Ultrasensitive and reusable electrochemical aptasensor for detection of tryptophan using of [Fe(bpy)3](p-CH3C6H4SO2)2 as an electroactive indicator

Publication date: Available online 3 October 2018Source: Journal of Pharmaceutical and Biomedical AnalysisAuthor(s): Ayemeh Bagheri Hashkavayi, Jahan Bakhsh RaoofAbstractIn this paper, we report the application of a reusable electrochemical aptasensor for detection of tryptophan by using [Fe(bpy)3](p-CH3C6H4SO2)2 as an electroactive indicator and based on the target-compelled aptamer displacement. The aptasensor fabricated by self-assembling the thiolated probe on the surface of graphite screen-printed electrode modified with gold nanoparticles/multiwalled carbon nanotubes and chitosan nanocomposite (AuNPs/MWCNTs-Chit/SPE). Afterward, Trp aptamer (Apt) immobilized on the modified electrode surface through hybridization. In the absence of Trp, a sharp peak of [Fe(bpy)3](p-CH3C6H4 SO2)2 can be observed in differential pulse voltammetry (DPV) study. The introduction of Trp led to the formation of aptamer-Trp complex and dissociation of the aptamer from the DNA-Apt duplex on the electrode surface into the solution and decreases the peak current intensity of electroactive indicator. This is because, [Fe(bpy)3](p-CH3C6H4SO2)2 tends to bind to the two strands DNA. Therefore, the peak current of [Fe(bpy)3](p-CH3C6H4 SO2)2 linearly decreased with increasing the concentration of Trp over a range of 3.0 nM- 100 µM. The detection limit (3 σ) was 1.0 nM. In addition, we examined the selectivity of the constructed biosensor for tyrosine, histidine, arginine, lysine, valine and methio...
Source: Journal of Pharmaceutical and Biomedical Analysis - Category: Drugs & Pharmacology Source Type: research