Nucleic acid aptamers for biosensing are developed from a complex ssDNA library through Systematic Evolution of Ligands by Exponential Enrichment (SELEX) process. Monitoring of SELEX process is crucial for generating high-affinity aptamers. Extant methods for monitoring aptamer selection are either arduous or give false-positive signals, which adversely impact the outcome of selection. We describe a colorimetric, simple and cost-effective, novel method to monitor the progress of in vitro selections. The power of rolling circle amplification (RCA) and inherent Horse Radish Peroxidase (HRP)-mimicking activity of G-quadruplex/hemin DNAzyme were employed to produce a colorimetric signal. A unique extension of DNA population at 3ʹ-OH end by PCR generated concatenated repeats by rolling circle amplification (RCA) reaction. Oxidation of substrate ABTS (2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) in presence of H₂O₂ and hemin cofactor produced colorimetric signal. Analysis of the signal generated by the DNA pool bound to their target provided a quantitative measurement of SELEX. We demonstrate the reproducibility and accuracy of the method by evaluating the progress of two discrete selections.

用于生物传感的核酸适体是从复杂的ssDNA文库通过配体通过指数富集（SELEX）进行系统进化而开发的。监测SELEX过程对于产生高亲和力适体至关重要。现有的监测适体选择的方法要么费力，要么给出假阳性信号，这对选择的结果产生不利影响。我们描述了一种比色法，简单且经济高效的新颖方法来监测体外进展选择。G-四链体/ hemin DNAzyme的滚环扩增（RCA）和内在的辣根过氧化物酶（HRP）模拟活性被用来产生比色信号。通过PCR在3′-OH末端的DNA群体的独特延伸通过滚环扩增（RCA）反应产生串联的重复。在H ₂ O ₂和血红素辅助因子存在下，底物ABTS（2，2'-叠氮基双（3-乙基苯并噻唑啉-6-磺酸））的氧化产生比色信号。对结合至其靶标的DNA池产生的信号的分析提供了SELEX的定量测量。通过评估两个离散选择的进度，我们证明了该方法的可重复性和准确性。