Improved nano diamonds production to improve bio imaging of proteins

By developing a new way to keep tiny nano-sized diamonds separated during production, Australian scientists have opened new avenues in medical imaging.

With the new discovery, scientists can see new light properties not exhibited by larger diamonds.

Led by associate professor James Rabeau of Macquarie University in Sydney, the researchers created and studied the tiny synthetic diamonds, which are between four and five nanometres in size— a thousand times smaller than the width of a human hair.

The researchers said that proteins are hard to track in living bodies, but by attaching bright markers, it's possible to see where they are and where they're going.

Existing techniques employ fluorescent probes which can often extinguish or turn dark and may be toxic in a live body.

The researchers created the synthetic nano diamonds through a detonation process and isolated them from the carbon graphite matrix using acid cleaning and ultrasound.

The nano diamonds attach to the proteins, making it easier to detect with medical imaging devices.

"The key was keeping the nano diamonds separate and stopping them from clumping back together. This gave us a chance to study them in isolation using a laser to see how bright they are," ABC Science quoted Rabeau as saying.

"And we were able to determine that the nitrogen impurities which helps them glow, was present in these nano diamonds,” he added.

The discovery that they blink is an important clue about how the light is changed depending on the size of the crystal, said Rabeau.

"In larger diamonds, the light emission or fluorescence remains steady, essentially immune to blinking on and off. But we found that when the atoms are trapped in nano-diamonds which are much smaller, they start to act a bit differently by blinking, most likely because of their closer proximity to the nano diamond surface," he said.

The researchers found that by encapsulating the nano diamonds in a polymer sheath, this irregular fluorescence behaviour could be reversed.

He describes the work as a big step in developing existing ideas on using nano-diamonds for bio imaging, and said that it may herald new technologies, which exploit the blinking optical feature.

The study has been published in the journal Nature Nanotechnology.