Highly Sensitive Detection for Cocaine Using Graphene Oxide-Aptamer Based Sensors in Combination with Tween 20

Graphene oxide (GO), one of nanomaterials, has been used in the biomedical detection based on quenching the fluorescence of aptamers. However, there are still some problems. The physical adsorption methods prevent the sensitivity of detection from being further improved, and the false signals affect the results. Poly-cytosine (poly-C) DNA can strongly be adsorbed on many common nanomaterials. Herein, we used the aptamer with poly-C that can be adsorbed on the surface of GO to detect the cocaine. Cocaine can be adsorbed on the surface of bare GO to limit the further improvement on the sensitivity. Tween 20 is a nonionic surfactant that may strongly interact with GO through its hydrocarbon lipophilic group. Tween 20-protected GO was used to prevent the cocaine from nonspecific binding. The detection limit was improved to 2.45 pM. The results show that our method is a promising technique for the analytical application.