Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, IL, 60208, USA.
Applied Physics Graduate Program, Northwestern University, 2145 Sheridan Road, Evanston, IL, 60208, USA.
Macromol Rapid Commun. 2018 Jan;39(2). doi: 10.1002/marc.201700587. Epub 2017 Oct 24.
Supramolecular hydrogels (SMHs) are three-dimensional constructs wherein the majority of the volume is occupied by water. Since the bonding forces between the components of SMHs are noncovalent, SMH properties are often tunable, stimuli-responsive, and reversible, which enables applications including triggered drug release, sensing, and tissue engineering. Meanwhile, single-walled carbon nanotubes (SWCNTs) possess superlative electrical and thermal conductivities, high mechanical strength, and strong optical absorption at near-infrared wavelengths that have the potential to add unique functionality to SMHs. However, SWCNT-based SMHs have thus far not realized the potential of the optical properties of SWCNTs to enable reversible response to near-infrared irradiation. Here, we present a novel SMH architecture comprised solely of DNA and SWCNTs, wherein noncovalent interactions provide structural integrity without compromising the intrinsic properties of SWCNTs. The mechanical properties of these SMHs are readily tuned by varying the relative concentrations of DNA and SWCNTs, which varies the cross-linking density as shown by molecular dynamics simulations. Moreover, the SMH gelation transition is fully reversible and can be triggered by a change in temperature or near-infrared irradiation. This work explores a new regime for SMHs with potential utility for a range of applications including sensors, actuators, responsive substrates, and 3D printing.
超分子水凝胶（SMH）是三维结构，其中大部分体积被水占据。由于 SMH 组成部分之间的结合力是非共价的，因此 SMH 的性质通常是可调的、对刺激有响应的且是可逆的，这使其能够应用于包括触发药物释放、传感和组织工程等领域。同时，单壁碳纳米管（SWCNT）具有卓越的电导率和热导率、高机械强度和在近红外波长下的强光吸收能力，有可能为 SMH 增添独特的功能。然而，基于 SWCNT 的 SMH 迄今为止尚未实现 SWCNT 的光学性质的潜力，无法实现对近红外辐射的可逆响应。在这里，我们提出了一种由 DNA 和 SWCNT 组成的新型 SMH 结构，其中非共价相互作用提供了结构完整性，而不会损害 SWCNT 的固有性质。这些 SMH 的机械性能可以通过改变 DNA 和 SWCNT 的相对浓度轻松调节，如分子动力学模拟所示，这会改变交联密度。此外，SMH 的凝胶化转变是完全可逆的，可以通过温度变化或近红外辐射来触发。这项工作探索了 SMH 的一个新领域，其在包括传感器、执行器、响应性基板和 3D 打印在内的各种应用中具有潜在的用途。
