Polymer capsules called 'capsosomes' may revolutionise drug delivery system

Washington, May 20 (ANI): In a bid to transport medications in the body at the right place and right time, scientists have developed "capsosome"- polymer capsules in which liposomes have been embedded to form subcompartments.

Researchers led by Frank Caruso at the University of Melbourne have developed the capsosome as a microcontainer that can hold thousands of individual "carrier units", which can encapsulate medications and other substances and release them in a controlled fashion at the right moment.

Currently, the primary type of nano-transporter used for drugs is the capsule: Polymer capsules form stable containers that are semipermeable, which allows for communication with the surrounding medium.

But, these are not suitable for the transport of small molecules, which can easily escape.

Liposomes are good at protecting small drug molecules, but they are often unstable and impermeable to substances from the environment.

And thus, Aussie researchers have now combined the advantages of both systems in their capsosomes.

Capsosomes production involves several steps-first, a layer of polymer is deposited onto small silica spheres.

The polymer contains building blocks modified with cholesterol. Liposomes that have been loaded with an enzyme can be securely anchored to the cholesterol units and thus attached to the polymer film.

Then, more polymer layers are added and then cross-linked by disulfide bridges into a gel by means of a specially developed, very gentle cross-linking reaction.

And finally, the silica core is etched away without damaging the sensitive cargo.

Experiments with an enzyme as model cargo demonstrated that the liposomes remain intact and the cargo does not escape.

By adding a detergent, the enzyme is released in a functional state, and the enzymatic reaction causes a colour change of the solution, which could determine the number of liposome compartments to be about 8000 per polymer capsule.

"Because the capsosomes are biodegradable and non-toxic, they would also be suitable for use as resorbable synthetic cell organelles and for the transport of drugs", said Brigitte Staedler, a senior researcher in the group.

The study has been published in the journal Angewandte Chemie. (ANI)