Probing Membrane Receptor-Ligand Specificity with Surface- and Tip- Enhanced Raman Scattering

Area of Science:

• Biophysical Chemistry
• Molecular Spectroscopy
• Drug Discovery

Background:

• Investigating ligand-protein interactions, especially with membrane proteins, is crucial for minimizing drug off-target effects.
• Surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS) offer vibrational spectroscopy insights.
• Understanding binding affinity is key to developing targeted therapeutics.

Purpose of the Study:

• To correlate spectral variance in SERS and TERS with ligand specificity in affinity-based assays.
• To investigate ligand-receptor interactions using vibrational spectroscopy on isolated proteins and intact cell membranes.
• To demonstrate a novel approach for assessing drug specificity in complex biological environments.

Main Methods:

• Utilized SERS and TERS to analyze spectral variations of three peptide ligands with differing affinities to αvβ3 integrin.
• Acquired SERS spectra from purified αvβ3 integrin and from receptors within intact cancer cell membranes.
• Correlated spectroscopic data with single particle tracking experiments on ligand-functionalized nanoparticles.

Main Results:

• Spectral variance in SERS and TERS data differed among ligands, with larger variance indicating nonspecific interactions.
• SERS signals from purified proteins served as a baseline for analyzing cellular spectra.
• Spectroscopic findings aligned with single particle tracking results, validating the approach.

Conclusions:

• Observed spectral variance in SERS and TERS can elucidate protein-ligand recognition and binding specificity.
• This vibrational spectroscopy approach provides a new method for investigating drug specificity in intact cell membranes.
• The findings offer perspective on developing more targeted small-molecule ligands for therapeutic applications.