One Step Fabrication Of Au Nanoparticles-Ni-Al Layerddouble Hydroxide Composite Film For The Determination Of L–cysteine

Gold nanoparticles has good biocompatibility and conductivity and can accelerate the electrons reaching the electrode. Layerd double hydroxides(LDHs) are important lamellar materials consisting of positively charged brucite-like layers and exchangeable interlayer anions. Due to its large surface area and active sites, LDHs have been widely used as the electrode modification species to electrochemically detect biomolecules. However, LDHs are weakly conductive solids, which results in the poor charge transport, restricting its electrochemical performance.Herein, we report an one-step electrodeposition method to fabricate Au nanoparticles(Au NPs)-Ni-Al LDHs composite film on the surface of glassy carbon electrode to sense L-cysteine. The main results of this dissertation are summarized as below:1. An Au NPs-Ni-Al LDHs composite film was obtained on the surface of GCE by cathodic reduction electrodeposition of a solution(pH 3.8) containing 22.5 mmol/L Ni(NO3)2, 7.5 mmol/L Al(NO3)3, 0.3 mol/L KNO3 and 0.1 mmol/L HAuCl4 at an applying potential of ?0.9 V for 30 s. The performance、morphology and structure of Au NPs-Ni-Al LDHs composite film were characterized using electrochemical impedance spectroscopy(EIS) 、scanning electron microscopy(SEM),X-ray diffraction(XRD),transmission electron microscopy(TEM) and X-ray photoelectron spectrometer(XPS) techniques.It is shown that Au NPs-Ni-Al LDHs composite film was successfully prepared on the surface of GCE and improved conductivity was obtained by the Au NPs codeposited on LDHs film.2. The synergic effect of LDHs and Au NPs dramatically improves the performance of the response of modified electrode for L-cysteine electro-oxidation, which exhibits low oxidation peak potential(0.16 V) and significantly enhanced peak current in Tris-HCl buffer solution(pH 7.0). A wide detection range from 10.0 ?mol/L?to 10.0 mmol/L for L-cysteine was obtained. The sensitivity value is ??????/mmol. Furthermore, the existence of ascorbic acid with 900 ?mol/L or glutathione with 1.0 mmol/L and amino acids(L-tyrosine, alanine, tryptophan, citric acid, tartaric acid, benzoic acid and sodium oxalate) with 5.0 mmol/L has no efficient on the electrochemical response of L-cysteine.Thus the electrode was used to sense L-cysteine with the high sensitivity and good selectivity.