Ratiometric electrochemical lateral flow immunoassay for the detection of Streptococcus suis serotype 2

Area of Science:

• Biosensor Technology
• Electrochemistry
• Immunodiagnostics

Background:

• Streptococcus suis serotype 2 is a significant pathogen requiring rapid and accurate detection methods.
• Existing diagnostic methods may lack the speed, reproducibility, or sensitivity needed for timely clinical intervention.

Purpose of the Study:

• To develop a highly reproducible electrochemical lateral flow immunoassay (eLFIA) strip for the rapid and accurate detection of Streptococcus suis serotype 2.
• To integrate ratiometric electrochemical detection with LFIA for improved biosensing performance.

Main Methods:

• Fabrication of a dual-working screen-printed graphene electrode (SPGE) with ferrocene carboxylic acid (Fc) as a signal probe and sunset yellow (SY) as an internal reference.
• Immobilization of S. suis serotype 2-specific antibodies on the LFIA nitrocellulose membrane.
• Development of a ratiometric detection strategy where the Fc current decreases proportionally to the analyte concentration while the SY current remains constant.

Main Results:

• The developed ratiometric eLFIA (R-eLFIA) strip demonstrated 3.8 times improved reproducibility compared to a single electrode.
• The biosensor exhibited a linear detection range of 10^2-10^10 CFU/mL with a low limit of detection of 10 CFU/mL.
• Rapid detection was achieved within 15 minutes, with excellent reproducibility, high selectivity, and successful application in human serum samples.

Conclusions:

• The R-eLFIA biosensor effectively combines the advantages of ratiometric detection and LFIA for sensitive and reproducible Streptococcus suis serotype 2 detection.
• This developed biosensor shows significant potential as an effective tool for rapid clinical diagnostics of S. suis serotype 2 infections.