Evanescent Wave Biosensor For Detection Of Uranyl Ions In Water Samples Based On DNAzyme

In this study,a sensitive and rapidly method for the detection of UO₂²⁺was successfully established,which was besed on the specific cleavage reaction between DNAzyme and uranyl ions,and integrated with the all-fiber evanescent wave biosensor platform developed by our research group.The reseach results were described as follows:?1?The reaction conditions of DNAzyme and uranyl ions were optimized,such as the concentration of the substrate chain and the enzyme chain,the ratio between the substrate chain and the enzyme chain,the reaction time of the cleavage reaction.The above-optimized results would provide foundation for the DNAzyme application on the fiber biosensor platform.Based on the optical fiber modification step,including the hydroxylation,silanization,crosslink with glutaraldehyde and immobilization of functional nucleic acids on the fiber surface,the DNAzyme fiber suitable for the evanescent wave biosensor was prepared.After the optimization of the blocking agent,the glycine was identified as the appropriate blocking agent,which could reduce the effect of nonspecific adsorption on detection.?2?Based on a two-step strategy,which means the cleavage reaction in solution first and then hybridization on solid phase,the detection of uranyl ions by fiber evanescent wave biosensor was successfully established.The method showed high sensitivity with the detection limit of 0.5nM?0.12?g/L?,rapid detection time?less than 16min?and good selectivity.The fiber could be used repeatedlly for more than 100 times without significant attenuation of the signal.?3?Through the systematic study about the effects of arious substrates such as ionic strength,hardness,inorganic anion and humic acid,the suitable boundary conditions for each index were proposed.The recovery tests of six different real water samples showed that it could reach more than 80%in drinking water and surface water with good quality,defining the water quality scope of established method.Humic acid and ionic strength was the major inference factor on detection performance.?4?The standard operating procedure for the evaluation index of the detection method were proposed,such as the linear range,detection limit,precision,accuracy,repeatability and memory effect.The standardized scheme for the detection of UO₂²⁺based on fiber evanescent wave biosensor and DNAzyme was proposed,which provided technical support for the detection method appication in environmental monitoring.