Biomass pyrolysis liquid-chitosan-based bacteriostatic conductive hydrogel as well as preparation method and application thereof
By dissolving chitosan in biomass pyrolysis solution and crosslinking it with polyvinyl alcohol and boric acid, followed by LiCl solution treatment, a hydrogel with high antibacterial properties, stable conductivity, and mechanical strength was prepared. This solved the problem of insufficient antibacterial and conductivity properties of chitosan-based conductive hydrogels and is suitable for flexible sensors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING FORESTRY UNIVERSITY
- Filing Date
- 2026-03-09
- Publication Date
- 2026-06-05
Smart Images
Figure SMS_1 
Figure SMS_2
Abstract
Description
Technical Field
[0001] This invention relates to the field of biomass resource utilization technology, and in particular to a biomass pyrolysis liquid-chitosan-based antibacterial conductive hydrogel, its preparation method and application. Background Technology
[0002] With the popularization of the concept of sustainable development, biomass resources (such as crustacean shells and plant cellulose) have become important raw materials for the development of functional materials due to their renewability, biocompatibility, and low cost. Among them, chitosan, as a star product in the field of biopolymer materials, is widely used in the preparation of hydrogels due to its unique cationic properties, biodegradability, and gelling ability. The amino and hydroxyl groups in chitosan molecules provide active sites for its chemical modification, enabling it to form hydrogels with specific properties through cross-linking or compounding with other functional materials.
[0003] Chitosan-based conductive hydrogels have attracted attention due to their natural antibacterial properties and biocompatibility; however, their conductivity is typically low, requiring the use of composite conductive fillers or in-situ polymerized conductive polymers to improve it. Furthermore, chitosan suffers from poor solubility and insufficient inherent functionality (natural antibacterial properties). Currently, researchers typically dissolve chitosan in solutions such as acetic acid and then combine it with other functional materials to prepare chitosan-based functional materials.
[0004] The high water content (typically >90%) of hydrogels provides an ideal growth environment for microorganisms (such as bacteria and fungi), and microbial growth can easily lead to device performance degradation. Currently, the preparation of chitosan-based conductive hydrogels focuses primarily on improving conductivity, while insufficient attention is paid to their antibacterial properties during long-term use. Furthermore, traditional antibacterial methods and the construction of conductive networks often conflict (for example, silver nanoparticles may interfere with electron transport in conductive polymers). Therefore, developing a hydrogel that combines highly efficient antibacterial properties, stable conductivity, and good mechanical strength remains a challenge. Summary of the Invention
[0005] To address the aforementioned technical challenges, this invention provides a method for preparing a biomass pyrolysis solution-chitosan-based antibacterial conductive hydrogel, comprising: dissolving chitosan and boric acid in a biomass pyrolysis solution to obtain a mixed solution; mixing the mixed solution with a polyvinyl alcohol solution to obtain a precursor solution; subjecting the precursor solution to freeze-thaw cycles to obtain a chitosan-biomass pyrolysis solution pregel; and immersing the chitosan-biomass pyrolysis solution pregel in a LiCl solution to obtain the biomass pyrolysis solution-chitosan-based antibacterial conductive hydrogel.
[0006] This invention involves a simple method of directly dissolving chitosan in an acidic biomass pyrolysis solution with strong antibacterial properties, then further cross-linking it with polyvinyl alcohol and boric acid, and finally soaking it in a lithium chloride solution to obtain a hydrogel that combines highly efficient antibacterial properties, stable conductivity, and good mechanical strength.
[0007] In some embodiments, the preparation method of the biomass pyrolysis solution includes: pyrolyzing biomass materials, collecting the distillate and condensing it to obtain the solution.
[0008] Preferably, the preparation method of the biomass pyrolysis solution includes: pyrolyzing hardwood at 380℃~420℃, collecting the fraction below 400℃, and condensing it to obtain the biomass pyrolysis solution.
[0009] In some embodiments, the preparation method of the biomass pyrolysis solution further includes: refining and removing wood tar after condensation to obtain the biomass pyrolysis solution.
[0010] In the specific implementation process, the refining method includes, but is not limited to, any refining method disclosed in the prior art, such as sequentially performing settling, activated carbon adsorption and distillation operations to remove harmful substances such as wood tar. This refining method is not limited here.
[0011] Preferably, in the mixture, the mass ratio of chitosan, boric acid and biomass pyrolysis solution is (1~5):1:(30~100).
[0012] More preferably, in the mixture, the mass ratio of chitosan, boric acid and biomass pyrolysis liquid is 1:1:(30~32).
[0013] Preferably, the chitosan accounts for 2.8% to 3.2% of the mass percentage of the mixture, more preferably 2.9% to 3%.
[0014] Preferably, the polyvinyl alcohol solution is a polyvinyl alcohol aqueous solution with a mass concentration of 14% to 16%.
[0015] Preferably, the mixture is mixed with the polyvinyl alcohol solution at a mass ratio of 1:(0.8~1.2).
[0016] Preferably, boric acid accounts for 1% to 20% of the mass percentage of the mixture, more preferably 1% to 3%, and even more preferably 2.9% to 3%.
[0017] By controlling the amount of boric acid in the system within the above range, the conductivity of the hydrogel can be further improved.
[0018] Preferably, boric acid accounts for 1% to 5% of the mass of the precursor solution.
[0019] Preferably, polyvinyl alcohol accounts for 6% to 10% of the mass of the precursor liquid, and more preferably 7% to 8%.
[0020] In some embodiments, the freeze-thaw cycle is freezing at -25°C to -15°C and then thawing at room temperature; Preferably, the freeze-thaw cycle is performed three or more times.
[0021] In some embodiments, the concentration of the LiCl solution is 5-10 M; preferably, the soaking time is 6 hours or more.
[0022] In some implementations, after soaking in LiCl solution, the LiCl solution on the surface of the material is wiped off with absorbent paper to obtain the biomass pyrolysis solution-chitosan-based antibacterial conductive hydrogel.
[0023] More preferably, the preparation method includes: Chitosan and boric acid are dissolved in a biomass pyrolysis solution to prepare a mixed solution; the mixed solution is mixed with a polyvinyl alcohol solution to prepare a precursor solution; the precursor solution is subjected to freeze-thaw cycles to prepare a chitosan-biomass pyrolysis solution pregel; the chitosan-biomass pyrolysis solution pregel is soaked in LiCl solution to prepare a biomass pyrolysis solution-chitosan-based antibacterial conductive hydrogel; wherein, the preparation method of the biomass pyrolysis solution includes: pyrolyzing hardwood at 400°C, collecting the fraction below 400°C, and condensing it to obtain the biomass pyrolysis solution; The mass ratio of chitosan, boric acid, and biomass pyrolysis solution is 1:1:(30~32); the boric acid accounts for 2.9%~3% of the mass percentage of the mixture; the polyvinyl alcohol solution is a polyvinyl alcohol aqueous solution with a mass concentration of 14%~16%; the mixture and polyvinyl alcohol solution are mixed at a mass ratio of 1:(0.8~1.2); the freeze-thaw cycle is freezing at -20℃ and then thawing at room temperature, and the number of freeze-thaw cycles is more than 3; the concentration of LiCl solution is 7~9M; the soaking time is more than 6 hours.
[0024] Furthermore, the present invention provides a biomass pyrolysis solution-chitosan-based antibacterial conductive hydrogel prepared by any of the above-described methods.
[0025] Furthermore, this invention provides the application of the aforementioned biomass pyrolysis liquid-chitosan-based antibacterial conductive hydrogel in the preparation of flexible sensors.
[0026] In some implementations, the flexible sensor can be used to meet the practical needs of accurately monitoring various human movements.
[0027] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention provides a biomass pyrolysis fluid-chitosan-based antibacterial and conductive hydrogel. This hydrogel possesses highly efficient antibacterial properties, stable conductivity, and good mechanical strength. Furthermore, its preparation process is simple and efficient, significantly reducing costs and enhancing the application value of biomass pyrolysis fluids. In addition, the hydrogel of this invention can be used to fabricate flexible sensors, showing broad application prospects in the field of medical materials. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. In the embodiments provided in this specification, where specific techniques or conditions are not specified, they are performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.
[0029] In the following examples, the degree of deacetylation of chitosan is ≥95%, and the viscosity is 100~200 mpa∙s.
[0030] In the following examples, the polyvinyl alcohol (PVA) is type 1799, with a degree of alcoholysis of 98-99 (mol / mol); the average molecular weight of the polyvinyl alcohol is 70,000-80,000.
[0031] In the following examples, the boric acid was of analytical grade (AR≥99.5%).
[0032] In the following embodiments, the preparation method of biomass pyrolysis liquid includes: pyrolyzing hardwood (pine, pine wood, and poplar) at 400°C, collecting the fraction below 400°C, and condensing it to obtain biomass pyrolysis liquid.
[0033] Example 1 This embodiment provides a biomass pyrolysis fluid-chitosan-based antibacterial conductive hydrogel, prepared by the following method: (1) Add 1.5g of chitosan powder and 0.5g of boric acid to 48g of biomass pyrolysis solution, stir mechanically at 1500rpm for 30min, then mix with a prepared 15% PVA aqueous solution at a mass ratio of 1:1, centrifuge to remove foam, and obtain the precursor solution for the preparation of biomass pyrolysis solution-chitosan hydrogel. Pour the precursor solution into a mold, freeze at -20℃ and thaw at room temperature for 3 cycles to obtain the pregel. (2) The pregel was soaked in 8M LiCl solution for 6 hours. After the hydrogel was taken out, the surface of the LiCl solution was wiped off with absorbent paper to obtain the final biomass pyrolysis liquid-chitosan-based antibacterial conductive hydrogel.
[0034] Example 2 This embodiment provides a biomass pyrolysis fluid-chitosan-based antibacterial conductive hydrogel, the preparation method of which differs from that of Example 1 only in that: Add 1.5g of chitosan powder and 1.0g of boric acid to 47.5g of biomass pyrolysis solution.
[0035] Example 3 This embodiment provides a biomass pyrolysis fluid-chitosan-based antibacterial conductive hydrogel, the preparation method of which differs from that of Example 1 only in that: Add 1.5g of chitosan powder and 1.5g of boric acid to 47.5g of biomass pyrolysis solution.
[0036] Example 4 This embodiment provides a biomass pyrolysis fluid-chitosan-based antibacterial conductive hydrogel, the preparation method of which differs from that of Example 1 only in that: Add 5.0g of chitosan powder and 1.5g of boric acid to 47.5g of biomass pyrolysis solution.
[0037] Comparative Example 1 This comparative example provides a hydrogel, the preparation method of which differs from that of Example 1 only in that: Add 1.5g of chitosan powder and 0g of boric acid to 48.5g of biomass pyrolysis solution.
[0038] Comparative Example 2 This comparative example provides a hydrogel, the preparation method of which differs from that of Example 3 only in that it is not soaked in LiCl solution.
[0039] Comparative Example 3 This comparative example provides a hydrogel, the preparation method of which differs from that of Example 3 only in that: The biomass pyrolysis solution was replaced with an equal volume of acetic acid solution with the same acidity, and LiCl solution was not soaked in it.
[0040] Comparative Example 4 This comparative example provides a hydrogel, the preparation method of which differs from that of Example 3 only in that: Replace the biomass pyrolysis solution with an equal amount of acetic acid solution with the same acidity.
[0041] Test case This experimental example tests the mechanical properties, antibacterial properties, and electrical properties of the biomass pyrolysis solution-chitosan-based antibacterial and conductive hydrogel prepared in the above examples and the hydrogel prepared in the comparative example.
[0042] The mechanical properties were tested as follows: The hydrogel was prepared into dumbbell and cylindrical shapes. The tensile strength of the dumbbell shape was measured, and the compressive strength of the cylindrical shape was measured. The thickness of five random points was measured with a micrometer and the average value was taken. The mechanical properties of the hydrogel were measured with a universal testing machine. The initial distance between the clamps at both ends of the instrument was 30 mm, the tensile speed was 100 mm / min, and three sets of parallel samples were made for each sample and the average value was taken.
[0043] The antibacterial activity was tested as follows: The antibacterial activity was determined using the agar perforation method. Specifically, bacterial suspensions of a certain concentration of *E. coli* and *S. aureus* were separately spread onto sterilized agar solid medium, and then circular hydrogel samples were placed on top. The samples were incubated in a 37 ℃ constant temperature and humidity biochemical incubator for 12 h. The antibacterial performance of the samples was evaluated by measuring the diameter of the inhibition zone.
[0044] The conductivity test method is as follows: The salted-out sample is cut into 2 cm × 2 cm pieces, with a thickness of 1.9 mm. The sample is sandwiched between two copper sheets of equal width, and the sample is measured using an electrochemical workstation. The formula for calculating ionic conductivity is as follows: Where L (cm) is the spacing between the copper sheets, S (cm²) is the contact area between the sample and the copper sheets, and R (ohms) is the resistance value at the real intercept of the Nyquist plot.
[0045] The test results are shown in Table 1.
[0046] Table 1
[0047] It can be seen that the hydrogel of the present invention can have both high antibacterial properties, stable conductivity and good mechanical strength. Moreover, the content of boric acid will affect the ionic conductivity to a certain extent. Example 3 is the best example.
[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for preparing a biomass pyrolysis liquid-chitosan-based antibacterial conductive hydrogel, characterized in that, include: Chitosan and boric acid were dissolved in a biomass pyrolysis solution to prepare a mixed solution; the mixed solution was then mixed with a polyvinyl alcohol solution to prepare a precursor solution; the precursor solution was subjected to freeze-thaw cycles to prepare a chitosan-biomass pyrolysis solution pregel; the chitosan-biomass pyrolysis solution pregel was then soaked in a LiCl solution to prepare a biomass pyrolysis solution-chitosan-based antibacterial conductive hydrogel.
2. The preparation method according to claim 1, characterized in that, The preparation method of the biomass pyrolysis solution includes: pyrolyzing biomass materials, collecting the distillate and condensing it to obtain the solution.
3. The preparation method according to claim 2, characterized in that, The preparation method of the biomass pyrolysis solution includes: pyrolyzing hardwood at 380℃~420℃, collecting the fraction below 400℃, and condensing it to obtain the biomass pyrolysis solution.
4. The preparation method according to any one of claims 1 to 3, characterized in that, In the mixture, the mass ratio of chitosan, boric acid and biomass pyrolysis solution is (1~5):1:(30~100).
5. The preparation method according to any one of claims 1 to 3, characterized in that, The polyvinyl alcohol solution is a polyvinyl alcohol aqueous solution with a mass concentration of 14% to 16%; Preferably, the mixture is mixed with the polyvinyl alcohol solution at a mass ratio of 1:(0.8~1.2).
6. The preparation method according to any one of claims 1 to 3, characterized in that, The boric acid accounts for 1% to 20% of the mass percentage of the mixture, more preferably 1% to 3%, and more preferably 2.9% to 3%.
7. The preparation method according to any one of claims 1 to 3, characterized in that, The freeze-thaw cycle involves freezing at -25°C to -15°C and then thawing at room temperature. Preferably, the freeze-thaw cycle is performed three or more times.
8. The preparation method according to any one of claims 1 to 3, characterized in that, The concentration of the LiCl solution is 5-10 M; preferably, the soaking time is 6 hours or more.
9. A biomass pyrolysis solution-chitosan-based antibacterial conductive hydrogel, characterized in that, It is prepared by any one of claims 1 to 8.
10. The application of the biomass pyrolysis liquid-chitosan-based antibacterial conductive hydrogel according to claim 9 in the preparation of flexible sensors.