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

Area of Science:

• Coordination chemistry and materials science
• Biochemical sensing and immunoassays
• Fluorescence spectroscopy

Background:

• Alkaline phosphatase (ALP) is a crucial biomarker in various biological processes and disease diagnostics.
• Enzyme-linked immunosorbent assays (ELISA) widely utilize ALP as an enzyme label.
• Developing sensitive and specific fluorescent detection methods for ALP and related biomarkers is essential.

Purpose of the Study:

• To fabricate an alkaline phosphatase (ALP)-responsive coordination polymer (CP) composite for fluorescent sensing.
• To develop an ALP-based fluorescent immunoassay for the sensitive detection of mouse immunoglobulin G (mIgG).
• To demonstrate the practical application of the developed immunoassay in biological samples.

Main Methods:

• Synthesis of a thioflavin T (ThT)-encapsulated coordination polymer (CP) composite (ThT@GMP/Eu) using europium ion (Eu3+) and guanine monophosphate (GMP).
• Investigation of the fluorescence response of ThT@GMP/Eu to ALP, observing fluorescence quenching upon ALP-induced disruption of the CP structure.
• Development and validation of an ALP-based fluorescent immunoassay for mIgG detection using the ThT@GMP/Eu sensor.

Main Results:

• The ThT@GMP/Eu composite exhibited fluorescence quenching in the presence of ALP, with a linear response range of 0.8–120 mU/mL and a detection limit of 0.26 mU/mL.
• The sensor demonstrated high specificity for ALP over other enzymes.
• The developed fluorescent immunoassay detected mIgG in a linear range of 0.8–100 ng/mL with a detection limit of 0.16 ng/mL.
• Successful determination of mIgG in serum samples using the fluorescent immunoassay.

Conclusions:

• The ThT@GMP/Eu coordination polymer composite serves as an effective fluorescent probe for ALP detection.
• The developed ALP-based fluorescent immunoassay offers a sensitive and specific method for mIgG quantification.
• This approach holds promise for the development of advanced biosensing platforms for clinical diagnostics.