Biomolecular Quantum Sensing

In recent years, color centers in diamond have been shown to be an outstanding atomic-scale sensor for magnetic fields. With these defects in diamond – more precisely nitrogen-vacancy (NV) centers – nuclear magnetic resonance (NMR) signals from a few cubic nanometer sample volumes or even single molecules have been detected. We aim to establish NV-diamond NMR as a tool in chemistry and life sciences by an interdisciplinary approach at the interface of chemistry, physics and biology. 

We are currently funded by the Deutsche Forschungs Gemeinschaft (DFG) within the Emmy Noether program, by the European Research Council with an ERC Starting Grant, by the Munich Excellence Clusters MCQST and E-conversion as well as by the Fonds der Chemischen Industrie.

Most recent papers

Surface NMR using quantum sensors in diamond

Kristina S. Liu, Alex Henning, Markus W. Heindl, Robin D. Allert, Johannes D. Bartl, Ian D. Sharp, Roberto Rizzato, Dominik B. Bucher

 Characterization of the molecular properties of surfaces under ambient or chemically reactive conditions is a fundamental scientific challenge. Moreover, many traditional analytical techniques used for probing surfaces often lack dynamic or molecular selectivity, which limits their applicability for mechanistic and kinetic studies under realistic chemical conditions. Nuclear magnetic resonance spectroscopy (NMR) is a widely used technique and would be ideal for probing interfaces due to the molecular information it provides noninvasively. However, it lacks the sensitivity to probe the small number of spins at surfaces. Here, we use nitrogen vacancy (NV) centers in diamond as quantum sensors to optically detect nuclear magnetic resonance signals from chemically modified aluminum oxide surfaces, prepared with atomic layer deposition (ALD). With the surface NV-NMR technique, we are able to monitor in real-time the formation kinetics of a self assembled monolayer (SAM) based on phosphonate anchoring chemistry to the surface. This demonstrates the capability of quantum sensors as a new surface-sensitive tool with sub-monolayer sensitivity for in-situ NMR analysis with the additional advantage of a strongly reduced technical complexity. 

Geometry dependence of micron-scale NMR signals on NV-diamond chips

F. Bruckmaier, K. Briegel, D .B. Bucher

 Small volume nuclear magnetic resonance spectroscopy (NMR) has recently made considerable progress due to rapid developments in the field of quantum sensing using nitrogen vacancy (NV) centers. These optically active defects in the diamond lattice have been used to probe unprecedented small volumes on the picoliter range with high spectral resolution. However, the NMR signal size depends strongly on both the diamond sensor’s and sample’s geometry. Using Monte-Carlo integration of sample spin dipole moments, the magnetic field projection along the orientation of the NV center for different geometries has been analyzed. We show that the NMR signal strongly depends on the NV-center orientation with respect to the diamond surface. While the signal of currently used planar diamond sensors converges as a function of the sample volume, more optimal geometries lead to a logarithmically diverging signal. Finally, we simulate the expected signal for spherical, cylindrical and nearly-2D sample volumes, covering relevant geometries for interesting applications in NV-NMR such as single-cell biology or NV-based hyperpolarization. The results provide a guideline for NV-NMR spectroscopy of microscopic objects.