Secondary structures in long circulating tumor nucleic acids have potential obstacles for specific location point hybridized detection of gene fragments. The exploration of biosensing strategies requires selectively changing the nucleic acids conformation and inducing signal switching. Herein, a self-assembled magnetic composite probe (MCP) was fabricated by the hybridization reaction of Linker DNA and a “Y”-junction-DNA nanostructure on the surface of magnetic beads, contributing to the capture, secondary structure unlocking, and enrichment of the PML/RARα DNA “L” subtype. Then, by integrating the MCP-actuated reactor, a one-step “off–on” signal switching MoS₂@FAM-probe biosensing method was developed for the efficient detection of the PML/RARα DNA “L” subtype. The proposed biosensor was capable of detecting 100 bases PML/RARα DNA “L” subtype with a wide linear range of 1 pM to 200 nM and a limit of detection down to 0.223 pM without signal amplification. In addition, the biosensing method was successfully applied for the detection of target in serum samples. It is worth pointing out that this simple biosensing strategy could enable long nucleic acids fragments with secondary structures from ctDNA and ctRNA to be quantitatively assayed based on direct hybridization.

中文翻译：

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二硫化钼@ 5-羧基荧光素探针生物传感器，用于基于磁性复合探针驱动的二级结构解封的长核酸中未扩增的特异性片段检测。

长循环肿瘤核酸中的二级结构对于基因片段的特异性定位点杂交检测具有潜在的障碍。生物传感策略的探索需要选择性地改变核酸构象并诱导信号转换。在此，通过连接子DNA与磁珠表面的“ Y”-结-DNA纳米结构的杂交反应，制备了自组装磁性复合探针（MCP），有助于探针的捕获，二级结构解锁和富集。 PML /RARαDNA“ L”亚型。然后，通过集成MCP驱动的电抗器，一步一步“关-开”信号切换MoS ₂开发了@ FAM-probe生物传感方法，用于有效检测PML /RARαDNA“ L”亚型。提出的生物传感器能够检测100个碱基的PML /RARαDNA“ L”亚型，线性范围为1 pM至200 nM，检测限低至0.223 pM，而无需信号放大。此外，生物传感方法已成功应用于血清样品中目标的检测。值得指出的是，这种简单的生物传感策略可以基于直接杂交对ctDNA和ctRNA具有二级结构的长核酸片段进行定量分析。