GOLD SELEX, a novel SELEX approach has been developed that obviates the need for target immobilization for aptamer development. The approach purely relies on the affinity of the aptamers towards its target, to get detached from the gold nanoparticle (GNP) surface (weak attraction) after binding with its target. Thus, only the completely detached aptamers are selected for the next round of SELEX. This, in-process, also addresses the issue of residual binding and thus improves the sensitivity of the developed aptamers. As a proof of concept for establishing the utility of the approach for small molecules, we have developed aptamers against dichlorvos (DV), a pesticide in just 8 rounds. Using these aptamer candidates, we have developed an aptamer-NanoZyme (GNP having peroxidase mimic activity) based colorimetric assay. The developed aptamer displayed high affinity (Kd in sub micromolar range) and selectivity for DV. The developed assay could detect as low as 15 μM DV. The best-performing aptamer was also able to work in real samples like river water and commercial apple juice. The GOLD SELEX approach developed in this study, we believe, can act as a template for future SELEX strategy development and can replace the conventional SELEX strategy.

中文翻译：

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GOLD SELEX：一种新的 SELEX 方法，用于开发针对小分子的无残留活性的高亲和力适体

GOLD SELEX 是一种新颖的 SELEX 方法，它无需为适体开发进行目标固定。该方法完全依赖于适体对其目标的亲和力，在与其目标结合后从金纳米颗粒 (GNP) 表面分离（弱吸引力）。因此，只有完全分离的适体被选择用于下一轮 SELEX。这在过程中也解决了残留结合的问题，从而提高了开发的适体的灵敏度。作为建立小分子方法实用性的概念证明，我们开发了针对敌敌畏 (DV) 的适体，这是一种仅用 8 轮的杀虫剂。使用这些适体候选物，我们开发了基于比色测定的适体-NanoZyme（具有过氧化物酶模拟活性的 GNP）。开发的适体显示出高亲和力（亚微摩尔范围内的 Kd）和对 DV 的选择性。开发的测定可以检测低至 15 μM DV。性能最好的适体还能够在河水和商业苹果汁等真实样品中发挥作用。我们相信，本研究中开发的 GOLD SELEX 方法可以作为未来 SELEX 策略开发的模板，并可以取代传统的 SELEX 策略。