Impedimetric immunosensors based on the conjugated polymer PPV

Area of Science:

• Biomaterials Science
• Chemical Engineering
• Analytical Chemistry

Background:

• Semiconducting polymers offer unique electronic and optical properties for biosensing applications.
• Antibody immobilization on surfaces is crucial for developing specific and sensitive biosensors.
• Fluorescent dyes like fluorescein isothiocyanate (FITC) and Cy5 are common labels in biological assays.

Purpose of the Study:

• To investigate the interaction between the semiconducting polymer MDMO-PPV and antibodies against FITC and Cy5.
• To develop and characterize antibody-functionalized polymer films for biosensing.
• To evaluate the performance of a biosensor prototype utilizing these films.

Main Methods:

• Atomic Force Microscopy (AFM) to visualize antibody adsorption on polymer films.
• Contact angle measurements to determine surface properties and antibody density.
• Confocal fluorescence microscopy to confirm specific binding of fluorescent antigens.
• Differential Impedance Spectroscopy (DIS) for biosensor response detection.

Main Results:

• Antibodies were physically adsorbed onto MDMO-PPV polymer films on gold electrodes.
• Antibody concentration tuning allowed control over surface density, varying contact angles from 95 to 50 degrees.
• Confocal microscopy confirmed specific binding of FITC and Cy5 antigens by their respective antibodies.
• Lack of cross-sensitivity demonstrated specific antigen-antibody recognition.
• The biosensor prototype showed a clear response to 1 ppb antigen solution with a 2-3 minute time constant.

Conclusions:

• MDMO-PPV polymer films functionalized with antibodies can serve as effective biosensing platforms.
• The developed biosensor exhibits specific detection of fluorescent antigens at low concentrations.
• The study highlights the potential of semiconducting polymers in advanced biosensor development.