It may seem unusual to coat something rare (tiny pieces of diamond) with the main ingredient in sand, but the end result has many valuable applications. The catch is that no one is sure how the two ingredients go together.

Now researchers at San Jose State University (SJSU) report in the journal ACS Nanoscience AuIt was concluded that alcohol chemical groups on the diamond surface are responsible for the uniform silica shell, which could help create better silica-coated nanodiamonds (tiny tools). with applications from cancer cell biolabeling to quantum sensing.

A team of researchers uncovered the coupling mechanism thanks to powerful X-ray radiation produced by the Stanford Synchrotron Radiation Facility (SSRL) at DOE’s SLAC National Accelerator Laboratory.

“Now that we know these finer details—how the connection works rather than just guessing—we can better explore new diamond hybrid systems,” said Abraham Wolcott, the study’s principal investigator and SJSU professor.

Much of Wolcott’s work involves nanodiamonds, which are synthetic diamonds broken into pieces so small that 40,000 of them would be needed to cover the width of a single human hair. In theory, nanodiamonds have perfect carbon lattices, but sometimes a nitrogen atom sneaks in and replaces the carbon atom next to the missing carbon atom. Technically it’s a flaw, but it’s useful; the defect responds to magnetic fields, electric fields, and room temperature light; This means nanodiamonds have many applications.

They can be used as qubits, the basic unit of a quantum computer. When you shine a green light on them, they glow red, so biologists can place them inside living cells and watch them move. However, scientists cannot easily program nanodiamonds to go where they want, and the edges of diamonds are sharp and can tear cell membranes.

Coating them with silica solves both problems. Silica forms a smooth, uniform shell that covers sharp edges. It also creates a modified surface that scientists can decorate with labels to direct the particles to specific cells, such as cancer cells or neurons. “The silica-coated diamond becomes a controlled system,” Wolcott said.

But Wolcott said scientists have not agreed for some time on how this crust formed. His team showed that ammonium hydroxide with ethanol, chemicals often involved in the coating process, produced many alcohol groups on the nanodiamond surface, and that these alcohols contributed to the growth of the shell.

“No one could explain this for over 10 years, but we were able to extract this information,” Wolcott said.

After examining the particles using transmission electron microscopes at Lawrence Berkeley National Laboratory, the researchers applied SSRL X-rays on the nanodiamonds to probe surfaces hidden beneath the silica coating.

SSRL’s Transition Edge Sensor, an ultrasensitive thermometer that collects temperature changes and converts them into X-ray energy, discovered which chemical groups are present on the surface of nanodiamonds.

Using a second method, X-ray absorption spectroscopy (XAS), the team produced moving electrons on the nanodiamond surface and then captured them as they escaped through the silica shell. The thicker the coating, the fewer electrons reached the surface. The signals acted like a small tape measure, indicating the thickness of the silicone coating on the nanometer scale.

“XAS is powerful because you can detect something submerged, hidden in water, like a diamond, underneath the silicate shell,” Wolcott said. “People have never done this with nanodiamonds before, so in addition to elucidating the mechanism of attachment, we have shown that XAS is also useful to materialists and chemists.”

Known for providing applied research opportunities, Wolcott wants to involve students in coating nanodiamonds with other materials in the future. For example, oxides of titanium, zinc and other metals could open new opportunities for quantum sensing and biolabeling applications.

Ph.D. in biomedical engineering. “Nanodiamonds are incredible micro-tools that can be applied instantly,” said Karen Lopez. student at UC Irvine, like other SJSU authors, worked on the study as an undergraduate. “Now that we understand how the silicate shell forms, we can begin to optimize it and extend it to other types of materials.” Source