Ultrasensitive and Rapid Detection of N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP) Using Fiber Optic Nanogold-Linked Immunosorbent Assay

The N-terminal pro-brain natriuretic peptide (NT-proBNP) is considered an important blood biomarker for heart failure. Herein, we report about a fiber optic nanogold-linked immunosorbent assay (FONLISA) method for the rapid, sensitive, and low-cost detection of NT-proBNP. The method is based on a sandwich immunoassay approach that uses two monoclonal NT-proBNP antibodies, a capture antibody (Ab(C)), and a detection antibody (Ab(D)). Ab(D) is conjugated to a free gold nanoparticle (AuNP) to form the free AuNP@Ab(D) conjugate, and Ab(C) is immobilized on an unclad segment of an optical fiber. The detection of analyte (A), in this case NT-proBNP, is based on the signal change due to the formation of an AuNP@Ab(D)-A-Ab(C) complex on the fiber core surface, where a green light transmitted through the optical fiber will decrease in intensity due to light absorption by AuNPs via the localized surface plasmon resonance effect. This method provides a wide linear dynamic range of 0.50 similar to 5000 pg.mL(-1) and a limit of detection of 0.058 pg.mL(-1) for NT-proBNP. Finally, the method exhibits good correlation (r = 0.979) with the commercial central laboratory-based electrochemiluminescent immunoassay method that uses a Roche Cobas e411 instrument. Hence, our method is potentially a suitable tool for point-of-care testing.

Automated summary

In this study, a fiber optic nanogold-linked immunosorbent assay (FONLISA) method was developed for the rapid, sensitive, and low-cost detection of the important blood biomarker for heart failure, N-terminal pro-brain natriuretic peptide (NT-proBNP). The method utilizes a sandwich immunoassay approach and detects the analyte through changes in light intensity caused by AuNPs on the fiber core surface. The method exhibits a wide dynamic range and a low limit of detection, and shows good correlation with a commercial laboratory-based method. This method has the potential to be used as a point-of-care testing tool.