When we think about precious gems and beautiful fabrics, complex medical procedures are most likely the last thing that comes to mind. For researchers at the universities of Melbourne, Sydney and Tufts however, silk and diamonds have proven invaluable in a new drug delivery system. Nanodiamonds have been around for years, helping bring cancer-fighting therapies directly to tumours without hurting the surrounding tissues. They form clusters that bind to the injected drug, releasing it slowly, and keeping harmful side effects to a minimum. By targeting tumours more efficiently, nanodiamonds have helped reduce patient suffering. And now, researchers have discovered how to make them even better – by covering them with silk.
The significance of the silk cloak
Quite a bit of clinical research has been done to keep an eye on the nanodiamond-delivered drug once it has been administered to the patient. Adding fluorescence to diamonds makes their edges too rough to be administered to cells, which are harmed upon entry and exit. Researchers originally solved the problem by coating the diamonds in lipids, which helped illuminate their progress – but now they’ve discovered that silk protein does the trick up to four times better, creating a stronger glow by which doctors can track patients’ response to the drug. The silk can also be engineered to break down slowly, helping to control the rate of drug release.
Silk has also received acclaim as a highly effective delivery system in its own right. Scientists at the Indian Institute of Technology in Kharagpur have created nanoparticles out of silk fibers that can deliver drugs to specific targets when combined with the protein found in egg whites and blood plasma. The protein strengthens the already powerful silk, and can better encapsulate and deliver the drug. Professionals in the field and students in pharmaceutical courses understand that the way in which drugs travel through the body and release their contents is critical to their success. During tests, the silk-protein bond prevented leaking, helped the medicine reach its target intact, and allowed for a controlled release of a cancer drug over the course of almost 2 weeks.
Silk and nanoneedles
Tufts University researchers David Kaplan and Fiorenzo Omenetto believe that silk can be used to improve current microneedle drug delivery systems that rely on sugar, synthetic polymers and other materials. Silk-based systems, they determined, could be more precise, safer, help keep patients from developing skin infections and also control drug release with greater precision. It also turns out that silk microneedles are more biodegradable than alternatives and help reduce the pain associated with their hypodermic counterparts. Moving through phases of pharmaceutical quality control, researchers are now testing the use of microneedles to deliver vaccines for flu and polio.