Real-Time Quantitation of Cu(II) by a Fluorescence-Based Biosensing Approach

摘要

Recently, there has been substantial interest in reducing the levels of toxic heavy metals in wastewater effluents from activities such as shipyards. Of particular interest is copper, which comprises tens of percent by weight of the hundreds of pounds of antifouling paint coating the bottom of a large vessel, but which is toxic to commercially important shellfish at sub-part per billion levels. As a result wastewater effluents must be monitored closely with sensor(s) capable of rapidly and accurately detecting excess copper in time to prevent release. We have pursued a fluorescence-based biosensing approach to obtain sub-ppb sensitivity for Cu(Ⅱ) and immunity from interference from other cations abundant in sea water, such as Ca, Mg, and Sr. Our approach uses a protein, apocarbonic anhydrase Ⅱ, as a very sensitive and selective ligand for Cu(Ⅱ) which transduces the (reversible) binding of the metal as a change in fluorescence intensity, lifetime, or anisotropy, the first two of which may be conveniently measured through optical fiber. Thus we have been able to measure sub-ppb levels of Cu added to sea water, and to characterize the speciation of the Cu(Ⅱ) to some degree, due to the presence of other ligands.