Amplified electrochemical determination of UO22+ based on the cleavage of the DNAzyme and DNA-modified gold nanoparticle network structure

A superior electrochemical biosensor was designed for the determination of UO 2 2+ in aqueous solution by integration of DNAzyme and DNA-modified gold nanoparticle (DNA-AuNP) network structure. Key features of this method include UO 2 2+ inducing the cleavage of the DNAzyme and signal amplification of DNA-AuNP network structure. In this electrochemical method, the DNA-AuNP network structure can be effectively modified on the surface of gold electrode and then employed as an ideal signal amplification unit to generate amplified electrochemical response by inserting a large amount of electrochemically active indicator methylene blue (MB). In the presence of UO 2 2+ , the specific sites on DNA-AuNP network structure can be cleaved by UO 2 2+ , releasing the DNA-AuNP network structure with detectable reduction of electrochemical response intensity. The electrochemical response intensity is related to the concentration of UO 2 2+ . The logarithm of electrochemical response intensity and UO 2 2+ concentration showed a wide linear range of 10~100 pM, and the detection limit reached 8.1 pM (S/ N  = 3). This method is successfully used for determination of UO 2 2+ in water samples. Fabricated DNAzyme network structure for enhanced electrical signal. Numerical experiments show that the current signal decreases as the concentration of UO 2 2+ increases. It can be seen that the biosensors could be used to detect UO 2 2+ in aqueous solution effectively.