Polylactic Acid Piezo-Biopolymers: Chemistry, Structural Evolution, Fabrication Methods, and Tissue Engineering Applications

Polylactide acid (PLA), as an FDA-approved biomaterial, has been widely applied due to its unique merits, such as its biocompatibility, biodegradability, and piezoelectricity. Numerous utilizations, including sensors, actuators, and bio-application—its most exciting application to promote cell migration, differentiation, growth, and protein–surface interaction—originate from the piezoelectricity effect. Since PLA exhibits piezoelectricity in both crystalline structure and an amorphous state, it is crucial to study it closely to understand the source of such a phenomenon. In this respect, in the current study, we first reviewed the methods promoting piezoelectricity. The present work is a comprehensive review that was conducted to promote the low piezoelectric constant of PLA in numerous procedures. In this respect, its chemistry and structural origins have been explored in detail. Combining any other variables to induce a specific application or to improve any PLA barriers, namely, its hydrophobicity, poor electrical conductivity, or the tuning of its mechanical properties, especially in the application of cardiovascular tissue engineering, is also discussed wherever relevant.

Antimicrobial behavior, low-stress mechanical properties, and comfort of knitted fabrics made from poly (hydroxybutyrate-co-hydroxyvalerate)/polylactide acid filaments and cotton yarns

This article presents a systematic investigation of the knitted fabrics made from various blends of intrinsically antimicrobial poly (hydroxybutyrate-co-hydroxyvalerate)/polylactide acid filaments and cotton staple fibers. The effects of blend yarn, fabric structures, and distributions of fibers on antimicrobial properties of resultant yarns and knitted fabrics were studied. The relationships among fiber distribution, blend ratio, and anti-microbial properties were experimentally determined for three blend yarns made by sirofil, wrap-spun, and core-spun spinning technologies. The fabrics made from the sirofil-spun and wrap-spun yarns show better anti-microbial effects against Staphylococcus aureus, Klebsiella pneumoniae, and Candida albicans than those of the core-spun yarns, according to the standard AATCC100-2012 Antibacterial Finishes on Textile Materials (American Association of Textile Chemists and Colorists, 2012). An alternative blending method of co-knitting of the pure poly (hydroxybutyrate-co-hydroxyvalerate)/polylactide acid yarns and cotton yarns achieved excellent antimicrobial effects. Furthermore, a wearing trial of underwear made from the blended knitted fabrics was conducted in a nursing home. The wearing comfort of the garments, low-stress mechanical and surface properties of fabrics were evaluated objectively by the Kawabata Evaluation System of Fabric (KESF) system and subjectively by a questionnaire survey to users.

3D-printing on textiles – an investigation on adhesion properties of the produced composite materials

The actual paper is related to adhesive properties of 3D objects printed on cotton textile fabrics. For practical applications of 3D prints in the textile sector, the adhesion of the printed object on the textile substrate is an important issue. In the current study, two different types of polymers are printed on cotton – polylactide acid (PLA) and polyamide 6.6 (Nylon). Altogether six cotton fabrics differing in structure, weight and thickness are evaluated. Also, the effect of washing and enzymatic desizing is investigated. For printing parameters, best results are gained for elevated process temperatures, intermediate printing speed and low Z-distance between printing head and substrate. Also, a textile treatment by washing and desizing can improve the adhesion of an afterwards applied 3D print. The presented results are quite useful for future developments of 3D printing applications on textile substrates, e.g. to implement new decorative features or protective functions.

Marine Algae Incorporated Polylactide Acid Patch: Novel Candidate for Targeting Osteosarcoma Cells without Impairing the Osteoblastic Proliferation

Biodegradable collagen-based materials have been preferred as scaffolds and grafts for diverse clinical applications in density and orthopedy. Besides the advantages of using such bio-originated materials, the use of collagen matrices increases the risk of infection transmission through the cells or the tissues of the graft/scaffold. In addition, such collagen-based solutions are not counted as economically feasible approaches due to their high production cost. In recent years, incorporation of marine algae in synthetic polymers has been considered as an alternative method for preparation grafts/scaffolds since they represent abundant and cheap source of potential biopolymers. Current work aims to propose a novel composite patch prepared by blending Sargassum vulgare powders (SVP) to polylactide (PLA) as an alternative to the porcine-derived membranes. SVP-PLA composite patches were produced by using a modified solvent casting method. Following detailed material characterization to assess the cytocompatibility, human osteoblasts (HOBs) and osteosarcoma cells (SaOS-2) were seeded on neat PLA and SVP-PLA patches. MTT and BrdU assays indicated a greater cytocompatibility and higher proliferation for HOBs cultured on SVP-PLA composite than for those cultured on neat PLA. SaOS-2 cells cultured on SVP-PLA exhibited a significant decrease in cell proliferation. The composite patch described herein exhibits an antiproliferative effect against SaOS-2 cells without impairing HOBs’ adhesion and proliferation.

SCAFFOLD FROM MICRO ELECTROSPUN POLYLACTIDE ACID AND WET CHEMICAL HYDROTHERMAL REACTION HYDROXY APATITE USED FOR BIOMEDICAL APPLICATION

Polylactic acid (PLA) microfibrous composite scaffolds having hydroxy apatite (HA) particles in the fibers were prepared by electrospinning of PLA and wet chemical hydrothermal reaction HA with average diameter of 8.13 µm. The fibers were compressed in mould into bulk scaffolds. Microscopy characterizations confirmed integration of the crystalline HA and PLA fibers in both before and after compression. The morphology, porosity of scaffolds were examined by scanning electron microscope (SEM). The HA content were observed by SEM and determined by Thermogravimetry Analysis (TGA). Agglomeration gradually appeared and increased on the fiber surface along with the increase of HA concentration. The fiber diameter also increased with the HA concentration. Mechanical property of scaffold was examined by compressional strength test. The scaffold prepare for bone substitute implant application with suitable mechanical performance and morphology.

Development of Bionanocomposites Based on Poly(3-Hydroxybutyrate-co-3-Hydroxyvalerate)/PolylActide Blends Reinforced with Cloisite 30B

In the present study, poly(3-hydroxybuturate-co-3-hydroxyvalerate) (PHBV) and plasticized polylactide acid (PLA) blends were processed by melt extrusion with different weight ratio (up to 20 wt.% of PHBV). Bionanocomposites were obtained through the incorporation of an organomodified montmorillonite (C30B) at 3 wt.%. The main features of the processing and physico-chemical characterization of films and injected samples were assessed and the influence of the components on the chemical, thermal and mechanical properties of the bionanocomposites was investigated. The results indicated that plasticized PLA/PHBV/C30B bionanocomposites present optimal mechanical properties for sanitary applications. Moreover, plasticized PLA/PHBV could lead to finely tuned biomaterials able to form electrospun nanofibers.

Qualitative Assessment of Four Types of Three-Dimensional Printed Anatomical Tibial Bone Models Compared to Commercially Available Models

Objective The aim of this study was to compare technical and physical features of four three-dimensional printed bone models used for teaching purposes to commercial models. Study Design A canine tibia was imaged using computed tomography and used for model development. Tibial models were printed using Resin, polylactide acid (PLA), acrylonitrile butadiene styrene (ABS) and high-impact polystyrene (HIPS). They were compared with two commercial models (SAWBONES 2117 and 2108). Models were drilled in three locations and then cut transversely. Subjective quality of models, time and cost of production were compared. Results Print time was approximately 3 hours for Resin and 4 hours for each of the PLA, ABS and HIPS models. Unlike the Resin and SAWBONES, the PLA, HIPS and ABS had higher heat generation during both drilling and cutting with mild construct deformation at cut surfaces in ABS and PLA models. Characteristics of real bone during drilling and cutting were best simulated in decreasing order by Resin, PLA, ABS and HIPS followed by SAWBONES 2117 and 2108 models. Material costs were $14.6 (Resin), $0.48 (PLA/ABS), $1.52 (HIPS), $23.50 and $17.50 for SAWBONES 2117 and 2108 per model, respectively. Resin performed best and had the closest subjective tactile properties to real bone. Conclusion The three-dimensional printed tibial bone models provide a cost-effective alternative to commercially available bone models in veterinary medicine as teaching models.

Impact of 3D-printing structure on the tribological properties of polymers

Purpose The purpose of this paper is to examine the impact of three-dimensional (3D)-printing process settings (particularly print orientation) on the tribological properties of different polymers. Design/methodology/approach In this study, fused deposition modelling 3D-printing technology was used for fabricating the specimens. To evaluate the influence of print orientation, the test pieces were manufactured horizontally (X) and vertically (Z). The tribological properties of various printed polymers, which are polylactide acid, high tensile/high temperature-polylactide acid and polyethylene terephthalate-glycol have been studied. The tribological tests have been carried out under reciprocating sliding and dry condition. Findings The results show that the presence of various orientations during the 3D-printing process makes a difference in the coefficient of friction and the wear depth values. Findings suggest that printing structure in the horizontal orientation (X) assists in reducing friction and wear. Originality/value To date, there has been very limited research on the tribology of objects produced by 3D printing. This work was made as an attempt to pave the way for future research on the science of tribology of 3D-printed polymers.

Simultaneously improving the fire performance and toughness of polylactic acid by reactive blending with castor oil-based polyurethane and ammonium polyphosphate

A new method has been presented to simultaneously enhance both the flame retardancy and toughness of polylactide acid composites by introducing castor oil-based polyurethane and ammonium polyphosphate via reactive blending. The in situ polymerization of castor oil and toluene diisocyanate in the polylactide acid matrix has been confirmed by the Fourier transform infrared spectroscopy. The flame retardant test results indicate that the introduction of 20% ammonium polyphosphate can increase the limiting oxygen index of polylactide acid composites from 19.3% to 27.2%, upgrade the UL-94 rating from no rating to V-0, and decrease the peak heat release rate from 505.5 to 337.0 kW/m2. Moreover, the toughness of polylactide acid is also improved significantly, with the elongation at break and notched impact strength increasing to 37.0% and 7.59 kJ/m2, respectively. The possible mechanisms for both flame retardancy and toughness are also discussed and proposed.