双重响应性生物基自修复凝胶的制备及其性能

Preparation and Properties of Dual Responsive Self-healing Bio-based Hydrogels

为拓宽多重响应性凝胶在生物医学领域中的应用,本文基于生物大分子构筑具有p H响应、糖响应性的可自修复性水凝胶。本文选用3-氨基苯硼酸(APBA)和2,3-环氧丙基三甲基氯化铵(CHGTA)分别对聚谷氨酸(γ-PGA)和瓜尔胶(GG)进行改性制备了聚谷氨酸-g-氨基苯硼酸(γ-PGA-g-APBA)和阳离子瓜尔胶,在此基础上,对γ-PGA-g-APBA和阳离子瓜尔胶进行物理共混制备生物基凝胶。通过傅里叶变换红外光谱仪(FTIR)、核磁共振波谱仪(1H NMR)和流变仪对聚合物化学结构、接枝率、流变性能和力学性能进行表征,并考察了凝胶在不同p H值及糖浓度下刺激响应性。结果表明,凝胶具有自修复性,修复效率可达100%;具有p H响应性,在环境p H值较高时更易形成凝胶,且凝胶强度随p H值升高而增大;同时所制凝胶具有糖响应性,在4 g/L的葡萄糖溶液中浸泡后即可导致凝胶解体。这些结果说明功能基团APBA的引入可赋予凝胶多重响应性。所制的双重响应性生物基凝胶具有良好的生物相容性,有望应用于生物医学、功能器件、传感等领域。

Phenylboronic acid and derivatives that conjugate with diol units to form a reversible ester bond can be used to prepare self-healing and stimuli-responsive materials. Stimuli-responsive hydrogels based on phenylboronic acid have been reported to have excellent self-healing properties. However, in these examples,employed polymers are not fully degradable nor have low biocompatibility. Therefore, this study aims to prepare a bio-based hydrogel for potential biomedical applications. Poly(γ-glutamic acid- g -3-aminophenylboronic acid)(γ-PGA- g -APBA) was synthesized by grafting 3-aminophenylboronic acid(APBA) in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide(EDC) and N -hydroxysuccinimide(NHS) as catalysts, and guar gum was modified by cationic etherification agent, 2,3-epoxypropyltrimethylammonium chloride( CHGTA ). These two modified bio-polymers were characterized by Fourier transform infrared(FT-IR) spectroscopy , nuclear magnetic resonance(^1 H NMR), and ultraviolet-visible(UV-Vis) spectrophotometer, and were mixed to form hydrogels. Mechanical properties of the prepared hydrogels were characterized by the rheometer. The results show that(γ-PGA- g -APBA/CGG) hydrogels have self-healing and pH-responsive properties . The structure of the gels is damaged with large strain and reconstructed completely with small strain, indicating that the hydrogel have the self-healing property and the repeatability. With the increase of pH value from 7 to 9, the hydrogels are formed and their strengths increase with pH, due to the conversion of the trigonal boronic-ester bond to tetrahedral boronic-ester bond. In the presence of 4 g/L glucose, the formed gel dissociates and changes to sol, because of the competing reaction between glucose and guar gum with PBA group. Moreover, rheology test indicates the shear-thinning and injectable properties of the hydrogels. Thus, the bio-based(γ-PGA- g -APBA/CGG ) hydrogels have the potential applications in sensors, medicine and tissue engineering .