Cheaper alternatives to nanodiamonds, such as fluorescent dyes or small chunks of semiconductor known as quantum dots, are in use already. The diamonds, though, are less prone to blinking on and off than fluorescent dyes, and are not toxic to cells, unlike quantum dots.
Image showing the internalization of green fluorescent diamonds by a cancer cell
FNDs are usually made by firing a high-energy electron beam into commercially available diamond powder and heating it up to 800 °C. Huan-Cheng Chang and colleagues at Academia Sinica in Taipei shoot a much less intense, and hence cheaper, beam of helium ions at diamond powder to make FNDs of the same quality.
The Taiwanese researchers used a purpose-built machine to bombard nanodiamonds with high-energy helium ions. This causes defects to form in the structure of the diamonds so that they fluoresce when they are hit by laser light.
‘Our high-fluence medium-energy (40 keV) helium ion beam can be operated safely and routinely in ordinary laboratories,’ says Huan-Cheng Chang, who led the team with Wunshain Fann at the National Taiwan University. The team have already started selling their nanodiamonds – charging around £150 for 10mg – a hundredth of the cost of those made by conventional methods
About $300 for 10 milligrams.
Chang’s team could track the movement of a single fluorescent nanodiamond within a cell for over 3 minutes.
The researchers have also explored other applications for their cheap diamonds, such as using them to monitor stem cells in developing tissue, or to carry drugs into cells.
“In particular, we have demonstrated that FNDs are able to interact with plasmid DNA and to deliver different genes into cultured human cells,” Chang told New Scientist. That could be used for gene therapy, or DNA vaccines.
Chang and his colleagues have set up a commercial operation selling their nanodiamonds and are working on making them even smaller and to fluoresce more brightly.
The cheaper diamond chips need to be made smaller, though, if they are to perform well as markers to reveal the inner workings of cells, he adds.