Abstract
A simple strategy for determination of tryptophan (TRP) based on Fe3O4@SiO2/GO nanocomposite modified graphite screen printed electrode (Fe3O4@SiO2/GO/SPE) is reported. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to characterize the performance of the sensor. The Fe3O4@SiO2/GO/SPE displayed excellent electrochemical catalytic activities. The oxidation overpotentials of tryptophan decreased significantly and its oxidation peak current increased dramatically at Fe3O4@SiO2/GO/SPE. Under the optimized experimental conditions tryptophan showed linear response over the range of 1.0-400.0 μM. The lower detection limit was found to be 0.2 μM for tryptophan. The practical application of the modified electrode was demonstrated by measuring the concentration of tryptophan in real samples.
Highlights
Tryptophan (Trp) is a vital amino acid for humans and herbivores as the precursor of hormones, neurotransmitters and other relevant biomolecules
The electrochemical behaviour of tryptophan was studied in 0.1 M phosphate buffer saline (PBS) at different pH values (2.0-9.0) at the surface of Fe3O4@SiO2/GO/SPE by voltammetry
Since differential pulse voltammetry (DPV) has the advantage of having an increase in sensitivity and better characteristics for analytical applications, DPV experiments were performed by using Fe3O4@SiO2/GO/SPE in 0.1 M PBS containing various concentrations of tryptophan (Fig. 6)
Summary
Tryptophan (Trp) is a vital amino acid for humans and herbivores as the precursor of hormones, neurotransmitters and other relevant biomolecules. Determination of tryptophan is very important in blood and urine sample in these disease This compound is sometimes added to dietary, food products, pharmaceutical formulas due doi:10.5599/jese.576. Graphene is a two dimensional (2-D) sheet of carbon atoms in a hexagonal configuration with atoms bonded by sp bonds These bonds and this electron configuration provide this arterial with extraordinary properties, such as large surface area, theoretically 2630 m2 /g for a single layer, and double that of single walled carbon nanotubes (SWCNTs). Magnetic iron oxide nanoparticles such as maghemite (γ-Fe2O3) or magnetite (Fe3O4), are used in decoration of graphene to obtain improved magnetic, optical, and electrochemical properties in graphene. The present work aims to employ the electrochemical method for determination of tryptophan at the newly synthesized Fe3O4@SiO2/GO nanocomposite modified screen printed electrode. The modified electrode was used successfully as an electrochemical sensor for determination of tryptophan in the real sample as a sensitive, selective, simple and rapid method. The tryptophan contents was analysed by the proposed method by using the standard addition method
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