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Nanocomposites based on poly(lactic acid) (PLA) and magnetite nanoparticles (MNP-Fe3O4) show promise for applications in biomedical treatments. One key challenge is to improve the stabilization and dispersion of MNP-Fe3O4. To address this, we synthesized MNP-Fe3O4/PLA nanocomposites using ultrasound mediation and a single iron(II) precursor, eliminating the need for surfactants or organic solvents, and conducted the process under ambient conditions. The resulting materials, containing 18 and 33 wt.% Fe3O4, exhibited unique thermal behavior characterized by two mass losses: one at a lower degradation temperature (Td) and another at a higher Td compared to pure PLA. This suggests that the interaction between PLA and MNP-Fe3O4 occurs through hydrogen bonds, enhancing the thermal stability of a portion of the polymer. Fourier Transform Infrared (FT-IR) analysis supported this finding, revealing shifts in bands related to the terminal –OH groups of the polymer and the Fe–O bonds, thereby confirming the interaction between the groups. Raman spectroscopy demonstrated that the PLA serves as a protective layer against the oxidation of MNP-Fe3O4 in the 18% MNP-Fe3O4/PLA nanocomposite when exposed to a high-power laser (90 mW). Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) analyses confirmed that the synthetic procedure yields materials with dispersed nanoparticles within the PLA matrix without the need for additional reactants. [ABSTRACT FROM AUTHOR]

Poly(lactic acid) (PLA) is an important polymer that is based on renewable biomass resources. Because of environmental issues, more renewable sources for polymers synthesis have been sought for industrial purposes. In this sense, cheaper monomers should be used to facilitate better utilization of less valuable chemicals and therefore granting more sustainable processes. Some points are raised about the need to study the total degradability of any PLA, which may require specific composting conditions (e.g., temperature, type of microorganism, adequate humidity and aerobic environment). Polymerization processes to produce PLA are presented with an emphasis on D,L-lactic acid (or rac-lactide) as the reactant monomer. The syntheses involving homogeneous and heterogeneous catalytic processes to produce poly(D,L-Lactic acid) (PDLLA) are also addressed. Additionally, the production of blends, copolymers, and composites with PDLLA are also presented exemplifying different preparation methods. Some general applications of these materials mostly dedicated to the biomedical area over the last 10–15 years will be pointed out. [ABSTRACT FROM AUTHOR]

Tissue engineering is a branch of regenerative medicine, which comprises the combination of biomaterials, cells and other bioactive molecules to regenerate tissues. Biomaterial scaffolds act as substrate and as physical support for cells and they can also reproduce the extracellular matrix cues. Although tissue engineering applications in cellular therapy tend to focus on the use of specialized cells from particular tissues or stem cells, little attention has been paid to endothelial progenitors, an important cell type in tissue regeneration. We combined 3D printed poly(lactic acid) scaffolds comprising two different pore sizes with human adipose-derived stromal cells (hASCs) and expanded CD133+ cells to evaluate how these two cell types respond to the different architectures. hASCs represent an ideal source of cells for tissue engineering applications due to their low immunogenicity, paracrine activity and ability to differentiate. Expanded CD133+ cells were isolated from umbilical cord blood and represent a source of endothelial-like cells with angiogenic potential. Fluorescence microscopy and scanning electron microscopy showed that both cell types were able to adhere to the scaffolds and maintain their characteristic morphologies. The porous PLA scaffolds stimulated cell cycle progression of hASCs but led to an arrest in the G1 phase and reduced proliferation of expanded CD133+ cells. Also, while hASCs maintained their undifferentiated profile after 7 days of culture on the scaffolds, expanded CD133+ cells presented a reduction of the von Willebrand factor (vWF), which affected the cells’ angiogenic potential. We did not observe changes in cell behavior for any of the parameters analyzed between the scaffolds with different pore sizes, but the 3D environment created by the scaffolds had different effects on the cell types tested. Unlike the extensively used mesenchymal stem cell types, the 3D PLA scaffolds led to opposite behaviors of the expanded CD133+ cells in terms of cytotoxicity, proliferation and immunophenotype. The results obtained reinforce the importance of studying how different cell types respond to 3D culture systems when considering the scaffold approach for tissue engineering.

The presented research focused on improving the mechanical properties of PLA-based composites reinforced with buckwheat husks (BH) particles. The research work was carried out in two stages. Firstly, the blend was prepared with the addition of polybutylene adipate terephthalate (PBAT) and thermoplastic starch (TPS), manufactured by injection molding technique, then the selected materials were prepared with the addition of BH filler, and the samples were prepared using the fused deposition modeling method (FDM). All samples were subjected to the assessment of material properties. Thermal and thermomechanical properties were evaluated using differential scanning calorimetry analysis (DSC) and dynamic thermal mechanical analysis (DMTA). Mechanical characteristic was evaluated using static tensile and flexural measurements and Charpy impact resistance tests. The research was supplemented with scanning electron microscopy analysis (SEM). It was found that the addition of PBAT and TPS greatly improves impact strength and elongation, especially with the addition of reactive compatibilizer. As expected, TPS, PBAT, and BH reduced the stiffness of the composites during DMTA testing. The presence of BH particles in the polymer matrix was observed to improve the crystallization behavior of PLA. The optimal content of BH filler in the composite was found to be 10%, which allowed to preserve good mechanical properties. [ABSTRACT FROM AUTHOR]

The presented research focused on improving the mechanical properties of PLA-based composites reinforced with buckwheat husks (BH) particles. The research work was carried out in two stages. Firstly, the blend was prepared with the addition of polybutylene adipate terephthalate (PBAT) and thermoplastic starch (TPS), manufactured by injection molding technique, then the selected materials were prepared with the addition of BH filler, and the samples were prepared using the fused deposition modeling method (FDM). All samples were subjected to the assessment of material properties. Thermal and thermomechanical properties were evaluated using differential scanning calorimetry analysis (DSC) and dynamic thermal mechanical analysis (DMTA). Mechanical characteristic was evaluated using static tensile and flexural measurements and Charpy impact resistance tests. The research was supplemented with scanning electron microscopy analysis (SEM). It was found that the addition of PBAT and TPS greatly improves impact strength and elongation, especially with the addition of reactive compatibilizer. As expected, TPS, PBAT, and BH reduced the stiffness of the composites during DMTA testing. The presence of BH particles in the polymer matrix was observed to improve the crystallization behavior of PLA. The optimal content of BH filler in the composite was found to be 10%, which allowed to preserve good mechanical properties. [ABSTRACT FROM AUTHOR]

In this work, the use of an environmentally friendly plasticizer derived epoxidized cottonseed oil (ECSO) for poly(lactic acid) (PLA) is proposed. Melt extrusion was used to plasticize PLA formulations with different ECSO contents in the 0–10 wt.%. PLA formulation with 10 wt.% shows a remarkable increase in mechanical ductile properties with a percentage increase in elongation at break of more than 1100% and a noticeable increase in the impact absorbed energy. Differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) revealed a clear decrease in the glass transition temperature of neat PLA as the ECSO content increased. Field emission scanning electron microscopy (FESEM) of fractured surfaces from impact tests showed an improvement of ductility with typical rough and porous topographies. Migration tests in n -hexane at different temperatures revealed very low migration properties thus leading to new interesting plasticizers for improved PLA industrial formulations. [ABSTRACT FROM AUTHOR]