New Microcapsules Can Provide Safe and Effective Bimolecular Drug Delivery

Release Date: 05-Oct-2019

Recently, a team of researchers at Harvard's Wyss Institute for Biologically Inspired Engineering and John A. Paulson School of Engineering and Applied Sciences (SEAS), created an advanced type of microcapsules that can deliver the drug more accurately. They created microcapsules with shells of non-uniform thickness that allows them to burst at lower osmotic pressures, making them safer for use in the human body. The research is published in Small.

The researchers used a glass capillary device, which is microfluidic, for the creation of their inhomogeneous microcapsules. The microfluidic device is able to employ a water-in-oil-in-water method to encapsulate a water solution containing sucrose, an osmotic agent, within a shell of monomers suspended in oil.

After that, the monomers are exposed to UV light and they starts reacting each other and crosslink to form a solid, polymer shell around the sucrose solution. By altering the rates at which the sucrose solution and the monomer oil flow through the device, the researchers discovered that they could introduce variations in the thickness of the shells that formed, creating lopsided capsules with thicker walls on one side and thinner on the other.

According to Weixia Zhang, Ph.D., first author and Postdoctoral Fellow, Wyss Institute and SEAS, “Our shells' weakest part is 40 times thinner than their strongest part, which makes it much easier for them to break and release their cargo. On the flip side, these microcapsules are exceedingly durable and do not leak if they are not exposed to elevated osmotic pressure, making them very stable and capable of storing their contents for a long time.”

The team is currently working on the development of their microcapsules by improving the shell material to further decrease the osmotic pressure required to rupture them. They plan to apply their technology to the delivery of biomolecular drugs, such as therapeutic antibodies, with the main aim of utilising the human body's high water content to act as the rupture trigger after injection.

According to the co-author Donald Ingber, M.D., Ph.D., Founding Director of Wyss Institute's the Judah Folkman Professor of Vascular Biology at HMS and the Vascular Biology Program at Boston Children's Hospital, and Professor of Bioengineering at SEAS, “This project is a great example of how simpler solutions can often be better than complicated ones, as the only input needed to burst the microcapsules is mechanical pressure, rather than complex chemistries or molecular switches.”