Graduate Institute of Biomedical Materials and Tissue Engineering, Taipei Medical University , 250 Wu-Xing Street, Taipei City, 30010 Taiwan.
Biomacromolecules. 2017 Apr 10;18(4):1162-1171. doi: 10.1021/acs.biomac.6b01841. Epub 2017 Mar 9.
Stimulus-responsive hydrogels make up an important class of programmable materials for a wide range of biomedical applications. Ultrasound (US) is a stimulus that offers utility because of its ability to permeate tissue and rapidly induce chemical alterations in aqueous media. Here we report on the synthesis and US-mediated disintegration of stimulus-responsive telechelic Dopa-modified polyethylene glycol-based hydrogels. Fe-[PEG-Dopa] hydrogels are formed through Fe-induced cross-linking of four-arm polyethylene glycol-dopamine precursors to produce networks. The relative amounts of H-bonds, coordination bonds, and covalent bonds can be controlled by the [Fe]:[Dopa] molar ratio in precursor solutions. Networks formed from precursors with high [Fe]:[Dopa] ratios create mechanically robust networks (G' = 6880 ± 240 Pa) that are largely impervious to US-mediated disintegration at intensities of ≤43 W/cm. Conversely, lightly cross-linked networks formed through [Fe]:[Dopa] molar ratios of <0.73 are susceptible to rapid disintegration upon exposure to US. Pulsatile US exposure allows temporal control over hydrogel disintegration and programmable self-healing. Sustained US energy can also stabilize hydrogels through the formation of additional cross-links via free radical-mediated coupling of pendant catechols. Taken together, the diverse ranges of mechanical behavior, self-healing capability, and differential susceptibility to ultrasonic disintegration suggest that Fe-[PEG-Dopa] hydrogels yield a class of application-specific stimulus-responsive polymers as smart materials for applications ranging from transient medical implants to matrices for smart drug delivery.
刺激响应水凝胶是一类在广泛的生物医学应用中具有重要应用价值的可编程材料。超声（US）是一种很有用的刺激源，因为它能够穿透组织并迅速在水介质中引起化学变化。在这里，我们报告了刺激响应的末端多巴修饰的聚乙二醇基水凝胶的合成和 US 介导的崩解。Fe-[PEG-Dopa]水凝胶是通过 Fe 诱导的四臂聚乙二醇-多巴胺前体的交联形成网络来制备的。氢键、配位键和共价键的相对数量可以通过前体溶液中[Fe]：[Dopa]摩尔比来控制。由高[Fe]：[Dopa]摩尔比的前体制备的网络形成机械强度高的网络（G'=6880±240 Pa），在强度≤43 W/cm 的 US 介导下基本不透水。相反，通过[Fe]：[Dopa]摩尔比<0.73形成的轻度交联网络在暴露于 US 时容易迅速崩解。脉动 US 暴露允许通过对水凝胶崩解的时间控制和可编程的自修复来实现。持续的 US 能量也可以通过自由基介导的侧链儿茶酚的偶联形成额外的交联来稳定水凝胶。总的来说，机械性能、自修复能力以及对超声崩解的不同敏感性的广泛范围表明，Fe-[PEG-Dopa]水凝胶产生了一类具有特定应用的刺激响应聚合物，作为智能材料可用于从瞬态医疗植入物到智能药物输送的基质等各种应用。
