| In this paper, the two novel function film were prepared by the layer-by-layerself-assembly method. They are the composite film [PEI/PB/PEI/PW9V3]6based onkeggin-type phosphovanadotungstate and PB nanoparticles, the inorganic/organiccomposite film [PEI/PMo9V3/PEI/CoTsPc]6based on keggin-typephosphovanadomolybdate and cobalt（II） tetrasulfonate phthalocyanine. Thecomposite films were characterized by UV-vis spectroscopy, X-ray photoelectronspectroscopy （XPS） and atomic force microscopy （AFM）. At the same time, theelectrochemical behavior of the composite films was investigated by cyclicvoltammetry, amperometry and electrochemical impedance spectra. Furthermore,this paper also conducted a systematic study of two composite film aselectrochemical sensor to detect small biomolecules ascorbic acid or L-cysteine.First of all, the growth process of the composite films was monitored by UV-visspectroscopy. It showed that the process were stable and irreversible. Compared tothe single component phosphovanadotungstate or PB nanoparticles film, thecomposite film [PEI/PB/PEI/PW9V3]6exhibited enhanced electrocatalyticperformance for the oxidation of ascorbic acid at physiological conditions. Itdemonstrated that the enhanced electrical conductivity, electron transfer capabilityand sensing properties of the composite film by synergistic contributions ofphosphovanadotungstate and PB nanoparticles. Experimental results showed that theproposed sensing composite film toward oxidation of ascorbic acid shows a widerange of linear response, rather high sensitivity, low detection limit and satisfactoryanti-interference ability. Furthermore, the real sample analysis indicates the recoveryand other information of the electrochemical sensors were in the applied range.Research on the composite film [PEI/PMo9V3/PEI/CoTsPc]6exhibited, the compositefilm [PEI/PMo9V3/PEI/CoTsPc]6showed enhanced electrocatalytic performance of L-cysteine at the synergistic contributions of phosphovanadomolybdate and cobalt（II）tetrasulfonate phthalocyanine, At physiological conditions, the proposedelectrochemical sensor for detecting L-cysteine shows a linear response range from2.5×10-7to1.7×10-4M, rather high sensitivity of0.02μM/μA, low detection limitof1.0×10-7M （S/N=3） and anti-interference property in the presence of commoninterfering species. The real sample analysis indicates the recovery and relativestandard deviation of the electrochemical sensors were allowed.In conclusion, the advantage of these electrochemical sensors were ease ofpreparation, low self-cost and could control of layer thickness, which can bepotentially used for practical applications in electrochemical sensors. |
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