Effect of process parameters on the properties of selective laser sintered Poly(3-hydroxybutyrate) scaffolds for bone tissue engineering

Porous scaffolds are biocompatible and bioactive temporary substrates. They should present appropriated microstructure, mechanical properties and surface properties for guiding bone tissue regeneration. In this work, scaffolds of Poly(3-hydroxybutyrate) (PHB) were printed by Selective Laser Sintering (SLS). The effect of scan spacing (SS) and powder layer thickness (PLT) on the morphology, mechanical properties and dimensional deviations related to the digital model of sintered scaffolds was evaluated. Curling was observed in the first built layers of scaffolds, mainly for scaffolds printed with the lowest PLT. Besides designed pores, the scaffolds also presented micropores derived from the incomplete sinterisation of PHB particles. This morphology can be advantageous for bone regeneration. The variation of PLT caused a higher difference between the values of scaffold mechanical properties than the variation of SS. The scaffolds, except the one printed with the highest PLT or SS, showed mechanical properties within the lower range of human trabecular bone.     

Advances and Perspectives in Dental Pulp Stem Cell Based Neuroregeneration Therapies

Human dental pulp stem cells (hDPSCs) are some of the most promising stem cell types for regenerative therapies given their ability to grow in the absence of serum and their realistic possibility to be used in autologous grafts. In this review, we describe the particular advantages of hDPSCs for neuroregenerative cell therapies. We thoroughly discuss the knowledge about their embryonic origin and characteristics of their postnatal niche, as well as the current status of cell culture protocols to maximize their multilineage differentiation potential, highlighting some common issues when assessing neuronal differentiation fates of hDPSCs. We also review the recent progress on neuroprotective and immunomodulatory capacity of hDPSCs and their secreted extracellular vesicles, as well as their combination with scaffold materials to improve their functional integration on the injured central nervous system (CNS) and peripheral nervous system (PNS). Finally, we offer some perspectives on the current and possible future applications of hDPSCs in neuroregenerative cell therapies.     

生物基异己糖醇聚酯的制备及其构效关系研究进展

异己糖醇是一类碳水化合物衍生二元醇,具有高刚性、手性、亲水性和低毒等特性,在制备新型生物基、生物可降解高分子材料方面具有广阔的发展前景。围绕近年来研究较为充分的全脂肪型及半芳香型异己糖醇基均聚酯与共聚酯,综述了其合成、热学性能、力学性能、生物降解性能及潜在应用,探讨此类聚酯的高效聚合反应工艺及构效关系。异己糖醇结构单元的引入可有效提高聚合物的玻璃化转变温度,以及促进其水解和生物降解性能,在构建具有更高性能的环境友好型聚酯方面具有较高潜力,有望应用于工程塑料、纤维、生物医药等领域。此类生物基聚酯的大规模商业化需进一步开发更高效、温和的聚合反应工艺以攻克其热敏感和热降解问题。     

Preparation of poly(ε‐caprolactone)/poly(ε‐caprolactone‐co‐lactide) (PCL/PLCL) blend filament by melt spinning

Poly(ε‐caprolactone)/poly(ε‐caprolactone‐co‐lactide) (PCL/PLCL) blend filaments with various ratios of PCL and PLCL were prepared by melt spinning. The effect of PLCL content on the physical properties of the blended filament was investigated. The melt spinning of the blend was carried out and the as spun filament was subsequently subjected to drawing and heat setting process. The addition of PLCL caused significant changes in the mechanical properties of the filaments. Crystallinity of blend decreased with the addition of PLCL as observed by X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM) revealed that the fracture surface becomes rougher at higher PLCL content. It may be proposed that PCL and PLCL show limited interaction within the blend matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Coupling Interrupted Fischer and Multicomponent Joullié-Ugi to Chase Chemical Diversity: from Batch to Sustainable Flow Synthesis of Peptidomimetics

The generation of peptidomimetic substructures for medicinal chemistry purposes requires effective and divergent synthetic methods. We present in this work an efficient flow process that allows quick modulation of reagents for Joullié-Ugi multicomponent reaction, using spiroindolenines as core motifs. This sterically hindered imine equivalent could successfully be diversified using various isocyanides and amino acids in generally good space-time yields. A telescoped flow process combining interrupted Fischer reaction for spiroindolenine synthesis and subsequent Joullié-Ugi-type modification resulted in product formation in very good overall yield in less than 2 hours compared to 48 hours required in batch mode. The developed protocol can be seen as a general tool for rapid and facile generation of peptidomimetic compounds. We also showcase preliminary biological assessments for the prepared compounds.     

Production of hyaluronic‐acid‐based cell‐enclosing microparticles and microcapsules via enzymatic reaction using a microfluidic system

This article describes the preparation of cell‐enclosing hyaluronic acid (HA) microparticles with solid core and microcapsules with liquid core through cell‐friendly horseradish peroxidase (HRP)‐catalyzed hydrogelation. The spherical vehicles were made from HA derivative possessing phenolic hydroxyl moieties (HA‐Ph) cross‐linkable through the enzymatic reaction by extruding cell‐suspending HA‐Ph aqueous solution containing HRP from a needle of 180 μm in inner diameter into the ambient coaxial flow of liquid paraffin containing H₂O₂ in a microtubule of 600 μm in diameter. By altering the flow rate of liquid paraffin, the diameters of gelatin and HA‐Ph microparticles were varied in the range of 120–220 μm and 100–300 μm, respectively. The viability of the enclosed human hepatoma HepG2 cells in the HA‐Ph microparticles of 180 μm in diameter was 94.2 ± 2.3%. The growth of the enclosed HepG2 cells was enhanced by decreasing the HRP concentration. The microcapsules of 200 μm in diameter were obtained by extruding HA‐Ph aqueous solution containing thermally liquefiable cell‐enclosing gelatin microparticles of 150 μm in diameter using the same microfluidic system. The enclosed cells grew and filled the cavity within 10 days. Spherical tissues covered with a heterogeneous cell layer were obtained by degrading the microcapsule membrane using hyaluronidase after covering the surface with a heterogeneous cell layer. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43107.     

Polylactide‐perylene derivative for blue biodegradable organic light‐emitting diodes

In this work we demonstrate, for the first time, the use of polylactic acid (PLA) as a biodegradable host matrix for the construction of the active emissive layer of organic light‐emitting diode (OLED) devices for potential use in bioelectronics. In this preliminary study, we report a robust synthesis of two fluorescent PLA derivatives, pyrene‐PLA ( AH10 ) and perylene‐PLA ( AH11 ). These materials were prepared by the ring opening polymerisation of l ‐lactide with hydroxyalkyl‐pyrene and hydroxyalkyl‐perylene derivatives using 1,8‐diazabicyclo[5.4.0]undec‐7‐ene as catalyst. OLEDs were fabricated from these materials using a simple device architecture involving a solution‐processed single‐emitting layer in the configuration ITO/PEDOT:PSS/PVK:OXD‐7 (35%): AH10 or AH11 (20%)/TPBi/LiF/Al (ITO, indium tin oxide; PEDOT:PSS, poly(3,4‐ethylenedioxythiophene) doped with poly(styrenesulfonic acid); PVK, poly(vinylcarbazole); OXD‐7, (1,3‐phenylene)‐bis‐[5‐(4‐tert‐butylphenyl)‐1,3,4‐oxadiazole]; TPBi, 2,2′,2″‐(1,3,5‐benzenetriyl)tris(1‐phenyl‐1H‐benzimidazole)). The turn‐on voltage for the perylene OLED at 10 cd m^–2 was around 6 V with a maximum brightness of 1200 cd m^–2 at 13 V. The corresponding external quantum efficiency and device current efficiency were 1.5% and 2.8 cd A^–1 respectively. In summary, this study provides proof of principle that OLEDs can be constructed from PLA, a readily available and renewable bio‐source. © 2020 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Industrial Chemistry.