A new kind of artificial protein-like molecule created at Ohio State University could lead to new drugs, medical treatments and faster computer chips.
‘Proteins come in so many shapes and sizes that they are able to perform a wide variety of functions,’ said Jonathan Parquette, assistant professor of chemistry at Ohio State. ‘We wanted to mimic that versatile structure in a synthetic form.’
Parquette and his students built the molecules, called dendrimers, from tiny, plastic filaments. Researchers have long tried to mimic the shape of proteins using dendrimers, but the Ohio State group is said to be the first to coax the soft, tangled filaments to maintain a shape that suits needed applications.
The sub-biomedical microelectromechanical (BioMEM) molecule is shaped like a sphere and is supported by branching beams of polymer inside, with hollow portions that could theoretically hold drugs or other chemicals.
Ultimately, synthetic proteins could act as devices to deliver medicine to tumours or other sites of disease in the body. They could also act as catalysts for chemical reactions that produce drugs, or form computer chips for light-responsive molecular electronics.
For these molecules to perform such tasks, the outer shell would have to open and close on cue, Parquette explained. A molecule could locate a tumour, for instance, and unravel its structure to release cancer-fighting medicine from within.
‘Along the outside of the molecule, the atoms fasten together like a zipper,’ Parquette explained. ‘Getting them to zip up is half the puzzle. Getting them to unzip on demand is the other half.’
With chemicals, the researchers caused the normally long, stringy dendrimers to fold into a protein-like shape. Then they added other chemicals that bound themselves to select sites along the dendrimers, effectively zipping together layers of folds and stiffening the structure overall.
Currently, Parquette and his colleagues are investigating whether light could be used as a stimulus to make the dendrimers unfold. If so, the protein-like molecules could form the basis for extremely tiny, very fast computer chips.
Whereas semiconductor computer chips carry a digital signal of ‘one’ or ‘zero’ based on the presence of an electron, molecular computer chips stimulated by light from fibre optics could carry a signal based on whether individual molecules were ‘zipped’ or ‘unzipped.’
‘On the nanoscale, it seems that atoms have a way of co-operating together to assume certain structures for specific functions,’ said Parquette. ‘If we can learn to harness that cooperativity, we may be able to form better synthetic molecules.’
Parquette described his work in September at the BioMEMS and Biomedical Nanotechnology World 2001 meeting in Columbus, Ohio.