Disclosure of Invention
The invention aims to provide a carboxymethyl aminopolysaccharide derivative and a preparation method and application thereof.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a carboxymethyl glycosaminoglycan derivative has a structural formula shown in formula (1),
wherein the average polymerization degree n ranges from 10 to 3000.
A preparation method of carboxymethyl aminopolysaccharide derivatives comprises the following steps: reacting chitosan with chloroacetic acid under an alkaline condition to prepare carboxymethyl chitosan, and performing ion exchange on the obtained carboxymethyl chitosan and epoxypropyl trimethyl ammonium chloride to obtain a carboxymethyl chitosan derivative-carboxymethyl aminopolysaccharide derivative shown in the formula (1);
the mass of the sodium hydroxide is 5-6 times of that of the chitosan; the molar weight of the chloroacetic acid is 5 to 6 times of that of the chitosan; the molar weight of the epoxypropyl trimethyl ammonium chloride is 2 to 3 times of that of the carboxymethyl chitosan.
The carboxymethyl chitosan is prepared by adding chitosan into excessive isopropanol to fully swell (the isopropanol only serves as a solvent and does not participate in reaction, and the aim is to dissolve the chitosan, namely the amount of the solvent for dissolving the chitosan completely), then adding sodium hydroxide, fully stirring, reacting for 10-12h at-18-20 ℃, then adding chloroacetic acid in batches, reacting for 5-10h at 50-60 ℃, adding water after reaction to dissolve solids in a reaction system, adjusting the pH of the system to 8, pouring the obtained solution into absolute ethyl alcohol to precipitate, performing suction filtration, washing and drying to obtain the carboxymethyl chitosan.
Dissolving the carboxymethyl chitosan in excessive deionized water, adding epoxypropyltrimethylammonium chloride after dissolving, reacting for 12-24h at room temperature, dialyzing through a dialysis bag with the molecular weight cutoff of 500Da after reacting, dialyzing for 48-60h by using deionized water as a solvent, dialyzing the excessive epoxypropyltrimethylammonium chloride and a reaction byproduct sodium chloride, and freeze-drying liquid in the dialysis bag to obtain the carboxymethyl chitosan derivative shown in the formula (1).
An application of carboxymethyl aminopolysaccharide derivatives, namely an application of carboxymethyl aminopolysaccharide derivatives shown in formula (1) in preparation of film-forming agents.
The application of the carboxymethyl aminopolysaccharide derivative shown in the formula (1) in preparing the fig preservative.
The invention has the advantages that:
(1) the compound obtained by the invention is synthesized by replacing inorganic salt through ion exchange by utilizing quaternary ammonium salt cationic groups carried by epoxypropyltrimethylammonium chloride and carboxylate anion groups carried by carboxymethyl chitosan and then combining through ionic bonds.
(2) The invention combines the advantages of the macromolecular structure property of carboxymethyl chitosan and the moisture retention property of epoxypropyl trimethyl ammonium chloride, and the like to obtain the macromolecular polymer with stronger water volatilization resistance.
(3) The compound of the invention has simple synthesis steps, easy acquisition of required equipment and raw materials, low cost and easy popularization, and the yield of the obtained compound is high and can reach more than 60 percent. The product obtained by the invention can be widely used in the fields of biology, food and the like.
Detailed Description
The following examples are presented to further illustrate embodiments of the present invention, and it should be understood that the embodiments described herein are for purposes of illustration and explanation only and are not intended to limit the invention.
The invention firstly reacts chitosan with chloroacetic acid under alkaline condition to prepare carboxymethyl chitosan, the carboxymethyl chitosan is dissolved in water and directly reacts with epoxypropyl trimethyl ammonium chloride through ion exchange reaction to obtain carboxymethyl aminopolysaccharide derivatives, and the application of the carboxymethyl aminopolysaccharide derivatives as film forming agents is researched.
The synthetic route of the carboxymethyl aminopolysaccharide derivative is as follows:
wherein the average polymerization degree n ranges from 10 to 3000.
Example 1
In this embodiment, a carboxymethyl glycosaminoglycan derivative as a target compound is synthesized according to the above synthetic route, which specifically comprises:
1) preparing carboxymethyl chitosan: 5g of chitosan is weighed and added into 35mL of isopropanol to be stirred and swelled for 2h, then 25g of sodium hydroxide is dissolved in 25mL of water and poured into the swelled solution, and an alkaline chitosan-isopropanol system is obtained. After being stirred uniformly, the mixture is placed in an environment with the temperature of 18 ℃ below zero for 12 hours. Weighing 17.61g of chloroacetic acid, heating and dissolving in 10mL of isopropanol, adding into the alkaline chitosan-isopropanol system in five batches under an ice bath, then reacting for 5h at 60 ℃, pouring 100mL of water into the reaction system after the reaction, dissolving the solid in the reaction system, adjusting the pH of the system to 8 by using 10% hydrochloric acid, then pouring the obtained solution into 800mL of absolute ethyl alcohol for precipitation, carrying out suction filtration, washing by using the absolute ethyl alcohol, and carrying out vacuum drying for 24h at-50 ℃ to obtain 10.08g of carboxymethyl chitosan (see figure 2) for later use.
2) Preparation of carboxymethyl chitosan derivative: dissolving 1.70g (see figure 2) of the obtained carboxymethyl chitosan in 100mL of deionized water, then adding 2.28g of epoxypropyltrimethylammonium chloride, rapidly stirring at room temperature for reaction for 24 hours, then directly pouring into a dialysis bag with the molecular weight cutoff of 500Da, dialyzing for 60 hours by using the deionized water as a solvent, changing the deionized water every 2 hours, and freeze-drying the liquid in the dialysis bag after dialysis to obtain the carboxymethyl chitosan derivative (see figure 3) shown in the formula (1), wherein n is 10-3000.
Example 2
The difference from the embodiment 1 is that:
1) preparing carboxymethyl chitosan: 5g of chitosan is weighed and added into 40mL of isopropanol to be stirred and swelled for 2h, and then 30g of sodium hydroxide is dissolved in 30mL of water and poured into the swelled solution to obtain the alkaline chitosan-isopropanol system. After being stirred evenly, the mixture is placed in an environment with the temperature of minus 20 ℃ for 10 hours. Weighing 14.67g of chloroacetic acid, heating and dissolving in 10mL of isopropanol, adding into the alkaline chitosan-isopropanol system in five batches under an ice bath, reacting for 10h at 50 ℃, pouring 100mL of water into the reaction system after the reaction, dissolving the solid in the reaction system, adjusting the pH of the system to 8 by using 10% hydrochloric acid, pouring the obtained solution into 800mL of absolute ethyl alcohol for precipitation, carrying out suction filtration, washing by using the absolute ethyl alcohol, and carrying out vacuum drying at-50 ℃ for 24h to obtain 9.62g of carboxymethyl chitosan (see figure 2) for later use.
2) Preparation of carboxymethyl chitosan derivative: dissolving 1.70g (see figure 2) of the obtained carboxymethyl chitosan in 100mL of deionized water, then adding 1.52g of epoxypropyltrimethylammonium chloride, rapidly stirring at room temperature for reaction for 12 hours, then directly pouring into a dialysis bag with the molecular weight cutoff of 500Da, dialyzing for 48 hours by using the deionized water as a solvent, changing the deionized water every 2 hours, and freeze-drying the liquid in the dialysis bag after dialysis to obtain the carboxymethyl chitosan derivative (see figure 3) shown in the formula (1), wherein n is 10-3000.
Example 3
The difference from the embodiment 1 is that:
1) preparing carboxymethyl chitosan: 5g of chitosan is weighed and added into 35mL of isopropanol to be stirred and swelled for 2h, then 25g of sodium hydroxide is dissolved in 25mL of water and poured into the swelled solution, and an alkaline chitosan-isopropanol system is obtained. After being stirred evenly, the mixture is placed in an environment with the temperature of minus 20 ℃ for 10 hours. Weighing 17.61g of chloroacetic acid, heating and dissolving in 10mL of isopropanol, adding into the alkaline chitosan-isopropanol system in five batches under an ice bath, then reacting for 10h at 50 ℃, pouring 100mL of water into the reaction system after the reaction, dissolving the solid in the reaction system, adjusting the pH of the system to 8 by using 10% hydrochloric acid, pouring the obtained solution into 800mL of absolute ethyl alcohol for precipitation, carrying out suction filtration, washing by using the absolute ethyl alcohol, and carrying out vacuum drying for 24h at-50 ℃ to obtain 10.51g of carboxymethyl chitosan (see figure 2) for later use.
2) Preparation of carboxymethyl chitosan derivative: dissolving 1.70g of the obtained carboxymethyl chitosan (see figure 2) in 100mL of deionized water, then directly pouring into a dialysis bag with the molecular weight cutoff of 500Da, dialyzing for 48h by using 500mL of 1% epoxypropyltrimethylammonium chloride aqueous solution as a solvent, changing the dialysate every 4h, and freeze-drying the liquid in the dialysis bag after dialysis to obtain the carboxymethyl chitosan derivative (see figure 3) shown in the formula (1), wherein n is 10-3000.
Example 4
The difference from the embodiment 1 is that:
1) preparing carboxymethyl chitosan: 5g of chitosan is weighed and added into 40mL of isopropanol to be stirred and swelled for 2h, and then 30g of sodium hydroxide is dissolved in 30mL of water and poured into the swelled solution to obtain the alkaline chitosan-isopropanol system. After being stirred uniformly, the mixture is placed in an environment with the temperature of 18 ℃ below zero for 12 hours. Weighing 17.61g of chloroacetic acid, heating and dissolving in 10mL of isopropanol, adding into the alkaline chitosan-isopropanol system in five batches under an ice bath, then reacting for 5h at 60 ℃, pouring 100mL of water into the reaction system after the reaction, adjusting the pH of the system to 8 by using 10% hydrochloric acid, pouring the obtained solution into 800mL of absolute ethanol for precipitation, carrying out suction filtration, washing by using the absolute ethanol, and carrying out vacuum drying at-50 ℃ for 24h to obtain 11.26g of carboxymethyl chitosan (see figure 2) for later use.
2) Preparation of carboxymethyl chitosan derivative: dissolving 1.70g of the obtained carboxymethyl chitosan (see figure 2) in 100mL of deionized water, then directly pouring into a dialysis bag with the molecular weight cutoff of 500Da, dialyzing for 60h by using 500mL of 1% epoxypropyltrimethylammonium chloride aqueous solution as a solvent, changing the dialysate every 4h, and freeze-drying the liquid in the dialysis bag after dialysis to obtain the carboxymethyl chitosan derivative (see figure 3) shown in the formula (1), wherein n is 10-3000.
Application example
And (3) testing the fruit preservation performance:
the water loss rate of the synthesized carboxymethyl chitosan and the obtained carboxymethyl chitosan derivative coating liquid to fig is respectively tested under the environment of relative humidity of 60% and 25 ℃ and compared:
the carboxymethyl chitosan prepared in the embodiment and the carboxymethyl chitosan derivative obtained in the embodiment are dried at 60 ℃ for 48 hours to constant weight, and then are respectively prepared into different coating solutions with the concentration of 1% (w/v) by deionized water. Soaking fructus fici in different coating solutions for 30 s, and air drying. The fruit mass is weighed once every 24h under the environment with the relative humidity of 60% and the temperature of 25 ℃, the water loss rate of the sample is calculated, 10 fruits are taken as a group, and water is taken as a blank control.
Water loss (%) - (W)0-W1)×100/W0
W0And W1The mass (g) of the sample before and after the sample was set.
TABLE 1 Ficus carica applied with 1% carboxymethyl chitosan and carboxymethyl aminopolysaccharide derivative water loss (%)
|
24h
|
48h
|
72h
|
96h
|
Water (W)
|
13.98±0.46
|
24.62±0.61
|
34.70±0.49
|
44.73±1.37
|
Carboxymethyl chitosan
|
13.52±1.17
|
24.03±1.34
|
33.02±0.90
|
41.64±1.41
|
Carboxymethyl chitosan derivative
|
7.84±0.84
|
14.75±1.37
|
22.91±1.58
|
26.37±1.80 |
The experimental results are as follows: the water loss rate of fig coated with carboxymethyl chitosan and carboxymethyl aminopolysaccharide derivatives synthesized by the invention is shown in table 1, the data in table 1 show that the prevention effect of carboxymethyl chitosan on the water loss phenomenon of fig is not obvious, and the carboxymethyl chitosan derivatives synthesized by ion exchange with epoxypropyl trimethyl ammonium chloride have the obvious prevention effect on the water loss phenomenon of fig, so that the water loss of fig is effectively slowed down, and the fig has a better fresh-keeping effect. The synthesized carboxymethyl chitosan derivative mainly forms a layer of polysaccharide film on the surface of fig, and the film has excellent moisturizing effect, slows down the volatilization of water of fig and plays a role in keeping fresh. The carboxymethyl aminopolysaccharide film-forming agent synthesized by the method is expected to be applied to the field of fruit preservation.