Polymeric materials have numerous applications from the industrial to medical fields because of their vast controllable properties. In this study, we aimed to synthesize series of poly(butylene succinate-dilinoleic succinate-ethylene glycol succinate) (PBS-DLS-PEG) copolymers, by two-step polycondensation using a heterogeneous catalyst and a two-step process. PEG of different molecular weights, namely, 1000 g/mol and 6000 g/mol, was used in order to study its effect on the surface and thermal properties. The amount of the PBS hard segment in all copolymers was fixed at 70 wt%, while different ratios between the soft segments (DLS and PEG) were applied. The chemical structure of PBS-DLS-PEG was evaluated using Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Gel permeation chromatography was used to determine the molecular weight and dispersity index. The results of structural analysis indicate the incorporation of PEG in the macrochain. The physical and thermal properties of the newly synthesized copolymers were also evaluated using water contact angle measurements, differential scanning calorimetry and dynamic thermomechanical analysis. It was found that increasing the amount of PEG of a higher molecular weight increased the surface wettability of the new materials while maintaining their thermal properties. Importantly, the two-step melt polycondensation allowed a direct fabrication of a polymeric filament with a well-controlled diameter directly from the reactor. The obtained results clearly show that the use of two-step polycondensation in the melt allows obtaining novel PBS-DLS-PEG copolymers and creates new opportunities for the controlled processing of these hydrophilic and thermally stable copolymers for 3D printing technology, which is increasingly used in medical techniques.

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Appropriate selection of suitable materials and methods is essential for scaffolds fabrication in tissue engineering. The major challenge is to mimic the structure and functions of the extracellular matrix (ECM) of the native tissues. In this study, an optimized 3D structure containing poly(3-hydroxybutyrate) (P3HB), multiwalled carbon nanotubes (MCNTs) and curcumin (CUR) was created by electrospinning a novel biomimetic scaffold. CUR, a natural anti-inflammatory compound, has been selected as a bioactive component to increase the biocompatibility and reduce the potential inflammatory reaction of electrospun scaffolds. The presence of CUR in electrospun scaffolds was confirmed by 1H NMR and Fourier-transform infrared spectroscopy (FTIR). Scanning electron microscopy (SEM) revealed highly interconnected porosity of the obtained 3D structures. Addition of up to 20 wt% CUR has enhanced mechanical properties of the scaffolds. CUR has also promoted in vitro bioactivity and hydrolytic degradation of the electrospun nanofibers. The developed P3HB-MCNT composite scaffolds containing 20 wt% of CUR revealed excellent in vitro cytocompatibility using mesenchymal stem cells and in vivo biocompatibility in rat animal model study. Importantly, the reduced inflammatory reaction in the rat model after 8 weeks of implantation has also been observed for scaffolds modified with CUR. Overall, newly developed P3HB-MCNTs-CUR electrospun scaffolds have demonstrated their high potential for tissue engineering applications.

Abstract. The aim of this study is to evaluate the e ects of Multi-Walled Carbon NanoTubes (MWNTs) on the structural and mechanical properties of poly-3-hydroxybutyrate (P3HB) electrospun sca olds. To achieve optimal properties of the electrospinning machine, P3HB polymer solutions were prepared at di erent concentrations and spinned in di erent electrospinning parameters. After optimization, MWNTs in di erent weight percentages (0.5%, 0.75%, 1%, and 1.25%) were added to the polymer solutions and electrospinned. The e ects of MWNTs on the structure of bers were investigated using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) techniques. The addition of MWNTs increased the average ber diameter from 210 (neat P3HB) to 700 nm at 1.25% MWNTs. In addition, SEM photomicrographs and the MATLAB software program showed an increase in porosity from 81% to 84% in the presence of MWNTs. Tensile strength of P3HB/MWNTs composites revealed 158% improvement over pure P3HB sca old. According to mechanical and structural properties, the best amount of MWNTs was 0.5 wt%. Therefore, MWNTs with low percentages can signi cantly improve the mechanical properties of pure P3HB sca old, so that they can become favorable mechanically for tissue engineering applications.

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Keratin was extracted from chicken feather to produce scaffolds with poly(3-hydroxybutyrate) (P(3HB)) for tissue engineering applications. The scaffolds with different concentrations (10%, 20%, and 30%) of keratin were produced by electrospinning. The keratin presence in the produced scaffold was confirmed by FTIR analysis. The surface wettability of the P(3HB)/keratin scaffold was much higher compared to neat P(3HB) scaffold because of hydrophilic nature of the keratin. All the scaffolds showed over 80% porosity with an average fiber diameter of less than 750 nm. Mechanical properties of the P(3HB) scaffolds with up to 20% keratin were superior compared to neat P(3HB) scaffold. However, the mechanical properties of the P(3HB)/keratin scaffolds were deteriorated when the keratin concentration was 30% in the scaffold. The observed mechanical properties reduction was mainly attributed to the poor interaction between the keratin and P(3HB) matrix. Due to better biocompatibility of keratin, cell culture studies suggested that the P(3HB)/ keratin scaffolds can have better cell attachment and proliferation compared to the neat P(3HB) scaffold. Owing to good biological response and mechanical properties, the P(3HB)/keratin scaffolds with an optimal concentration of keratin (20%) could be used as potential material for tissue engineering application.