Diamond Biosensors Detect 49 Biomolecules for Faster Diagnostics

Detecting specific biomolecules quickly and accurately remains a major challenge in biological research and medical diagnosis, often requiring complex and time-consuming techniques. Ignacio Chi-Durán from The University of Chicago, Evan J. Villafranca from Quantum Diamond Technologies Inc., and Peter C. Maurer from The University of Chicago, and their colleagues, have developed a new biosensing platform that promises to overcome these limitations. Their work introduces a scalable system integrating a high-density DNA microarray directly onto a diamond surface, enabling the simultaneous detection of 49 distinct biomolecular features. This innovative approach converts molecular recognition into a clear signal, offering a high-throughput and multiplexed sensing capability that could revolutionise molecular diagnostics and facilitate the creation of large-scale biological networks operable in complex environments.

Thanks to their high sensitivity, NV sensors could, in principle, detect specific binding events with metabolites and proteins in a massively parallel and label-free way, avoiding the complexity of mass spectrometry. Realising this vision has been hindered by the lack of quantum sensor arrays that unite high-density spatial multiplexing with uncompromising biochemical performance. Current quantum sensing approaches often struggle to balance the need for many sensors, which is essential for statistically robust measurements, with the demanding requirements of biological experiments, such as small sensing volumes and compatibility with aqueous environments. These sensors offer the potential to dramatically improve biological research and medical diagnostics by providing a massively parallel, label-free method for identifying specific molecules, bypassing the limitations of current techniques like mass spectrometry. The core of this technology lies in the ability of NV centers to sensitively respond to changes in their local environment, allowing for the detection of even subtle binding events. The team developed a method for modifying the diamond surface, creating a reactive layer that can bind to biomolecules.

This process involves applying a silane compound, followed by a series of crosslinkers and binding molecules, ultimately immobilizing the target protein. The NV centers are then characterised to understand their initial properties, such as spin coherence and relaxation times. Changes in these properties are monitored to detect the binding of the target protein, providing a clear signal of its presence. This approach requires careful control of the surface chemistry to ensure stable and well-defined functionalization. Minimising non-specific binding of proteins to the diamond surface is also crucial, as is understanding the density and distribution of NV centers. The team also considers factors like spin relaxation, electrolyte effects, and the orientation of molecules on the surface to optimise the sensor’s performance. This research provides a foundation for developing highly sensitive nanoscale biosensors for a wide range of applications.

Diamond Arrays Enable High-Throughput Biomolecule Detection

Diamond Biosensors Unlock High-Throughput Molecular Detection Researchers have developed a novel biosensing platform leveraging the unique properties of diamond to detect biomolecules with unprecedented density and specificity. This new technology promises to revolutionise fields like medical diagnostics and molecular biology by enabling massively parallel, label-free detection of a wide range of targets, bypassing the complexities of current methods like mass spectrometry. The core of this innovation lies in creating a highly sensitive array directly on a diamond surface, capable of simultaneously detecting numerous biomolecular features. The team achieved this breakthrough by developing a new method for functionalizing diamond surfaces, eliminating the need for intermediate layers typically required in these processes.

This streamlined approach significantly reduces preparation time and ensures the biomolecules are positioned as close as possible to the diamond’s sensing elements. The resulting surface supports a remarkably high density of immobilized biomolecules, approximately 27,500 per square micrometer, creating a robust platform for high-throughput analysis. Detailed imaging confirms the uniformity and quality of this functionalized layer. The biosensor operates by detecting changes in the spin relaxation of nitrogen-vacancy (NV) centers within the diamond. When a target biomolecule binds to a corresponding probe on the array, it triggers the release of a molecule attached to the diamond surface, altering the NV center’s spin and generating a detectable signal.

This “displacement assay” provides a clear binary readout, indicating the presence or absence of the target. Demonstrating the platform’s capabilities, the researchers created a 7×7 array capable of simultaneously detecting 49 different biomolecular features with high spatial resolution and reproducibility. This technology offers significant advantages over existing biosensors, enabling more comprehensive and efficient analysis in complex biological environments.

Diamond Biosensing via Quantum Spin Relaxation

Researchers have created a scalable quantum biosensing platform integrating high-density DNA microarrays directly onto a diamond surface, enabling multiplexed molecular recognition and quantum readout. By combining a streamlined surface functionalization strategy with precise DNA patterning, the team achieved robust immobilization of 49 distinct sensing elements on a single diamond chiplet. Crucially, the platform utilises a target-triggered displacement mechanism where DNA hybridization removes a paramagnetic label, restoring the spin relaxation time of nitrogen-vacancy (NV) centers and producing a detectable quantum signal. The successful demonstration of this approach addresses key challenges in NV-based biosensing, specifically surface functionalization, multiplexing, and achieving biochemical specificity.

This platform offers a blueprint for high-throughput, label-free molecular detection in complex biological environments and paves the way for developing integrated quantum diagnostics and sensor arrays. While the initial experiments focused on DNA sensing, the researchers note the platform can be readily adapted to detect a wide range of small molecules or proteins by substituting the complementary DNA strand with an appropriate aptamer. Further research is needed to explore the platform’s performance in more complex biological media and to optimise the signal-to-noise ratio for enhanced sensitivity.