阅读说明：本技术 一种微生物矿化增强水凝胶的方法 (Method for improving hydrogel through microbial mineralization ) 是由 王瑞兴 张思逸 章炜 徐刚 于 2020-06-15 设计创作，主要内容包括：本发明公开了一种微生物矿化增强水凝胶的方法,该方法包括以下步骤：1)脲酶菌菌液的培养以及浓缩菌液的制备；2)配制均一透明的凝胶基体溶液,之后加入尿素及氯化钙搅拌均匀,室温下加入浓缩菌液搅拌均匀得到混合液；3)将混合液真空抽滤除泡后模具成型,冻融循环后得到所述的微生物矿化增强的水凝胶。此方法可通过微生物矿化在凝胶内部生成碳酸钙网络结构,从而达到凝胶增强的目的。(The invention discloses a method for preparing a microbe mineralized reinforced hydrogel, which comprises the following steps: 1) culturing urease bacteria liquid and preparing concentrated bacteria liquid; 2) preparing a uniform and transparent gel matrix solution, then adding urea and calcium chloride, uniformly stirring, adding concentrated bacterial liquid at room temperature, and uniformly stirring to obtain a mixed solution; 3) and (3) carrying out vacuum filtration, defoaming and mould forming on the mixed solution, and carrying out freeze-thaw cycling to obtain the microbial mineralization enhanced hydrogel. The method can generate a calcium carbonate network structure in the gel through the mineralization of microorganisms, thereby achieving the purpose of enhancing the gel.)

1. A method of microbial mineralization of enhanced hydrogel, comprising: the method comprises the following steps:

1) culturing urease bacteria liquid and preparing concentrated bacteria liquid;

2) preparing a uniform and transparent gel matrix solution, then adding urea and calcium chloride, uniformly stirring, adding concentrated bacterial liquid at room temperature, and uniformly stirring to obtain a mixed solution;

3) and (3) carrying out vacuum filtration and defoaming on the mixed solution, then carrying out die forming, carrying out freeze-thaw circulation, and then placing at room temperature for reaction to obtain the microbial mineralization enhanced hydrogel.

2. The method for preparing the microbial mineralization-enhanced hydrogel according to claim 1, wherein the concentration of the concentrated bacterial liquid in the step 1) is (1-10) × 10⁹cell/mL，OD₆₀₀The value is 1.8-2, and the urease bacterial liquid is obtained by centrifuging 8-15 min at the rotating speed of 7000-10000 rpm.

3. A method of microbial mineralization enhanced hydrogel according to claim 1, wherein: the uniform and transparent gel matrix solution in the step 2) is a polyvinyl alcohol solution or a polyvinyl alcohol-tannic acid solution.

4. A method of microbial mineralization enhanced hydrogel according to claim 3, wherein: when the gel matrix solution is a polyvinyl alcohol solution, the concentration of polyvinyl alcohol in the mixed solution in the step 2) is 4-10 wt%; when the gel matrix solution is a polyvinyl alcohol-tannic acid solution, the concentration of polyvinyl alcohol in the mixed solution in the step 2) is 4-10 wt%, and the concentration of tannic acid in the mixed solution is 5-20 wt% of the concentration of polyvinyl alcohol.

5. A method of microbial mineralization enhanced hydrogel according to claim 1, wherein: the concentration of urea and calcium ions in the mixed solution in the step 2) is 0.5-1.5M, the concentration ratio of the urea to the calcium ions is 1: 1-3: 1, and the doping amount of the concentrated bacterial solution is 5% -30% of the mixed solution according to volume percentage.

6. A method of microbial mineralization enhanced hydrogel according to claim 1, wherein: and 3) carrying out vacuum filtration and bubble removal on the mixed solution, and then carrying out mold forming, namely carrying out vacuum pumping on the mixed solution to 0.1 +/-0.02 MPa for bubble removal for 5-10 min, and repeating for 2-4 times to carry out mold forming.

7. A method of microbial mineralization enhanced hydrogel according to claim 1, wherein: the freeze-thaw cycle in the step 3) is freezing at-18 +/-2 ℃ for 16-20 h, then thawing at room temperature for 4-8 h, and alternately cycling for 3-5 times.

8. A method of microbial mineralization enhanced hydrogel according to claim 1, wherein: and (3) placing the freeze-thaw cycle in a reaction at room temperature for 3-7 d.

Technical Field

The invention relates to a method for mineralizing and enhancing hydrogel by microorganisms, and belongs to the field of hydrogel preparation.

Background

Hydrogels are hydrophilic materials with a three-dimensional network structure. The hydrogel has a certain shape and soft property, can absorb a large amount of water, and is very good in biocompatibility, so that the hydrogel is widely applied to the field of medicines, such as: drug delivery release, tissue engineering, etc.; nowadays, due to the high water absorption and water retention, the application of the water-retaining agent is expanded to a plurality of fields such as daily necessities, industrial and agricultural water retention and dust removal. Correspondingly, gel base materials used in different fields are different, and can be roughly divided into two categories of natural gel and synthetic gel, wherein the natural gel has good biocompatibility and low price, but has poor stability and is easy to degrade; the structure and the performance of the synthesized gel can be regulated and controlled. However, the hydrogel has its disadvantages of poor mechanical properties, thus limiting its applications, especially in tissue engineering.

There are several ways of gel reinforcement, mainly: double-network hydrogel, nano-composite hydrogel and macromolecular microsphere hydrogel. The double networks are generally formed by compounding a rigid network and a flexible network, so that certain self-repairing performance can be endowed to the gel, but the requirement on the first network is higher, the disadvantage is improved by research nowadays, but most of the used chemical binders have toxicity, so that the biocompatibility of the matrix is reduced; the nano-composite is generally organic-inorganic composite, and special properties can be endowed to the gel by changing the types of compound nano-particles, such as: ag⁺The inorganic nano particles are antibacterial, but the inorganic nano particles are easy to agglomerate in gel so as to generate negative influence on strength, and the requirement on an initiator is relatively high; the macromolecular microsphere gel can well realize the effect of stress dispersion, so is often used for improving the compressive strength, but the corresponding effect on the tensile strength is poor.

Therefore, there are many places to be researched and improved deeply for the method for enhancing the gel performance, and the invention is based on the double-network and nano-composite technology, and the microorganism mineralization mode is provided to generate a fine and uniform calcium carbonate network in the gel so as to achieve the purpose of enhancing the gel.

Disclosure of Invention

The technical problem is as follows: the invention mainly aims at the disadvantage of application limitation caused by poor mechanical property of hydrogel, and provides a method for strengthening the hydrogel by mineralization of microorganisms, which mainly depends on a gel support to grow a calcium carbonate layer so as to realize the purpose of strengthening; compared with the traditional nano composite gel, the nano composite gel has small influence on the uniformity of a gel matrix, has operability on most of gel matrices, and can endow the gel with certain self-healing performance in this way, thereby having better social value.

The technical scheme is as follows: the invention provides a method for mineralizing and enhancing hydrogel by microorganisms, which is characterized by comprising the following steps: the method comprises the following steps:

1) culturing urease bacteria liquid and preparing concentrated bacteria liquid;

2) preparing a uniform and transparent gel matrix solution, then adding urea and calcium chloride, uniformly stirring, adding concentrated bacterial liquid at room temperature, and uniformly stirring to obtain a mixed solution;

3) and (3) carrying out vacuum filtration and defoaming on the mixed solution, then carrying out die forming, carrying out freeze-thaw circulation, and then placing at room temperature for reaction to obtain the microbial mineralization enhanced hydrogel.

Wherein:

the concentration of the concentrated bacterial liquid in the step 1) is (1-10) × 10⁹cell/mL，OD₆₀₀The value is 1.8-2, and the urease bacterial liquid is obtained by centrifuging 8-15 min at the rotating speed of 7000-10000 rpm.

The uniform and transparent gel matrix solution in the step 2) is a polyvinyl alcohol (PVA) solution or a polyvinyl alcohol-tannic acid (PVA-TA) solution.

When the gel matrix solution is a polyvinyl alcohol solution, the concentration of polyvinyl alcohol in the mixed solution in the step 2) is 4-10 wt%; when the gel matrix solution is a polyvinyl alcohol-tannic acid solution, the concentration of polyvinyl alcohol in the mixed solution in the step 2) is 4-10 wt%, and the concentration of tannic acid in the mixed solution is 5-20 wt% of the concentration of polyvinyl alcohol.

The concentration of urea and calcium ions in the mixed solution in the step 2) is 0.5-1.5M, the concentration ratio of the urea to the calcium ions is 1: 1-3: 1, and the doping amount of the concentrated bacterial solution is 5% -30% of the mixed solution according to volume percentage.

And 3) the step of carrying out vacuum filtration and bubble removal on the mixed solution and then forming the mold refers to carrying out vacuum pumping on the mixed solution to 0.1 +/-0.02 MPa for bubble removal for 5-10 min, repeating the step for 2-4 times and then forming the mold, wherein the size of the used mold is 90mm multiplied by 10mm multiplied by 3 mm.

The freeze-thaw cycle in the step 3) is freezing at-18 +/-2 ℃ for 16-20 h, then thawing at room temperature for 4-8 h, and alternately cycling for 3-5 times.

And (3) placing the freeze-thaw cycle in a reaction at room temperature, wherein the reaction is carried out under the action of mineralization and deposition at room temperature, and the reaction time is 3-7 d.

The urease bacteria concentrated bacterial liquid, nutrient substances required by metabolism of the urease bacteria and a calcium source are added in the preparation process, the gel is rich in water and can stimulate the activity of the urease bacteria, so that the complete mineralization and deposition of microorganisms are realized, and tiny calcium carbonate is generated in situ in the gel to deposit and realize the effect of enhancing the gel.

Has the advantages that: the invention provides a technology for reinforcing gel by using biomineralization, which can widen the application scene of the gel, and the method can be applied to the mineralization reinforcement of most gel matrixes and has the advantages of simple preparation process and environmental friendliness, thereby having better economic and social benefits. Compared with the prior art, the technology has the following advantages:

1. the invention takes the mineralization of microorganisms as the enhancement mechanism of the gel;

2. according to the invention, the internal structure of the organic material is reinforced by adopting the traditional inorganic material, so that the performance of the organic material is better;

3. reagents used by the microorganism mineralization enhancement mechanism adopted in the invention are all nontoxic and harmless, and basically accord with the concept of environment-friendly and green development.

Drawings

FIG. 1 is an XRD representation of hydrogels prepared in examples 1, 2, and 3;

FIG. 2 is an SEM representation (1000X) of the hydrogel prepared in example 1;

FIG. 3 is an SEM characterization (4000X) of the hydrogel prepared in example 2;

FIG. 4 is an FTIR characterization of the hydrogels prepared in examples 1 and 2.

Detailed Description

The present invention is further described below for better understanding, but it should not be understood that the present invention is applicable to the following examples, and those skilled in the art can make modifications and adaptations of the present invention based on the above disclosure without departing from the scope of the present invention.