New nanogel to deliver multiple drugs

Scientists have designed a new type of self-healing hydrogel that could be injected through a syringe. It can be used in killing tumours, among other applications.

The gel can carry one or two drugs at a time and could be useful for treating cancer, macular degeneration or heart disease, among other diseases, the researchers say.

Scientists are interested in using gels to deliver drugs because they can be moulded into specific shapes and designed to release their payload over a specified time period.

However, current versions aren't always practical because they must be implanted surgically.

"Now you have a gel that can change shape when you apply stress to it, and then, importantly, it can re-heal when you relax those forces.

"That allows you to squeeze it through a syringe or a needle and get it into the body without surgery," said study author Mark Tibbitt of the Massachusetts Institute Of Technology.

Scientists have previously constructed hydrogels for biomedical uses by forming irreversible chemical linkages between polymers.

These gels, used to make soft contact lenses, among other applications, are tough and sturdy, but once they are formed their shape cannot be easily altered.

The MIT team set out to create a gel that could survive strong mechanical forces, known as shear forces, and then reform itself.

"We're working with really simple materials. They don't require any advanced chemical functionalisation," Tibbitt said.

The MIT approach relies on a combination of two readily available components. One is a type of nanoparticle formed of PEG-PLA copolymers, to form a hydrogel, the researchers mixed these particles with a polymer - in this case, cellulose.

Using two components to form the gel also gives the researchers the opportunity to deliver two different drugs at the same time.

Furthermore, the properties of each gel component can be tuned so the drugs they carry are released at different rates, allowing them to be tailored for different uses.

The researchers are also pursuing the possibility of using this gel to deliver cancer drugs to kill tumour cells that get left behind after surgery.

In that case, the gel would be loaded with a chemical that lures cancer cells toward the gel, as well as a chemotherapy drug that would kill them.

This could help eliminate the residual cancer cells that often form new tumours following surgery.

"We can tailor the materials to provide us with the drug-release profile that makes it the most effective at actually recruiting the cells," the researchers wrote.

The findings were published in Nature Communications.