Study On The Application Of Paper-based Fluorescence Sensors With CdTe Quantum Dots For The Detection Of Environmental Hg²⁺ And Gonyautoxin

In recent years,environmental water pollution has gradually become serious.People have put forward higher requirements for environmental analysis and testing,and there is a greater need to develop analytical and testing tools that are low-cost,easy to operate,sensitive and efficient.Microfluidic paper-based chips can satisfy the current demand because of their low-cost,easy fabrication,capillary action and good biocompatibility.In this work,a fluorescent sensing microfluidic chip based on CdTe quantum dots with low-cost,rapid detection,convenient operation and high sensitivity was constructed and successfully used for the rapid detection of divalent Hg²⁺and Gonyautoxin 1,4 in the aqueous environment.The main contents of this paper are as follows:（1）A visual fluorescence sensing paper chip that can be used for ultra-sensitive detection of Hg²⁺in water.The fluorescence emitted by CdTe quantum dots at 525 nm could be quickly and effectively quenched by Hg²⁺.After grafting the quantum dots on silica nanospheres and adding them dropwise on the paper chip,the fluorescence color signal of the paper chip could be captured by a smartphone camera under UV light,and this mechanism formed a stable visualization of fluorescence sensing.The method could be completed in 90 s.The detection concentration range for Hg²⁺was 5-100μg/L,and the limited of detection was 2.825μg/L.We successfully achieved the trace spiking detection of seawater（from three regions）,lake water,river water and tap water with recoveries in the range of 96.8%-105.4%by this method..The method is effective,low-cost,user-friendly,and has good prospects for commercial application,in addition,the work is expected to be utilized for automated big data collection of a large number of environmental samples（2）The CdTe quantum dot fluorescent sensing paper chip based on molecularly imprinted capped MnO₂ nanospheres for detection of GTX1,4 in seawater.MnO₂nanospheres capped with molecularly imprinted polymers that can specifically recognize GTX1,4 were synthesized using guanosine as a virtual template.Fluorescence sensing was formed by the mechanism that MnO₂ nanospheres catalyze the decomposition of H₂O₂,which makes the quenching effect of H₂O₂ on CdTe quantum dots diminish.When the presence of GTX1,4 was present,the imprinted pores on the surface of the molecularly imprinted polymer were occupied,preventing the inner core MnO₂ nanospheres from continuing to catalyze the decomposition of H₂O₂,and the quantitative detection of GTX1,4 was realized by the change of fluorescence intensity.After experimental optimization,the method successfully achieved the rapid qualitative and quantitative detection of GTX1,4 at concentrations ranging from 0.5 to50μg/L with the limited of detection was 0.14μg/L.The method had good selectivity and stability,and the recoveries of real water samples spiked in seawater ranged from96.8-103.2%.