Nanovesicle with
closed protein gates (red).
(October 10, 2015) Researchers
at the University of Basel have succeeded in building protein gates for
artificial nano-vesicles that become transparent only under specific conditions.
The gate responds to certain pH values, triggering a reaction and releasing
active agents at the desired location. This is demonstrated in a study
published in the journal Nano Letters.
Tiny nanovesicles can protect active agents until they
arrive in specific environments, such as at the target site in the body. In
order to trigger a chemical reaction and release the contents at that
loca-tion, the outer casing of the synthetically produced vesicles must become
permeable at the correct point in time. Working under Prof. Cornelia Palivan,
researchers from the Swiss Nanoscience Insti-tute have now developed a membrane
gate that opens on demand. This means that the enzymes inside a nanocapsule
become active under exactly the right conditions and act on the diseased tissue
directly.
Reacting to changes
in pH
The gate is made up of the chemically modified membrane
protein OmpF, which responds to certain pH values. At neutral pH in the human
body, the membrane is impermeable – but if it encounters a region with acidic
pH, the protein gate opens and substances from the surrounding area can enter
the nanocapsule. In the resulting enzymatic reaction, the capsule’s contents
act on the incoming substrate and the product of this reaction is released.
This method could be applied, for example, to inflamed or cancerous tissue,
which often exhibits a slightly acidic pH value.