Synthesis and properties of thermosensitive hydrogel of allyl silk fibroin

doi:10.11949/0438-1157.20200626

Abstract

Abstract:

For the sake of solving the problems of poor mechanical strength and dissolve-loss ratio of Antheraea pernyi silk fibroin (ASF), allyl silk fibroin (ASF-AGE) was synthesized through nucleophilic substitution using ASF as substrate and allyl glycidyl ether (AGE) as modifier under basic conditions. And a series of gel were manufactured though in situ polymerization using ASF-AGE and N-isopropylacrylamide (NIPAAm) monomer without any crosslinking agent. The amino conversion rate of ASF was confirmed by ninhydrin colorimetry, the molecular structure of ASF-AGE was characterized by ¹H NMR and the influence of ASF-AGE content on crystal structure, temperature sensitivity, dissolution stability and mechanical properties of hydrogels were also investigated by XRD, DSC, compression test and so on. The results indicated that allyl was successfully introduced into ASF, the amino conversion rate of ASF was 55.21% when the reaction condition was 1∶8 mass ratio (ASF/AGE), T=20℃ and pH=10.5. The stable hydrogels can be obtained by ASF-AGE and NIPAAm polymerization. The hydrogels showed lower critical solution temperatures (LCST) at about 32℃, which revealed obvious thermosensitive characteristic. When the ratio of ASF-AGE to NIPAAm is 4/6, the hydrogel has good dissolution stability and comprehensive mechanical properties.

Key words: silk fibroin, hydrogel, polymerization, thermosensitivity, elasticity

摘要：

为解决以柞蚕丝素蛋白（ASF）为基材的生物材料力学性能差、水溶失率高等问题，首先，以ASF为原料，烯丙基缩水甘油醚（AGE）为改性剂，在碱性条件下ASF与AGE发生亲核取代反应，形成具有反应性的烯丙基丝素蛋白（ASF-AGE）；然后，以N-异丙基丙烯酰胺（NIPAAm）为单体，在不使用任何交联剂的情况下，将ASF-AGE与NIPAAm进行聚合，最终形成烯丙基丝素蛋白温敏p（ASF-AGE-NIPAAm）水凝胶。采用茚三酮比色法对ASF-AGE的氨基转化率进行测定，采用¹H NMR对ASF-AGE分子结构进行表征；采用XRD、DSC、压缩测试等方法研究ASF-AGE含量对水凝胶结晶结构、温敏特性、溶失稳定性和力学性能的影响。结果表明：烯丙基双键成功引入ASF大分子链上，ASF与AGE的质量比为1∶8，温度20℃，pH=10.5，反应24 h时，得到的ASF-AGE的氨基转化率为55.21%；ASF-AGE与NIPAAm聚合形成稳定形态的水凝胶，水凝胶的LCST约为32℃，具有明显的温敏特性；ASF-AGE与NIPAAm配比为4/6时，水凝胶具有良好的溶失稳定性和综合力学性能。

关键词: 丝素蛋白, 水凝胶, 聚合, 温敏性, 弹性

CLC Number:

O 636.9

WANG Boxiang,LIU Li,LI Jia,LU Yanhua,CHENG Dehong,JIN Huiyu,ZHOU Ling. Synthesis and properties of thermosensitive hydrogel of allyl silk fibroin[J]. CIESC Journal, 2020, 71(12): 5821-5830.

王勃翔,刘丽,李佳,路艳华,程德红,靳惠宇,周凌. 烯丙基丝素蛋白温敏水凝胶的合成及性能研究[J]. 化工学报, 2020, 71(12): 5821-5830.

Figures/Tables 12

Table 1 Reaction conditions of preparation for p(ASF-AGE-NIPAAm) gel

样品	ASF-AGE/NIPAAm质量比	ASF-AGE/mg	NIPAAm/ml	APS/mg	5%TEMED/μl
pAGN1	1/9	52.5	6.3	0.95	19
pAGN2	2/8	105	5.6	0.84	16.8
pAGN3	3/7	157.5	4.9	0.74	14.8
pAGN4	4/6	210	4.2	0.63	12.6
pAGN5	5/5	262.5	3.5	0.53	10.6

Fig.1 Standard curve of alanine solution

Fig.2 Preparation mechanism of ASF-AGE

Fig.3 1H NMR gspectra of ASF (a) and ASF-AGE (b)

Fig.4 Gelation behavior of ASF-AGE solution (a); thermosensitive behavior of linear PNIPAAm (b)

Fig.5 Preparation process of p(ASF-AGE-NIPAAm) hydrogel

Fig.6 XRD patterns of ASF and ASF-AGE (a), and p(ASF-AGE-NIPAAm) hydrogels with different ASF-AGE content (b)

Fig.7 DSC curves for p(ASF-AGE-NIPAAm) hydrogels with different ASF-AGE content

Fig.8 Reversible swelling-shrink process of PNIPAAm

Fig.9 ESR curves (a) and integral curves (b) for p(ASF-AGE-NIPAAm) hydrogels under different temperature

Fig.10 Dissolve-loss ratio of p(ASF-AGE-NIPAAm) hydrogels with different ASF-AGE content

Fig.11 Stress-strain curves (a) and elasticity modulus (b) of p(ASF-AGE-NIPAAm) hydrogels with different ASF-AGE content

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