Primer exchange reaction (PER) is an emergent method for non-templated synthesis of single stranded DNA molecules. PER has been shown to be effective in cell imaging systems and for detection of macromolecules. A particular application of PER is to detect a specific target nucleic acid. To this endeavor, two coupled DNA hairpins, a detector and an amplifier, play in accordance to extend a target nucleic acid with a concatemer DNA sequence. Here we introduced unified-amplifier based primer exchange reaction (UniAmPER) that beneficially extends the target by a unified-amplifier. The unified-amplifier operates as both detector and amplifier hairpins. The extension resulted in synthesis of concatemer G-rich sequences. The G-rich sequences were expected to form G-quadruplex (GQ) structures. Presence of the GQ structures were investigated by peroxidase activity of GQs in presence ^{of hemin, H}2°2 ^{and 3,3′,5,5′-Tetramethylbenzidine (TMB) as well as by fluorescence signal} generation upon intercalation of thioflavin T (ThT). The presented unified-amplifier in this study facilitates application of PER systems for development of colorimetric or fluorogenic biosensors. As a proof of principle, the method has been applied for detection of reversely transcribed cDNAs from clinical SARS-CoV-2 samples.

引物交换反应（PER）是一种新兴的单链DNA分子非模板合成方法。 PER 已被证明在细胞成像系统和大分子检测中有效。 PER 的一个特殊应用是检测特定的靶核酸。为了实现这一目标，两个耦合的 DNA 发夹、一个检测器和一个放大器，按照串联体 DNA 序列延伸靶核酸的方式发挥作用。在这里，我们介绍了基于统一放大器的引物交换反应（UniAmPER），它可以通过统一放大器有益地扩展靶标。统一放大器既充当检测器又充当放大器发夹管。延伸导致富含 G 的多联体序列的合成。富含 G 的序列预计会形成 G 四链体 (GQ) 结构。通过在^{氯高铁血红素、H} 2°2^{和 3,3',5,5'-四甲基联苯胺 (TMB) 存在下 GQ 的过氧化物酶活性以及硫黄素 T (ThT) 嵌入时产生的荧光信号}来研究 GQ 结构的存在。 ）。本研究中提出的统一放大器促进了 PER 系统在比色或荧光生物传感器开发中的应用。作为原理证明，该方法已应用于检测临床 SARS-CoV-2 样本中的逆转录 cDNA。