In Spain they have been developing a chemical process whereby nano-particles can be hollowed out into different shapes and used in aiding scans and drug therapies. Scientists at the Catalan Institution of Nanotechnology has been refining the 'galvanic effect', whereby gold cations oxidise silver atoms at room temperature. The silver ions formed then dissolves in a given solution and the solid gold metal is deposited on the silver cube. This leads so some surfaces of the silver solid being protected whilst further redox occurs; this leads to a single hole in the cube. This then catalyses the 'Kirkendall effect' where silver atoms 'migrate' to the gold on the outside creating a void in the cube.
The galvanic effect and the Kirkendall effect have been around for years however the reactions were too aggressive. Now the process is more successful; scientists have altered the method to make the silver more resistant, the cationic gold less aggressive and bi-products which do not interfere. This gives scientists an increased ability to control the shape of the nano particles. These can be used to develop MRI scanning techniques and administrating controlled drugs on a nano-scale.
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