Fabrication of Mg alloy tubes for biodegradable stent application

Hanada, K.; Matsuzaki, Kunio; Huang, Xinsheng; Chino, Yasumasa

doi:10.1016/j.msec.2013.07.033

Cited by 60 publications

(30 citation statements)

References 31 publications

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“…However, biodegradable magnesium stents are able to temporarily open the blood vessels until they remodel and then can be absorbed into the body reducing the likelihood of long-term complications or risks (Erbel et al;Hanada, Matsuzaki, Huang, & Chino, 2013). Several magnesium alloys, such as AE21 (2 wt.% Al and 1wt.% rare earth elements) and WE43 (4 wt.% Y and 3 wt.% rare earth elements), have been investigated in recent years (Heublein et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents

Yao-wu

Kent

Wang

et al. 2014

Journal of the Mechanical Behavior of Biomedical Materials

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The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents, Journal of the Mechanical Behavior of Biomedical Materials, http://dx.doi.org/10. 1016/j.jmbbm.2014.07.026 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractMg alloys are receiving considerable attention for biomedical stents due to their combination of good mechanical properties and high biodegradability. Cold rolling is necessary to process Mg alloy tubes before final drawing and fabrication of the magnesium stents. In this paper, cold-rolled tubes were subjected to a crosssectional reduction rate (ε) of up to 19.7%, and were further processed at various ratios of wall-thickness to diameter reduction (Q) from 0 to 2.24 with a constant ε of 19.7%. The results show that the cold-rolled tubes exhibited a rise in ultimate tensile strength (UTS), yield strength (YS), and a reduction in elongation as ε increased from 5.5% to 19.7%. UTS, YS and elongation decreased when Q was increased from 0 to 2.24.Mechanical twinning was observed and analysed. Extension twins increased with increasing ε and were almost saturated at an ε of 16.5%. Extension twins play an important role in determining the evolution of mechanical behaviour in the case of increasing ε, whilst contraction/double twins and secondary extension twins have a large effect on mechanical behaviour in the case of varying Q. The results indicate that the proportions and types of twins play a major role in determining the mechanical behaviour of the AZ31 tubes.

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Section: Introductionmentioning

confidence: 99%

The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents

Yao-wu

Kent

Wang

et al. 2014

Journal of the Mechanical Behavior of Biomedical Materials

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“…Biodegradable magnesium stents, on one hand, are capable of providing good mechanical properties and can achieve properties similar to conventional stents. On the other hand, they are able to temporarily open the blood vessels until they remodel and are then absorbed into the body, thereby reducing the likelihood of long-term complications or risks [24,25]. Hence, magnesium alloys have been attracting increasing attention due to their promise in applications for biodegradable fine tube stents [1,24].…”

Section: 1mentioning

confidence: 99%

“…On the other hand, they are able to temporarily open the blood vessels until they remodel and are then absorbed into the body, thereby reducing the likelihood of long-term complications or risks [24,25]. Hence, magnesium alloys have been attracting increasing attention due to their promise in applications for biodegradable fine tube stents [1,24]. Several magnesium alloys, such as AE21 (2 wt.% Al and 1wt.% rare earth elements) and WE43 (4 wt.% Y and 3 wt.% rare earth elements) have been investigated for use in biodegradable implants in recent years [1,26].…”

Section: 1mentioning

confidence: 99%

“…As promising candidate for biodegradable stents, Mg alloys have attracted interest due to their excellent biodegradability and biocompatibility [24,98,99]. Mg alloys have been used for biodegradable orthopedic implants [1], but their application to stents are still in experimental stage.…”

Section: Magnesium Alloysmentioning

confidence: 99%

“…However, biodegradable magnesium stents are able to temporarily open the blood vessels until they remodel and then can be absorbed into the body reducing the likelihood of long-term complications or risks [24,25]. Several magnesium alloys, such as AE21 (2 wt.% Al and 1wt.% rare earth elements) and WE43 (4 wt.% Y and 3 wt.% rare earth elements), have been investigated in recent years [26].…”

Section: Introductionmentioning

confidence: 99%

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Mechanical and microstructural characterisation in the processing of biomedical metallic fine tubes

Yao-wu¹

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Fine tube stents are used for maintaining localised flow in stenotic blood vessels. Elasticity and plasticity for expansion, rigidity for resisting bending under force and strength to prevent unexpected failure, are required properties of the tubes from which these stents are formed. Biomedical metastable β titanium alloys have been developed as implant materials for a large number of biomedical applications due to a combination of favourable characteristics, e.g. good biocompatibility, excellent toughness and corrosion resistance. A metastable β alloy, Ti-25Nb-3Mo-3Zr-2Sn, has been developed without toxic alloying elements, which is a promising candidate material for stent applications. Metallic materials used for stents are commonly not biodegradable and implanted in the vessel permanently, which may provoke in-stent restenosis and stent thrombosis. In order to remove the implanted materials after service, biodegradable materials, absorbed by the body slowly, are also a field of research interest. Magnesium alloys have been used in studies for biomedical stent applications as a new biodegradable material. Magnesium stents can reopen the blocked blood vessels temporarily before degrading in physiological environments. In addition to the biodegradable characteristics, their mechanical properties are reasonable. The Mg-3Al-1Zn (AZ31) alloy is the subject of some research on the processing of biomedical magnesium alloys as it is a commonly available commercial alloy. Consequently, the Ti-25Nb-3Mo-3Zr-2Sn alloy and the AZ31 magnesium alloy have been used in this thesis to investigate the evolution of mechanical properties and microstructure in the processing of fine tubes.The deformation mechanisms during cold deformation of metastable β titanium alloys are mainly associated with martensitic phase transformations and mechanical twinning. It has been reported that stress-induced phase transformations and {112}〈111〉, {332}〈113〉 twinning modes may be activated under different stress states in metastable β titanium alloys. They can exhibit varying elasticity, Young's modulus and strain hardening behaviour. Because the martensitic start temperature is below room temperature for most metastable β titanium alloys, the α″ martensitic transformation can easily occur under a small amount of external stress. Mechanical twins were reported to hinder slip and dislocation motion thereby increasing the strain hardening rate. The development of β and α″ texture during processing is another critical influence on the mechanical properties of fine tubes. Therefore, studies on the martensitic transformation, mechanical twins and texture evolution is of significance in order to understand the processing of β titanium fine tubes.ii Magnesium alloys deform through the formation of a large amount of mechanical twins due to the relatively low critical stress to activate twinning in comparison with 〈 + 〉 slip. There are typically two primary mechanical twinning modes for magnesium alloys, {101 ̅ 2} extension twins and {101 ̅ 1} cont...

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Biodegradable AZ91 magnesium alloy/sirolimus/poly D, L‐lactic‐co‐glycolic acid‐based substrate for cardiovascular device application

Mohanta,

Ramdhun,

Thirugnanam

et al. 2023

J Biomed Mater Res

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Biodegradable drug‐eluting stents (DESs) are gaining importance owing to their attractive features, such as complete drug release to the target site. Magnesium (Mg) alloys are promising materials for future biodegradable DESs. However, there are few explorations using biodegradable Mg for cardiovascular stent application. In this present study, sirolimus‐loaded poly D, L‐lactic‐co‐glycolic acid (PLGA)‐coated/ sirolimus‐fixed/AZ91 Mg alloy‐based substrate was developed via a layer‐by‐layer approach for cardiovascular stent application. The AZ91 Mg alloy was prepared through the squeeze casting technique. The casted AZ91 Mg alloy (Mg) was alkali‐treated to provide macroporous networks to hold the sirolimus and PLGA layers. The systematic characterization was investigated via electrochemical, optical, physicochemical, and in‐vitro biological characteristics. The presence of the Mg17Al12 phase in the Mg sample was found in the x‐ray diffraction system (XRD) spectrum which influences the corrosion behavior of the developed substrate. The alkali treatment increases the substrate's hydrophilicity which was confirmed through static contact angle measurement. The anti‐corrosion characteristic of casted‐AZ91 Mg alloy (Mg) was slightly less than the sirolimus‐loaded PLGA‐coated alkali‐treated AZ91 Mg alloy (Mg/Na/S/P) substrate. However, dissolution rates for both substrates were found to be controlled at cell culture conditions. Radiographic densities of AZ91 Mg alloy substrates (Mg, Mg/Na, and Mg/Na/S/P) were measured to be 0.795 ± 0.015, 0.742 ± 0.01, and 0.712 ± 0.017, respectively. The star‐shaped structure of 12% sirolimus/PLGA ensures the bioavailability of the drugs. Sirolimus release kinetic was fitted up to 80% with the “Higuchi model” for Mg samples, whereas Mg/Na/S/P showed 45% fitting with a zero‐order mechanism. The Mg/Na/S/P substrate showed a 70% antithrombotic effect compared to control. Further, alkali treatment enhances the antibacterial characteristic of AZ91 Mg alloy. Also, the alkali‐treated sirolimus‐loaded substrates (Mg/Na/S and Mg/Na/S/P) inhibit the valvular interstitial cell's growth significantly in in‐vitro. Hence, the results imply that sirolimus‐loaded PLGA‐coated AZ91 Mg alloy‐based substrate can be a potential candidate for cardiovascular stent application.

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Fabrication of Mg alloy tubes for biodegradable stent application

Cited by 60 publications

References 31 publications

The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents

The cold-rolling behaviour of AZ31 tubes for fabrication of biodegradable stents

Mechanical and microstructural characterisation in the processing of biomedical metallic fine tubes

Biodegradable AZ91 magnesium alloy/sirolimus/poly D, L‐lactic‐co‐glycolic acid‐based substrate for cardiovascular device application

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