All-fiber quantum relaxometry for biochemical sensing based on diamond NV centers

Area of Science:

• Quantum sensing
• Nanotechnology
• Biochemical analysis

Background:

• Nitrogen-vacancy (NV) centers in nanodiamonds are sensitive to surface noise, enabling quantum relaxometry.
• This sensitivity has been leveraged for advanced biochemical sensing applications.

Purpose of the Study:

• To develop a compact, all-fiber quantum probe utilizing NV center relaxometry.
• To investigate the influence of surface electric and magnetic noise on NV center longitudinal relaxation time (T1).
• To demonstrate the probe's capability for sensitive and specific biochemical detection.

Main Methods:

• Chemically anchoring nanodiamonds onto a cone fiber tip to create an all-fiber probe.
• Theoretical analysis and experimental validation of T1 dependence on pH (electric noise) and Gd3+ concentration (magnetic noise).
• Implementation of a Gd3+-tagged-biotin and streptavidin model for detecting biotin.

Main Results:

• T1 of NV centers decreased with increasing pH and Gd3+ concentration, aligning with theoretical predictions.
• The all-fiber probe detected biotin with a limit of 168 nM.
• The probe exhibited good specificity in detecting biotin.

Conclusions:

• A novel all-fiber quantum probe based on NV center longitudinal relaxometry was successfully developed.
• The probe leverages the unique spin properties of NV centers for enhanced sensitivity and specificity.
• This technology holds significant potential for advanced biological detection and sensing applications.