A disposable enzyme-free biosensing platform for the sensitive and selective voltammetric determination of miRNAs is reported. The bioplatform implies a sandwich-type hybridization configuration involving the use of two synthetic DNA probes that hybridize contiguously with the target miRNA-21. A thiolated capture probe was immobilized through thiol chemistry on disposable carbon electrodes modified with a hybrid nanomaterial composed of reduced graphene oxide (rGO) and gold nanoparticles (AuNPs). A biotinylated detection probe was conjugated with ferrocene-capped AuNPs modified with streptavidin (Fc-AuNPs-Strep) which were used as labeling nanocarriers. The extent of the hybridization event was followed by differential pulse voltammetric measurement of the Fc oxidation peak. Under the optimized conditions, the developed biosensor provides attractive characteristics for the determination of the synthetic target miRNA, with a linear range between 10 fM and 2 pM and a limit of detection (LOD) of 5 fM, fully discrimination towards a highly homologous miRNA (with just one mismatched base) and a storage stability of at least two months. The biosensor was able to determine accurately the target miRNA directly in scarcely diluted serum from breast cancer (BC) patients with no need for a previous total RNA (RNAt) extraction and in a very small amount of RNAt extracted from breast adenocarcinoma cells without the need for amplification or reverse transcription to complementary DNA.

中文翻译：

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使用无酶生物传感器飞摩尔直接伏安法测定癌症患者血清中循环 miRNA

报告了一种用于敏感和选择性伏安法测定 miRNA 的一次性无酶生物传感平台。生物平台意味着夹心型杂交配置，涉及使用两个与目标 miRNA-21 连续杂交的合成 DNA 探针。通过硫醇化学将硫醇化捕获探针固定在用由还原氧化石墨烯 (rGO) 和金纳米粒子 (AuNPs) 组成的混合纳米材料修饰的一次性碳电极上。生物素化检测探针与用链霉亲和素 (Fc-AuNPs-Strep) 修饰的二茂铁封端的 AuNP 结合，用作标记纳米载体。杂交事件的程度之后是 Fc 氧化峰的差分脉冲伏安测量。在优化条件下，开发的生物传感器为合成目标 miRNA 的测定提供了有吸引力的特性，线性范围在 10 fM 和 2 pM 之间，检测限 (LOD) 为 5 fM，完全区分高度同源的 miRNA（只有一个错配碱基） ) 和至少两个月的储存稳定性。该生物传感器能够直接在几乎不稀释的乳腺癌 (BC) 患者血清中准确测定目标 miRNA，无需之前提取总 RNA (RNAt)，并且无需提取从乳腺癌细胞中提取的极少量 RNAt。用于扩增或逆转录为互补 DNA。完全区分高度同源的 miRNA（只有一个错配碱基）和至少两个月的储存稳定性。该生物传感器能够直接在几乎不稀释的乳腺癌 (BC) 患者血清中准确测定目标 miRNA，无需之前提取总 RNA (RNAt)，并且无需提取从乳腺癌细胞中提取的极少量 RNAt。用于扩增或逆转录为互补 DNA。完全区分高度同源的 miRNA（只有一个错配碱基）和至少两个月的储存稳定性。该生物传感器能够直接在几乎不稀释的乳腺癌 (BC) 患者血清中准确测定目标 miRNA，无需之前提取总 RNA (RNAt)，并且无需提取从乳腺癌细胞中提取的极少量 RNAt。用于扩增或逆转录为互补 DNA。