Implants that deliver a drug to just the right place in the body could become 鈥渂iobatteries鈥� that release the drug at exactly the right rate.
At present, it is difficult to control how quickly implants release their payload. The biobattery produces a current of a known strength, and it is this that controls the drug鈥檚 release.
The smart implant is based on magnesium alloy stents that are being developed for surgeons to use as temporary splints to keep damaged blood vessels in shape while they heal. Magnesium is used because it will corrode away inside the body safely when the stent鈥檚 job is done.
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A team led by Gordon Wallace of the University of Wollongong in New South Wales, Australia, made use of this to make a biobattery from a magnesium alloy anode and a conducting polymer cathode that carried an anti-inflammatory drug. They immersed the device in an electrolyte to simulate the body fluids around a real implant.
As the magnesium oxidised and the polymer reduced, a current was generated in the device that reversed the electrostatic charges holding the drug molecules to the polymer.
To fine-tune the rate of , the team coated the magnesium alloy with a biodegradable polymer that slowed its corrosion. The drug release rate is engineered into the device鈥檚 structure, Wallace told the in Lorne near Melbourne last week. The devices could be used in any implant that corrodes, such as titanium hip joints, which form titanium oxide on their surface.
