The Fabrication Of Flexible And Portable Electrochemical Sensors And Detection Of Sulfonamides

Sulfonamides（SAs）is a synthetic antibacterial agent with p-aminobenzene sulfonamide structure,which can prevent and treat diseases infected by most gram-positive bacteria and many gram-negative bacteria.Because of its wide antibacterial spectrum,favorable price and stable nature,SAs is widely used in breeding industry.SAs will accumulate in livestock and poultry body,residues in food,subsidiary agricultural products and the environment by overdosage and disuse,they will eventually enter the human body along the food chain and harm people’s health.Compared with traditional SAs detection methods,electrochemical sensing method has low-cost,high sensitivity,fast detection speed,and its instrument is easy to operate,integrate and portable.Based on Ionic liquid（IL）-carboxylated carbon nanotubes（c CNTs）composite modified commercial screen printed carbon electrode（SPCE）and homemade hexagonal boron nitriding modified flexible integrated three electrode（h-BN/LIPG₀）,two portable sensors were fabricated for the detection of sulfamethoxazole（SMZ）,and several kinds of sulfamethoxazole drugs were also determined.The main research contents are as follows:（1）The IL-c CNTs/SPCE electrode was selected with the maximum respose of SMZ and the experiment parameters were optimized.The electrode showed good stability,small impedance,large effective area.In the linear range of 1.04-233μM,the reciprocal of SMZ concentration and the reciprocal of peak current had a good linear relationship,the correlation coefficient（R²）was 0.9972,the limit of detection（LOD）was 0.009μM,and the limit of quantification（LOQ）was 0.030μM.Artificial neural network（ANN）and least square support vector machine（LS-SVM）models were constructed by machine learning to analyze SMZ residue.By comparing R²,root mean square error（RMSE）,mean absolute error（MAE）and relative percent deviation（RPD）.The intelligent analysis results of SMZ by LS-SVM was better than that by ANN.By this sensor and high performance liquid chromatography（HPLC）method,the recovery rates of SMZ in samples were 96.4-117.7%and 93.2-108.1%,respectively.The experimental results of the two methods were analyzed by t test,and there was no significant difference,the result indicated that the IL-c CNTs/SPCE portable smart sensor was feasible for SMZ analysis in animal-derived food.（2）The laser-induced porous graphene flexible electrode（LIPG）was prepared by laser direct writing technology,and then the h-BN/LIPG₀flexible integrated electrode was obtained by modifying the parts of working electrode and reference electrode with hexagonal boron nitride and silver/silver chloride inks,respectively,finally,a portable flexible intelligent sensing device consists of this obtained electrode,a portable workstation and one smart-phone.The electrode had uniform porous structure,good stability and large electrochemical effective area.SMZ has lower electrocatalytic oxidation potential and higher peak current response on the flexible portable sensor than on the traditional electrochemical workstation and SPCE combined portable workstation.In the linear range of 0.5-362.5μM,R² was 0.9963,LOD was 0.011μM,LOQ was 0.037μM.The recoveries of SMZ in lake water and milk samples were detected in the range of 97.5-101.3%and 99.2-108.2%by this sensor and HPLC,respectively.The experimental results of the two methods were analyzed by t test,and there was no significant difference.Compared with the commercial SPCE,the home-made flexible integrated three electrode in this chapter had low cost,simple preparation and environmentally friendly,and it has a broad application potential in the field of food and environmental safety detection.（3）IL-c CNTs/SPCE and h-BN/LIPG₀ flexible potable sensors were used for rapid detection of four SAs（SN,SIZ,SM2 and SPY）,respectively.The results showed that there was a good linear relationship between the concentration of four SAs and the current response in the same parameters and the concentration range of 1.04-233.33μM,and R²was greater than 0.9868.IL-c CNTs/SPCE sensor had a higher sensitivity to SAs,and h-BN/LIPG₀ sensor had a lower redox potential to SAs.The recoveries of four SAs in fish samples were detected on the two sensors,and the sample recoveries were in the range of96.4-112.3%and 96.2-114.2%,respectively,which all met the detection requirements of actual samples.And there was no significant difference between the two methods.In this study,the flexible portable device has replaced the traditional electrochemical workstation,the low-cost,simple and pollution-free flexible integrated three-electrode system has replaced the traditional non-integrated three-electrode system,and the self-made flexible integrated three-electrode system is more likely to replace the commercial SPCE electrode to achieve rapid on-site detection.