| Cuprein widely exists in living organisms. It has a variety of physiologicalfunctions, such as oxygen carrier, electron transfer and oxidant, etc. Hemocyanin (Hc)and diamine oxidase (DAO) are all copper containing proteins. Hc is one of the threerespiratory proteins in animal kingdom. It is a multi-functional protein acting asoxygen carrier, adjustment of the osmotic pressure in animal body, storage of theenergy. It probably possesses the catalytic activities of phenol oxidase according tothe recent reports. DAO is a important catalytic protease in the family of cuprein,which plays a vital important role in metabolism process of amine substances, such ashistamine, putrescine and cadaverine, etc. However, there is few reports onelectrochemical study of Hc and DAO prior to this work. The study of cuprein will beof great help in the understanding of the evolution and origin of species.In the meantime, the studies on the direct electrochemical behaviors and catalyticmechanisms of Hc and DAO biosensors will aid us in better understanding thephysiological function of Hc and DAO in organisms, and be of great help in the fieldof medical research, environmental monitoring and biosensing. In this thesis, severalelectrodes have been fabricated with the aim of studying the direct electrochemistryand electrocatalyticbehaviors of Hc and DAO. The main contents of the thesis are asfollows:1) A easy prepared novel gold nanoparticles (Au@QC NPs) was applied toimmobilize Hc with the aid of carbon black. The direct electron transfer of Hc inAu@QC NPs/CB film were achieved and a pair of well-defined and quasi-reversiblecyclic voltammetric peaks for the protein hemo Cu(II)/Cu(I) redox couples wereobserved at about0.180V (vs. SCE). The Hc/Au@QC NPs/CB film exhibited aexcellent electrocatalytic activity toward the redox of hydroquinone (HQ) andcatechol(CC) and then a electrochemical method for the simultaneous detect of HQand CC is developed. The peak currents of HQ and CC increased linearly with theconcentration of HQ and CC in the range of0.045μM–24μM and0.37μM–50μM,respectively.. The detection limit (3σ) for the determination of HQ and CC wereobtained as0.008μM and0.087μM for HQ and CC, respectively. Our results showedthat Hc/Au@QC NPs/CB hybrid film may be ideal support material for many proteinor enzyme systems, being both biosourced and biologically compatible. 2) An enzyme sensor employing diamine oxidase (DAO) from porcine kidney hasbeen developed and optimised to estimate the content of amine substances. Theenzyme DAO was immobilized on a Au@QC NPs/CB film in combination withhydrophilic ionic liquids (IL). The direct electrochemistry of DAO was studied and apair of well-defined and quasi-reversible redox peaks was observed and the formalpotential of DAO was about0.204V. The DAO/Au@QC NPs/CB/IL film exhibited aexcellent electrocatalytic activity toward the oxidation of amine substances, such ashistamine, putrescine and cadaverine. The amperometric current increased linearlywith the concentration of mixture of diamines in the range of2.5μM–56μM, with adetect limit of0.87μM (3σ).3) The/Hc modified electrode was successfully assembled by immobilization ofthe Hc on the carbon paste electrode fabricated using CB/IL and a sensitive bisphenolA biosensor was constructed. The Hc immobilized on the CB/IL can realize its directelectrochemical behaviors and the Hc/CB/IL composite film showed a pair ofwell-defined, quasi-reversible redox peaks with a formal potential of0.201V,characteristic features of hemo Cu(II)/Cu(I) redox couple of Hc. The Hc/CB/IL filmexhibited an excellent electrocatalytic activity toward the oxidation of bisphenol A.The peak currents of bisphenol A increased linearly with the concentration ofbisphenol A in the range of0.085μM–38μM. The detection limit (3σ) for thedetermination of bisphenol A was obtained as0.037μM. |
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