DNA nanocage confined DNAzyme for detection of lead ions coupled with CRISPR-Cas12a system

As one of the most toxic heavy metals, trace lead ions (Pb2+) can cause serious harm to human, so rapid detection of trace Pb2+ has always attracted wide attention. DNAzyme is important for the detection of Pb2+, whereas its recognition efficiencies is always affected by the interfering substances in the complicated matrix. In order to enhance the performance of DNAzyme, DNA nanocage is intelligently introduced to construct new probe, i.e. DNA nanocage confined DNAzyme (ncCDzy). Due to the spatial confinement effect, the thermodynamic stability of ncCDzy is significantly improved with the 30 % higher catalytic activity than that of free DNAzyme. Coupled with the CRISPR-Cas12a system, a new specific and sensitive method has been further developed to detect Pb2+ with the linear range of 10-800 nM and the LOD of 1.025 nM. Further, the method can detect Pb2+ spiked in milk and can be applied for analysis of heavy metal ions in complicated samples. In a word, the explored new probe ncCDzy and the corresponding method will own good potential for on-site detection of diverse metal ions.