Search Results (8)

This work focused on the development of porous scaffolds based on biocomposites comprising two biodegradable and biocompatible biopolymers: a terpolyester, poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (PHBHVHHx), and the bacterial polysaccharide FucoPol. The PHBHVHHx terpolymer was composed of 3-hydroxybutyrate (55 wt%), 3-hydroxyvalerate (21 wt%), and 3-hydroxyhexanoate (24 wt%). This hydrophobic polyester has low crystallinity and can form elastic and flexible films. Fucopol is a fucose-containing water-soluble polysaccharide that forms viscous solutions with shear thinning behavior and has demonstrated emulsion-forming and stabilizing capacity and wound healing ability. Emulsion-templating was used to fabricate PHA-based porous structures in which FucoPol acted as a bioemulsifier. Compared with the scaffolds obtained from emulsions with only water, the use of FucoPol aqueous solutions resulted in structures with improved mechanical properties, namely higher tensile strength (4.4 MPa) and a higher Young’s Modulus (85 MPa), together with an elongation at break of 52%. These features, together with the scaffolds’ high porosity and pore interconnectivity, suggest their potential to sustain cell adhesion and proliferation, which is further supported by FucoPol’s demonstrated wound healing ability. Therefore, the developed PHBHVHHx:FucoPol scaffolds arise as innovative porous bioactive structures with great potential for use in tissue engineering applications. Full article

Currently, the selection of materials for tissue engineering scaffolds is still limited because some tissues require flexible and compatible materials with human cells. Medium-chain-length polyhydroxyalkanoate (MCL-PHA) synthesized in microorganisms is an interesting polymer for use in this area and has elastomeric properties compatible with the human body. MCL-PHAs are elastomers with biodegradability and cellular compatibility, making them an attractive material for fabricating soft tissue that requires high elasticity. In this research, MCL-PHA was produced by fed-batch fermentation that Pseudomonas Putida ATCC 47054 was cultured to accumulate MCL-PHA by using glycerol and sodium octanoate as carbon sources. The amounts of dry cell density, MCL-PHA product per dry cells, and MCL-PHA productivity were at 15 g/L, 27%, and 0.067 g/L/h, respectively, and the components of MCL-PHA consisting of 3-hydroxydecanoate (3HD) 64.5%, 3-hydroxyoctanoate (3HO) 32.2%, and 3-hydroxyhexanoate (3HHx) 3.3%. The biosynthesized MCL-PHA terpolyester has a relatively low melting temperature, low crystallinity, and high ductility at 52 °C, 15.7%, and 218%, respectively, and considering as elastomeric polyester. The high-resolution scaffold of MCL-PHA terpolyester biomaterial-ink (approximately 0.36 mm porous size) could be printed in a selected condition with a 3D printer, similar to the optimum pore size for cell attachment and proliferation. The rheological characteristic of this MCL-PHA biomaterial-ink exhibits shear-thinning behavior, leading to good shape fidelity. The study results yielded a condition capable of fabricating an elastomer scaffold of the MCL-PHA terpolyester, giving rise to the ideal soft tissue engineering application. Full article

In the present study, a new poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) [P(3HB-co-3HV-co-3HHx)] terpolyester with approximately 68 mol% of 3-hydroxybutyrate (3HB), 17 mol% of 3-hydroxyvalerate (3HV), and 15 mol% of 3-hydroxyhexanoate (3HHx) was obtained via the mixed microbial culture (MMC) technology using fruit pulps as feedstock, a processing by-product of the juice industry. After extraction and purification performed in a single step, the P(3HB-co-3HV-co-3HHx) powder was melt-mixed, for the first time, in contents of 10, 25, and 50 wt% with commercial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). Thereafter, the resultant doughs were thermo-compressed to obtain highly miscible films with good optical properties, which can be of interest in rigid and semirigid organic recyclable food packaging applications. The results showed that the developed blends exhibited a progressively lower melting enthalpy with increasing the incorporation of P(3HB-co-3HV-co-3HHx), but retained the PHB crystalline morphology, albeit with an inferred lower crystalline density. Moreover, all the melt-mixed blends were thermally stable up to nearly 240 °C. As the content of terpolymer increased in the blends, the mechanical response of their films showed a brittle-to-ductile transition. On the other hand, the permeabilities to water vapor, oxygen, and, more notably, limonene were seen to increase. On the overall, this study demonstrates the value of using industrial biowaste derived P(3HB-co-3HV-co-3HHx) terpolyesters as potentially cost-effective and sustainable plasticizing additives to balance the physical properties of organic recyclable polyhydroxyalkanoate (PHA)-based food packaging materials. Full article

To improve the dimensional thermal stability of polyethylene terephthalate (PET), a poly(ethylene glycol 1,4-cyclohexane dimethylene (CHDM) isosorbide (ISB) terephthalate) (PEICT) known as ECOZEN^®T110 (EZT) was introduced into PET using a melt blending technique. The miscibility, morphology, and thermal properties of the PET/EZT samples were investigated. The introduction of amorphous EZT into semi-crystalline PET increased the glass transition temperature (T_g) but decreased the crystallinity, which could be related to the transesterification reaction. By adding EZT contents up to 20%, the PET/EZT samples showed a single T_g, which indicated the miscibility between PET and EZT. However, two T_g values were observed in the PET/EZT samples with higher EZT contents (30–70%), indicating partial miscibility. This may have been due to the slightly different rheological and thermodynamic parameters that were affected by a higher ratio of bulky (rigid ISB and ductile CHDM) groups in EZT. However, the heat distortion temperature of the PET/EZT samples remarkably increased, which indicated that the dimensional stability was truly enhanced. Although the crystallinity of the PET/EZT samples decreased with increasing EZT content, the tensile strength and Young’s modulus decreased slightly. Based on these results, the as-prepared PET/EZT samples with high dimensional stability can be used as a high-temperature polymeric material in various applications. Full article

This research synthesizes novel copolyester (PCITN) containing biobased isosorbide, 1,4-cyclohexandimethanol, terephthalic acid, and 2,6-naphthalene dicarboxylic acid and characterize its properties. The PCITN copolyester was extruded into film, and its performance properties including: tensile strength, Young’s modulus, thermal, dimensional stability, barrier (water barrier), and optical (birefringence and transmittance) were analyzed after uniaxial stretching. The films have higher T_g, T_m, dimensional stability, and mechanical properties than other polyester-type polymers, and these performance properties are significantly increased with increasing stretching. This is due to the increased orientation of molecular chains inside the films, which was confirmed by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and birefringence results. Good water barrier (0.54%) and lower birefringence (△n: 0.09) of PCITN film compared to poly(ethylene terephthalate) (PET), poly(ethylene 2,6-naphthalate) (PEN), and polyimide (PI) films, used as conventional substrate materials for optical devices, make it an ideal candidate as performance material for next-generation flexible devices. Full article

We demonstrate a sequential electrospinning process involving the adsorption of ZnO nanoparticles on the surface of bio-based polyester, which is a terpolyester of a renewable isosorbide (ISB) monomer, ethylene glycol, 1,4-cyclohexane dimethanol, and terephthalic acid, the-so-called PEICT, to fabricate stable ZnO nanoparticles/PEICT nanofiber composite system protected with other two PEICT nanofiber mats. We found that post-electrospinning treatment with a particular solvent was effective to remove a residual solvent molecule in the PEICT nanofibers, which induced significant aggregation of the nanoparticles, leading to non-uniform distribution of the particles on the surface. Sequential electrospinning of the PEICT solution to sandwich ZnO nanoparticle-decorated PEICT nanofiber mat enabled to attain protected the inorganic/organic hybrid nanofiber mat, improving the long-term stability, and the reproducibility of the inorganic particles decorated nanofiber fabrication. Full article

During the two years that have passed since the first volume of “Advances in Polyhydroxyalkanoate (PHA) production” was published, the progress in PHA-related research was indeed tremendous, calling for the next, highly bioprocess- and bioengineering-oriented volume. This editorial paper summarizes and puts into context the contributions to this second volume of the Bioengineering Special Issue; it covers highly topical fields of PHA-related R&D activities, covering, beside the pronounced bioengineering-related articles, the fields of the microbiology of underexplored, but probably emerging, PHA production strains from the groups of Pseudomonas, cyanobacteria, methanotrophs, and from the extremophilic domain of haloarchaea. Moreover, novel second-generation lignocellulose feedstocks for PHA production from agriculture to be used in biorefinery concepts, new approaches for fine-tuning the composition of PHA co- and terpolyesters, process simulation for PHA production from methane-rich natural gas, the challenges associated with rheology-governed oxygen transfer in high cell density cultivations, rapid spectroscopic in-line analytics for process monitoring, and the biomedical application of PHA biopolyesters after appropriate advanced processing are the subjects of the presented studies. Full article

The thermal and mechanical properties of two types of polyester nanofiber, poly (1,4-cyclohexanedimethylene isosorbide terephthalate) (PICT) copolymers and the terpolyester of isosorbide, ethylene glycol, 1,4-cyclohexane dimethanol, and terephthalic acid (PEICT), were investigated. This is the first attempt to fabricate PICT nanofiber via the electrospinning method; comparison with PEICT nanofiber could give greater understanding of eco-friendly nanofibers containing biomass monomers. The nanofibers fabricated from each polymer show similar smooth and thin-and-long morphologies. On the other hand, the polymers exhibited significantly different mechanical and thermal properties; in particular, a higher tensile strength was observed for PICT nanofiber mat than for that of PEICT. We hypothesized that PICT has more trans-configuration than PEICT, resulting in enhancement of its tensile strength, and demonstrated this by Fourier transform infrared spectroscopy. In addition, PICT nanofibers showed clear crystallization behavior upon increased temperature, while PEICT nanofibers showed completely amorphous structure. Both nanofibers have better tensile properties and thermal stability than the typical polyester polymer, implying that they can be utilized in various industrial applications. Full article