Quantum relaxometry for detecting biomolecular interactions with single NV centers

Area of Science:

• Biophysics
• Quantum Sensing
• Nanotechnology

Background:

• Investigating biomolecular interactions at the single-molecule level is crucial for understanding life science.
• Current methods often rely on ensemble-level detection, limiting resolution.
• Spins in biological systems offer a unique detection degree of freedom.

Purpose of the Study:

• To develop a single-molecule level molecular interaction analysis method.
• To utilize relaxometry with nitrogen-vacancy (NV) centers in diamond as quantum sensors.
• To enhance sensitivity and resolution for biomolecular interaction studies.

Main Methods:

• Utilized an optimized diamond surface functionalized with a polyethylenimine nanogel layer.
• Achieved ~10 nm average protein distance, mitigating steric hindrance.
• Employed relaxometry with ensemble and single NV centers for micrometer and nanoscale measurements.

Main Results:

• Successfully measured strong (streptavidin-biotin) and weak (bovine serum albumin-biotin) interactions.
• Enhanced sensitivity in micrometer-scale measurements by reexamining fast relaxation components.
• Achieved nanoscale detection approaching single-molecule level using single NV centers.

Conclusions:

• The developed NV-center-based relaxometry method enables single-molecule level biomolecular interaction analysis.
• This technique offers enhanced sensitivity and resolution compared to previous ensemble methods.
• Holds promise for molecular screening, identification, and kinetic studies at the single-molecule level.