Scientists at the University of Bath have developed an affordable microneedle skin patch to deliver medicine directly into the body, helping to eliminate the need for injections or oral medication.
The microneedle skin patch developed at the University of Bath | Photo © Joseph Turner, University of Bath
It is hoped that the patches, which provide a controlled dosage, will be ready for use within the next five to 10 years.
The microneedle patches are unique as they are made from a hydrogel, a gel-like substance in which water forms the liquid component, with the active ingredient encapsulated inside the microneedle structure rather than in a separate reservoir.
They are also more affordable than other commercially available microneedle patches, as they are produced from 3D-printed moulds.
Moulds produced this way are easy to customise, which keeps the costs down.
The patch, which is smaller than a pound coin, features barely visible microneedles that painlessly pierce the first few layers of skin.
Contact with fluid beneath the skin barrier causes the ‘hydrophilic’ (water-loving) needles to swell, prompting a specific dosage of the drug to be delivered into the body.
In experiments carried out at the University of Bath, upon swelling, the patches delivered doses of antibiotics that elicited a strong response against two bacteria known to cause serious infections – Escherichia coli (E. coli) and Staphylococcus aureus.
The patch also works in reverse, extracting small quantities of fluid from beneath the skin for medical analysis.
This may be helpful for monitoring the levels of lactate and other chemicals in patients with an infection.
Bath Chemical Engineer Dr Hannah Leese, who continues to refine the skin patch design along with fellow engineers PhD student Joseph Turner and Professor Pedro Estrela, and biologist Dr Maisem Laabei, explained that microneedle-based skin patches are an ideal system for delivering drugs and have clear benefits over traditional delivery approaches.
She said: “Injections are invasive and expensive, and they don’t suit everyone.
“A lot of people are needle-phobic and are understandably reluctant to receive medicine by injection even when treatment is really needed. Others are ill-suited to injections – for instance, elderly patients with thin skin.
“Also, sometimes the use of needles can introduce pathogens, such as bacteria, that may cause infections, especially in people with low immunity.”
She added that people generally have fewer objections to taking drugs by mouth, but there are downsides to oral medication too.
She continued: “You can experience gastrointestinal side-effects; there is a delay between taking the medication and the drug getting to where it’s needed in the body; doses need to be higher because a lot of the formulation is broken down in the gut, and if the patient is taking antibiotics, this can also contribute to antimicrobial drug-resistance.
“Our next step is to continue to refine the microneedle platform and run animal studies before moving to human clinical trials.
“I’m hopeful these patches will be ready for patient use within the next five to 10 years.”
Dr Leese anticipates that the patches will be able to deliver both drugs that circulate the entire body and drugs that need to remain more localised – for instance, when there is an infection in a discrete section of skin.
There is also scope for the patches to deliver vaccines and monitor hormone levels.
Dr Leese added: “We can also see there being a role for these patches in the health and wellness fields.
“I can picture the day people have microneedles under their smartwatches to detect fluctuations in the stress hormone, cortisol.”
This research was funded by EPSRC and Abbott Diabetes Care.
