具有碱性 pH 响应性和可调凝胶 pH 值的内部硼-氮配位硼酸酯水凝胶的模块化设计和键合机制,Chemistry of Materials

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具有碱性 pH 响应性和可调凝胶 pH 值的内部硼-氮配位硼酸酯水凝胶的模块化设计和键合机制
Chemistry of Materials ( IF 7.2 ) Pub Date : 2023-03-06 , DOI: 10.1021/acs.chemmater.2c03550
Haifei Kang ₁ , Wenying Wei ₁ , Lingshun Sun ₁ , Ran Yu ₁ , Erkang Yang ₁ , Xiaopei Wu _{1,

2} , Honglian Dai _{1,

2,

3}

Affiliation

硼酸酯水凝胶因其对多种疾病相关触发因素的刺激反应而广泛应用于生物医学领域。然而，凝胶化受限的 pH 值和较差的水解稳定性限制了它们在可变生理微环境中的应用。在这里，我们报告了一种模块化共轭方法，通过用苯硼酸或N , N构建聚合物来设计内部硼氮配位硼酸酯 (IBNCB) 水凝胶-基于酰胺的双（2-羟乙基）部分。制备了八种不同的由聚合物/聚合物或聚合物/小分子组成的 IBNCB 水凝胶模型，在碱性环境中表现出独特的 pH 响应性、增强的水解稳定性、双向 pH 可调机械性能以及较低和可调的凝胶 pH 值。此外，IBNCB 水凝胶保持了对活性氧 (ROS)、葡萄糖和温度的溶胶-凝胶过渡响应。特别是，我们发现形成理想的 IBNCB 水凝胶所需的 pH 值应大于苯硼酸的 p K _a但低于N，N-双（2-羟乙基）的p K _{a ，并降低 p}K _a苯硼酸的加入可以降低凝胶化的 pH 值。N，N-双（2-羟乙基）中叔胺的p K _a被证明在 B-N 配位键的形成中很重要，这影响了 IBNCB 键的形成。最后，我们探讨了主链电荷对凝胶性的影响，并提出了水凝胶中IBNCB键的动态平衡机制。我们期望多重刺激响应的 IBNCB 水凝胶将为设计对物理化学信号敏感的智能材料提供一种新策略。此外，基于酰胺的模块化共轭可用于生成理论上无限数量的新型 IBNCB 材料，包括微凝胶、聚合物囊泡和微纳米颗粒。

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Modular Design and Bonding Mechanism of Internal Boron–Nitrogen Coordinated Boronic Ester Hydrogels with Alkaline pH Responsiveness and Tunable Gelation pH

Boronic ester hydrogels have been widely used in biomedical fields for their stimuli responsiveness to multiple disease-related triggers. However, the restricted pH for gelation and the poor hydrolysis stability limit their application in variable physiological microenvironments. Here, we report a modular conjugation method for designing internal boron–nitrogen coordinated boronic ester (IBNCB) hydrogels by constructing polymers with phenylboronic acid or N,N-bis(2-hydroxyethyl) moieties based on amides. Eight distinct IBNCB hydrogel models composed of polymer/polymer or polymer/micromolecule were prepared, exhibiting a unique pH responsiveness in the alkaline environment, an enhanced hydrolysis stability, bidirectional pH-tunable mechanical properties, and a lowered and tunable pH for gelation. In addition, the IBNCB hydrogels maintained a sol–gel transitional responsiveness to reactive oxygen species (ROS), glucose, and temperature. Especially, we found that the pH required to form an ideal IBNCB hydrogel should be greater than the pK_a of phenylboronic acid but lower than the pK_a of N,N-bis(2-hydroxyethyl), and reducing the pK_a of phenylboronic acid could lower the gelation pH. The pK_a of the tertiary amine in N,N-bis(2-hydroxyethyl) was shown to be important in the creation of the B–N coordination bond, which influenced the formation of the IBNCB bond. Finally, we explored the effect of the main chain’s charge on gelability and proposed the dynamic equilibrium mechanism of IBNCB bonds in the hydrogel. We expect that the multi-stimuli-responsive IBNCB hydrogels will provide a new strategy for designing smart materials sensitive to physicochemical signals. Furthermore, the amide-based modular conjugation could be exploited to generate a theoretically limitless number of novel IBNCB materials including microgels, polymer vesicles, and micro–nano particles.

更新日期：2023-03-06

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