Highly sensitive aptasensor based on synergetic catalysis activity of MoS2-Au-HE composite using cDNA-Au-GOD for signal amplification

Abstract

Single or few-layer nanosheets of MoS₂ (MoS₂ nanosheets) and a composite composed of MoS₂ nanosheets, Au nanoparticles (AuNPs) and hemin (HE) (denoted as MoS₂-Au-HE) were prepared. The composites possessed high synergetic catalysis activity towards the electroreduction of hydrogen peroxide. Furthermore, glucose oxidase (GOD) and AuNPs were used as marker of the complementary DNA (cDNA) strand of kanamycin aptamer to prepare a conjugate (reffered as cDNA-Au-GOD) that was designed as the signal probe. Both cDNA-Au-GOD and MoS₂-Au-HE were applied to fabricate aptasensor for kanamycin. MoS₂-Au-HE acted as solid platform for kanamycin aptamer and signal transmitters. AuNPs were employed as the supporter of cDNA and GOD which catalyze dissolved oxygen to produce hydrogen peroxide in the presence of glucose. Then cathodic peak current of H₂O₂ was recorded by differential pulse voltammetry (DPV). The electrochemical reduction of H₂O₂ was catalyzed by MoS₂-Au-HE that was modified onto the surface of a glassy carbon electrode (GCE). The cathodic peak current of H₂O₂ was highly linearly decreased with an increase of kanamycin concentrations from 1.0ng/L to 1.0×10⁵ng/L, with a detection limit of 0.8ng/L. This aptasensor can be used to detect kanamycin in milk with high specificity, sensitivity and selectivity.

Keywords: Aptasensor; Glucose oxidase; Hemin; Kanamycin; Molybdenum disulfide.