Sensitive Electrochemical Detection of Tryptophan Using a Hemin/G-Quadruplex Aptasensor

• Main Authors: Ayemeh Bagheri Hashkavayi, Jahan Bakhsh Raoof, Ki Soo Park
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: Chemosensors
• Subjects: magnetic nanocomposite; aptamer; tryptophan; G-quadruplex; electrochemical sensor; dendritic gold nanostructures
• Online Access: https://www.mdpi.com/2227-9040/8/4/100

In this study, we design an electrochemical aptasensor with an enzyme-free amplification method to detect tryptophan (Trp). For the amplified electrochemical signal, the screen-printed electrode was modified with dendritic gold nanostructures (DGNs)/magnetic double-charged diazoniabicyclo [2.2.2] octane dichloride silica hybrid (Fe₃O₄@SiO₂/DABCO) to increase the surface area as well as electrical conductivity, and the hemin/G-quadruplex aptamer was immobilized. The presence of Trp improved the catalytic characteristic of hemin/G-quadruplex structure, which resulted in the efficient catalysis of the H₂O₂ reduction. As the concentration of Trp increased, the intensity of H₂O₂reduction signal increased, and Trp was measured in the range of 0.007–200 nM with a detection limit of 0.002 nM. Compared with previous models, our sensor displayed higher detection sensitivity and specificity for Trp. Furthermore, we demonstrated that the proposed aptasensor successfully determined Trp in human serum samples, thereby proving its practical applicability.