Bioinspired polymers self-assemble like proteins

RESEARCHERS in the US have worked out how to make polymer chains self-assemble into a desired structure in a similar way to biological molecules like proteins, by tuning the electrostatic charges.

In proteins, the amino acid monomers self-assemble in precise sequences to control the function of the protein. While the complexity of the information stored within proteins is difficult to replicate, researchers at the University of Illinois and the University of Massachusetts, Amherst, sought to find a technique to control the sequence of synthetic polymer monomers to control their function. They say that their “charge patterning” technique” could lead to new ways to design and assemble bioinspired smart materials for uses such as drug delivery and sensors.

The team used polymers called complex coacervates for their experiments. The polymers separate into two phases, a polymer-dense coacervate phase and a polymer-dilute supernatant phase, much like oil and water, and form a gel-like substance.

“Manufacturers commonly use coacervates in cosmetics and food products to encapsulate flavours and additives, and as a way of controlling the 'feel' of the product. The challenge has been if they need to change the texture or the thickness, they would have to change the material being used,” said Illinois professor of chemical and biomolecular engineering Charles Sing.

The monomers in coacervates are electrostatically charged. By changing the sequence or pattern of charges along the polymer chain, the researchers found that they rearrange, providing a way to engineer the properties of the gel.

“This is how biology makes the endless diversity of life with only a small number of molecular building blocks,” said Massachusetts chemical engineering professor Sarah Perry. “We envision bringing this bioinspiration concept full circle by using coacervates in biomedical and environmental applications.”

Nature Communications doi.org/cf2t