Spin-enhanced nanodiamond biosensing for ultrasensitive diagnostics.

Area of Science:

• Quantum sensing
• Nanotechnology
• Biomedical diagnostics

Background:

• Nitrogen-vacancy defects in diamond possess quantum spin properties applicable to quantum technologies.
• Fluorescent nanodiamonds offer attractive characteristics for in vitro biosensing, such as brightness and cost-effectiveness.
• Current nanoparticle biosensors often lack the sensitivity required for early disease detection.

Purpose of the Study:

• To investigate fluorescent nanodiamonds as an ultrasensitive label for in vitro diagnostics.
• To enhance biosensor sensitivity by modulating nanodiamond emission using microwave fields and frequency-domain analysis.

Main Methods:

• Utilized fluorescent nanodiamonds as labels in a lateral flow assay.
• Employed microwave fields to modulate nanodiamond emission intensity.
• Applied frequency-domain analysis to distinguish signals from background autofluorescence.

Main Results:

• Achieved a detection limit of 8.2 × 10⁻¹⁹ molar for biotin-avidin, 10⁵ times more sensitive than gold nanoparticles.
• Demonstrated single-copy detection of HIV-1 RNA with a 10-minute isothermal amplification step.
• Successfully validated the platform using a clinical plasma sample.

Conclusions:

• Fluorescent nanodiamonds provide an ultrasensitive platform for in vitro diagnostics, significantly improving upon existing nanoparticle biosensors.
• The quantum diagnostics platform is versatile and applicable to various diagnostic formats and diseases.
• This technology holds potential for transforming early disease diagnosis, benefiting patient outcomes and public health.