If you are suffering from cancer and need interferon therapy, or if you need human growth hormone for the treatment of short stature, you could not escape unpleasant repetitive injections. The former requires thrice-a-week injections and the latter needs daily injections. However, such frequent injections are no longer necessary, thanks to a new drug delivery device developed by a POSTECH research team.

For long-term controlled delivery, protein drugs had been encapsulated within biodegradable polymers such as poly (lactic-co-glycolic acid), PLGA. Despite successful commercialization, however, the product had been withdrawn from the market due to the protein denaturation along with the degradation of PLGA. There was a danger that the remedial result may be weakened or the patient may suffer from immune responses caused by the denatured protein drugs.

Recently, a joint research team at POSTECH has developed a device which releases the protein drugs continuously for up to two months with one injection only. Interestingly enough, this invention shares a simple basic of an hourglass. The team’s research focuses on a very small cylindrical block copolymer channel of the size of nanometers, to make medication flow through a tiny passageway in slow and constant manner, or in ‘single file diffusion.’

Members from various POSTECH departments worked in collaboration including Professor Jin Kon Kim of the Chemical Engineering Department, Professor Sei Kwang Hahn of the Materials Science Department, and Professor Kwan Yong Choi of the Life Science Department. Post doctorate researcher Seung Yun Yang of Chemical Engineering and Ph.D. candidate Jeong-A Yang of Materials Science also contributed to the research.

The new delivery device uses the self-assembling property of block copolymers in order to make a nanoporous membrane that has a cylindrical nanochannel. As the narrow middle part of an hourglass lets a restricted amount of sand flow through, the new device operates by similar fundamentals, though for a different purpose. By altering the size of the nanochannel to become 1.7 times bigger than the size of a protein drug, it inducts single file diffusion, which is similar to how hourglasses work.

Consequently, only one protein particle passes through the pathway, which yields a very interesting effect. Regardless of the amount of medication in the storage section, the speed in which protein is released into the human body becomes constant. Furthermore, since the outpour of protein is not forced by external forces, it is unlikely for degeneration to occur, eventually providing a desirable condition with less side effects.

Professor Kim commented on the merits of his team’s recent achievement that the device can be utilized by simply being mounted on various medical instruments. He added that it can also be applied to a wide range of protein pharmaceuticals or ‘biosimilars’, which are generics of bio-medicine such as hormones or proteins produced through gene recombination or cell culture techniques. He also emphasized that the device is more convenient and economically beneficial compared to conventional methods.

The work has drawn significant attention when introduced to the July issue of ACS Nano, a well-renowned journal for nanosciences.