Discrimination and ultrasensitive detection of β 2-agonists using copper nanoclusters as a fluorescent probe

The authors describe a rapid method for the determination of 11 β 2-agonists by exploiting the color changes and fluorescence intensity changes of copper nanoclusters coated with bovine serum albumin (BSA-CuNCs). On addition to a solution of the BSA-CuNCs, some β 2-agonists (metaproterenol, terbutaline, dopamine hydrochloride, isoproterenol, fenoterol) cause color transitions to occur, while the others do not cause an effect. In addition, β 2-agonists such as isoxsuprine, ritodrine, ractopamine, metaproterenol, terbutaline, dopamine, isoproterenol and fenoterol quench the fluorescence of the CuNCs (best measured at excitation/emission wavelengths of 325/410 nm), while the others do not quench. By combining the effects on color and fluorescence, one can differentiate the various types of agonists. The possible quenching mechanism is investigated. The strong decrease in fluorescence intensity upon addition of certain β 2-agonists can also be used quantify the concentration of the β 2-agonists.