Drug delivery – and in particular the delivery of anti-cancer therapeutics – has emerged as one of the major applications of nanotechnology in medicine. There’s a nice brief review of the subject by Ruth Duncan in this month’s issue of Nano Today: – Nanomedicine gets clinical . An interesting paper in this week’s Nature reports a significant new development from Sasisekharan’s group at MIT, in which two drugs are combined in a single delivery system. This nanovector first selectively targets tumour tissue, then releases a drug which cuts off the blood supply to the tumour, isolating and starving it, and then releases a second drug which directly attacks the tumour cells.
The full article can be found here, and there’s a commentary about it here. A subscription to Nature may be required for these articles, but you can also look at the Nature’s editor’s summary and the press release from MIT.
What’s interesting about this work is the way it brings together quite a lot of different tricks to make something that is starting to look like a piece of integrated nanoengineering. You have the coupling of a drug to a polymer which slowly breaks down in water; then this drug-polymer conjugate is prepared in the form of nanoparticles. These nanoparticles are, together with a second drug, encapsulated in a liposome, a self-assembled hollow shell formed by a phospholipid sheet which has folded round on itself to form an enclosed surface. The size of these liposomes is controlled so they selectively find their way into the tumour tissue and their surfaces are decorated with hairy layers of water soluble polymers to hide them from the immune system. Individually, none of these features is novel, but their combination in an integrated nanosystem is very impressive.