Preparation Of Enzyme Biosensor Based On One-dimensional Gold Nanomaterials

One-dimensional gold nanomaterials with their special physical structureand electrochemical properties set the stage for their combination with biologicalmacromolecules, because they have good combination ability with biologicalmacromolecules group, such as amino, mercapto etc. The biosensors obtained bytaking the advantage of one-dimensional gold nanomaterials and the enzymewhich have specific catalytic property and large surface area, have theadvantages of high sensitivity, specificity, lower detection limit, good stability,and analysis of high precision, low cost, high speed etc compared to thetraditional trace detection equipment. It makes the biosensors have been widelyused in biomedical, environmental monitoring and food engineering. Currently,exploring the fixed advanced materials and immobilization technology is theimportant work of research and development of biosensors. Therefore, this paperfocuses on exploring the preparation of one-dimensional gold nanomaterials forenzyme immobilization, and fabrication of glucose biosensors and phosphatebiosensor by electrochemical method.（1） In this paper one-dimensional gold nanomaterials were prepared byelectrochemical deposition method combined with alumina template. Porousaluminum oxide （AAO） template was prepared by twice anodization method.After0.5M H₃PO₄reaming10min, AAO template with the thickness of about25μm and the average pore diameter of about86.49nm was obtained. Andtemplate morphology has highly ordered and uniform characteristics. It is foundoxidation voltage has great influence on the morphology of the AAO template.Too low or too high voltage will reduce the ordered and homogeneity morphologyof the template.（2） The diameters of gold nanowires and alloy gold nanowires were limitedby the AAO template aperture diameter. The length of gold nanowires and alloygold nanowires was influenced by electrodeposition time. After the orthogonalexperiment we found that when the proportion of Au³⁺:Cu²⁺is1:5, the voltage ofchronoamperometry changed from-0.6to-0.7V, the alloy gold nanowires withthe content of Cu atoms of60⁷0%were obtained. The Cu was removed byetched in0.5M HNO3for25minutes to obtain porous gold nanowires. The high-resolution TEM showed that the internal of the porous gold nanowires werepolycrystalline structure.（3） This paper also studied the gold nanowires and porous gold nanowiresmodified by Glucose oxidase （GOx）, using physical adsorption method. The GOxenzyme adsorption time effected the detection of the biosensor, and usually thebest adsorption time is96h. The GOx biosensors prepared by physical adsorptionare less stable. The current response attenuated nearly80%after more than aweek’s detection. The porous gold nanowires were better than gold nanowiresdue to their greater specific surface area, so the effects of their physicaladsorption of GOx enzyme were better. The current response was three timeshigher than gold nanowires when detecting0.1mM Glucose solution. Finally,phosphate biosensor was prepared by crosslinking method. It was proved that themethods of PNP, XOD double enzyme system modified one-dimensional goldnanomaterials were feasible, though the results were not as good as expected. Ihope the following research work can further improve the detection limit.