Preparation And Research Of Colorimetric Sensor Strips For Copper (?) Assay Based On Electropsun Nanofibers

Copper,a necessary trace element of the human body,plays a vital role in human immune,nervous and digestive systems.At the same time,copper,as a common heavy metal in the environment,can be concentrated in the human body through the food chain,thus causing irreversible damage to the biological system.The WHO stipulates that the content of copper ions in drinking water should not exceed 2mg/L?31.4?M?,and the US-EPA stipulates 1mg/L?15.7?M?.Traditional detection of Cu²⁺have high sensitivity,low detection limit,high accuracy,such as AAS,ICP-MS,DPD and so on,but the instrument price is high,it needs a long time to get the result and also need specialized tester.Making it is not fit the demand of the rapidly on-site detection.Colorimetric sensors have become one of the most promising Cu²⁺detection method for its easy operation,low cost,selectivity and can be detected by naked eye.At present,researchers have studied the colorimetric Cu²⁺detection from the liquid phase and solid phase.However,liquid detection system usually has the problems of insufficient anti-interference ability,harsh storage conditions and poor portability.Although the solid detection system has solved the problems of portability and stability,the sensor still has low sensitivity and the limit of detection by naked eye cannot meet the needs of the practical application.Based on the deficiency of existing method,this study used the nanofibers members with large specific surface area as the detection carrier,and design a Cu²⁺detection system with high sensitivity and selectivity.Our study was carried out as follows:the PAN/PVP composite nanofiber membrane was prepared by electrospun,and then remove the PVP by water heat treatment to obtain the porous PAN nanofiber membrane.The effect of PVP/PAN ration and water treatment conditions on the structure of nanofiber membrane were studied.The SSA of PVP/PAN=1/1 nanofiber membrane with after treatment was the highest,which can reach up to 38.6 m²/g which was good for high sensitivity test of copper ions.The content of-NH₂ on nanofiber membrane was 2.69 mmol/g after aminated by ethanediamine.The 13.7nm gold nanoparticles were prepared by sodium citrate reduction method firstly,then the silver nitrate were reduced to silver by sodium citrate,which can cover to the surface of gold nanoparticles to form Ag@Au NPs,and the size of composites nanoparticles was 21.0 nm.The Ag@Au NPs probes were loaded on the nanofiber membrane by soaking.By the optimizing of the sensor preparation and detection parameters,soaking times?11 times?,concentration of NH₄Cl?50mM?,pH?optimal pH 11?,concentration of Na₂S₂O₃?9.0 mM?,reaction time?5 min?,to make sure that the Ag@Au NPs-APAN sensor achieve the optimal detection performance for Cu²⁺.In addition,the sensitivity,selectivity and repeatability of sensors were investigated under optimal detection conditions.And the results show that the detection limit of the naked eye was 50nM,and the detection performance remains unchanged after 6 times detection,which show a good repeatability.And it also shows a good selectivity for Cu²⁺by comparing with other 16 common mental ions.