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Smart nanogels offer injection-free drug treatments

14 February 2019

Scientists are investigating a new way of delivering potentially life-saving drugs directly through the skin without the need for injections. The work carried out at ISIS Neutron and Muon Source by a team from Queen Mary University of London, could revolutionise how drugs are administered for diseases such as cancer and diabetes.

Not every medical condition can be tackled with a single round of treatment – in fact many conditions, such as cancer, require that a patient be injected with drugs over the course of many weeks. Visiting a doctor for multiple injections can be time-consuming and stressful for the patient and the drugs that are injected circulate through, and affect, the whole body instead of the place where they are most needed – which decreases the drug’s effectiveness and increases the risk of side-effects.

Scientists are interested in developing gels that contain drug-carrying nanoparticles (particles measuring a few hundred billionths of metre) that can deliver drugs directly through the skin without the need of injections (rather like a nicotine patch). Instead of passing through the whole body, the nanoparticles contained within these ‘nanogels’ would pass through the skin, travel directly to the place they are needed, and then release their payload of drugs. Better still, the properties of each component in the nanogel could be tuned so that the drugs they deliver are released at different rates. This would allow multiple drugs to be delivered at different times over a long period – greatly reducing the number of hospital visits a patient has to undertake and, potentially, the side-effects they have to endure.

In order to target their drug delivery, nanogels can be designed that react to a wide array of stimuli. Some can be designed that detect high levels of glucose in the blood of diabetes patients, which triggers the release of insulin, and others can be designed to react to the presence of bacteria and release antibiotics directly at the point of infection. The team from Queen Mary University of London (QMUL) have been studying a type of nanogel, called a NIPAM-based nanogel, that is sensitive to changes in temperature.

NIPAM-based nanogels (or N-isopropylacrylamide-based if you want something to twist your tongue around) are considered ‘smart’ or ‘switchable’ materials because they are triggered to release their payload by changes in temperature. In particular they are trigged at a temperature of around 37°C – the body temperature of a human – which makes them ideal transdermal (through the skin) delivery systems because they are activated on contact with warm skin.

Skin is effectively a three-layer protective blanket that covers the entire body and is designed to keep things out. In order to get inside the body and deliver their drugs, the nanoparticles have to not only fight their way through three layers of skin but also penetrate the layer of greasy, water-repelling, fat molecules, known as lipids, that cover its surface. In order to develop effective transdermal nanogels, scientists need to understand how they behave and interact at the skin barrier. It is this that the QMUL team have been studying at ISIS Neutron and Muon Source.

The team used a technique called neutron reflectivity, which uses particles called neutrons to study the structure of extremely small samples (down to the atomic scale) without causing any damage to the object. Their aim was to see how the nanogel behaves at the skin barrier both by itself and when combined with other materials – to see whether they enhanced the gel’s ability to penetrate the lipid layer and the skin. They found that the addition of a cross-linking agent (which promotes changes in the gel’s polymer structure) combined with a skin penetration enhancer (basically alcohol, which fatty stuff like lipids really don’t like) greatly enhanced the ability of the NIPAM-based nanogel to breach the lipid barrier and be transported through the skin.

The team's work has provided important advances in understanding how nanogels interact at the skin boundary, which will help lead to the development of nanoparticles that are better able to penetrate biological barriers.

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Last updated: 25 February 2019


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