| AFB1 is one of the most common fungal toxins in agricultural and sideline products.It has been identified to have mutagenic,teratogenic,immunosuppressive,and other harmful properties.Traditional methods for detecting AFB1 include thin-layer chromatography(TLC),high-performance liquid chromatography(HPLC),and enzyme-linked immunosorbent assay(ELISA).But some of these detection methods require professional operators and large and expensive equipment,while others require complex processing of test samples,which cannot meet the needs of on-site rapid detection.Electrochemical sensors are low-cost,small in size,sensitive and portable,making them suitable for the development of portable devices.Therefore,based on electrochemical sensing technology,this study first prepare an electrochemical sensor that can be used to detect AFB1.The hardware circuit was built using STM32F103ZET6 as the core,and the host computer software was developed on the Lab VIEW platform,then a portable system that can be used for AFB1 detection of actual samples was obtained.The main contents of this study are as follows:(1)Preparation of AFB1 electrochemical sensor: In order to detect AFB1 in actual samples,a electrochemical sensor was prepared with AFB1 aptamer as the recognition element.Screen-printed electrode(SPE)was used as the substrate electrode,and the performance of the sensor was enhanced by layer-by-layer modification of mixed materials of graphene oxide and carbon nanotubes(COOH-GO-COOH-MWNT),polydopamine(p DA),and gold nanoparticles(Au NPs).The prepared sensor can detect AFB1 in the range of 0.1fg/ml to 100pg/ml.The recovery rate of milk sample is between 96.8% and 106%,indicating that the sensor has practical application potential.(2)Design of hardware and software for portable detection system: Firstly,using STM32F103ZET6 as the core,the DPV waveform generation circuit,constant potential circuit,microcurrent detection module were built,and the PCB design and production were completed;then,the driver program of digital-to-analog(DA)conversion,analog-to-digital(AD)conversion,and serial port module as well as the software process of the lower computer was configured;finally,the Lab VIEW was used to develop the host computer software,which can denoise the data,graphically display the data,and calculate the AFB1 concentration.(3)Performance of the entire system: relevant experiments were designed to verify the accuracy of each module of the hardware circuit.The linear correlation coefficient between the theoretical output of DPV waveform generation voltage and the actual measurement value is0.99;the maximum deviation between the set value and the actual measurement value of the constant potential circuit is not more than 4m V;the maximum deviation between the theoretically calculated amplification voltage and the actual measurement value of the microcurrent detection module is not more than 54 m V,which proves that the hardware circuit can meet the requirements and has sufficient accuracy.Then,the entire system was combined together,and the detection performance of the entire system was verified using standard solutions of AFB1 and actual samples.In the standard solution,the maximum relative error between the portable system and the electrochemical workstation was 7.37%.When testing actual peanut oil and peanut samples,the relative error between the portable system and the workstation did not exceed 7.10%.This proves that the entire detection system has great potential for application in actual sample detection. |
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