Novel CNT Supported Molybdenum Catalyst for Detection of L-Cysteine in Its Natural Environment

Kadir Selçuk,Hilal Kivrak,Nahit Aktaş

doi:10.3390/catal11121561

Abstract

In this study, novel carbon nanotube-supported Mo (Mo/CNT) catalysts were prepared with the sodium borohydride reduction method for the detection of L-cysteine (L-Cys, L-C). Mo/CNT catalysts were characterized with scanning electron microscopy with elemental dispersion X-ray (EDX-SEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectrometry (UV-vis), temperature-programmed reduction (TPR), temperature programmed oxidation (TPO), and temperature-programmed desorption (TPD) techniques. The results of these advanced surface characterization techniques revealed that the catalysts were prepared successfully. Electrochemical measurements were employed to construct a voltammetric L-C sensor based on Mo/CNT catalyst by voltammetric techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Further measurements were carried out with electrochemical impedance spectroscopy (EIS). Mo/CNT/GCE exhibited excellent performance for L-C detection with a linear response in the range of 0–150 µM, with a current sensitivity of 200 mA/μM cm2 (0.0142 μA/μM), the lowest detection limit of 0.25 μM, and signal-to-noise ratio (S/N = 3). Interference studies showed that the Mo/CNT/GCE electrode was not affected by D-glucose, uric acid, L-tyrosine, and L-trytophane, commonly interfering organic structures. Natural sample analysis was also accomplished with acetyl L-C. Mo/CNT catalyst is a promising material as a sensor for L-C detection.

Highlights

L-cysteine (L-Cys, L-C), a semi-essential and proteinogenic amino acid, contains a sulfur-containing thiol group in its side chain
The surface and chemical properties of this catalyst were determined by SEM-EDX, X-ray diffraction (XRD), UV-Vis, H2-temperature-programmed reduction (TPR), O2-temperature programmed oxidation (TPO), and NH3-temperature-programmed desorption (TPD) methods
The surface chemical properties were characterized with H2-TPR, O2-TPO, and NH3-TPD methods

Summary

Introduction

L-cysteine (L-Cys, L-C), a semi-essential and proteinogenic amino acid, contains a sulfur-containing thiol group in its side chain. EIS measurements were performed to understand the charge transfer properties of this Mo/CNT-modified GCE electrode. EIS graphs were taken for Mo/CNT/GCE obtained at different electrode potentials in 0.1 M PBS + 5 mM Sensitivity measurements by DPV, limit of blank (LOB), the lowest detection limit (LOD) and limit of quantification (LOQ) were determined for the Mo/CNT/GCE L-C electrochemical sensor. Mo/CNT/GCE obtained at different electrode potentials in 0.1 M PBS + 5 mM It was clear that recovery values were acceptable and the relative standard deviation of the sample for 10 consecutive determinations was less than 3% This result showed that the Mo/CNT/GCE performed well for the real sample

Experimental

Findings

Conclusions