A quick and easy colorimetric sensor based on gold nanoparticles (GNPs) and aptamers for the detection of cocaine was developed. The sensor was named as ‘GAPTA’ and showed extremely interesting results regarding cocaine detection with a sensitivity to doses of 0.2 nM. The experimental approach consisted of creating a conjugate between GNPs (10 nm size) and aptamers as a sensing base with the addition of an electrolyte (NaCl) that plays the role of aggregation inducer. In the absence of the aptamer, the electrolyte was able to induce aggregation of the GNPs turning the color of the solution from red to blue while the presence of the aptamer is able to hinder the charges attraction and protects the GNPs from aggregating. The optimization of the aptamer and electrolyte concentration was determined to be 118 nM and 55 mM, respectively, and the resultant GAPTA sensor had a detection limit of 0.97 nM. Furthermore, the selectivity of the platform was tested in the presence of different interferents and showed a specific response towards cocaine while interference ranged between 20 and 40%. The applicability of the GAPTA biosensor was tested on synthetic saliva and demonstrated a sensitivity range between 0.2 and 25 nM. These results suggest the potential of the current colorimetric sensor in abuse drugs screening and creates a stable base for new routine platforms for biomedical and toxicology applications.

Graphical abstract

中文翻译：

---

基于电解质诱导的胶体排斥/吸引作用的可卡因检测用超灵敏共价连接Aptasensor。

开发了一种基于金纳米颗粒（GNP）和适体的快速简便的比色传感器，用于检测可卡因。该传感器被命名为“ GAPTA”，在可卡因检测方面显示出非常有趣的结果，对剂量的敏感度为0.2 nM。实验方法包括在GNP（10 nm大小）和适体之间建立共轭物作为传感基础，并添加起聚集诱导剂作用的电解质（NaCl）。在不存在适体的情况下，电解质能够诱导GNP聚集，从而使溶液的颜色从红色变为蓝色，而适体的存在能够阻碍电荷吸引并保护GNP不会聚集。适体和电解质浓度的优化分别确定为118 nM和55 mM，所得的GAPTA传感器的检出限为0.97 nM。此外，在存在不同干扰物的情况下测试了平台的选择性，并显示了对可卡因的特定反应，而干扰范围为20％至40％。GAPTA生物传感器在合成唾液上的适用性进行了测试，其灵敏度范围为0.2到25 nM。这些结果表明当前比色传感器在滥用药物筛选中的潜力，并为生物医学和毒理学应用的新常规平台奠定了稳定的基础。GAPTA生物传感器在合成唾液上的适用性进行了测试，其灵敏度范围为0.2到25 nM。这些结果表明当前比色传感器在滥用药物筛选中的潜力，并为生物医学和毒理学应用的新常规平台奠定了稳定的基础。GAPTA生物传感器在合成唾液上的适用性进行了测试，其灵敏度范围为0.2到25 nM。这些结果表明当前比色传感器在滥用药物筛选中的潜力，并为生物医学和毒理学应用的新常规平台奠定了稳定的基础。

图形概要