Filter Paper Based Fluorescent Sensors Rapid Detection Niclosamide In The Environment

Schistosomiasis remains one of the most prevalent parasitic infections and has significant economic and public health consequences.Oncomelania hupensis is the only intermediate host of schistosomiasis.One of the most effective strategies to reduce the prevalence and morbidity of schistosomiasis in endemic areas is the combined application of molluscicides against the vector snails of schistosomiasis.Niclosamide(NCL)is currently the only molluscicide recommended by WHO for snail control programmes.In China,schistosomiasis persists in the Yangtze River Basin and its south region,niclosamide has been widely used as a molluscicide,however,trace amounts of niclosamide is highly toxic to aquatic animals like fish and shellfish.Therefore,Developing highly rapid and sensitive monitoring devices for in-field and real-time detections of niclosamide is pressing needed.Paper-based analytical devices have many practical advantages,including simplicity,speed,high resolution,which shows increasing application on not only medical detection and health-related analyses,but also food and environmental monitoring.In this work,a novel paper-based fluorescent sensor for determination of niclosamide was developed,which mainly includes the following two aspects:Firstly,niclosamide fluorescence detection: in acidic condition,niclosamide reacts with zinc to produce animoniclosamide for fluorescence determination under alkaline conditions.The experimental conditions of excitation wavelength,emission wavelength,reduction time,reducing agent,solution acidity,type and concentration of surfactants were optimized.The results showed that the optimum fluorescence excitation wavelength was 365 nm and the emission wavelength was 430 nm.In 20 m L,2.0 ?g/m L of the niclosamide solution,10.0 mg zinc powder was added,after slowly adding 1.0m L 3.0 mol/L of hydrochloric acid,reaction was complete at 8 min.When the p H value was 11 and the concentration of hexadecyl trimethylammonium chloride(CTAC)was 10.0 mg/m L,the fluorescence intensity was optimal.Under the optimized experimental conditions,niclosamide show good linear relationship in the range from 0.5 to 2.5 ?g/m L,with the correlation coefficient of 0.9998 and the limit of detection(LOD)of 0.0668 ?g/m L.The average recovery rate of niclosamide ranged from 97.56% to 103.42% at different added level,and the relative standard deviation from 2.58 % to 4.03%.The proposed method provides reliable strategy for detection of niclosamide with excellent sensitivity,and hence suitable for water samples detection.Secondly,the construction of paper-paper based fluorescent sensor and the detection of environmental samples: zinc nanoparticles(zinc NPs)ink was prepared with polyvinyl alcohol(PVA),graphene dispersions and other solvents.A thin film of zinc NPs ink was printed on the filter paper as the reducing agent,which converts niclosamide into aminoniclosamide for fluorescence determination.The formula of zinc NPs ink,the size of the filter paper reaction area,the number of printing layers,reduction reaction acidity,the reaction time and solution acidity were optimized.The results showed that: 1.0 ×1.2 cm2 of the filter paper reaction area,8 printing layers of zinc NPs ink,p H 4 of reduction reaction acidity,6 min of reduction time,and 0.1 mol/L of alkali concentration were the optimal conditions.The feasibility of the printed fluorescence sensor for detecting niclosamide was investigated.Under the optimized conditions,the linear range was obtained from 0.1 to 25.0 ?g/m L,with the correlation coefficient of 0.9974 and the limit of detection(LOD)of 0.80 ×10-2 ?g/m L.The average recovery rate of niclosamide ranged from 92.89% to 106.57% at different added level,and the relative standard deviation from 6.98% % to 7.29% in real water.The residual of niclosamide in leaves surface of common aquatic plants and fish scales were determined by the method of recovery of standard addition,the results show that fish scales have a certain enrichment effect on the niclosamide detection and the enrichment factors between 2.27 and 3.36.The method described here has been compared with high performance liquid chromatography(HPLC)and showed excellent agreement in the detection of niclosamide,with relative standard deviation from 3.45% to 6.15%.This newly developed method provides advantages of rapidity,simplicity,cost effectiveness and accuracy,which opens a very potential way for sensitive and selective detection at complicated matrix...