DNAzyme And Metal-organic Frameworks Based Optical Biosensing Methods For Lead Ions Detection

With the development of industry,heavy metal pollution in the environment is becoming more and more serious.Although heavy metal elements such as copper,iron,and manganese are necessary for human life,some of the excess even trace amounts of highly toxic heavy metals?such as lead,mercury,etc.?can not be biodegradable.The continuous enrichment by the food chain causes a great threat to the ecological environment and human safety.Therefore,it is of great significance to establish heavy metal ion detection method with simple operation and quick response.Despite the advantages of high sensitivity and high selectivity in heavy metal detection with traditional large precision instruments,its complex sample pretreatment and enrichment processes,expensive instruments and the disadvantages of requiring specialized operators limit its further application.Compared with traditional detection methods,optical sensing methods based on DNAzyme and metal organic framework?MOFs?materials have the advantages of low cost,simple operation,high sensitivity,high specificity,and high stability.The main research content of this article is to use lead ions(Pb²⁺)as the detection target,use the cutting ability of lead ions to specific DNAzyme,and combine the DNAzyme with the ZIF-8 material to improve its stability.An optical biosensing method based on ZIF-8@DNAzyme composite material was constructed to achieve the detection of lead ions in vivo and in vitro.The main research contents and conclusions are as follows:Based on the specific recognition ability of DNAzyme for metal ions and the porosity and stability of ZIF-8 nanometer material,the DNAzyme was fixed by ZIF-8 through the method of biomineralization,and the optical sensor based on ZIF-8@DNAzyme composite material was constructed.The fixation of ZIF-8 not only keeps the catalytic activity of DNAzyme,but also enhances the enzyme digestion stability of DNAzyme.When lead ion is present,the DNAzyme will break from the cleavage site.As the double strands are separated,the original FAM fluorescent group and BHQ-1 quenching group are also separated,and the fluorescence intensity recovered.Through quantitative analysis of the change of lead ion concentration and fluorescence intensity,it was observed that when the lead ion concentration was 50-500 nM,the system fluorescence intensity and lead ion concentration showed a good linear relationship,and the detection limit was calculated to be 39 nM.At the same time,in the presence of a variety of interfering metal ions,the sensor exhibits specific detection of lead ions.While possessing the advantages of high sensitivity and high specificity,the sensor also shows resistance to enzymes.Due to the protection of ZIF-8,ZIF-8@DNAzyme still has considerable activity after being treated by DNase I,and free DNAzyme lost its original activity after treatment.Based on the stability of the sensor,we realized the detection of lead ions in 293T and Huh-7 cells.In this study,the fluorescent sensing method based on the ZIF-8@DNAzyme composite was used to achieve highly sensitive and specific detection of lead ions in vivo and in vitro.Changing the type of DNAzyme can achieve the ability to detect other heavy metal ions,which provides a new method for the detection of heavy metal ions in vitro.