The aptamer recognition mechanisms have been well developed based on equilibration between aptamer conformations modulated by ligand, and can be compatible with almost all kinds of readout techniques for aptamer-based biosensors (i.e., aptasensors). A novel and robust aptasensing strategy named “kinetic competition” has also been investigated in which the blocker kinetically competes the aptamer and probe DNA (e.g., molecular beacon). It improved general methodology for developing aptasensors because it does not require a lengthy pre-equilibration, but the pre-binding of target and its aptamer alters kinetic competition for transducing signal. However, some disadvantages still limited its practical applications, such as high background signal, low sensitivity and accuracy in complex matrices and so on. Herein, we firstly reported the ratiometric “kinetic competition” aptasensor for ricin A chain (RTA) detection. It can well avoid false positive results and minimize background signals, which achieves more sensitive, accurate, reliable and effective detection. Under optimal conditions, this strategy effectively improved the sensitivity and reduced the background signal. A limit of detection (LOD) of 0.23 nM for RTA could be achieved without any separation and amplification techniques. The recovery data (73.8%-111.0%) was also satisfactory for RTA analysis in food powder samples and serum matrix.

基于由配体调节的适体构象之间的平衡，适体识别机制已经得到很好的发展，并且可以与基于适体的生物传感器（即适体传感器）的几乎所有种类的读出技术兼容。还研究了一种称为“动力学竞争”的新颖而强大的适体策略，其中阻滞剂在动力学上竞争适体和探针DNA（例如分子信标）。它改进了开发适体传感器的通用方法，因为它不需要冗长的预平衡，但是靶标及其适体的预结合改变了信号传导的动力学竞争。但是，一些缺点仍然限制了它的实际应用，例如高背景信号，低灵敏度和复杂矩阵的准确性等。在这里 我们首先报道了用于蓖麻毒素A链（RTA）检测的比例式“动力学竞争”适体传感器。它可以很好地避免出现假阳性结果，并最大限度地减少背景信号，从而实现更灵敏，准确，可靠和有效的检测。在最佳条件下，该策略可有效提高灵敏度并减少背景信号。无需任何分离和扩增技术，即可实现RTA的检测限（LOD）为0.23 nM。对于食品粉末样品和血清基质中的RTA分析，回收率数据（73.8％-111.0％）也令人满意。该策略有效地提高了灵敏度并减少了背景信号。无需任何分离和扩增技术，即可实现RTA的检测限（LOD）为0.23 nM。对于食品粉末样品和血清基质中的RTA分析，回收率数据（73.8％-111.0％）也令人满意。该策略有效地提高了灵敏度并减少了背景信号。无需任何分离和扩增技术，即可实现RTA的检测限（LOD）为0.23 nM。对于食品粉末样品和血清基质中的RTA分析，回收率数据（73.8％-111.0％）也令人满意。