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Microfiber yarns (MY) have been widely employed to construct tendon tissue grafts. However, suboptimal ultrastructure and inappropriate environments for cell interactions limit their clinical application. Herein, we designed a modified electrospinning device to coat poly(lactic-co-glycolic acid) PLGA nanofibers onto polylactic acid (PLA) MY to generate PLGA/PLA hybrid yarns (HY), which had a well-aligned nanofibrous structure, resembling the ultrastructure of native tendon tissues and showed enhanced failure load compared to PLA MY. PLGA/PLA HY significantly improved the growth, proliferation, and tendon-specific gene expressions of human adipose derived mesenchymal stem cells (HADMSC) compared to PLA MY. Moreover, thymosin beta-4 (Tβ4) loaded PLGA/PLA HY presented a sustained drug release manner for 28 days and showed an additive effect on promoting HADMSC migration, proliferation, and tenogenic differentiation. Collectively, the combination of Tβ4 with the nano-topography of PLGA/PLA HY might be an efficient strategy to promote tenogenesis of adult stem cells for tendon tissue engineering.

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Abstract:The aims of this study were to prepare a thermosensitive composite hydrogel (TCH) by mixing 24% (w/v) poloxamer 407 (P407), 16% (w/v) poloxamer 188 (P188) and 0.1% (w/v) carbopol 940 (C940), and to determine the effect of natural borneol/ (2-hydroxypropyl)-β-cyclodextrin (NB/HP-β-CD) inclusion complex on the phase transition temperature, mechanical, rheological properties, and release behaviors of the TCH using the tube inversion method, a texture analyzer, a rheometer, and in vitro release , respectively. The results showed that as the concentration of NB/HP-β-CD increased, the phase transition temperature of the TCH was increased from 37.26 to 38.34 °C and the mechanical properties of the TCH showed that the hardness, cohesiveness, strength, and adhesiveness were increased from 0.025 to 0.064 kg, 0.022 to 0.064 kg, 0.110 to 0.307 kg and 0.036 to 0.105 kg, respectively, but the rheological properties of the TCH showed that G′, G′′ and η were decreased from 7,760 to 157.50 Pa, 1,274 to 36.28 Pa and 1,252 to 25.37 Pas, respectively. The in vitro release showed that an increasing NB/HP-β-CD concentration decreased the release rate of NB from the TCH, but the amount of NB released was more than 96% at 60 min, which showed the TCH had good release behavior.

As a high-performance fiber, high modulus polyethylene fiber (HMPE) has been widely used in the rope industry. However, due to its low melting point and poor thermal conductivity, it tends to break under the conditions of repeated yarn on yarn abrasion during tension-tension fatigue or tension-bending fatigue. This paper puts forward a method to improve the yarn on yarn abrasion performance of HMPE using a functional graphene/polyurethane composites coating (FG/PU) and discussed the influence of yarn tension, abrasion frequency on the yarn on yarn performance. Based on the yarn morphology and abrasion temperature observation, the failure mechanism was discussed. The experimental results show that the FG/PU coating obtained can improve the yarn on yarn abrasion performance obviously, especially in the case of high-frequency and large tension condition.

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