Fluoroimmunosensing System Using Ferulic Acid as the Substrate for the Determination of Transferrin

Abstract

A fluoroimmunosensing system with the use of ferulic acid as the substrate for the determination of transferrin in serum samples has been developed. It was based on paraffin–graphite–transferrin antiserum immunocomposite, which permits its surface to be easily renewed by polishing. The renewed surface serves as a platform for the competitive immunoreaction of HRP-transferrin and free transferrin (analyte) with the antibody bound to the surface. By using ferulic acid as a substrate, the amount of HRP-transferrin bound was quantified fluorimetrically, which was in turn related to free transferrin content in the samples. Ferulic acid as the substrate possesses a better stability towards H₂O₂ as compared to TMB. The analytical conditions, such as pH, the amount of labeled transferrin, incubation time, and temperature were studied. Under the optimized experimental conditions, a detection limit was 30 ng/mL and the linear detection range was from 39.3 to 177 ng/mL. This approach has been applied to clinical samples with satisfactory results.

Keywords:

• Fluoroimmunosensing
• Ferulic acid
• Transferrin
• Transferrin antiserum

Acknowledgment

This work was supported by the National Science Foundation of China (Grants Nos. 20975006 and 29975006) and the Foundation for Scientific Committee of Hunan Province.