J Am Chem Soc. 2018 Apr 18;140(15):5061-5064. doi: 10.1021/jacs.8b02793. Epub 2018 Apr 6.
Stimuli-responsive nanomaterials with reconfigurable structures and properties have garnered significant interest in the fields of optics, electronics, magnetics, and therapeutics. DNA is a powerful and versatile building material that provides programmable structural and dynamic properties, and indeed, sequence-dependent changes in DNA have already been exploited in creating switchable DNA-based architectures. However, rather than designing a new DNA input sequence for each intended dynamic change, it would be useful to have one simple, generalized stimulus design that could provide multiple different structural outputs. In pursuit of this goal, we have designed, synthesized, and characterized pH-dependent, switchable nanoparticle superlattices by utilizing i-motif DNA structures as pH-sensitive DNA bonds. When the pH of the solution containing such superlattices is changed, the superlattices reversibly undergo: (i) a lattice expansion or contraction, a consequence of the pH-induced change in DNA length, or (ii) a change in crystal symmetry, a consequence of both pH-induced DNA "bond breaking" and "bond forming" processes. The introduction of i-motifs in DNA colloidal crystal engineering marks a significant step toward being able to dynamically modulate crystalline architectures and propagate local molecular motion into global structural change via exogenous stimuli.
具有可重构结构和性质的刺激响应型纳米材料在光学、电子学、磁学和治疗学等领域引起了极大的兴趣。DNA 是一种强大而多功能的建筑材料，提供可编程的结构和动态特性，实际上，已经利用 DNA 序列依赖性变化来创建可切换的基于 DNA 的结构。然而，与其为每个预期的动态变化设计新的 DNA 输入序列，不如设计一个简单的通用刺激设计，该设计可以提供多种不同的结构输出。为了实现这一目标，我们设计、合成并表征了 pH 依赖性、可切换的纳米粒子超晶格，利用 i-motif DNA 结构作为 pH 敏感的 DNA 键。当含有这种超晶格的溶液的 pH 值发生变化时，超晶格会发生以下可逆变化：（i）晶格的膨胀或收缩，这是由于 DNA 长度随 pH 变化引起的；或（ii）晶体对称性的变化，这是由于 pH 诱导的 DNA“键断裂”和“键形成”过程的共同作用。在 DNA 胶体晶体工程中引入 i-motif 标志着能够通过外源性刺激动态调节晶体结构并将局部分子运动传播到全局结构变化的重要一步。
