Development Of A Test Strip Platform For On-site And Ultrasensitive Detection Of Heavy Metal Ions

With the rapid development of economy, the pollution of heavy metal ions becomes more andmore serious, which is recognized as one of the most serious environment problems. Therefore, thedetection of heavy metal ions in environment has significant importance for human health andenvironmental safety. The current methods for the detection of heavy metal ions usually requiretime-consuming sample pretreatment, expensive instrumentation, and highly skilled personnel, andthus they are not suitable for on-site and rapid detection. Therefore, a rapid, simple, sensitive andaccurate method for on-site detection of heavy metal ions remains desirable. The research of thisthesis emphasized on the detection of Hg²⁺and Pb²⁺that are most toxic and serious pollutants.With the use of nanotechnology and biotechnology, a simple, highly selective and sensitive teststrip method for the on-site detection of Hg²⁺and Pb²⁺was thus developed. The details are asfollows:Test strips for on-site detection of Hg²⁺have been developed. Hg²⁺can bind betweenthymines to form stable thymine–Hg²⁺–thymine (T–Hg²⁺–T) base pairs in DNA. Based onT–Hg²⁺–T coordination chemistry and AuNPs, we designed DNA sequences that have specificrecognition ability to Hg²⁺and then prepared three test strips for on-site detection of Hg²⁺withdifferent mechanism. The mechanism of detection was discussed. The effect of each influencingfactor in test strip preparing and testing was studied and the optimized conditions were obtained.The CVAAS analysis was performed as a confirmatory method for the validity of test strips. Thesetest strips have been used for detecting Hg²⁺in different environmental water samples. Thedetection limits for Hg²⁺were3,5and6nM, respectively.A test strip for on-site detection of Pb²⁺has been developed. Based on17E DNAzyme thathas specific recognition ability to Pb²⁺, AuNPs and bio-barcode assay, we prepared a test strip foron-site and rapid detection of Pb²⁺. We discussed the mechanism of detection, studied the effect ofeach influencing factor in test strip preparing and testing and analyzed the mechanism of highselectivity and sensitivity for Pb²⁺. The ICP–MS analysis was performed as a confirmatory methodfor the validity of the test strip. The test strip proposed has been used for detecting Pb²⁺in differentenvironmental water samples. The detection limit for Pb²⁺was10nM.