Biocompatible surface functionalization architecture for a diamond quantum sensor

TL;DR

This paper presents a biocompatible surface functionalization method for diamond quantum sensors, enabling stable, high-coherence quantum sensing of individual biomolecules in physiological conditions.

Contribution

It introduces a novel thin functionalization architecture that allows precise control of biomolecule immobilization and maintains qubit coherence and stability in biological environments.

Findings

Achieved near-surface qubit coherence approaching 100 μs.

Demonstrated stable biomolecule immobilization on diamond surface for over five days.

Provided a chemically stable interface compatible with physiological conditions.

Abstract

Quantum metrology enables some of the most precise measurements. In the life sciences, diamond-based quantum sensing has enabled a new class of biophysical sensors and diagnostic devices that are being investigated as a platform for cancer screening and ultra-sensitive immunoassays. However, a broader application in the life sciences based on nanoscale nuclear magnetic resonance spectroscopy has been hampered by the need to interface highly sensitive quantum bit (qubit) sensors with their biological targets. Here, we demonstrate a new approach that combines quantum engineering with single-molecule biophysics to immobilize individual proteins and DNA molecules on the surface of a bulk diamond crystal that hosts coherent nitrogen vacancy qubit sensors. Our thin (sub-5 nm) functionalization architecture provides precise control over protein adsorption density and results in near-surface qubit coherence approaching 100 {\mu}s. The developed architecture remains chemically stable under physiological conditions for over five days, making our technique compatible with most biophysical and biomedical applications.