Nanoprobes Combined With Enzyme Inhibition For Cupric Ions Detection In Water Environment

Heavy metal contaminants are harmful to both ecological environment and humanhealth, so it is important and urgent to establish sensitive, fast and efficient methods fordetecting heavy metal ions. The current detection techniques were established on thebasis of large instruments, which require harsh detection conditions, long time and highcost, so it’s difficult to meet the needs of heavy metal ions detection. With the rapiddevelopment of nanotechnology, many nanoscaled materials have been widely used inchemical and biological analysis due to their outstanding properties different from thebulk materials. In order to achieve highly sensitive and specific detection of copper ions,this study used two kinds of nanoprobes—CdTe quantum dots （QDs） and goldnanoparticles （NPs） combined with the inhibition of enzymatic activity by copper ions,to construct a copper ions sensor based on the fluorescence and color changes of thenanoprobes. Alcohol oxidase （AO） catalyzed the oxidation of methanol to H₂O₂,inducing the quenching of QDs fluorescence. Additionally, H₂O₂can be used as areducing agent to promote the growth of gold NPs, causing the color change of goldNPs from red to purple, even to blue. But in the presence of Cu²⁺, the AO activity wasgreatly inhibited and therefore, the quenching of QDs fluorescence and the growth ofgold NPs was reduced. The detection limit can be as low as0.176ng/mL （for CdTe QDs）and1ng/mL （for Au NPs）. Other interference ions showed no intensive inhibition to theAO activity even at10or100times Cu²⁺concentration, presenting a high selectivity ofthe two hybrid systems. The coupling of nanoprobes with the effective enzymeinhibition provides a simple, ultrasensitive and selective method for copper ionsmonitoring.