We report a novel assembly of polyethyleneimine (PEI)-coated Fe₃O₄ nanoparticles (NPs) with single-stranded DNA (ssDNA), and the fluorescence of the dye labeled in the DNA is remarkably quenched. In the presence of a target protein, the protein–DNA aptamer mutual interaction releases the ssDNA from this assembly and hence restores the fluorescence. This feature could be adopted to develop an aptasensor for protein detection. As a proof-of-concept, for the first time, we have used this proposed sensing strategy to detect thrombin selectively and sensitively. Furthermore, simultaneous multiple detection of thrombin and lysozyme in a complex protein mixture has been proven to be possible.

中文翻译：

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聚乙烯亚胺包覆的Fe ₃ O ₄纳米颗粒可有效淬灭荧光DNA，可开发为蛋白质检测的新平台

我们报告与单链DNA（ssDNA）的聚乙烯亚胺（PEI）涂层的Fe ₃ O ₄纳米粒子（NPs）的新型组装，并标记在DNA中的染料的荧光被显着淬灭。在目标蛋白存在的情况下，蛋白与DNA的适体相互作用会从该装配中释放ssDNA，从而恢复荧光。可以采用此功能来开发用于蛋白质检测的适体传感器。作为概念验证，我们首次使用了这种拟议的传感策略来选择性，灵敏地检测凝血酶。此外，已经证明可以同时检测复杂蛋白质混合物中的凝血酶和溶菌酶。