Scientists from Tomsk Polytechnic University with colleagues from Great Britain Germany, China, and Switzerland have proposed a new way of delivering anti-thrombosis drugs to the damaged areas of the blood vessels. According to the propose system, stents that are installed to expand vessels also serve as transport for drugs: they are cover by a thick film of a biodegradable polymer with small cavities -the so-called micro-chambers.
They contain molecules of medicinal compounds. Their task is to improve the effectiveness of the install stent and to prevent the further development of thrombosis. The study results are publish in the European Polymer Journal (IF 3.741, Q1). Vascular stenosis, caused by various reasons, leads to the fact that the cardiac muscle suffers from the lack of oxygen. After some time it can lead to the development of coronary heart disease.
In order to expand vessels, doctors resort to stenting that implies the introduction of a special stent into the vessel, that serves a framework for the vessel. The stent itself is a small metal tube out of wire cells. Associate Professor Sergey Tverdokhlebov from the TPU Weinberg Research Center says: ‘Drug-eluting stents with polymer coatings for vascular surgery are already being produce.
We propose an approach that allows you to control the release of drugs from polymers, that is, to adjust the rate of drug release for prolonged impact’ Yulia Zykova who is a co-author and engineer at the TPU Laboratory for Plasma Hybrid Systems, says: ‘Our colleagues from the Queen Mary University of London initially proposed such a system for tackling the issue of loading low molecular weight water-soluble substances.
These include some anti-cancer, anti-thrombosis drugs; and antibiotics. Due to the small size of molecules, it is difficult to place in the delivery system and hold in place. Such micro-chambers on the polylactic acid film are good containers for the molecules. In Tomsk Polytechnic University we proposed using the films for vascular stents.’The micro-chambers are obtain using silicon stamping tool with small grooves.
Sound waves accelerate
It is dipped in a solution with polylactic acid and then dri; which is how the first film layer is obtain. Then it is dip in a solution with biologically active substance again; where the molecules naturally fill the cavities and cover with another polymer layer. The stent is literally wrapp in a film.
When the stent is expanding, the film is also stretching.It is possible to influence the release rate of the drug molecules using, for example; ultrasound. Sound waves accelerate the process of polymer destruction and hence the rate of release of microcapsules contents. By adjusting the power of ultrasound the scientists can control the rate of release of molecules from the micro-chambers.