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Scientists Develop Novel Storage Module to Dispense Precise Dosages of Drugs in the Body

Until now, there has been a ceiling to the level of the precision of the administration of pharmaceutical substances in general. However, thanks to an invention developed by researchers in two groups at the University of Freiburg, clinical practitioners in the near future will be able to administer highly precise dosages of drugs.

Concisely, the method involves storing drugs in a unique storage module which when placed in the body will maintain its structure, releasing its stored pharmacologically active substances only in very controlled and precise dosages.

apothecary cabinet

The storage layer (green) can be used to stock drugs; the surface layer (blue) enables their release in calculated dosages.
(Image Credits: Christian Böhler/University of Freiburg)

A junior research group led by Dr. Maria Asplund and Christian Böhler – Asplund’s doctoral candidate – provided the foundations for the new molecular storage method. The multi-disciplinarian group, comprising materials scientists, microsystem engineers, and electrical engineers, is from the Cluster of Excellence BrainLinks-BrainTools at the University of Freiburg.

Starting off, the team had first to convert a synthetic material from a liquid state to a solid state. To do this, they used a technique never before used successfully, to infuse gas into the molecular structure of the synthetic material to strengthen the material from the inside. The name of the technique is atomic layer deposition (ALD). The synthetic material is the polymer polyethylene glycol, and the gas used is zinc oxide.

The unique molecular structure of the organic-inorganic hybrid compound produced from the ALD process, made it suitable to store a wide variety of pharmaceutical substances. The hybrid substance is also water-soluble, which makes it ideal as a drug carrier, coupled with its ability to release substances stored in it easily and repeatedly.

At this point, the team had to seek the characteristic properties of a polymer called PEDOT, to confer the unique ability to dispense doses precisely. In an overly simplified analogy, Böhler explained that PEDOT works like a net with holes that open and close depending on the nature of the charge applied. Thus, when the charge is negative, the holes open, and when the charge is positive, the holes close.

To confer this unique ability on the organic-inorganic hybrid compound, the team applied two thin films of PEDOT to the surface of the organic-inorganic hybrid compound. This proved to be sufficient to ensure stability of the storage module and provide precise control of the release of stored substances.

However, similar systems to this storage module previously produced had certain drawbacks. They were comparatively less compact, could not store molecules with different charges, had smaller storage volume, and sometimes led to unintended chemical reactions.

To prevent these, Asplund’s team collaborated with a team led by Professor Margit Zacharias from the Laboratory of Nanotechnology in the Department of Microsystems Engineering (IMTEK) of the University of Freiburg. The IMTEK team went on to improve the storage module by implementing an innovative technology using fluorescein.

With fluorescein baked into the storage system, the researchers at IMTEK ascertained from experiments that the multilayered module exhibits desirable properties for dispensing precise doses of a large variety of related molecules at a certain point over a given period. In follow-up experiments, the group aims to determine whether the storage system can hold non-related molecules at the same time or if separation of the different molecules in chambers is necessary.

At the moment though, the technology holds great promise. First off, it would be particularly useful in processes that involve exchange and analysis of substances in a very small space. The common term for such process is lab-on-a-chip method.

In addition, it would be of immense therapeutic use. For example, the storage system could be used as an implant or reservoir placed under the skin. Then the system releases controlled dosages of drugs imbedded in the storage system directly onto a tumor.

The IMTEK researchers have already ruled off the potential hold-off of the system not being safe for use in a human body, after tests on cell cultures led to positive results without complications. Thus, with the stage set, the question that remains is how long before the innovative storage module makes a debut in health care systems around the world.

Details of the study are published in the journal Scientific Reports.

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