Concerned about the damage of heavy metal ions to both the environment and organisms. Our team believes that it is necessary to develop a sensitive, accurate and uncomplicated heavy metal ion detection system. Having this goal in mind, we researched upon the potential solutions to approach this lethal problem and eventually we decided on the DNAzyme technology which could be a tremendous breakthrough in this project. Not only do they have high sensitivity and selectivity for detecting heavy metal ions but they are also capable of biosafty and portability. Together we designed and tested four different DNAzymes: 8-17, GR-5, S9, and F8-X. We determined each DNAzyme's detection limit, and for GR-5, S9, and F8-X we also demonstrated their specificity for specific heavy metal ion
Furthermore, beyond DNAzyme's capability of cutting the single substrate DNA strand when combined to heavy metal ions, we also extended this approach by incorporating different kinds signal amplification systems: including HTDC Assay, Toehold Switch, TO-DNA T7 Promoter and CRISPR-Cas12a. Of these amplification systems, HTDC Assay and CRISPR-Cas12a are proved effective, so we combined them with four DNAzymes for further testings. Eventually, we determined two effective combinations--8-17 & HTDC, S9 & Cas12a. At the same time, we also incorporated the purchased test strip to HTDC Assay in order to simplify the detection process and lower the cost for detection.
Eventually, we hope to apply these DNAzyme-based biosensors to our real life. They are able to quickly discover whether water, food, soil, etc., are polluted by heavy metals, thus alleviating the environmental problems of soil and water pollution and the potential dangers of heavy metal poisoning.