The development of powerful techniques for sensitive detection of nucleic acids has attracted much attention for fabricating accurate biosensors in various fields, such as genomics, clinical diagnostics, and forensic sciences. Up to now, different systems have been introduced, the majority of which are expensive, time-consuming, and relatively low selectivity/limit of detection. These limitations caught our attention to fabricate a nucleic acid responsive system by combining three layers of signal amplification strategy, namely a split proximity circuit (SPC), a catalytic hairpin assembly (CHA), and a DNA hydrogel. Herein, by SPC operation, two initiators and a target strand were assembled and activated the CHA reaction in the presence of three 5'-cytosine (C)-rich hairpins. Then, produced C-rich embedded three-way junction structures could form i-motif structures under acidic environment followed by a transition from sol to gel state. To acquire a quantitative and colorimetric measurement, gold nanoparticles (GNPs) were used that encapsulated and sediment by the gel formation. The resulting platform detected the target with a limit of detection of 1 pM and considerable selectivity.

中文翻译：

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使用 DNA 邻近电路和催化发夹组装开发比色核酸响应 DNA 水凝胶

用于灵敏检测核酸的强大技术的发展在基因组学、临床诊断和法医学等各个领域制造准确的生物传感器方面引起了广泛关注。到目前为止，已经引入了不同的系统，其中大多数系统昂贵、耗时且选择性/检测限相对较低。这些限制引起了我们的注意，通过结合三层信号放大策略，即分离邻近电路 (SPC)、催化发夹组件 (CHA) 和 DNA 水凝胶来制造核酸响应系统。在此，通过 SPC 操作，在三个富含 5'-胞嘧啶 (C) 的发夹的存在下，组装了两个引发剂和一条目标链并激活了 CHA 反应。然后，产生的富含 C 的嵌入三路连接结构可以在酸性环境下形成 i-motif 结构，然后从溶胶状态转变为凝胶状态。为了获得定量和比色测量，使用金纳米颗粒 (GNP)，通过凝胶形成包裹和沉淀。由此产生的平台以 1 pM 的检测限和相当大的选择性检测目标。