Sub-attomolar detection of cholera toxin using a label-free capacitive immunosensor

Area of Science:

• Biomedical Engineering
• Biosensor Technology
• Analytical Chemistry

Background:

• Cholera toxin (CT) poses a significant public health risk.
• Accurate and sensitive detection methods for CT are crucial for disease surveillance and control.
• Existing detection methods may lack sensitivity or require complex procedures.

Purpose of the Study:

• To develop a label-free immunosensor for the direct and highly sensitive detection of cholera toxin (CT).
• To achieve sub-attomolar detection limits for CT in various sample matrices.

Main Methods:

• Development of a label-free immunosensor based on potential-step capacitance measurements.
• Modification of a gold electrode with polytyramine and adsorption of anti-CT antibodies on gold nanoparticles (AuNPs).
• Detection of CT by measuring capacitance changes due to antibody-antigen complex formation.

Main Results:

• The developed immunosensor achieved a limit of detection of 9 x 10(-20) M (0.09 aM) for CT.
• A wide dynamic range from 0.1 aM to 10 pM was observed.
• The assay demonstrated excellent analytical reproducibility (RSD of 2.5% for 36 injections) and functionality in turbid water samples.

Conclusions:

• The gold nanoparticle-enhanced polytyramine-modified electrode provides a highly sensitive platform for CT detection.
• The label-free potential-step capacitance method offers a promising approach for rapid and sensitive cholera toxin monitoring.
• The developed immunosensor shows potential for real-world applications in detecting CT in environmental water sources.