阅读说明：本技术 一种氨基纳米纤维素及其制备方法 (Amino nano-cellulose and preparation method thereof ) 是由 王晓映 王守娟 于亚童 孔凡功 于 2021-08-06 设计创作，主要内容包括：本发明提供了一种氨基纳米纤维素及其制备方法,属于氨基纳米纤维素制备技术领域。本发明利用1-乙基-(3-二甲基氨基丙基)碳酰二亚胺(EDC)和4-二甲氨基吡啶(DMAP)作为催化剂,将赖氨酸接枝到纳米纤维素表面,实现纳米纤维素的氨基化；所制备的氨基纳米纤维素中,赖氨酸与纳米纤维素直接相连,有利于提高氨基纳米纤维素的生物相容性,拓展氨基纳米纤维素在生物医药领域中的应用范围。(The invention provides amino nano-cellulose and a preparation method thereof, belonging to the technical field of amino nano-cellulose preparation. According to the invention, 1-ethyl- (3-dimethylaminopropyl) carbodiimide (EDC) and 4-Dimethylaminopyridine (DMAP) are used as catalysts to graft lysine onto the surface of nano-cellulose, so that the amination of the nano-cellulose is realized; in the prepared amino nano-cellulose, lysine is directly connected with nano-cellulose, which is beneficial to improving the biocompatibility of the amino nano-cellulose and expanding the application range of the amino nano-cellulose in the field of biological medicines.)

1. A preparation method of amino nano-cellulose is characterized by comprising the following steps: in the pH buffer solution, carboxyl in lysine and hydroxyl in the nano-cellulose are connected by using EDC and DMAP as cross-linking agents to generate the amino nano-cellulose.

2. The preparation method according to claim 1, characterized in that the specific steps of the preparation method are as follows:

(1) preparing a pH buffer solution with the concentration of 0.01-1M;

(2) diluting the nano-cellulose with a pH buffer solution until the solid content is not more than 4% (the mass of the nano-cellulose/the volume of water, g/mL), homogenizing the nano-cellulose by a homogenizer, and standing by after the nano-cellulose is uniformly dispersed;

(3) adding homogenized nanocellulose into a reaction container, then respectively adding lysine, 1-ethyl- (3-dimethylaminopropyl) carbonyldiimine (EDC) and 4-Dimethylaminopyridine (DMAP), wherein the final concentration of the three reagents is 1-3 times of that of a lysine substance, the final concentration of the EDC substance is 0.01-1M, and the final concentration of the DMAP substance is 0.01-0.4M, so as to obtain a solution A;

(4) or changing the order of adding the reactants in the step (3) into: preparing a mixed solution of lysine, EDC and DMAP by using a pH buffer solution, reacting for 5-60 minutes under the condition of stirring, adding the homogenized nanocellulose obtained in the step (2), and finally obtaining a solution B, wherein the concentration of each substance is 1-3 times that of a substance of a glucose unit in the nanocellulose, the concentration of a substance of EDC is 0.01-1M, and the concentration of a substance of DMAP is 0.01-0.4M;

(5) reacting the solution A obtained in the step (3) or the solution B obtained in the step (4) at normal temperature and pressure for 2-28 hours, wherein aggregation among nanocelluloses is reduced by stirring and other methods in the reaction process, and the mass transfer efficiency of reactants is improved;

(6) after the reaction is finished, the cellulose is washed by pure water, so that the final conductivity is not more than 10 mu S/cm.

3. The method according to claim 2, wherein the pH buffer solution in the step (1) is a morpholine ethanesulfonic acid buffer solution.

4. The production method according to claim 2, wherein the solvent of the buffer solution in the step (1) is pure water.

5. The method according to claim 2, wherein the nanocellulose in the step (2) is selected from any one of cellulose nanofibrils, cellulose nanocrystals and bacterial cellulose.

6. An amino nanocellulose obtained by the production method according to any one of claims 1 to 5.

Technical Field

The invention relates to amino nano-cellulose and a preparation method thereof, in particular to a method for preparing amino nano-cellulose at normal temperature and normal pressure, belonging to the technical field of amino nano-cellulose preparation.

Background

The cellulose is a naturally-occurring compound with the largest reserve, is a renewable resource, and the amino cellulose prepared by modifying the cellulose not only has antibacterial property, but also has good biocompatibility (for example, the lysine modified nano-cellulose can reduce the cytotoxicity of nano-materials), thereby showing good application prospect in the field of biological medicine. However, the existing preparation process of the aminated nano-cellulose is complex, and some compounds toxic to organisms can be introduced in part of reaction processes, so that the cost of environmental treatment is greatly increased, and the application of the aminated nano-cellulose in the field of biomedicine is limited.

Disclosure of Invention

The invention aims at the problems and provides amino nanocellulose and a preparation method thereof. The preparation process is green and environment-friendly, is favorable for maintaining good biocompatibility of cellulose, and expands the application range of the amino nano cellulose regeneration medicine field. The technical scheme of the invention is as follows:

a preparation method of amino nano-cellulose is characterized in that lysine is crosslinked to the surface of the nano-cellulose at normal temperature and pressure to realize the preparation of the amino nano-cellulose, and the preparation method comprises the following specific steps:

(1) preparing a pH buffer solution with the concentration of 0.01-1M, preferably a morpholine ethanesulfonic acid (MES) buffer solution;

(2) diluting the nano-cellulose with a pH buffer solution until the solid content is not more than 4% (mass of nano-cellulose/volume of water, g/mL), homogenizing the nano-cellulose by a homogenizer, and keeping the nano-cellulose for later use after the nano-cellulose is uniformly dispersed, wherein the pH of the solution is 5.5-7.0;

(3) adding homogenized nanocellulose into a reaction container, then respectively adding lysine, 1-ethyl- (3-dimethylaminopropyl) carbonyldiimine (EDC) and 4-Dimethylaminopyridine (DMAP), wherein the final concentration of the three reagents is 1-3 times of that of a lysine substance, the final concentration of the EDC substance is 0.01-1M, the final concentration of the DMAP substance is 0.01-0.4M, and thus obtaining a solution A, wherein the pH value of the solution in the reaction process is 5.5-7.0;

(4) or changing the order of adding the reactants in the step (2) into: preparing a mixed solution of lysine, EDC and DMAP by using a pH buffer solution, reacting for 5-60 minutes under the condition of stirring, adding the homogenized nanocellulose obtained in the step (2), and finally obtaining a solution B, wherein the concentration of each substance is 1-3 times that of a substance of a glucose unit in the nanocellulose, the concentration of a substance of EDC is 0.01-1M, and the concentration of a substance of DMAP is 0.01-0.4M, and the pH of the solution in the reaction process is 5.5-7.0;

(5) reacting the solution A obtained in the step (3) or the solution B obtained in the step (4) at normal temperature and pressure for 2-28 hours, wherein aggregation among nanocelluloses is reduced by stirring and other methods in the reaction process, and the mass transfer efficiency of reactants is improved;

(6) after the reaction is finished, the cellulose is washed by pure water, so that the final conductivity is not more than 10 mu S/cm.

Preferably, the solvent of the buffer solution in the step (1) is pure water.

Preferably, the nanocellulose in the step (2) is selected from any one of cellulose nanofibrils, cellulose nanocrystals or bacterial cellulose;

the invention also discloses the amino nano-cellulose obtained by the preparation method.

Compared with the prior art, the invention has the following advantages:

(1) the reaction is carried out in the normal temperature and normal pressure environment, the reaction condition is mild, the use of an organic solvent is avoided, the process of environmental treatment is reduced, the preparation cost of the amino nano-cellulose is reduced, and a green method for preparing the amino nano-cellulose is provided;

(2) carboxyl in lysine is directly combined with hydroxyl in the nano-cellulose through the catalytic action of EDC and DMAP, so that the process flow of preparing the amino nano-cellulose is simplified;

(3) lysine in the reaction product is directly connected with the nano-cellulose, which is favorable for improving the biocompatibility of the amino nano-cellulose and expanding the application of the amino nano-cellulose in the field of biological medicine.

Drawings

FIG. 1 is a flow chart of the reaction process of the invention in which lysine is bound on the surface of nanocellulose to produce amino nanocellulose.

Detailed Description

The invention will be further described with reference to specific embodiments, and the advantages and features of the invention will become apparent as the description proceeds. The examples are illustrative only and do not limit the scope of the present invention in any way. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be made without departing from the spirit and scope of the invention.

Example 1: amino nano-cellulose and preparation method thereof

The method comprises the following steps:

(1) preparing MES buffer solution with the concentration of 0.1M, wherein the pH value is 6.0;

(2) adding lysine, EDC and DMAP into MES buffer solution respectively to make the final concentration of three reagents respectively be 0.6mM, 0.2M and 0.2M, dissolving, and reacting for 10 min under the condition of stirring;

(3) adding the cellulose nanofibrils into MES buffer solution to prepare 0.2% solution, adding the solution into the step (2) after homogenizing and dispersing uniformly, continuing stirring, and reacting for 24 hours at normal temperature and normal pressure;

(4) after the reaction is finished, the reaction solution is washed by pure water until the conductivity is not more than 10 mu S/cm.

Example 2: amino nano-cellulose and preparation method thereof

The method comprises the following steps:

(1) preparing a phosphate buffer solution with the concentration of 0.2M and the pH value of 6.5;

(2) adding lysine, EDC and DMAP into phosphate buffer solution respectively to make the final concentration of three reagents be 0.2mM, 0.8M and 0.2M respectively, dissolving them, and reacting them for 30 min under the condition of stirring;

(3) adding bacterial cellulose into MES buffer (0.2M, pH 6.5) to prepare 0.8% solution, homogenizing and dispersing uniformly, adding into the solution (2), stirring, and reacting at normal temperature and pressure for 26 hr;

(3) after the reaction is finished, the reaction solution is washed by pure water until the conductivity is not more than 10 mu S/cm.

Example 3: amino nano-cellulose and preparation method thereof

The method comprises the following steps:

(1) preparing MES buffer solution with the concentration of 0.1M, wherein the pH value is 6.0;

(2) adding cellulose nanocrystals into MES buffer solution to prepare 0.2% solution, and homogenizing and dispersing uniformly to obtain nanocellulose for later use;

(3) adding lysine, EDC and DMAP into MES buffer solution respectively to make the final concentration of three reagents respectively be 0.6mM, 0.2M and 0.2M, adding the nano-cellulose homogenized in the step (2), stirring, and reacting for 16 hours at normal temperature and pressure;

(3) after the reaction is finished, the reaction solution is washed by pure water until the conductivity is not more than 10 mu S/cm.

Example 4: amino nano-cellulose and preparation method thereof

The method comprises the following steps:

(1) preparing a phosphate buffer solution with the concentration of 0.2M and the pH value of 6.8;

(2) adding cellulose nanofibrils into a phosphate buffer solution to prepare a 0.5% solution, and homogenizing and dispersing uniformly for later use;

(2) adding lysine, EDC and DMAP into phosphate buffer solution respectively to make the final concentration of three reagents respectively be 0.2mM, 0.2M and 0.2M, adding the nano-cellulose homogenized in the step (1), stirring, and reacting for 4 hours at normal temperature and normal pressure;

(3) after the reaction is finished, the reaction solution is washed by pure water until the conductivity is not more than 10 mu S/cm.

Test examples

A flow chart of a reaction process of combining lysine on the surface of nano-cellulose to generate amino nano-cellulose is shown in fig. 1, wherein the combination of lysine on the surface of nano-cellulose enables the surface of nano-cellulose originally with negative charges to have positive charges; the Zeta potential detection of the amino nano-cellulose prepared by the invention is shown in table 1:

TABLE 1

Sample name	Zeta potential (mV)
		Nanofibrillar cellulose	–40.5±1.9
Amino nanocellulose obtained in example 1	37.3±2.3
		Example 2 amino nanocellulose obtained	32.3±2.3
Amino nanocellulose obtained in example 3	31.8±1.7
		Example 4 amino nanocellulose obtained	26.5±2.6