Construction Of Ratiometric Fluorescence Probe Of Copper Nanoclusters And Determination Of Lead,Mercury And Cadmium In Porphyra

Porphyra is popular among consumers because of its delicious taste and rich nutrition,but it's easy to accumulate heavy metals in water,which may cause toxicity accumulation damage to human body.Several techniques are typically used to detect trace amounts of heavy metals in the food,such as atomic absorption spectroscopy?AAS?,inductively coupled plasma-mass spectrometry?ICP-MS?,electrochemical methods,and fluorescent sensor methods.Among these methods,fluorescent sensor methods have been praised as notably effective protocols for determining concentrations of trace metal ions because of the feature of effective selectivity,and high sensitivity.At present,the research of fluorescence analysis methods still has the following deficiencies:the fabrication cost is high and the stability is poor,so,the anti-interference ability of the constructed fluorescent sensor system is weak.In order to solve the above problems,high stability and low-cost fluorescent probes need to be further developed.The dual emission function of ratiometric fluorescence probe has both correction signal and response signal,which can reduce the detection error caused by external environmental factors and its own concentration,enhance the detection stability and improve the anti-interference ability,copper nanoclusters?CuNCs?are based on copper and have the advantages of low cost and stable signal.Therefore,in this study,CuNCs was used to prepare low cost and stable fluorescent signal,and the ratiometric fluorescence probe was used to detect the characteristics of strong stability and strong anti-interference ability,three ratiometric fluorescence probes were constructed based on CuNCs combined with CQDs,CNQDs and CdTe QDs to detect mercury(Hg²⁺),lead(Pb²⁺)and cadmium(Cd²⁺)in Porphyra,the main research contents are as follows:?1?The ratiometric fluorescence probe based on CuNCs and CQDs to detecte Hg²⁺in Porphyra.Firstly,CQDs and CuNCs were prepared,and CQDs-CuNCs composite system with dual-emission peaks was constructed by self-assembly.Then,through characterization and fluorescence response analysis,the response characteristics of CQDs-CuNCs composite system to Hg²⁺were studied with I_443nm/I_545nm as the response value to Hg²⁺.The results show that,this system exhibited excellent sensitivity toward Hg²⁺in the range of 0.02².41 mg·L^-1,R²=0.9950,with a detection limit of 2.57?g·L^-1,and the relative standard deviation?RSD?in porphyra was less than 5%.Compared with the single emission system under temperature fluctuation?5³0°C?,the deviation of the detection results constructed in this study is reduced by 0.3%⁵%,which has strong detection stability.?2?The ratiometric fluorescence probe based on CuNCs and CNQDs to detecte Pb²⁺in Porphyra.Firstly,CNQDs were prepared,CuNCs–CNQDs nanohybrid with dual-emission peaks was synthesized on the basis of CNQDs.Then,through characterization and fluorescence response analysis,the response characteristics of CuNCs–CNQDs nanohybrid to Pb²⁺were studied with I_632nm/I_468nm as the response value to Pb²⁺.The results show that,this system exhibited excellent sensitivity toward Pb²⁺in the range of 0.01².52 mg·L^-1,R²=0.9971,with a detection limit of 3.09?g·L^-1,and the relative standard deviation?RSD?in porphyra was less than 5%.Compared with gold and silver nanomaterials,the ratiometric fluorescence probe constructed by CuNCs can effectively reduce the cost of the probe.?3?The ratiometric fluorescence probe based on CuNCs and CdTe QDs to detecte Cd²⁺in Porphyra.Firstly,CuNCs@SiO₂ and CdTe QDs were prepared by hydrothermal method,and CuNCs@SiO₂-CdTe QDs ratiometric fluorescence probe with dual-emission peaks was constructed.Then,through characterization and fluorescence response analysis,the response characteristics of the ratiometric fluorescence probe to Cd²⁺were studied with I_580nm/I_436nm as the response value to Cd²⁺.And RGB information was extracted by the change of fluorescent color and iphone app?colorpicker?for the colorimetric detection of Cd²⁺.The results show that,this system exhibited excellent sensitivity toward Cd²⁺in the range of 0.01².05 mg·L^-1,R²=0.9857,with a detection limit of 1.75?g·L^-1,and the relative standard deviation?RSD?in porphyra was less than 5%,the colorimetric detection of Cd²⁺in the range of 0.05¹.10mg·L^-1 was realized.This study further improved the detection efficiency of Cd²⁺,reduced the detection cost,and provided the research basis for the subsequent fluorescence colorimetric analysis.In conclusion,three fluorescence systems based on CuNCs were employed to the rapid detected mercury,lead and cadmium in Porphyra,which provided technical support for the low-cost,rapid and accurate detection of heavy metals in foods.