Researchers at MIT have developed a biocompatible polymer gel with potential for drug delivery. The new gel uses caffeine as a gentle and biocompatible catalyst during its manufacture, unlike many other gels that require harsh catalysts or manufacturing conditions that can ruin sensitive biological drugs intended for delivery or pose health risks for patients.
The researchers are developing a variety of biocompatible drug delivery materials. In the case of hydrogels, these consist of a flexible polymer matrix loaded with a therapeutic drug, which is released over time, either at a site of implantation, or in the gut if the gel is ingested. Gel-loaded drugs could provide a “gummy-bear” chewable alternative to conventional tablets. “It’s really appealing for patient populations, especially children, who have difficulty with swallowing capsules and tablets,” says Giovanni Traverso, a researcher involved in the study.
One of the main challenges in this field involves modifying a polymer material so that it is suitable for a given purpose, without destroying its therapeutic drug cargo. Many polymer gels require metal catalysts, which could pose risks to patients if traces of them remain in the gel. The MIT researchers were inspired to find new catalysts that are based on food products, and safe to ingest. They turned to a familiar plant-based substance to catalyze their gel: caffeine.
“Most synthetic approaches for synthesizing and cross-linking polymeric gels and other materials use catalysts or conditions that can damage sensitive substances such as biologic drugs. In contrast, here we used green chemistry and common food ingredients,” said Robert Langer, a researcher involved in the study. “We believe these new materials could be useful in creating new medical devices and drug delivery systems.”
The research team used caffeine to prompt citric acid (another plant-based edible material) to form a polymer network with polyethylene glycol (PEG). PEG has a long history as a biocompatible polymer and is a component of consumer products such as toothpaste. The gels contain about as much caffeine as found in a cup of tea and initial safety tests in rats have shown no harmful effects.
The resulting rubbery gel has significant potential as a drug delivery material. By changing the composition of the gel, the research team could vary its mechanical and chemical properties, allowing them to tune the strength of the material, and how quickly it released loaded drugs. “Depending on what the application may be, or what drugs are being incorporated, you could mix and match to find an optimal mixture,” said Traverso.
Study in Biomaterials: Caffeine-catalyzed gels…