This is what fenugreek looks like can help repel insects. Credit: Uni Halle/Fanfan Du

New printable and wearable insect repellent.

Martin Luther University Halle-Wittenberg (MLU) Scientists have invented a new type of insect repellent delivery device. The active ingredient is first “encapsulated” and formed into an appropriate shape, such as a ring, which can then be worn and release an agent intended to repel mosquitoes for an extended period of time. The team published their findings in International Journal of Pharmaceutics.

The researchers used IR3535, an insect repellent developed by MERCK, to create their prototype.

“Mosquito sprays containing IR3535 are very gentle on the skin and have been used all over the world for many years. That is why we have been using the agent in our experiments,” says Professor Rene Androuche from MLU.

It usually comes in the form of a spray or lotion and provides protection for several hours. However, Andrush and his colleagues are looking for ways to release the agent over a longer period of time, such as encasing it in a wearable ring or bracelet.

The insect repellent was carefully infused into a biodegradable polymer using specialized 3D printing technology, and the mixture of materials was successfully molded in various ways. “The basic idea is that insect repellents continually evaporate and form a barrier to insects,” explains lead author of the study, Fanfan Du, a doctoral student at MLU.

The rate at which repellents evaporate depends on many different factors, including temperature, concentration, and the structure of the polymer used. After running several experiments and simulations, the team predicts that the repellent will need more than a week to evaporate completely at a temperature of 37 degrees Celsius (98.6 degrees Fahrenheit, that is, body temperature).

While researchers have proven that it is entirely possible to develop a wearable repellent, the rings and other shapes created for the study are only prototypes. According to Andrush, more research needs to be done to determine how well the rings work under actual conditions. Packaging materials can also be further improved.

Reference: “3D printing of a poly(l-lactic) polymer/insect repellent system[{” attribute=””>acid)/ethyl butylacetylaminopropionate (PLLA/IR3535)” by Fanfan Du, Harald Rupp, Katalee Jariyavidyanont, Andreas Janke, Albrecht Petzold, Wolfgang Binder and René Androsch, 14 July 2022, International Journal of Pharmaceutics.
DOI: 10.1016/j.ijpharm.2022.122023

The study was funded by the German Research Foundation and within the framework of the graduate school “AGRIPOLY” at MLU. “AGRIPOLY” is funded by the European Social Fund (ESF) and the state of Saxony-Anhalt.