Fluorescent enzyme-linked immunosorbent assay based on alkaline phosphatase-responsive coordination polymer composite

Abstract

The fabrication of alkaline phosphatase (ALP)-responsive coordination polymer (CP) composite is demonstrated for establishing a fluorescent immunoassay. The CP composite (ThT@GMP/Eu) was synthesized by encapsulating thioflavin T (ThT) into the CP host that was composed of europium ion (Eu 3+ ) and guanine monophosphate (GMP). The ThT@GMP/Eu composite shows a strong fluorescence in aqueous solution due to the confinement effect of GMP/Eu CPs, which restricts the conformational rotation of ThT. However, upon the addition of ALP, the structure of GMP/Eu CPs was disrupted to release ThT into solution. This results in the quenching of the fluorescence of ThT@GMP/Eu. The fluorescence of ThT@GMP/Eu has a linear response that covers 0.8 to 120 mU/mL ALP with a detection limit of 0.26 mU/mL and exhibits excellent specificity towards ALP against other enzymes. On this basis, inspired by the wide application of ALP as an enzyme label in enzyme-linked immunosorbent assay (ELISA), an ALP-based fluorescent immunoassay was further developed for the detection of mouse immunoglobulin G (mIgG). The developed immunoassay displays a linear fluorescent response towards mIgG from 0.8 to 100 ng/mL, and the detection limit is 0.16 ng/mL. The fluorescent immunoassay was successfully applied to the determination of mIgG in serum samples.

Thioflavin-T-Enhanced Fluorescence in Cerium Adenosine Triphosphate Coordination Polymer Nanoparticles for Selective and Sensitive Copper(II) Detection in E-Waste and Biological Samples

“…and the sensing mechanism have not been extensively discussed. In another report, 31 Thioflavin-T (ThT)-incorporated europiumbased GMP was employed for the sensing of alkaline phosphatase, a biomarker. However, it should be noted that reports of CPNs-based materials that can work in a complex matrix like serum or e-waste acid leachate are lacking in the literature.…”

Overview on the Development of Alkaline-Phosphatase-Linked Optical Immunoassays

“…The ALP-catalyzed hydrolysis of the ligand will induce the destruction of the ICP structure accompanied by the change in optical properties [ 80 , 81 ]. Li et al reported a fluorescent immunoassay for mouse IgG detection based on ALP-responsive dye-doped ICP [ 82 ]. In this work, ICP composed of europium ions (Eu 3+ ) and guanine monophosphate (GMP) was used to encapsulate fluorescent thioflavin T (ThT) molecules.…”

A cationic AIEgen and hexametaphosphate based simple and convenient fluorometric assay for alkaline phosphatase and its inhibitor

“…3,5 Additionally, ALP, due to its good stability, high turnover number, low cost, and wide range of substrate specificity, is used as a labelling enzyme in many bioassays. 6,7 Therefore, ALP detection is not only important in clinical diagnosis but also valuable in biomedical research. Thus, due to its clinical relevance and biomedical importance, simple, sensitive and specific assays for monitoring ALP concentration levels are in high demand.…”