Researchers from San Jose State University (SJSU) have discovered the binding mechanism responsible for the formation of uniform silica coatings on nanodiamonds. The team used powerful X-rays generated by the Stanford Synchrotron Radiation Lightsource (SSRL) at the SLAC National Accelerator Laboratory to study the nanomaterials. The results, published in the journal ACS Nanoscience Au, provide crucial information about the chemistry involved in creating silica-coated nanodiamonds.

Nanodiamonds are ultra-small synthetic diamonds with remarkable properties. Despite their tiny size, nanodiamonds have perfect carbon structures and can exhibit responses to magnetic fields, electric fields, and light at room temperature. These unique characteristics make nanodiamonds suitable for various applications, such as quantum computing and biological cell marking.

To enhance the functionality of nanodiamonds, researchers have turned to coating the diamond particles with silica. Silica not only provides a smooth and protective layer for the nanodiamonds but also allows for surface modification. By adding specific labels to the silica coating, scientists can direct nanodiamonds to specific cells or locations. This control over the movement of nanodiamonds has significant implications in biomedical and biotechnology applications.

For over a decade, scientists have been wondering about the mechanism behind the formation of silica coatings on nanodiamonds. The SJSU researchers discovered that alcohol chemical groups on the surface of nanodiamonds play a crucial role in facilitating the growth of silica layers. They found that the introduction of ammonium hydroxide with ethanol during the coating process produces these alcohol groups.

To examine the hidden surfaces beneath the silica coating, the SJSU researchers utilized the X-ray facilities at the SSRL. They used a transition edge sensor, a super-sensitive thermometer, to detect temperature changes and convert them into X-ray energies. Through X-ray absorption spectroscopy (XAS), the team investigated the surfaces of the nanodiamonds and measured the thickness of the silica coating on a nanoscale. The results demonstrated the effectiveness of XAS in studying submerged materials like nanodiamonds.

The knowledge gained about the binding mechanism of silica-coated nanodiamonds opens up new avenues for researchers. Abraham Wolcott, the lead researcher of the study, plans to explore the use of other materials, such as titanium and zinc oxides, to coat nanodiamonds. These alternative coatings could further expand the applications of nanodiamonds in quantum sensing and biological marking.

The findings of this research provide valuable insights into the chemistry of nanodiamond coatings and offer opportunities to optimize the silica layer and explore other coating materials. With a better understanding of the chemical mechanism behind silica-coated nanodiamonds, researchers can continue unlocking the potential of these tiny diamonds for applications in quantum computing and biological marking.

– Perla, J. Sandoval et al. “Quantum Diamonds at the Beach: Chemical Insights into Silica Growth on Nanoscale Diamond using Multimodal Characterization and Simulation”, ACS Nanoscience Au (2023). DOI: 10.1021/acsnanoscienceau.3c00033