title: Sensitive and selective electrochemical sensing of L-cysteine based on a caterpillar-like manganese dioxide-carbon nanocomposite.
abstract: A novel one-dimensional (1-D) caterpillar-like manganese dioxide-carbon (MnO(2)-C) nanocomposite has been synthesized by a direct redox reaction between carbon nanotubes (CNTs) and permanganate ions for the first time. The as-prepared nanostructured MnO(2)-C composite mainly consisting of ε-MnO(2) nanoflakes had a unique microstructure, high specific surface area (200 m(2) g(-1)) and favourable conductivity. The nanostructured MnO(2)-C composite, added as a modification to the glassy carbon (GC) electrode via a direct electrochemical co-deposition process with a chitosan hydrogel, was found to exhibit excellent catalytic activity toward L-cysteine electro-oxidation because the specific interaction between the -SH group of L-cysteine and solid MnO(2) occurred to form surface complexes. A determination of L-cysteine at the MnO(2)-C/chitosan/GC (MnO(2)-C/chit/GC) electrode was carried out by amperometric measurement. Under the optimum experimental conditions, the detection response for L-cysteine was fast (within 7 s). The logarithm of catalytic currents shows a good linear relationship with that of the L-cysteine concentration in the range of 0.5-680 μM (R = 0.9986), with a low detection limit of 22 nM. The MnO(2)-C/Chit/GC electrode exhibited excellent stability (without any decrease of the response signal after 1 month) and admirable resistance against interference like glutathione and other oxidizable amino acids (tryptophan, tyrosine, L-lysine and methionine).
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, PR China.
authors.forename: Chunhui
authors.initials: C
authors.lastname: Xiao
authors.forename: Jinhua
authors.initials: J
authors.lastname: Chen
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Xiaochen
authors.initials: X
authors.lastname: Chu
authors.forename: Liang
authors.initials: L
authors.lastname: Wu
authors.forename: Shouzhuo
authors.initials: S
authors.lastname: Yao
mesh_terms: D002623:Chemistry Techniques, Analytical / Q000295:instrumentation*; D048271:Chitosan / Q000737:chemistry; D003545:Cysteine / Q000032:analysis* / Q000737:chemistry; D004563:Electrochemistry; D004566:Electrodes; D007259:Infrared Rays; D017895:Manganese Compounds / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D017895:Manganese Compounds; D037742:Nanotubes, Carbon; D010087:Oxides; D048271:Chitosan; D003545:Cysteine; C016552:manganese dioxide