Signal Amplification Electrochemical Biosensor For The Detection Of UO₂²⁺ Based On The Dnazyme-Modified Gold Nanoparticle

As one of the important radionuclides,Uranium has been widely used in the development of nuclear energy and nuclear warfare.The pollution of uranium can cause some potential harm to human health and ecological environment.As a result,the development of an efficient method for the detection of uranyl ions in water is of great significance for uranium recovery and environmental protection.In recent years,electrochemical biosensor technology has been favored by a large number of researchers due to its advantages such as fast detection speed,low cost,high sensitivity,and simple operation.Electrochemical biosensor has been widely used in the field of detecting biological macromolecules and heavy metal ions.In this paper,utilizing the DNAzyme’s specific cleavage of UO₂²⁺and gold nanoparticles assisted signal amplification,electrochemical biosensor devices have been designed for the analysis and detection of UO₂²⁺in water samples.The details are as follows:（1）A simple and sensitive electrochemical biosensor was designed to detection of UO₂²⁺in aqueous solution by integration DNAzyme and DNA-modified gold nanoparticles（DNA-AuNPs）network structure.Key features of this method included UO₂²⁺inducing DNAzyme cleavage and signal amplification of the DNA-AuNPs network structure.In this electrochemical sensor,the DNA-AuNPs network structure can be effectively modified on the surface of the gold electrode,and then used as an ideal signal amplification unit.The electrochemical signal is generated by inserting a large amount of methylene blue（MB）,an electrochemical response activity indicator.To achieve signal amplification.In the presence of UO₂²⁺,it can cleave specific sites on the DNA-AuNPs network structure and release MB,reducing the electrochemical reaction intensity.The electrochemical response intensity was related to the concentration of UO₂²⁺.The logarithm of electrochemical response intensity and UO₂²⁺concentration showed a great linear relationship in the range of 10¹00 pmol·L^-1,and the detection limit reached 8.1 pmol·L^-1（S/N=3）.This method has high sensitivity,strong stability and high specificity,and could be successfully used for the detection of UO₂²⁺in actual water samples.（2）A dual-signal-amplified electrochemical biosensor was designed to detect UO₂²⁺in aqueous solution.AuNPs were connected to the surface of the gold electrode through 1,4-benzenedithiol to increase the load of DNAzyme specifically cut by uranyl ions.In the presence of UO₂²⁺,the DNAzyme can be effectively cut and then triggering the hybridization chain amplification reaction（HCR）.After the reaction,a long dsDNA was formed,which can be used as an ideal signal amplification unit.AgNO₃ and NaBH₄ were incubated with the electrode to generate AgNCs used as signal molecules for DPV detection.The electrochemical response intensity has a linear relationship with the logarithm of UO₂²⁺concentration between 20 and 5000 pmol·L^-1,and the detection limit reaches 6.2 pmol·L^-1（S/N=3）.It has good development potential in detecting UO₂²⁺.