Construction Of Copper Ion Biosensor Electrodes And Selection Of Copper Recognition Membrane

Objective: Copper ion exists in many oxidoreductase enzyme’s active site, and plays an important role in the function of the enzyme. However, excessive copper easily lead to alzheimer’s disease that cause harm to human body. The copper salt is used in great quantities in aquaculture, easily result in water pollution and the excess of copper content in fish meat. This study applied the combination product of multi- walled carbon nanotubes（MWN T） and cysteine（Cys） assembly on screen printing gold electrode surface, using different pulse anodic stripping voltammetry（DPSVO） method as characterization, and building a rapid detection sensor of copper ion concentration in fish sample. In addition, the protein sequence activity site has a number of copper ions binding site. We chose some common amino acid res idues from the base sequence that bind to copper ions. Therefore, five oligopeptide sequences in which of Lys-Cys-Met-Cys（KCMC）, Lys-Cys-Met-Cys（KCMMC）, Lys-Cys-His-Cys（KCHC）, Lys-Cys-His-His-Cys（KCHHC）, Lys-Gly-His-Gly-His（KGHGH） are designed and studied to assess the the feasibility of copper ion sensors by using electrochemical method.Methods : FT-IR infrared spectra was performed to characterize the carboxyl degree of MWNT; Nano particle and Zeta potential analyzer machine was applied to measure the particle size of carbon nanotubes; Anodic stripping vo ltammetry（DPSVO） was used to test the concentration of C u; Inductively coupled plasma mass spectrometry（ICP-MS） was used to detect the standard concentration of copper ion solution; C yclic voltammetry（C V）, differentia l pulse voltammetry（DPV） and ac impedance（EIS） were used to characterize the oligopeptides conformational change when assembly on electrode surface.Results: Cu²⁺ concentration has a good linear relationship in 10nmol/l¹μmol/l, 1μmol/l⁹μmol/l, 9μmol/l⁰.9mmol/l, respectively. Wet digestion method was used to digest fish meat. The standard add ition recovery rate was 101.00%, which measured by ICP-MS, and relative standard deviation（RSD%） was 3.5%. Three standard addition tests of fish sample were detected by sensor, and relative standard deviation（RSD%）<5%. The semi-quantitative detection of Sb and Pb was test within the minimum detection limit of Sb and Pb, that are nmol/l levels, respectively. Oligopeptide without-SH assembly was stable and oligopeptide sensor that bind to copper needs simple environment. Multiple ion largely effects on the binding of oligopeptides and copper; KGHGH is p H-dependent when it was bound to metal ions.Conclusion: The screen printing electrode sensor can accurate ly quantify C u2+ concentration, and with the features of easy production, rapid detection, disposable use, etc. O ligopeptides need simple environment when bind to the metal ions, and characterized with the p H-dependent.