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Potentiostatic, Potentiodynamic and Impedance Study of TiO2 Layers Deposited of 316 LVM Steel Used for Coronary Stents

Basiaga M., Staszuk M., Walke W., Tański T., Kajzer W.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

821--824

EN

The objective of the study is assessment of suitability of the ALD method for application of a TiO2 layer on surface of 316LVM steel used for production of vessel stents. Selection of the appropriate process parameters for application of the layer affects its electrochemical properties, which largely determine resistance of the biomaterial to corrosion in the blood environment, thus affecting its hemocompatibility. To assess resistance of the AISI 316LVM steel with modified surface to corrosion, voltammetric and impedance measurements were conducted. The proposed variant of surface processing allows safe deformation of the TiO2 layer without its delamination.

2

Analysis and development of the adhesion of stent coatings

Bognar E., Ozsvath P., Kertesz A., Pelyhe L., Devenyi L.

Selected Engineering Problems

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2014

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nr 5

15--20

EN

The influence of the surface roughness on adhesion strength of polyurethane coating on stainless steel alloy (316LVM) is introduced. These coatings are one of the development directions in coronary stent production. One of the widely spread stent base material is the 316LVM, so in the presented study these materials were involved. The samples were prepared by etching and electro-polishing. The current density and polishing time were changed to create samples with different surface roughness. After electro-polishing polyurethane (Chronoflex®) coating was applied. The adhesion of the coating on different surfaces was tested by scratch test (nano indenter technique). The increasing surface roughness gives stronger adhesion. According to our experiments it was concluded that the coronary stents, treated by etching without polishing could cut out the balloons during expansion, therefore the surface roughness should be under this value. It is recommended to use an electro-chemical treatment that is resulting Ra=1.5-2.0 μm roughness.

3

Use of coronary stents - material and biophysical conditions

Paszenda Z.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 43, nr 1

125-135

EN

Purpose: The paper discusses application issues of using the metallic implants for treatment of the cardiovascular diseases. The analysis of the biophysical conditions of the heart – coronary vessels system has been used to distinguish the tissue environment properties which should be compatible with properties of the metal biomaterial and stent’s surface. On this basis the author presented results of experiments concerning the usefulness of the passive-carbon layer for surface treatment of vascular stents made of stainless steel. Design/methodology/approach: In order to determine the usefulness of the layer for implants in cardiology the following tests were carried out on the layer: structure, thickness, corrosion resistance, electrical properties and biocompatibility in experimental animals. The structure and thickness of the layer were tested in high resolution transmission electron microscope. Corrosion resistance was carried out by recording anodic polarization curves. Methodology of measurements took into consideration both implantation conditions and application of vascular stents. In tests concerning electrical properties of the layer, current-potential as well as capacity-potential characteristics were determined. Findings: The passive-carbon layer of nanocrystlline structure and high smoothness created on coronary stents’ surface fully ensures pitting corrosion resistance in both implantation and application conditions. Research limitations/implications: Deposition of the dielectric carbon layer on coronary stents’ made of stainless steel is effective method of reducing reactivity of their surface in blood environment and blood clotting in consequence. Originality/value: The need to determine the correct quality and properties of coronary stents was indicated. The properties refer to stents’ design, physio-chemical properties of the metallic biomaterial and its surface. Keywords: Biomaterials; Cr-Ni-Mo steel; Corrosion resistance; Electrical properties; Coronary stents

4

Effect of silica precursors-type on mechanical properties of sol-gel coatings

Grygier D., Dudziński W., Wiktorczyk T., Haimann K.

Acta of Bioengineering and Biomechanics

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2008

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Vol. 10, nr 1

27-35

EN

Reversion to narrowing, called restenosis, still remains an important problem of coronary angioplasty. Analysis of the problem revealed that the application of surface layers aimed at creating on the stent surface a neutral barrier between its metallic framework and tissues of the blood-vascular system is decidedly best to impede the restenosis. They also play the role of medicine carriers. This article presents a new sol-gel technology, to be applied in coronary stent coatings. Currently, this is one of the most progressive methods allowing the modification of surface layers of metallic biomaterials. The results presented prove that due to a proper selection of silica precursors it is possible to obtain continuous, smooth, plastic deformation-resistant sol-gel coatings, which additionally are characterised by very close adherence to the base material, nanometer thickness and low degree of surface development.

5

Analiza zmian komórkowych zachodzących w naczyniach wieńcowych po implantacji stentu

Grygier D., Kuropka P., Dudziński W.

Engineering of Biomaterials

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2007

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Vol. 10, no. 65-66

37-39

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Charakterystyka biomechaniczna stentu wieńcowego z technologią OCC

Walke W., Paszenda Z., Jurkiewicz W.

Inżynieria Biomateriałów

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2006

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R. 9, nr 58-60

209-211

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Optymalizacja geometrii oraz własności mechanicznych stentu wieńcowego ze stali Cr-Ni-Mo

Paszenda Z.

Inżynieria Biomateriałów

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2005

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R. 8, nr 45

5--11

PL

Prezentowana praca dotyczy problematyki optymalizacji cech geometrycznych oraz własności mechanicznych stentów wieńcowych wykonanych ze stali Cr-Ni-Mo. W pracy przedstawiono metodologię wyznaczania charakterystyki biomechanicznej układu stent-naczynie wieńcowe. Na jej podstawie dobrano własności mechaniczne stali, z której wykonano stenty. Weryfikację cech geometrycznych oraz własności mechanicznych stentów wieńcowych przeprowadzono na podstawie testów in vitro poprzez implantowanie ich do fantomu naczynia. Przeprowadzone testy potwierdziły prawidłowość doboru własności mechanicznych stali Cr-Ni-Mo, z której zostały wykonane stenty.

EN

Presented work concerns the issue of optimization of geometry and mechanical properties of coronary stents made of Cr-Ni-Mo steel. The methodology of determining the biomechanical characteristic of a stent - coronary vessel system was presented. The biomechanical characteristic, was the basis for the selection of mechanical properties of the stents were made of steel. The verification of geometrical features and mechanical properties of the coronary stents was carried out on the basis of in vitro tests by implantation of the stent into an artificial vessel. Tests confirmed the correct selection of the mechanical properties of the applied steel.

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Badania odporności korozyjnej stentów wieńcowych z uwzględnieniem specyfiki układu naczyń wieńcowych

Paszenda Z., Tyrlik-Held J., Nawrat Z., Żak J., Wilczek K.

Inżynieria Biomateriałów

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2004

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R. 7, nr 34

26-33

PL

W pracy zbadano przydatność warstwy pasywno-węglowej wytworzonej na powierzchni stentów wieńcowych ze stali Cr-Ni-Mo dla potrzeb kardiologii zabiegowej. W szczególności przeprowadzono badania odporności na korozję wżerową w sposób uwzględniający technikę implantacji. Przydatność warstwy oceniano również w warunkach zmiennych cykli obciążeń. Dla potrzeb pracy wykonano stanowisko do badań zmęczeniowych stentów stymulujące pracę serca. Badania zmęczeniowe prowadzono przez okres 3 miesięcy w środowisku płynu fizjologicznego Tyrode'a z częstotliwością 180 cykli na minutę. Po zakończeniu badań implanty poddano również ocenie odporności korozyjnej. Ponadto zbadano topografię warstwy węglowej stosując metodę mikroskopii sił atomowych. Uzyskane w pracy wyniki wskazują na przydatność wytworzonej warstwy pasywno-węglowej do uszlachetniania powierzchni stentów wieńcowych.

EN

In the work the usefulness of passive-carbon layer deposited on surface of coronary stents made from Cr-Ni-Mo steel has been investigated. Particularly, investigations of pitting corrosion resistance in conditions which are taking into consideration the technique of stents implantation have been carried out. Usefulness of the layer has also been evaluated in conditions of changing of cyclic loading. Special device for fatigue tests of the stents was made for better simulation of heart's work. Fatigue tests were carried out by 3 months in Tyrode's physiologic solution with frequency of 180 cycles per minute. After finishing that investigations for corrosion resistance tests of the implants have been additionally performed. Moreover, the topography of carbon layer by the use of atomic force microscopy method has been investigated. The obtained results have pointed out on the usefulness of passive-carbon layer for quality improvement of coronary stents surface.

9

Badania hemozgodności warstw pasywno-węglowych stosowanych do uszlachetnienia powierzchni stentów wieńcowych

Paszenda Z., Duda B., Wilczek P.

Inżynieria Biomateriałów

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2003

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R. 6, nr 26

3-11

PL

Prezentowana praca dotyczy problematyki uszlachetniania powierzchni implantów stosowanych w kardiologii zabiegowej. Zasadniczym jej celem była ocena biotolerancji w środowisku krwi warstw pasywnej i pasywno-węglowej wytworzonych na powierzchni implantów. Zgodnie z zaleceniami norm dla implantów będących w kontakcie z krwią ponad 30 dni zrealizowano badania dotyczące cytotoksyczności (na ekstraktach i w kontakcie bezpośrednim) oraz badania hemolizy i wykrzepiania. Uzyskane w pracy wyniki wskazują, że biotolerancja warstwy pasywnej oraz pasywno-węglowej oceniana na podstawie obowiązujących standardów w badaniach in vitro jest dobra.

EN

Presented work refers to the problem of improvement of the surfaces of stents used in the operative cardiology. Its main goal has been assessment of the biotolerance in the blood environment of the passive and passive-carbon coatings, developed on the implants' surfaces. According to recommendations of standards for implants interacting with blood for more than 30 days, investigations were carried out of the cytotoxicity (using extracts and in the direct contact), as well as haemolysis and coagulation. Research results collected suggest that the biotolerance of the passive and passive-carbon coatings evaluated basing on the standards binding in the in vitro tests is good.

10

Problematyka tworzyw metalowych stosowanych na implanty w kardiologii zabiegowej

Paszenda Z.

Inżynieria Biomateriałów

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2002

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R. 5, nr 21

3-9

PL

Prezentowana praca dotyczy problematyki biomateriałów metalowych przeznaczonych na implanty stosowane w leczeniu choroby niedokrwiennej serca. W pracy przedstawiono własności, którymi powinny charakteryzować się stenty wieńcowe oraz klasyfikację uwzględniającą technikę ich rozprężania, technologię wykonania oraz rodzaje stosowanych kształtów. Ponadto omówiono kryteria oceny jakości stali Cr-Ni-Mo stosowanej jako biomateriał w kardiologii zabiegowej.

EN

The presented work is connected with issues of metal biomaterials designed for implants used in treatment of the ischaemic heart disease. There are presented the properties that should characterize coronary stents and classification taking into account their method of development, manufacturing technology, and types of the shapes used. Moreover, criteria are discussed of evaluation of the Cr-Ni-Mo steel used as a material in the interventional cardiology.