Immunoassay readout method using extrinsic Raman labels adsorbed on immunogold colloids.

Area of Science:

• Analytical Chemistry
• Biotechnology
• Spectroscopy

Background:

• Immunoassays are crucial for detecting biomolecules.
• Surface-enhanced Raman scattering (SERS) offers high sensitivity for molecular detection.
• Existing methods may lack multiplexing capabilities or suffer from interference.

Purpose of the Study:

• To develop a novel SERS-based immunoassay readout method.
• To demonstrate simultaneous detection of multiple analytes in a single assay.
• To leverage SERS signals from co-immobilized reporter molecules for enhanced sensitivity and specificity.

Main Methods:

• A dual-analyte sandwich immunoassay format was employed.
• Antibodies were covalently bound to a solid substrate to capture specific antigens.
• Detection antibodies conjugated with SERS-active gold colloids, labeled with distinct Raman reporter molecules, were used.

Main Results:

• The method successfully detected two different antigenic species simultaneously.
• Characteristic SERS spectra of reporter molecules confirmed the presence of specific antigens.
• Near-infrared diode laser excitation minimized fluorescence interference, enhancing signal quality.

Conclusions:

• The developed SERS immunoassay readout strategy enables sensitive and simultaneous detection of multiple analytes.
• This approach shows significant potential for multiplexed biosensing applications.
• The use of distinct Raman reporters with minimal spectral overlap is key to multiplexing.