| Poly1,5-diaminonaphthalene （P1,5-DAN）, containing amine groups and secondaryamino groups in addition to an extended π-orbital system like polyaniline, is a typicalaromatic diamine conducting polymer. Thus, it can be functionalized by reversibly doped andundoped process, chelating with metal ions and combining with some molecules havingspecifc functional groups. The electrical conductivity changes over several orders ofmagnitude accompanied by functionalization process. It has received increasing attention infabricating of the third generation biosensor due to its easy preparation, stability in air andgood adhesion. Owing to poor conductivity at pH over5, its application in biosensor wasrestricted. Carbon nanotubes （CNTs）, owing high conductivity, good catalytic activity andhigh length-diameter ratio, can be used to dope polymer effectively and shift itselectroactivity to the neutral pH environment. Moreover, composite materials based on thecoupling of conducting polymers and CNTs have recently shown to possess properties of theindividual components and synergistic effect.In this article, a novel P1,5-DAN, CNTs and/or nano-Ag composites film modifedelectrode has been fabricated based the fact that composites possess the properties ofindividual components with a synergistic effect and overcome their own defects. The concretecontent is as follows:1. The MWCNTs/P1,5-DAN composite film modified electrode was constructed bydropping MWCNTs despersion in N,N-dimethyl formamide （DMF） onto the P1,5-DAN filmelectropolymerized with cyclic voltametry. The CNTs was immobilized on P1,5-DAN withπ-π nonconvalent binding and formed a three-dimensional reticular structure of interlockingpores which is characterized by high resolving power scanning electron microscope （SEM）.The composite film modified electrode exhibits excellent selectivity toward the oxidation ofuric acid （UA） solution containing high concentration ascorbic acid （AA）. The separation ofthe oxidation peak potentials for UA and AA is about404mV with Differential PulseVoltammetry （DPV）. Such large difference is enough to determine the UA and AAindividually and simultaneously. The peak current is linear on the concentration of UA at therange of1.0×10-52.0×10-3M with a detection limit of3.3×10-6M.2. The biosensor for the detection of H2O2are fabricated by immobilizing HRP on theMWCNTs/P1,5-DAN composite film which was obtained with the same method in Chapter2.Owning to the presence of amine and secondary amino group of P1,5-DAN and highbiological bonding energy of CNTs, the HRP was immobilized directly on composite film without the aid of cross-linking agent. The loose and porous structure composite film wascharacterized by SEM. The effects of pH, work potential and scan rate on the electrochemicalproperties were investigated. The results demonstrate that the HRP/MWCNTs/P1,5-DANmodified electrode has good electrocatalytic activity and short response time （<5s） for H2O2.The linear range is1.5×10-5M5.4×10-3M with the correlation coefficient of0.9970, and thedetection limit was5.6×10-6M.3. A novel biosensor based on HRP/MWCNTs/P1,5-DAN/nano-sliver modified electrodehas been developed. The electronic transfer promotion function of CNTs and electrocatalyticactivity of nano-Ag enhanced vastly the sensor performance. The result of electrochemicalimpedance spectroscopy （EIS） exihibited that the combination of nano-Ag, MWCNTs andP1,5-DAN greatly improved the conductivity, leading to the resultant film with lowelectron-transfer resistance （Ret） of17Ω. Compared the response performance for H2O2ofenzyme electrode containing nano-Ag with enzyme electrode without nano-Ag, theHRP/MWCNTs/P1,5-DAN/nano-Ag modified electrode show higher sensitivity, less responsetime （<3s）, expanded linear range with5×10-6M6.2×10-3M and lower detection limit with5.4×10-7M. |
PDF Full Text Request