Based on the layer-by-layer self-assembly of positively charged cetyltrimethylammonium bromide (CTAB) wrapped gold na- norods (AuNRs) and negatively charged superoxide dismutase (SOD) from their aqueous solutions on cysteine modified gold electrode (Cys/Au), a third generation electrochemical biosensor ((SOD/AuNRs)2/Cys/Au) for superoxide anion (O2·-) was developed. The two layers assembly of SOD/AuNRs can significantly enhance the direct electron transfer between SOD and the electrode. The functional enzymatic activities of the SOD offer an electrochemical approach to the determination of O2·-. In the reductive regions, the proposed sensor exhibits excellent analytical performances, such as wide linear range (200 nM to 0.2 mM O2·-), low detection limit (100 nM O2·-), high sensitivity (22.11 nA cm-2 μM-1), short response time (less than 5 s), good stability and reproducibility, while no obvious interferences are caused by commonly met interfering species including hydrogen peroxide (H2O2), uric acid (UA) and ascorbic acid (AA).
WANG MengDongHAN YiTaoLIU XingXingNIE ZhouDENG ChunYanGUO ManLiYAO ShouZhuo
Amino acid ionic liquids(AAILs) have attracted much attention due to their special chemical and physical properties,especially their outstanding biocompatibility and truly green aspect.In this work,a novel electrochemical biosensing platform based on AAILs/carbon nanotubes(CNTs) composite was fabricated.AAILs were used as a novel solvent for glucose oxidase(GOD) and the GOD-AAILs/CNTs/GC electrode was conveniently prepared by immersing the carbon nanotubes(CNTs) modified glassy carbon(GC) electrode into AAILs containing GOD.The direct electrochemistry of GOD on the GOD-AAILs/CNTs/GC electrode has been investigated and a pair of reversible peaks was obtained by cyclic voltammetry.The immobilized glucose oxidase could retain bioactivity and catalyze the reduction of dissolved oxygen.Due to the synergic effect of AAILs and CNTs,the GOD-AAILs/CNTs/GC electrode shows excellent electrocatalytic activity towards glucose with a linear range from 0.05 to 0.8 mM and a detection limit of 5.5 μM(S/N = 3).Furthermore,the biosensor exhibits good stability and ability to exclude the interference of commonly coexisting uric and ascorbic acid.Therefore,AAILs/CNTs composite can be a good candidate biocompatible material for the direct electrochemistry of the redox-active enzyme and the construction of third-generation enzyme sensors.
WANG MengDongDENG ChunYanNIE ZhouXU XiaHongYAO ShouZhuo
