A label-free visual immunoassay on solid support with silver nanoparticles as plasmon resonance scattering indicator

Area of Science:

• Nanotechnology
• Biomedical Engineering
• Analytical Chemistry

Background:

• Silver nanoparticles (Ag-NPs) exhibit strong plasmon resonance scattering (PRS) signals.
• Label-free assays reduce complexity and cost in diagnostics.
• Immunoassays are crucial for detecting specific biomolecules.

Purpose of the Study:

• To develop a label-free visual immunoassay using Ag-NPs for antibody detection.
• To investigate the adsorption mechanism of Ag-NPs on antibody-immobilized surfaces.
• To establish a method for both spectrofluorometric and visual detection of antibodies.

Main Methods:

• Immobilization of antigen on glass slides followed by antibody incubation.
• Adsorption of Ag-NPs onto the antibody-antigen complex under optimized pH conditions.
• Measurement of PRS signals using a spectrofluorometer and visual detection with an LED torch.

Main Results:

• Ag-NPs successfully adsorbed onto glass slides with immobilized antibodies.
• Adsorption was dependent on antibody concentration under optimal pH.
• Antibody detection range of 10 to 160 ng/mL was achieved using spectrofluorometry.
• Visual detection of antibodies was possible with an LED torch.

Conclusions:

• A novel label-free visual immunoassay for antibody detection based on Ag-NP PRS was developed.
• The method offers a simple, sensitive, and visual detection approach for antibodies.
• This technique holds potential for point-of-care diagnostics and resource-limited settings.