Junhong Chen, et al.Aptamer-based cell-free detection system to detect target protein, Synthetic and Systems Biotechnology,Volume 6, Issue 3, September 2021, Pages 209-215

Abstract
Biomarkers of disease, especially protein, show great potential for diagnosis and prognosis. For detecting a certain protein, a binding assay implementing antibodies is commonly performed. However, antibodies are not thermally stable and may cause false-positive when the sample composition is complicated. In recent years, a functional nucleic acid named aptamer has been used in many biochemical analysis cases, which is commonly selected from random sequence libraries by using the systematic evolution of ligands by exponential enrichment (SELEX) techniques. Compared to antibodies, the aptamer is more thermal stable, easier to be modified, conjugated, and amplified. Herein, an Aptamer-Based Cell-free Detection (ABCD) system was proposed to detect target protein, using epithelial cell adhesion molecule (EpCAM) as an example. We combined the robustness of aptamer in binding specificity with the signal amplification ability of CRISPR-Cas12a′s trans-cleavage activity in the ABCD system. We also demonstrated that the ABCD system could work well to detect target protein in a relatively low limit of detection (50–100 nM), which lay a foundation for the development of portable detection devices. This work highlights the superiority of the ABCD system in detecting target protein with low abundance and offers new enlightenment for future design and development.

摘要
疾病的生物标志物，尤其是蛋白质，在诊断和预后方面显示出巨大的潜力。为了检测某种蛋白质，通常会进行抗体结合试验。然而，抗体不具有热稳定性，当样品成分复杂时，可能导致假阳性。近年来，一种称为适体的功能性核酸已被用于许多生化分析案例中，该核酸通常是通过指数富集（SELEX）技术利用配体的系统进化从随机序列库中选择的。与抗体相比，适配子更热稳定，易于修饰、接合和扩增。在此，以上皮细胞粘附分子（EpCAM）为例，提出了一种基于适体的无细胞检测（ABCD）系统来检测目标蛋白。我们将适配子结合特异性的稳健性与ABCD系统中CRISPR-Cas12a的反式切割活性的信号放大能力相结合。我们还证明了ABCD系统能够很好地检测目标蛋白，其检测范围相对较低（50～100 nm），为便携式检测设备的研制奠定了基础。这项工作突出了ABCD系统在检测低丰度目标蛋白方面的优势，并为未来的设计和开发提供了新的启示。

本研究所采用链霉亲和素磁珠 http://www.purimagbead.com/Product/8271042221.html