A catalyst-free co-reaction system of long-lasting and intensive chemiluminescence applied to the detection of alkaline phosphatase

Abstract

A catalyst-free co-reaction luminol-H₂O₂-K₂S₂O₈ chemiluminescence (CL) system was developed, with long-life and high-intensity emission, and CL emission lasting for 6 h. A possible mechanism of persistent and intense emission in this CL system was discussed in the context of CL spectra, cyclic voltammetry, electron spin resonance (ESR), and the effects of radical scavengers on luminol-H₂O₂-K₂S₂O₈ system. H₂O₂ and K₂S₂O₈ co-reactants can promote each other to continuously generate corresponding radicals (OH^•, ¹O₂, O₂^•-, SO₄^•-) that trigger the CL emission of luminol. H₂O₂ can also be constantly produced by the reaction of K₂S₂O₈ and H₂O to further extend the persistence of this CL system. CL emission can be quenched via ascorbic acid (AA), which can be generated through hydrolysis reaction of L-ascorbic acid 2-phosphate trisodium salt (AAP) and alkaline phosphatase (ALP). Next, a CL-based method was established for the detection of ALP with good linearity from 0.08 to 5 U·L^-1 and a limit of detection of 0.049 U·L^-1. The proposed method was used to detect ALP in human serum samples.

Keywords: Alkaline phosphatase; Chemiluminescence; Co-reactants; Luminol.