A chemiluminescence-based biosensor for metal ion detection

Inhibition of the native metalloenzyme, alkaline phosphatase, in the presence of some metal ions, and the reactivation of its apoenzyme by Zn(II) ions is used to determine metal ion concentrations. Alkaline phosphatase-catalysed hydrolysis of a chemiluminescent substrate, chloro 3-(4-methoxy spiro [1,2-dioxetane-3-2′-tricyclo-[3.3.1.1]-decan]-4-yl) phenyl phosphate, generates light. By measuring the chemiluminescence signal strength in the presence or absence of metal ions, this reaction can be used to detect and determine metal ion concentrations. The immobilization of alkaline phosphatase on different glass surfaces by covalent coupling using a bifunctional reagent, glutaraldehyde, was demonstrated. Using chemiluminescence measurements, Zn(II), Be(II) and Bi(III) were detected in trace levels. This technique forms the basis in the development of a metal ion-based fibre optic sensor.