Mercury (?) Ion Biosensors Based On Thymine-mercury Coordination

Mercury???ion is well known as an extremely toxic element,the toxicological mechanism of various mercury compounds is different.But each is a danger to human health and the environment.With the growing of influence of mercury on ecological environment,the management for mercury is more strict in all the world.The industry standard of detection limit for mercury are also getting lower and lower.DNA sensors have advantages such as high sensitivity,low detection limit,fast response.It has been used in environmental monitoring,food safety,and many other areas,also providing a effective method for fast and accurate quantitative determination of mercury in water samples.However,it is a difficult question to highly selective determine mercury in water samples and develop a high sensitive and selective mercury sensor.Therefore,this paper dedicated to the research mercury???ion biosensors based on thymine-Mercury???coordination,innovative achievements are:1.A Hg²⁺ electrochemical biosensor is developed by integrating thymine-thymine base pairs with surface-initiated enzymatic polymerization?SIEP?for signal amplification.The fabrication begins with the covalent conjugation of capture DNA probe labeled with thiol at its 3'terminal onto the gold electrode.The presence of Hg²⁺ leads to DNA hybridization,in which complementary DNA was captured onto the biosensor surface,which subsequently catalyzed the addition of deoxynucleotides?dNTP?containing biotinlated 2'-deoxyadenosine5'-triphosphate?biotin-dATP?by terminal deoxynucleotidyl transferase?TdT?.The binding between biotin and strepavidin leads to the attachment of a large number of strepavidin functionalized silver nanoparticles?strepavidin-AgNPs?,which could generate electrochemical stripping signal of silver to monitor the concentration of Hg²⁺ in KCl solution.This assay method can detect aqueous Hg²⁺ with a detection limit of 0.024 nM.2.A Hg²⁺ UV-vis spectrophotometry biosensor is developed by integrating thymine-thymine base pairs with gold nanorods.The fabrication begins with the covalent conjugation of capture DNA probe labeled with thiol at its 3'terminal onto the surface of gold nanorods and the covalent conjugation of complementary DNA probe labeled with thiol at its 3'terminal onto the surface of other gold nanorods.The presence of Hg²⁺ leads to DNA hybridization,the distance between two gold nanorods is shorter.The UV-vis spectrophotometry could generate signal of gold nanorods to monitor the concentration of Hg²⁺.This assay method can detect aqueous Hg²⁺ of 10^-10 M.