Preparing low molecular weight chitosan by sensitizing radiation degradation method

A low-molecular-weight chitosan technology, which is applied in the field of low-molecular-weight chitosan preparation by radiation method, can solve the problems of difficult control of acid hydrolysis conditions, difficult product separation and purification, long production cycle, etc., and is conducive to large-scale industrial production , high yield of low molecular weight products, and reduced production costs

Inactive Publication Date: 2007-04-11
PEKING UNIV
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  • Abstract
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  • Application Information

AI Technical Summary

Problems solved by technology

Judging from the current situation, these methods still have certain problems: the conditions of the acid hydrolysis method are not easy to control, the selectivity is poor, the separation and purification are difficult, and the yield and efficiency are low, and the cost is high, which has a certain impact on production personnel and the environment; Enzymes are difficult to obtain, making production cost prohibitive
Moreover, these methods have defects such as cumbersome operation, complicated product separation, low yield, and long production cycle, which are not conducive to industrialization
[0004] In addition, Japan, Vietnam, and some domestic units use solid-state irradiation and solution irradiation to degrade chitosan. Although chitosan can be degraded by solid-state irradiation, it requires a high absorbed dose and high irradiation costs. And it is impossible to obtain water-soluble chitosan with molecular weight below 10,000; water-soluble chitosan below 10,000 can be obtained by solution degradation method, but due to the limitation of chitosan solubility, the concentration of chitosan in the solution is extremely low, Product separation and purification are difficult and cannot be applied to industrial production

Method used

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  • Preparing low molecular weight chitosan by sensitizing radiation degradation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Commercialized high molecular weight chitosan (molecular weight is about 500,000) is mixed with the aqueous solution containing hydrogen peroxide, wherein the mass concentration of chitosan is 20%, the mass concentration of hydrogen peroxide is 25%, and the pH is adjusted with hydrochloric acid to around 4. then use 60 Coγ-rays are irradiated at room temperature, and the absorbed dose is 1-8 kGy. The low molecular weight chitosan prepared under the above-mentioned different dosages is shown in the table below:

[0021] project

Dose (kGy)

Average relative molecular weight (Dalton)

Radiolysis sample one

1

29196.4

Radiolysis Sample II

2

10755.8

Radiolysis Sample Three

3

5394.8

Radiolysis Sample Four

4

2140.5

Radiolysis Sample Seven

6

1468.0

Radiolysis Sample Eight

8

1124.3

[0022] * The data was tested and provided by the Chitin Research ...

Embodiment 2

[0027] Because the source of chitosan is different, the producer of production is different, and its property such as the molecular weight of chitosan, deacetylation degree has bigger difference, when adopting the method described in embodiment 1 to degrade chitosan like this, can change according to different situations The mass concentration of chitosan, and the amount of hydrogen peroxide added. If the molecular weight of the original chitosan is on the low side, such as 150,000, the concentration of the chitosan can be increased to 25%, and the concentration of the sensitizer added is also increased to 30% accordingly; if the molecular weight of the original chitosan is too large , such as 800,000, the concentration of chitosan can be reduced to 16%, and the concentration of the added sensitizer is correspondingly reduced to 16%. Then adjust the pH to 4 with hydrochloric acid, 60 Co gamma-rays were irradiated at room temperature, and the molecular weight of chitosan obtai...

Embodiment 3

[0029] The hydrochloric acid in above-mentioned embodiment 1 is changed into acetic acid, then adopts same step, can obtain the low molecular weight chitosan product of acetic acid type, after adding acetic acid, the molecular weight ratio of gained chitosan under the same absorbed dose is in adding hydrochloric acid condition The molecular weight of chitosan obtained is slightly higher, and other properties are basically the same.

[0030] Note: Low molecular weight chitosan products of hydrochloric acid type or acetic acid type can be directly used as medicines and food additives.

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Abstract

The sensitizing and readiation degrading process of preparing low molecular weight chitosan includes the following steps: mixing refined solid chitosan with water solution of sensitizer to form semi-solid sample, regulating pH to 4 with inorganic acid or organic acid and reaching chitosan concentration of 16-25 wt% and sensitizer concentration of 15-30 wt%, gamma ray irradiation in the dosage of 1-10 kGy to degrade at room temperature, and spray drying or vacuum drying to obtain low molecular weight chitosan. Adding the sensitizer can lower the irradiation dosage greatly, and obtain chitosan product with narrow molecular weight distribution and small molecular weight. The present invention can obtain chitosan with molecular weight as low as 3000, and the process is convenient, safe, economic, practical, high in yield and environment friendly.

Description

technical field [0001] The invention relates to a method for preparing low-molecular-weight chitosan by a radiation method, in particular to a method for producing low-molecular-weight chitosan by adding a sensitizer at a low dose without pollution, low cost, and large-scale industrial production. Background technique [0002] Chitosan is the only basic polysaccharide among natural polysaccharides. It is a natural non-toxic polymer substance with biological activity and biodegradability. It is regarded as the most potential biopolymer active substance. The molecular weight of chitosan is usually around hundreds of thousands. Because of the hydrogen bond in the molecule, it can only be dissolved in a few dilute acid solutions, but not directly in water, so its application range is greatly limited. On the other hand, in addition to the unique biological activity of high molecular weight chitosan, low molecular weight chitosan has good water solubility, moisturizing and moistur...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08B37/08
Inventor 翟茂林杨仲田彭静魏根栓李久强黄凌
Owner PEKING UNIV
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