Chemotherapy can do a lot of good but it requires targeted delivery to become even better, preventing healthy cells from being damaged as medication seeks out cancer cells. Inspired by this need for targeted drug delivery, researchers developed a new way to package at least two ingredients into one capsule, triggering mixing as needed.

In a study published in Applied Physics Letters, the researchers detailed the method for encapsulating multiple ingredients as well as the mixing process that can be triggered when the drug is close to the tumor area.

According to Ronald Xu, one of the authors for the study, one of chemotherapy's limitations is that less than 5 percent of cancer drugs make it to the tumor's site. The rest is absorbed by other parts of the body.

One of the ways to address this problem is to make drugs non-toxic upon administration and then triggering the ingredients to mix so that toxic products are produced only once they are near the site of the tumor.

The tiny capsules developed by Xu and his team are about as small as a dust speck. To come up with designated capsule sizes, the researchers used models to assess the relationship between final capsule sizes and process parameters.

The capsules work by funneling ingredients through two inner needles enclosed by a larger needle. Droplets are formed as the ingredients pass through just one nozzle, which are then stabilized by an electric field. Depending on relative flow rates, every droplet may have two or more droplets inside.

During experiments, the researchers were able to produce up to 100,000 capsules for every second, with almost 100 percent efficiency in incorporating inner ingredients without waste. The ingredients don't mix automatically, however, needing triggered vibrations to force them to merge. To release the ingredients, the researchers dissolved the capsule's outer shell.

Fine-tuning the production process further can make it possible to create capsules about as big as red blood cells. Adding additional inner needles will also allow for three or more ingredients to be encapsulated.

While improving drug delivery is the primary focus of the study, the researchers said that the encapsulation technology can also be used wherever controlled reactions are needed, such as in chemical and nuclear engineering and regenerative medicine.

Photo: Bill Brooks | Flickr