A poly(L‐lactic acid) monofilament with high mechanical properties for application in biodegradable biliary stents

Tian, Yanhua; Zhang, Houcheng; Cheng, Jie; Wu, Gang; Zhang, Yi; Zhang, Ni; Zhao, Gutian

doi:10.1002/app.49656

Cited by 15 publications

(15 citation statements)

References 29 publications

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“…Such stents have been inserted, e.g., into the esophagus [14,15], intestine [16], bronchus [17], trachea [18] or bile duct [19]. PPDX stents have been widely studied in in vivo medical trials [14,16,[19][20][21][22], their mechanical properties have been investigated [23][24][25][26], and their degradation has also been studied to some extent from a physicochemical point of view [25,27]. Stents made of similar materials have also been analyzed in studies [28] (poly(L-lactic acid) endovascular stent) and [29] (intracoronary stent coated with poly(Llactic acid)).…”

Section: Introductionmentioning

confidence: 99%

Raman Spectroscopy as a Novel Method for the Characterization of Polydioxanone Medical Stents Biodegradation

et al. 2021

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Polydioxanone (PPDX), as an FDA approved polymer in tissue engineering, is an important component of some promising medical devices, e.g., biodegradable stents. The hydrolytic degradation of polydioxanone stents plays a key role in the safety and efficacy of treatment. A new fast and convenient method to quantitatively evaluate the hydrolytic degradation of PPDX stent material was developed. PPDX esophageal stents were degraded in phosphate-buffered saline for 24 weeks. For the first time, the changes in Raman spectra during PPDX biodegradation have been investigated here. The level of PPDX hydrolytic degradation was determined from the Raman spectra by calculating the area under the 1732 cm−1 peak shoulder. Raman spectroscopy, unlike Fourier transform infrared (FT-IR) spectroscopy, is also sensitive enough to monitor the decrease in the dye content in the stents during the degradation. Observation by a scanning electron microscope showed gradually growing cracks, eventually leading to the stent disintegration. The material crystallinity was increasing during the first 16 weeks, suggesting preferential degradation of the amorphous phase. Our results show a new easy and reliable way to evaluate the progression of PPDX hydrolytic degradation. The proposed approach can be useful for further studies on the behavior of PPDX materials, and for clinical practice.

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Section: Introductionmentioning

confidence: 99%

Raman Spectroscopy as a Novel Method for the Characterization of Polydioxanone Medical Stents Biodegradation

et al. 2021

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“…[14][15][16][17][18] To improve the mechanical properties of monofilaments, solid-state drawing (SSD) method is always chosen which is carried out between the glass transition temperature and the melting temperature of PLLA. 19,20 To fabricate the braided stent, stent is first braided on a special mold, and then annealed at 100 C for 1 h. 21 Many studies have shown that shrinkage occurs during unconstrained annealing process for solid-state drawn PLLA monofilaments. 22,23 However, the PLLA monofilaments used for weaving cannot shrink freely since they are taut with constrained ends in the braided stents.…”

Section: Introductionmentioning

confidence: 99%

Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing

Tian

Zhang

et al. 2021

Polymers for Advanced Techs

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Mechanical properties of poly(L-lactic acid) (PLLA) braided stents are closely related to the performance of the weaving monofilaments. In this study, the PLLA monofilaments were prepared via solid-state drawing (SSD) method and annealed with different constraint methods. Experimental results show that mechanical properties of fabricated monofilaments have been greatly improved by SSD method. With the constrained annealing method, mechanical properties can be further improved while negative effect is shown with unconstrained annealing method. The physicochemical properties of PLLA monofilaments were further characterized, and it is found that the draw ratio of SSD and annealing method can affect the crystallinity and crystallite size, which can directly influence the mechanical properties of the monofilaments.This work tells that it is necessary to consider collectively the effects of SSD method and annealing method of the monofilaments in order to obtain optimized mechanical properties of the braided stents.

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“…Therefore, PDO braided stents are preferable to treating some slight benign biliary strictures for several months' support. 10 However, due to complexity and diversity of etiologies, some severe benign biliary strictures will last for over half a year. In these backgrounds, PDO braided stents can not always provide enough support and collapse in advance, leading to adverse clinical events.…”

Section: Introductionmentioning

confidence: 99%

“…The PDO suture has low Young's modulus of about 2 GPa and short degradation period of about 6 months, equipping the BBS with limited radial force within half a year. Therefore, PDO braided stents are preferable to treating some slight benign biliary strictures for several months' support 10 . However, due to complexity and diversity of etiologies, some severe benign biliary strictures will last for over half a year.…”

Section: Introductionmentioning

confidence: 99%

A poly(l‐lactic acid) braided stent with high mechanical properties during in vitro degradation in bile

Zhao

Tian

Hua

et al. 2021

J of Applied Polymer Sci

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In this article, the mechanical properties and physicochemical indexes of a poly(L-lactic acid) (PLLA) braided stent during in vitro degradation in bile for 270 days are characterized to investigate its applications in treating biliary strictures. The PLLA braided stent always maintains structural integrity well macroscopically without cracks or pits microscopically. During degradation, radial compressive force and chronic outward force are increased by 25.1% and 14.3%, respectively, bending stiffness and axial force are increased by 3.0% and 4.9%, respectively. These results indicate that PLLA braided stent can keep sufficient radial force and good bending performance during degradation in bile for 270 days, showing promising application prospects in treating severe benign biliary strictures demanding support for over half a year. Furthermore, almost no mass loss and 42.4% attenuation in molecular weight indicate the degradation mechanism of bulk erosion without obvious autocatalysis, causing decrease in bile pH. Degradation rate constant is 0.002 day À1 and crystallinity is increased by 8%. These results explain that PLLA braided stent can keep high mechanical properties during degradation in bile for 270 days, which is in the early stage of degradation. This study may bring new ideas into the applications of PLLA braided stents in treating biliary strictures.

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A poly(L‐lactic acid) monofilament with high mechanical properties for application in biodegradable biliary stents

Cited by 15 publications

References 29 publications

Raman Spectroscopy as a Novel Method for the Characterization of Polydioxanone Medical Stents Biodegradation

Raman Spectroscopy as a Novel Method for the Characterization of Polydioxanone Medical Stents Biodegradation

Effects of annealing constraint methods on poly(L‐lactic acid) monofilaments for application in stents annealing

A poly(l‐lactic acid) braided stent with high mechanical properties during in vitro degradation in bile

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