MicroRNAs are essential post-transcriptional regulators and may act as the noninvasive biomarker for disease diagnosis. Sensitive and multiplexed detection of microRNAs may facilitate the accurate and early clinical diagnosis, but the available methods are usually compromised by using organic dyes as the signal probes, laborious chemical and enzymatic manipulations, and the complicated reaction schemes. Here we reported a siRNA-directed self-assembled quantum dot (QD) biosensor for facile and simultaneous detection of multiple microRNAs. In this biosensor, the binding of microRNA targets with corresponding QD nanoprobes leads to the formation of siRNA duplexes, which not only induces the spectrally resolved coding of microRNAs, but also facilitates the assembly of QDs:magnetic nanoparticle bioconjugates for the isolation and enrichment of target microRNAs. The disassembled QDs can be sensitively detected by single-molecule detection, enabling quantitatively sensing of microRNAs at the single-particle level. This biosensor employs only QDs as the signal reporters, which can simultaneously detect multiple microRNAs from the same sample and achieves femtomolar sensitivity and single-base mismatch selectivity without the involvement of any target labeling and amplification steps. Moreover, it can be successfully applied for simultaneous detection of circulating microRNAs in clinical serum samples, holding great potential in non-invasive early diagnosis and biomedical researches.

MicroRNA是转录后必不可少的调节剂，可作为疾病诊断的非侵入性生物标记。microRNA的灵敏和多重检测可能有助于准确和早期的临床诊断，但是可用的方法通常会因使用有机染料作为信号探针，费力的化学和酶操作以及复杂的反应方案而受到影响。在这里，我们报道了一种简便易行的同时检测多种microRNA的siRNA定向自组装量子点（QD）生物传感器。在这种生物传感器中，microRNA靶标与相应的QD纳米探针的结合导致siRNA双链体的形成，这不仅诱导了microRNA的光谱解析编码，而且还促进了QD的组装：磁性纳米粒子生物共轭物，用于目标微RNA的分离和富集。可以通过单分子检测灵敏地检测到拆卸的QD，从而可以在单颗粒水平上定量检测microRNA。这种生物传感器仅采用QD作为信号报告基因，可以同时检测同一样品中的多个microRNA，并具有飞摩尔灵敏度和单碱基错配选择性，而无需任何靶标标记和扩增步骤。而且，它可以成功地用于临床血清样品中循环微RNA的同时检测，在无创早期诊断和生物医学研究中具有巨大的潜力。能够在单颗粒水平上定量检测microRNA。这种生物传感器仅采用QD作为信号报告基因，可以同时检测同一样品中的多个microRNA，并具有飞摩尔灵敏度和单碱基错配选择性，而无需任何靶标标记和扩增步骤。而且，它可以成功地用于临床血清样品中循环微RNA的同时检测，在无创早期诊断和生物医学研究中具有巨大的潜力。能够在单颗粒水平上定量检测microRNA。这种生物传感器仅采用QD作为信号报告基因，可以同时检测同一样品中的多个microRNA，并具有飞摩尔灵敏度和单碱基错配选择性，而无需任何靶标标记和扩增步骤。而且，它可以成功地用于临床血清样品中循环微RNA的同时检测，在无创早期诊断和生物医学研究中具有巨大的潜力。