Nucleic Acid Aptamers Combined With Fluorescent Quantum Dots For Detection Of Heavy Metals In Apple Juice

Heavy metal is a key quality safety factor in apple and its processing industry.It poses a great threat to the processing and consumption of juice.It is necessary to establish a method for detecting heavy metals with high specificity and high sensitivity,and timely identify and discover the pollution of heavy metals in juice.It has always been a hot spot in scientific research and industrial production.The specific recognition of nucleic acid aptamers,the high affinity of gold nanoparticles for aptamers,and the high sensitivity signal changes of fluorescent quantum dots provide a new technical method for the detection of heavy metals.Therefore,based on the extinction of gold nanoparticles and nucleic acid aptamers,heavy metal ions and quantum dots were added to the coexistence system of gold nanoparticles and nucleic acid aptamers,and the rapid detection of heavy metals was realized by the change of fluorescence signals,a high sensitivity and specificity method for detecting heavy metals in juice.The main findings are as follows:（1）Based on the extinction of gold nanoparticles and nucleic acid aptamers and the changes of fluorescent quantum dot signals,four heavy metal ion detection methods for Pb²⁺,Hg²⁺,Cd²⁺and Ag⁺were constructed.The results showed that the detection limit of Pb²⁺was20.8 ng/L,the detection limit of Hg²⁺was 28.7 ng/L,the detection limit of Cd²⁺was 363ng/L,and the detection limit of Ag⁺was 13.6 ng/L.Compared with the existing reports,the method had great potential in the detection of these four heavy metal ions.（2）Simultaneous detection of Hg²⁺and Ag⁺in apple juice based on the extinction of gold nanoparticles and nucleic acid aptamers and changes in fluorescence quantum dot signals:In the fluorescence spectrum.The emission wavelengths of Hg²⁺and Ag⁺are 530nm and 600 nm,respectively.The detection limits of Hg²⁺and Ag⁺were 38.96 ng/L and 51.4ng/L,respectively,and the specificity was good.（3）A simultaneous detection method for Pb²⁺and Hg²⁺in apple juice was established.In the fluorescence spectrum,the emission wavelengths of Hg²⁺and Pb²⁺were 530 nm and600 nm,respectively.The detection limits of Hg²⁺and Pb²⁺were 34.83 ng/L and 1.46μg/L,respectively,with good specificity.