Abstract：
The existing aptamers for cadmium (Cd2+), the common toxic heavy metal contaminant in food, cannot meet the requirements for detecting Cd2+ in rapid detection methods. In previous work, we found that coupling aptamer-peptide conjugates (APCs) with peptides and aptamers can provide a less disruptive method with a significantly improved affinity. Moreover, we found that the spatial conformation of aptamers and peptides is crucial for obtaining proper affinity in APC. Therefore, we describe a simple design strategy to obtain a series of APCs with different affinities by designing peptide orientations (N-terminal, C-terminal). The best affinity was found for APC(C1-N) with a binding constant (Ka) of 2.23 × 106 M-1, indicating that the APC(C1-N) affinity was significantly increased by 829.17% over aptamer. Finally, a rolling-circle amplification (RCA)-coupled ratio fluorescence-based biosensor for Cd2+ detection was established with a detection limit of 0.0036 nM, which has great potential for practical aquatic product detection.
摘要：
现有的镉（Cd2+）适体，食品中常见的有毒重金属污染物，快速检测方法不能满足Cd2+的检测要求。在以前的工作中,我们发现,将适体-肽缀合物(APC)与肽和适体偶联可以提供一种破坏性较小的方法,并且亲和力显著提高.此外，我们发现适体和肽的空间构象对于在APC中获得适当的亲和力至关重要。因此,我们描述了一种简单的设计策略，通过设计肽取向（N端，C端子）。对于结合常数（Ka）为2.23×106M-1的APC（C1-N），发现了最佳的亲和力，表明APC（C1-N）亲和力比适体显着增加了829.17％。最后,建立了基于滚环扩增（RCA）耦合比荧光的Cd2+检测生物传感器，检出限为0.0036nM，这对于实际水产品检测具有很大的潜力。
