Skin patches instead of needles: can nanotechnology vaccinate the world?

Who likes getting a needle? I know I definitely don’t.

Someone else who doesn’t is Mark Kendall from the University of Queensland, winner of the Young Florey Medal 2016.

Mark’s work in developing the nanopatch has provided a clear pathway for vaccine delivery science to move beyond 160 year-old needle and syringe technology.

What is a nanopatch?

Think of a device which is around postage stamp size and has thousands upon thousands of tiny spikes on its surface: this is a nanopatch. There are approximately 20,000 projections per square centimeter on each patch, each around 60 to 100 micrometres in length. One micrometre is one million times smaller than a metre, so the height of these tiny spikes is approximately the width of a human hair.

The nanopatch is produced using a technique known as “deep reactive ion etching”, which essentially makes use of ions (charged atoms) in an electric field to selectively etch the surface of a material away. Controlling the electric field and the ions allows a high degree of control, so the microprojections are regularly spaced and of similar dimensions.

An added advantage of this approach is it has been used in the electronic circuit and solar energy industries for many years, and has the potential for increasing the scale of production.

It’s just one example of new manufacturing techniques that have become available through advances in nanotechnology, a process of engineering on the nanoscale (one nanometre is one billionth of a metre).

How nanopatches deliver vaccines

The tiny projections on each nanopatch are invisible to the naked eye, but are long enough to breach the outermost skin layer, the stratum corneum. The stratum corneum is a layer of dead skin cells which acts as the first barrier in protecting us from infection and skin water loss.

Cyro Scanning Electron Micrograph (SEM) of a nanopatch being applied to the skin. Shown is a projection, pushing through the stratum corneum (red), viable epidermis (brown) and dermis (magenta). Kendall group, The University of Queensland

The nanopatch projections penetrate through the stratum corneum to reach the living skin layers directly below, the epidermis and the dermis. In the epidermis are several types of immune cells that are vital for the vaccine to work.

Hence the nanopatch is well suited to the delivery of vaccines where targeting immune cells is vital for vaccination success. Examples include influenza, polio and cholera.

Mark Kendall and his colleagues have shown they are able to coat nanopatch microprojections with a vaccine, apply the nanopatch to the skin and achieve vaccination with one tenth to one thirtieth of the dose required using traditional needle and syringe approaches.

Surely needles aren’t that bad

But are needles really that bad? Is it worth all this effort to find an alternative?

Actually yes. At least 10% of the population has needle phobia, and actively avoid being vaccinated by needles.

Furthermore, the World Health Organisation estimates there are 1.3 million deaths which occur each year from needlestick injuries and cross contamination.

But it also boils down to practicality. Currently many vaccines must be kept refrigerated from the time of production through to the time of being administered. This can cause complications, particularly in the developing world where access to refrigeration is restricted and transportation from urban hubs can take days to reach remote villages and towns.

The nanopatch is able to alleviate the need for refrigeration, as the vaccine is dried onto the microprojections which protrude from the patch. The activity of vaccines remain stable for six months at room temperature storage. Other vaccines start to lose activity in a matter of hours when not stored in the fridge.

A revolution in vaccines

The nanopatch is revolutionising how vaccines are delivered. This technology has the potential to dramatically reduce the cost of vaccination programs and make vaccines more accessible worldwide.

But it’s more than just a good idea. Mark Kendall and his colleagues are now running human clinical trials of nanopatches in Brisbane, and the WHO is planning a polio vaccine trial in Cuba in 2017.

The future of this technology looks bright not only for vaccine delivery, but also for other diseases and injuries where targeting the body’s immune cells is an important component of treatment. Examples include influenza, cholera, polio and rabies.

In 1853 the first patent was filed for a needle and syringe, and the design has hardly changed since then. The nanopatch is on the right track to superceding this 160 year old technology.