A new study published in Nature Communications reveals how scientists have created an injectable hydrogel that can deliver drugs over specific time periods, eliminating the surgical implantation required with existing hydrogels. The researchers say the new hydrogel could help treat a number of diseases, including macular degeneration, heart disease and cancer. Share on Pinterest These images show the structure of the newly created hydrogel at different magnifications.

Image credit: Mark Tibbitt The use of gels to deliver drugs is an increasing area of interest for researchers. While conventional liquid solutions allow drugs to be dispersed throughout the body straight away, gel-based solutions can release drugs over long periods of time. In addition, gels can be molded into certain shapes, allowing drug delivery to specific parts of the body. But there is a problem with current drug-delivery gels; once molded, they cannot be reshaped, meaning they often need to be implanted with surgery. The research team – co-led by Mark Tibbitt of the Koch Institute for Integrative Cancer Research at Massachusetts Institute of Technology (MIT) – set out to tackle this problem.

Hydrogel made of polymer-containing nanoparticles and cellulose According to Tibbitt and colleagues, researchers have previously created drug-delivery hydrogels using chemical connections between polymers – long chains of molecules – that are irreversible. The researchers note that while such gels are extremely tough – a feature needed to withstand long-term use – it can be very difficult to alter their shape once they are molded. In the past, scientists have attempted to tackle this issue by developing proteins that assemble into hydrogels by themselves, but the MIT team says such a process is complex. In their study, they adopted a simpler approach. The researchers used nanoparticles consisting of PEG-PLA copolymers, which are widely used for drug delivery. In order to form their new hydrogel, the researchers combined these PEG-PLA copolymers with another polymer called cellulose. Since most nanoparticles have a weak bond with polymer chains, the connection between the PEG-PLA copolymer-containing nanoparticles and cellulose was loose. As such, each connection is able to soften under physical stress, allowing the hydrogel to be injected through a syringe. However, when such stress is absent, the nanoparticle and cellulose form new connections, meaning its toughness is restored. “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,” explains Tibbitt.