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Luxury new material for cell imaging and drug delivery

A team of researchers from Australia and the United States has created a new hybrid diamond-silk material for biological imaging and drug delivery, according to a paper published in The Optical Society’s (OSA) journal Biomedical Optics Express. In addition to the University of Melbourne, the researchers are affiliated with the University of Sydney and the Silk Lab at Tufts University in Massachusetts.

The new particles, which are tens of nanometres across, are made of diamond and covered in silk. They can be injected into living cells, and because they glow when illuminated with certain kinds of light, biologists can use them to peer inside cells and untangle the molecular circuitry that governs cellular behaviour, or to study how cells react to a new drug. The silk-coated diamond particles could also potentially be used someday in the clinic, by allowing doctors to send infection-fighting antibiotics to a targeted area of the body.

Nanodiamonds similar to those in this study have been explored previously for their potential medical uses, but this is the first time silk has been incorporated with nanodiamonds, said Asma Khalid of the University of Melbourne, who is the first author of the Biomedical Optics Express paper. ‘This nanodiamond-silk hybrid material is important due to the potential it offers to the fields of bioimaging, biosensing and drug delivery,’ she explained.

The diamonds are fed impurities to allow them to absorb and re-emit light of certain wavelengths. The diamonds are also harmless to living tissue and can work at room temperature; they are well suited to uses in biological imaging. However, they often have rough edges which can cause the nanodiamonds to become trapped in the cell membranes of the tissue it is inserted into.

By covering the nanodiamonds in silk, which is transparent, flexible, compatible with biological tissue, and biodegradable, no harmful byproducts are left inside the body.

The researchers also discovered that the silk not only preserves the optical properties of the nanodiamonds, but it enhances their brightness by two to four times. Also, the new material appears to be safe for use in the body as it left no damaging effects after being implanted inside living tissue for two weeks, suggesting that it is nontoxic and non-inflammatory, the researchers say.

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