Highly selective and sensitive electrochemical sensor for L-cysteine detection based on graphene oxide/multiwalled carbon nanotube/manganese dioxide/gold nanoparticles composite

A highly selective and sensitive electrochemical sensor for detection of L-cysteine based on a graphene oxide/carboxylated multiwalled carbon nanotube/manganese dioxide/gold nanoparticles composite (GO/CCNTs/AuNPs@ MnO2) was developed. The property of the glassy carbon electrode which was modified by GO/CCNTs/AuNPs@ MnO2 contributed to increasing the sensing surface area and the electronic transmission rate. Besides, the addition of MnO2 could effectively improve the selectivity and specificity of L-cysteine determination. The morphology and composition of GO/CCNT5/AuNP5@MnO2 were characterized by scanning electron microscope, energy dispersive spectrometer, fourier transform infrared spectroscopy and X-ray diffractometer and the results evidenced that GO/CCNT5/AuNPs@MnO2 flower-like structure was efficiently synthesized. The determination results of L-cysteine indicated that the surface area, electronic transmission rate and sensitivity of GO/CCNTs/ AuNP5@MnO2 sensor were highly increased. Under the optimal conditions, the electrochemical sensor exhibited excellent analytical performance with good selectivity, reproducibility and stability. The linear range of L-cysteine was from 1.0 x 10(-8) to 7.0 x 10(-6) mol L-1 and the detection limit was 3.4 x 10(-9) MOl L-1 (38). The proposed electrochemical sensor was successfully applied to the determination of trace kcysteine in spiked water samples. (C) 2015 Elsevier B.V. All rights reserved.