In developing nations, it can be very difficult for people to get to health care facilities on a frequent basis. This means that if someone is getting vaccinations that require multiple injections to be administered over multiple days, they often won't get them all. A solution may be on the way, however – scientists at MIT have created a system that allows many doses of medicine to be delivered over an extended time period, via a single injection.
Led by Prof. Robert Langer, the team developed microparticles made from a biocompatible, biodegradable, FDA-approved polymer. Looking sort of like tiny cube-shaped coffee cups, these particles get filled with a vaccine, which is then sealed inside by placing a "lid" on each cup.
Once injected into the body, the microparticles degrade at different rates, depending on how the polymer is formulated – upon degrading, they release the vaccine. This means that while some could release their payload quickly, others wouldn't do so for considerably longer. In lab tests on mice, the particles successfully released their payloads at 9, 20 and 41 days after all being injected together.
The microparticles are made by depositing layers of polymer over an array of silicon molds for the cups and the lids. Using an automated system, the cups are then filled with vaccine, after which the lids are aligned with them and lowered down into place. By applying heat, the cups and lids fuse together, trapping the medication inside.
The process is known as SEAL (StampEd Assembly of polymer Layers) and according to MIT, it could conceivably even allow for newborn babies to receive a single injection that would deliver all of the vaccines they would need during the first one or two years of life.
"We are very excited about this work because, for the first time, we can create a library of tiny, encased vaccine particles, each programmed to release at a precise, predictable time, so that people could potentially receive a single injection that, in effect, would have multiple boosters already built into it," says Langer. "This could have a significant impact on patients everywhere, especially in the developing world where patient compliance is particularly poor."