Coronary Angioplasty and Drug-Eluting Stents - Applications of Biotechnology in Cardiovascular Therapeutics - page 282

produce consistently pure particles within a specified size range and distribution.
ElectroNanoSpray ™ technology provides a novel approach for applying challenging
materials to the surfaces of medical devices. This process can generate both single-
and multiple-phase coatings and apply these with tight control to small, complex
surfaces. ElectroNanospray ™ process is being developed for applying nanoparticle-
based drug-eluting coatings to coronary stents.
Debiotech SA in collaboration with the Laboratory of Powder Technology at
Ecole Polytechnique Fédérale de Lausanne (Lausanne, Switzerland) is developing a
new type of structured ceramic coatings for drug-eluting stents and other implants.
Ceramics offer unique properties compared to polymers. Polymers dissolve over time
and residues provoke inflammation, whereas ceramic is stable and inert when in
contact with living tissue. With this coating, one can combine an active release of
drug during the first weeks after implantation with the long-term stability of the
ceramic. Nanostructured ceramics provide novel properties to biomaterials which are
not attainable with other materials. The challenge in this project is to process nano-
sized ceramic powders to reach unique surface structures, which show a controlled
porosity over a size range of 2,000 times between the smallest and largest pore. Based
on results of fundamental research activities in the field of ordered arrangement of
nanosized particles at surfaces, the knowledge of processing particles smaller than
10 nm at large scale has been established as a key competence to achieve that goal.

Nanopores to Enhance Compatibility of DES

Scientists at the Forschungszentrum Dresden-Rossendorf in Germany have devel-
oped an innovative method to create a large number of nanopores on the surface of
stainless steel. Bombarding the surface of a stent from all sides with a high dose of
noble gas ions generates a scaffold of nanopores in the material below the surface.
The desired porosity can be precisely engineered by tuning the ion energy, the flux,
and the temperature during the process. A larger amount of the highly effective
drugs can be deposited on the enlarged noble metal surface due to this nanoporous
structure, which enhances the biocompatibility of the implants in the human body.
Thus, this treatment results in the release of drugs over a longer period of time. This
method is currently being assessed as a platform technology for the next generation
of DES by the Boston Scientific Corporation. The objective of this research col-
laboration is to further develop this technique for commercialization.

The Ideal DES

The ideal characteristics of a DES for clinical application are:

• Controlled release of the incorporated drug

• Physician control over drug elution according to requirements of an individual

patient