Monolayer Sensitivity Enables a 2D IR Spectroscopic Immuno-biosensor for Studying Protein Structures: Application to...

Area of Science:

• Biophysics
• Spectroscopy
• Immunochemistry

Background:

• Immunosensors are crucial for disease biomarker detection but often lack protein structural insights.
• Understanding protein structure is vital for diagnosing and treating diseases like amyloidosis.

Purpose of the Study:

• To develop a surface-sensitive two-dimensional infrared (2D IR) spectroscopic immunosensor for protein structure analysis.
• To investigate the structural differences between amyloid fibril polymorphs using this new method.

Main Methods:

• Antibodies were immobilized on a plasmonic surface to create the immunosensor.
• Amyloid proteins (human islet amyloid polypeptide - hIAPP) were analyzed using 2D IR spectroscopy.
• Isotopic labeling was employed for residue-specific structural information.

Main Results:

• The 2D IR immunosensor provided global and residue-specific structural information of hIAPP.
• Two distinct fibrillar polymorphs of hIAPP were identified, differing at the G24 residue.
• The findings support the hypothesis of common oligomeric intermediates in hIAPP polymorph formation.

Conclusions:

• The study establishes a new 2D IR spectroscopic method for protein structure analysis.
• The developed immunosensor offers insights into hIAPP structure and its fibrillar polymorphs.
• This spectroscopic immunoassay is applicable for studying diverse disease biomarkers.