Adjusting Morphology, Structure, and Mechanical Properties of Electrospun High-Molecular-Weight Poly(l-Lactic-Acid) Nanofibrous Yarns Through Hot Stretching Treatment

An integrated strategy that combines innovative electrospinning technique with traditional hot-stretching post-treatment is designed and implemented to generate high-molecular-weight poly(l-lactic-acid) (hmwPLLA, Mw = 2 80 000 Da) electrospun nanofiber-constructed yarns (ENCYs). The internal fiber diameter within the hmwPLLA ENCYs is found to increase gradually with the increase of hmwPLLA solution concentration. The hmwPLLA ENCY generated from a concentration of 10% (w v-1) is demonstrated with uniform morphology with an average fiber diameter of 737.7 ± 72.2 nm and an average yarn diameter of 454.9 ± 3.5 µm. Compared with the unstretched hmwPLLA ENCY, increasing the hot-stretching temperature can significantly enhance the fiber orientation and crystallinity. Moreover, the mechanical properties of stretched ENCYs are obviously enhanced compared with the unstretched control. The fiber orientation and crystallinity of stretched ENCYs are also found to be significantly improved with the increase of hot stretching rate, further resulting in the obvious increase of breaking strength and Young's modulus. Importantly, the braided textiles made from stretched hmwPLLA ENCYs exhibited great biocompatibility by effectively guiding the cell alignment and supporting the cell adhesion and proliferation. In summary, the high performance hmwPLLA ENCYs show great potential for the future design and development of advanced biomedical textiles.

Anti-fibrotic and anti-stricture effects of biodegradable biliary stents braided with dexamethasone-impregnated sheath/core structured monofilaments

Endoscopic biliary stent insertion has been widely used for the treatment of benign biliary stricture (BBS). Thus, the development of stent materials in the perspectives of structure, mechanical properties, and biocompatibility has been also studied. However, conventional metal and plastic stents have several disadvantages, such as repeated procedures to remove or exchange them, dislodgment, restenosis, biocompatibility, and poor mechanical properties. Sustainable effectiveness, attenuation and prevention of fibrosis, and biocompatibility are key factors for the clinical application of stents to BBS treatment. In addition, loading drugs could show synergistic effects with stents' own performance. We developed a dexamethasone-eluting biodegradable stent (DBS) consisting of a sheath/core structure with outstanding mechanical properties and sustained release of dexamethasone, which maintained its functions in a BBS duct over 12 weeks in a swine model. The insertion of our DBS not only expanded BBS areas but also healed secondary ulcers as a result of the attenuation of fibrosis. After 16 weeks from the insertion, BBS areas were totally improved, and the DBS was degraded and thoroughly disappeared without re-intervention for stent removal. Our DBS would be an effective clinical tool for non-vascular diseases. STATEMENT OF SIGNIFICANCE: This study describes the insertion of a drug-eluting biodegradable stent (DBS) into the bile duct. The sheath/core structure of DBS confers substantial durability and a sustained drug release profile. Drug released from the DBS exhibited anti-fibrotic effects without inflammatory responses in both in vitro and in vivo experiments. The DBS maintained its function over 12 weeks after insertion into the common bile duct, expanding benign biliary stricture (BBS) and reducing inflammation to heal secondary ulcers in a swine BBS model. After 16 weeks from the DBS insertion, the DBS thoroughly disappeared without re-intervention for stent removal, resulting in totally improved BBS areas. Our findings not only spotlight the understanding of the sheath/core structure of the biodegradable stent, but also pave the way for the further application for non-vascular diseases.

Electrospun Medical Sutures for Wound Healing: A Review

With the increasing demand for wound healing around the world, the level of medical equipment is also increasing, but sutures are still the preferred medical equipment for medical personnel to solve wound closures. Compared with the traditional sutures, the nanofiber sutures produced by combining the preparation technology of drug-eluting sutures have greatly improved both mechanical properties and biological properties. Electrospinning technology has attracted more attention as one of the most convenient and simple methods for preparing functional nanofibers and the related sutures. This review firstly discusses the structural classification of sutures and the performance analysis affecting the manufacture and use of sutures, followed by the discussion and classification of electrospinning technology, and then summarizes the relevant research on absorbable and non-absorbable sutures. Finally, several common polymers and biologically active substances used in creating sutures are concluded, the related applications of sutures are discussed, and the future prospects of electrospinning sutures are suggested.

A Complex In Vitro Degradation Study on Polydioxanone Biliary Stents during a Clinically Relevant Period with the Focus on Raman Spectroscopy Validation

Biodegradable biliary stents are promising treatments for biliary benign stenoses. One of the materials considered for their production is polydioxanone (PPDX), which could exhibit a suitable degradation time for use in biodegradable stents. Proper material degradation characteristics, such as sufficient stiffness and disintegration resistance maintained for a clinically relevant period, are necessary to ensure stent safety and efficacy. The hydrolytic degradation of commercially available polydioxanone biliary stents (ELLA-CS, Hradec Králové, Czech Republic) in phosphate-buffered saline (PBS) was studied. During 9 weeks of degradation, structural, physical, and surface changes were monitored using Raman spectroscopy, differential scanning calorimetry, scanning electron microscopy, and tensile and torsion tests. It was found that the changes in mechanical properties are related to the increase in the ratio of amorphous to crystalline phase, the so-called amorphicity. Monitoring the amorphicity using Raman spectroscopy has proven to be an appropriate method to assess polydioxanone biliary stent degradation. At the 1732 cm⁻¹ Raman peak, the normalized shoulder area is less than 9 cm⁻¹ which indicates stent disintegration. The stent disintegration started after 9 weeks of degradation in PBS, which agrees with previous in vitro studies on polydioxanone materials as well as with in vivo studies on polydioxanone biliary stents.

A review on biodegradable biliary stents: materials and future trends

Biliary stricture is defined as the reduction and narrowing of the bile duct lumen, which can be caused by many factors such as cancer and inflammation. Biliary stent placement can effectively alleviate benign and malignant biliary strictures. However, the commonly used plastic or metallic biliary stents are far from ideal and do not satisfy all clinical requirements，although several types of biodegradable biliary stents have been developed and used clinically. In this review, we summarized current development status of biodegradable stents with the emphasis on the stent materials. We also presented the future development trends based on the published literature.

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Summary of current development status of bioresorbable biliary stents with the emphasis on the stent materials.

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The future development trends based on the published literature.

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The advantages of bioresorbable biliary stents compared with metallic and plastic biliary stents.

Emerging Trends in Biliary Stents: A Materials and Manufacturing Perspective

Biliary stent technology has come a long way since its inception. There have been significant advancements in materials used, designs, and deployment strategies. Options have expanded from thermoplastic and metallic...

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

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.