There is intense interest in quantifying the levels of microRNA because of its importance as a blood-borne biomarker. The challenge has been to develop methods that can monitor microRNA expression both over broad concentration ranges and in ultralow amounts directly in a patient’s blood. Here, we show that, through electric-field-induced reconfiguration of a network of gold-coated magnetic nanoparticles modified by probe DNA (DNA–Au@MNPs), it is possible to create a highly sensitive sensor for direct analysis of nucleic acids in samples as complex as whole blood. The sensor is the first to be able to detect concentrations of microRNA from 10 aM to 1 nM in unprocessed blood samples. It can distinguish small variations in microRNA concentrations in blood samples of mice with growing tumours. The ultrasensitive and direct detection of microRNA using an electrically reconfigurable DNA–Au@MNPs network makes the reported device a promising tool for cancer diagnostics.

由于微RNA作为血源性生物标志物的重要性，人们对微RNA的定量水平引起了浓厚的兴趣。面临的挑战是开发一种可以在广泛的浓度范围内以及直接在患者血液中以超低量监测microRNA表达的方法。在这里，我们表明，通过电场诱导的被探针DNA（DNA–Au @ MNPs）修饰的镀金磁性纳米粒子网络的重构，可以创建一个高度灵敏的传感器，用于直接分析核酸。样本与全血一样复杂。该传感器是第一个能够检测未经处理的血液样本中从10 aM到1 nM的microRNA浓度的传感器。它可以区分肿瘤生长的小鼠血液样本中microRNA浓度的微小变化。