Electric shock for controlled release
25 May 2006
US biomedical engineers have used gold electrodes to improve the method for controlled release of biomolecules. They say the method is a marked improvement on current technologies, giving greater control over when, where and how many biomolecules are released.
The team at Johns Hopkins University, Baltimore, led by Peter Searson, used thiol linkages to cover gold electrodes with a self-assembling layer of amine groups. They used a variable length spacer molecule to attach a suitable receptor molecule to a terminal succinimide group, which naturally binds to the amine groups. Finally, they attached the biomolecule to the receptor molecule.
Applying a current to the gold electrodes reduced the thiol, breaking the bond with the electrode and releasing the entire molecular chain, including the biomolecule. Using the protein biotin (which binds strongly with the protein avidin) as the receptor and coupling this with fluorescently-labelled avidin as the biomolecule, Searson's team showed they could release avidin from individual electrodes on command.
They also found they could release polystyrene nanoparticles on command, by either binding them to avidin or directly to the succinimide groups.
The researchers are now exploring the full potential of this new technique. 'We are working on developing a deeper scientific understanding of the fundamental processes and we are also exploring specific applications,' Searson told Chemistry World.
Other biomedical researchers praised the research. Thomas Webster, associate professor of biomedical engineering at Brown University, Providence, US, called it 'a beautiful example of nanomedicine research'. Tony Cass, deputy director of the Institute of Biomedical Engineering at Imperial College, London, said: 'Applications of this technology could include drug delivery and microinjection of proteins, nucleic acids or nanoparticles into cells.'
P Mali et al, Nano Letters (DOI: 10.1021/nl0609302)