Magnetically Detected Protein Binding Using Spin-Labeled Slow Off-Rate Modified Aptamers.

Area of Science:

• Biochemistry
• Analytical Chemistry
• Materials Science

Background:

• Aptamer chemistry advancements enable new protein biosensing tools.
• Slow off-rate modified aptamers (SOMAmers) offer high specificity for protein targets.
• Site-specific labeling is crucial for precise molecular probes.

Purpose of the Study:

• To develop and validate a novel protein biosensing platform using site-specifically labeled SOMAmers.
• To investigate the detection of protein binding events via changes in spin label mobility.
• To explore the integration of this system with diamond nitrogen-vacancy (NV) center relaxometry for enhanced detection.

Main Methods:

• Immobilization of site-specifically nitroxide radical-labeled SOMAmers using azide-alkyne click chemistry.
• Detection of protein binding by monitoring changes in spin label rotational mobility using electron paramagnetic resonance (EPR) spectroscopy.
• Modeling the combined system with diamond nitrogen-vacancy (NV) center relaxometry.

Main Results:

• Demonstrated workflow using SOMAmer SL5 and platelet-derived growth factor B (PDGF-BB).
• Identified optimal labeling sites on SOMAmers exhibiting significant mobility changes upon protein binding.
• Showcased the potential for NV center relaxometry to detect SOMAmer-protein interactions.

Conclusions:

• The developed spin label-mediated assay provides a general method for detecting protein binding events.
• This approach transduces molecular recognition into magnetically detectable signals.
• The system holds promise for sensitive and specific protein biosensing applications.