Analytical Chemistry Department, Center of Excellence in Electrochemistry, School of Chemistry, College of Science, University of Tehran, Tehran, Iran.
Analytical Chemistry Department, Center of Excellence in Electrochemistry, School of Chemistry, College of Science, University of Tehran, Tehran, Iran.
Anal Chim Acta. 2024 Sep 1;1320:342968. doi: 10.1016/j.aca.2024.342968. Epub 2024 Jul 11.
Cancer is known as one of the main non-communicable diseases and the leading cause of death in the new era. Early diagnosis of cancer requires the identification of special biomarkers. Currently, microRNAs (miRNAs) have attracted the attention of researchers as useful biomarkers for cancer early detection. Hence, various methods have been recently developed for detecting and monitoring miRNAs. Among all miRNAs, detection of miRNA-21 (miR-21) is important because it is abnormally overexpressed in most cancers. Here, a new biosensor based on silver nanoclusters (AgNCs) is introduced for detecting miR-21.
As a fluorescent probe, a rationally designed hairpin sequence containing a poly-cytosine motif was used to facilitate the formation of AgNCs. A guanine-rich sequence was also employed to enhance the sensing signal. It was found that in the absence of miR-21, adding a guanine-rich sequence to the detecting probe caused only a slight change in the fluorescence emission intensity of AgNCs. While in the presence of miR-21, the emission signal enhanced. A direct correlation was observed between the increase in the fluorescence of AgNCs and the concentration of miR-21. The performance of the proposed biosensor was characterized thoroughly and confirmed. The biosensor detected miR-21 in an applicable linear range from 9 pM to 1.55 nM (LOD: 2 pM).
The designed biosensor was successfully applied for detecting miR-21 in human plasma samples and also in human normal and lung and ovarian cancer cells. This biosensing strategy can be used as a model for detecting other miRNAs. The designed nanobiosensor can measure miR-21 without using any enzymes, with fewer experimental steps, and at a low cost compared to the reported biosensors in this field.
癌症是新时代主要的非传染性疾病和主要死因之一。癌症的早期诊断需要识别特殊的生物标志物。目前，microRNAs（miRNAs）作为癌症早期检测的有用生物标志物引起了研究人员的关注。因此，最近已经开发了各种用于检测和监测 miRNAs 的方法。在所有 miRNAs 中，检测 miRNA-21（miR-21）很重要，因为它在大多数癌症中异常过表达。在这里，引入了一种基于银纳米簇（AgNCs）的新型生物传感器来检测 miR-21。
作为荧光探针，使用经过合理设计的包含多胞嘧啶基序的发夹序列来促进 AgNCs 的形成。还使用富含鸟嘌呤的序列来增强传感信号。结果发现，在没有 miR-21 的情况下，向检测探针中添加富含鸟嘌呤的序列只会导致 AgNCs 的荧光发射强度略有变化。而在存在 miR-21 的情况下，发射信号增强。AgNCs 的荧光增加与 miR-21 的浓度之间存在直接相关性。对所提出的生物传感器进行了彻底的特征描述和验证。该生物传感器在适用的线性范围内检测到 9 pM 至 1.55 nM 的 miR-21（LOD：2 pM）。
设计的生物传感器成功地应用于检测人血浆样品中的 miR-21，以及人正常和肺癌和卵巢癌细胞中的 miR-21。这种生物传感策略可作为检测其他 miRNAs 的模型。与该领域报道的生物传感器相比，设计的纳米生物传感器无需使用任何酶，具有更少的实验步骤，并且成本更低。
