Warwick researchers develop new vehicle for drug release

Published: 1-Feb-2011

Plankton inspires creation of ‘stealth’ armour for slow release microscopic drug vehicles

Researchers at the University of Warwick in the UK have devised a simple way of giving drug-bearing polymer vesicles (microscopic polymer-based sacs of liquid) their own ‘armoured protection’ after being inspired by the ability of some forms of plankton and bacteria to build an extra natural layer of nanoparticle-like armour.

The scientists have been able to decorate these hollow structures with a variety of nanoparticles, opening a new strategy in the design of vehicles for drug release, for example by giving the vesicle ‘stealth’ capabilities which can avoid the body’s defences while releasing the drug.

Advances in polymerisation have boosted the creation of vesicles made from polymer molecules. Such vesicles have special chemical and physical properties, which make them potential drug delivery vehicles.

The University of Warwick team believed that more strength and tailored properties could be given to the vesicles if they could add an additional layer of colloidal ‘armour’ made from a variety of nanoparticles.

Lead researcher, Associate Professor Stefan Bon, said: ‘We took our inspiration from nature, in how it adds protection and mechanical strength in certain classes of cells and organisms. In addition to the mechanical strength provided by the cytoskeleton of the cell, plants, fungi, certain bacteria have an additional cell wall as outermost boundary.

‘Organisms that particularly attracted our interest were those with a cell wall composed of an armour of colloidal objects – for instance bacteria coated with S-layer proteins, or phytoplankton, such as the coccolithophorids, which have their own CaCO3-based nano-patterned colloidal armour.’

The Warwick researchers hit on a simple and effective method of adding different types of extra armour to the polymer-based vesicles. One example was a packed layer of microscopic polystyrene balls. Because the polystyrene balls had a crystalline-like ordered structure, the researchers could design a vesicle with an additional and precise permeable reinforced barrier for drug release.

The researchers used the same technique to add a gelatine-like polymer to provide ‘stealth’ armour to shield vesicles from unwanted attention from the body’s immune system while it slowly released its drug treatment.

This particular coating (a poly((ethyl acrylate)-co-(methacrylic acid)) hydrogel) absorbs so much surrounding water into its outer structure that it may be able to fool the body’s defence mechanism into believing it is in fact just water.

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