Medication through the Skin
If drugs are to enter the body painlessly and efficiently, they can be administered via skin patches. Researchers at Empa and the University of Fribourg are currently developing nanocontainers for therapeutic agents that can be controlled by light.
Not every medication can be swallowed as a pill or injected with a syringe. However, the skin offers a large and permeable surface to absorb active ingredients. Today, nicotine, painkillers and contraceptives can already be administered through the skin using patches. Researchers at Empa (Swiss Federal Laboratories for Materials Science and Technology) in St. Gallen and the Adolphe Merkle Institute at the University of Fribourg, Switzerland, are currently developing a system that controls the effect of medication using light switches. For example, this allows precise control of the dosage of active ingredients, opening up new possibilities for therapies with transdermal patches.
Skin patches with light switches
To ensure that the ingredients in the patch can be precisely controlled, the researchers have devised a molecular light switch inspired by nature. "Our light switch works similarly to the retina in the human eye," says Luciano Boesel from Empa's Laboratory for Biomimetic Membranes and Textiles. Like the natural pigments in the eye, these synthetic photochromes can also be activated by light. For initial experiments, the molecular switches were integrated into polymer nanospheres filled with test substances.
When these nanoreactors are exposed to light of a certain wavelength, they change their structure. This makes their surface permeable, allowing the chemically active substances to diffuse from the nanoreactor into the environment. For example, if the colour of the light changes from green to red, the chemical reaction stops within seconds. The shell of the nanoreactors becomes impermeable again, and the reaction vessels are ready for the next use. In future, these nanoreactors with integrated light switch are to be used as reservoirs for therapeutic agents. "Light switches can be used for the entire spectrum between 450 and 700 nanometres wavelength, i.e. for coloured light from blue to red," Boesel explains. This opens up many possibilities for the controlled delivery of several drugs or for complex reaction cascades in a single patch. The team is now working with the support of the Swiss National Science Foundation and the Swiss National Center of Competence in Research for Bio-Inspired Materials to further optimise the nanoreactor.