Precious Cargo: Nanotechnology enlists silk, diamonds and gold to improve molecular medicine

Nanomedicine incorporates some of the most prized materials on earth in order to improve not only its biocompatibility and imaging potential, but its ability to sneak up on and change the way that cells function for the tiniest aspect of personalized medicine.

Recent studies have presented such nanostructures that incorporate silk and nanodiamonds that improve optical imaging and gold ‘nanomotors’ that could potentially break down specific cancer cells or deliver drug treatment at the nanoscale.

In one study published Feb. 1 in Biomedical Optics Express, researchers including Asma Khalid from the School of Physics at the University of Melbourne, Parkville, Australia, enlisted silk as a highly transparent coating matrix in order to improve the optical imaging capability of fluorescent nanodiamonds. These structures have negatively charged nitrogen vacancy centers that are considered particularly photostable single photon emitters. Red fluorescence is emitted by the center when liaised with a green laser, and such optical excitation and imaging does not seem to disrupt cellular processes.

This material has the potential to surpass quantum dots in the realm of nanoimaging because the latter has limitations related to toxicity that hybrid silk-nanodiamond agents do not. Silk-fibrin films have been used for some time due to their biocompatible, degradable and flexible structures.

“These properties make silk an outstanding material and an excellent substrate for the fabrication of implantable and degradable bio-optical devices,” wrote Khalid et al.

Nanodiamonds are made even more valuable, and visible, with the help of a silk matrix because it appears to be non-toxic and raises imaging counts up almost four-times that of nanodiamonds that are not coated in silk.

“We expect numerous biotechnical and medical applications to emerge as these two extraordinary materials perfectly complement each other,” the authors wrote. “Future work includes integrating biochemistry into silk and testing the change of emission in [nanodiamond-silk] system upon a binding event. Investigation of more integrated pump and probing sources will be performed so that the device will, eventually, be one integrated chip.”

In another recent study published Jan 26. in Nature Nanotechnology, Leo Y. T. Chou, from the Institute of Biomedical materials and Bioengineering at University of Toronto, Canada, and colleagues are enlisting a different kind of precious material—DNA—to assemble nanoparticle superstructures that can be used in cancer imaging and therapeutics to improve tumor retention while also ensuring better whole body elimination. These inorganic structures can be built to 1-100 nanometer size and tend to be designed with robustness in mind in order for them to remain in tumors long enough to do their bidding. However larger particles tend to lead to chronic toxicity because they don’t biodegrade as well or pass out of the body easily.

In this study, researchers used DNA to build smarter, multi-layered colloidal nanostructures that act like organic structures at about the six-nanometer scale, which is eliminated with more ease by the kidneys. Gold nanoparticles were also found to avoid macrophage sequestration, ensuring better drug delivery and controlled elimination.

“The use of DNA and nanoparticle technologies together can help translate fundamental nanomaterial design principles that are being discovered into clinically relevant nanomedicine solutions,” the researchers wrote.

The promise of gold nanoparticles extends to a range of optical and biomedical applications, as published Jan. 13 in the Angewandte Chemie International Edition and later reported by CNN earlier this month. Didier Astruc, PhD, from the University of Bordeaux in Talence Cedex, France, et al reviewed Anisotropic gold nanoparticles for their enhanced ability to facilitate not just diagnostics, but theranostics that target and modify specific disease processes including cancer. And the advent of golden-rod ‘nanomotors’ means that cellular-level surgery could one day be possible, but probably not for some years to come.