for preparing the fully bio-based hydrogel sphere according to any one of claims 1 to 3, characterized in that: The method comprises the following steps: dissolving cellulose nanofibers, lignin nanobottles and sodium alginate in water, and stirring to form a composite colloid solution; and mixing the composite colloid solution with a crosslinking agent solution, and standing to obtain the composite colloid solution.

5. The preparation method according to claim 4, characterized in that: Stir continuously for 1-4 hours at 40-60°C and a stirring speed of 500-2000 rpm; Preferably, the composite colloidal solution is added dropwise into the cross-linking agent solution, wherein the cross-linking agent is CaCl2, and the concentration of the CaCl2 solution is 0.01-0.3 mol / L; Preferably, the volume ratio of the composite colloid solution to the CaCl2 solution is 1:(5-10); Preferably, the dripping rate is 1-5 mL / min, and the droplet falling height is 5-20 cm; Preferably, the standing temperature is 20-40° C. and the standing time is 3-15 hours.

6. The preparation method according to claim 4, characterized in that: The specific steps of dissolving the cellulose nanofibers, lignin nanobottles and sodium alginate in water and stirring to form a composite colloidal solution are: firstly preparing a cellulose nanofiber solution and a sodium alginate solution respectively, stirring and mixing them; then adding the lignin nanobottle solution, and continuing to stir to form a composite colloidal solution; Preferably, the concentration of the cellulose nanofiber solution is 1.0-2.0wt%; Preferably, the concentration of the sodium alginate solution is 1.0-2.0wt%; Preferably, the concentration of the lignin nanobottle solution is 1.0-2.0wt%; Preferably, the mass ratio of cellulose nanofibers, lignin nanobottles and sodium alginate is (1-3):(0-2):(0.1-2), preferably (1-3):(0.1-2):(0.1-2), and further preferably (1-2):(1-2):(1-2).

7. Use of the all-biobased hydrogel sphere described in any one of claims 1 to 3 or the all-biobased hydrogel sphere obtained by the preparation method of any one of claims 4 to 6 in bioengineering and separation engineering.

8. The use according to claim 7, characterized in that: The separation process includes protein adsorption separation; The protein adsorption separation includes vaccine purification, whey protein refining, and protein-containing wastewater treatment; The proteins are proteins with significantly different charge characteristics, including bovine serum albumin, lysozyme, and pepsin.

9. A method for protein adsorption separation, characterized in that: The method comprises the following steps: adding the fully bio-based hydrogel spheres described in any one of claims 1 to 3 into a protein solution, and oscillating at a constant temperature.

10. The method according to claim 9, characterized in that The protein solution is prepared by dissolving the protein in a buffer solution, and the buffer solution is a phosphate buffer solution; The constant temperature shaking is performed at 20-30° C. for 12-36 hours.

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