Construction Of Nano-ZnO Electrochemical Biosensors

Electrochemical biosensors have the advantages of rapid detection,high sensitivity,stable performance etc.,and they have a huge application potential in the area of food safety.P-selectin and nano-Zn O films modified electrochemical biosensors have been built for milk quality detection.The main research contents are as follows: 1)Photolithography has been used to build gold interdigitated electrode in different widths and gaps which are 30?m?50?m?70?m.And then nano-Zn O thin film has been deposited on the electrode surface by electrochemical method.Finally,P-selectin has been modified on the nano-Zn O thin film surface by biological binding.2)The modified results of sensors have been characterized by cyclic voltammetry,scanning electron microscopy and electron microscopy.3)Pure milk has been used as the test sample to measure the AC voltage amplitude in the range of 10 m V~500m V,and the test performance is stabale in the range of 100 m V~500m V,so 300 m V is selected as the test signal amplitude.The pre-experiment of sensors has been carried out with the test sample of the phosphate buffered saline solution and the pure milk.The frequency has been set between 10Hz~1MHz.4)Electrochemical impedance testing technology has been used to measure the impedance of milk samples which are in the range of 0 to 1.6 million cells per milliliter with nine kinds of sensors.The equivalent circuit model has been established to fit and analyse the impedance spectra of the milk samples.Compared with the bare sensor,the sensitivity and the detection accuracy of the nano-Zn O and P-selectin sensor are improved significantly,and the sensor of 70?m makes the best distinction between seven milk samples.At the frequency of 10 k Hz,The impedance value of double layer between cell and electrode of the nano-Zn O sensor and the P-selectin sensor has a good linear relationship with the concentration between 100,000 and 700,000 cells / ml.The detection threshold is 5%,and the coefficient of determination R2 is 0.996 and 0.981 respectively.The impedance behavior of double layer between cell and electrode can predict the level of N,T,and 1 of mastitis.