A Bifunctional Spin Label for Ligand Recognition on Surfaces.

Area of Science:

• Biophysical Chemistry
• Nanotechnology
• Spectroscopy

Background:

• In situ monitoring of biomolecular recognition at surfaces is challenging.
• Electron paramagnetic resonance (EPR) with spin-labeling offers sensitive detection but requires new strategies.
• Developing novel spin labels is crucial for advancing biomolecular interaction studies.

Purpose of the Study:

• To synthesize and characterize a novel bromoacrylaldehyde spin label (BASL) with orthogonal reactivity.
• To demonstrate the utility of BASL for conjugating ligands to gold nanoparticles.
• To investigate biomolecular recognition events using EPR spectroscopy with BASL-functionalized nanoparticles.

Main Methods:

• Synthesis of the bromoacrylaldehyde spin label (BASL).
• Conjugation of mannose and biotin ligands to carboxy-functionalized gold nanoparticles via BASL.
• Electron paramagnetic resonance (EPR) spectroscopy of free and nanoparticle-bound spin-labeled ligands.
• Assessing binding interactions with Con A (mannose-binding lectin) and avidin-peroxidase (biotin-binding protein).

Main Results:

• Successful synthesis and characterization of the BASL with dual attachment points.
• Demonstrated conjugation of mannose and biotin ligands to gold nanoparticles using BASL.
• Quantifiable changes in EPR spectra upon specific biomolecular recognition were observed.
• Binding profiles reflecting binding strength were obtained for Con A and avidin-peroxidase interactions.

Conclusions:

• The bromoacrylaldehyde spin label (BASL) is a versatile tool for biomolecular immobilization on nanoparticles.
• EPR spectroscopy with BASL-functionalized nanoparticles enables sensitive and selective detection of biomolecular binding.
• This approach provides a powerful method for studying biomolecular recognition in situ.