Immiscible polymer blends of semicrystalline biocompatible components: thermal properties and phase morphology analysis of PLLA/PCL blends

Tailored fabrication of biodegradable polymer/ Fe3O4 doped WO3 nano star-based porous membrane with enhanced photo fentonic activity for environmental remediation

The accelerated development of special-wetting polymeric materials with hierarchical pores for membrane applications is crucial to effectively separating water-soluble and insoluble pollutants, such as oily wastewater, emulsion, organic pollutants, and heavy metals. This pressing environmental and socioeconomic issue requires the implementation of effective remediation technologies. In this study, we successfully fabricated an environmentally friendly membrane with a flexible property by combining biopolymers and magnetic nanohybrids of iron oxide (Fe3O4)-doped tungsten oxide (WO3) through a thermal-induced phase separation process (TIPS). The resulting membrane exhibited a well-defined 3D-interconnected porous network structure when blending poly (ε-caprolactone)/poly (D,L-lactide) (PCL)/(PDLLA) in an 8:2 volume ratio. The Fe3O4@WO3 nanohybrids were synthesized using a hydrothermal process, resulting in a star-shaped morphology from the sea urchin-like WO3 clusters, which showed great potential to efficiently separate water/oil contamination and facilitate visible-light-driven photocatalytic degradation of organic dyes (MB, Rh B, BY, and CR) and photoreduction of hexavalent chromium (Cr (VI)). The obtained PCL/PDLLA/Fe3O4@WO3 nanocomposite membrane demonstrated hydrophobic properties, showing a water contact angle of 95 ± 2° and an excellent oil adsorption capacity of ∼4-4.5 g/g without fouling. The interconnected porous structure of the composite membrane enabled the efficient separation of emulsions (≥99.4 %) and achieved a high permeation flux of up to 1524 L m-2 h-1 under gravity separation. Overall, we obtained a novel high-performance composite material with specialized wetting properties, offering significant potential for effectively removing insoluble and soluble organic contaminants from wastewater.

Advanced Bioresin Formulation for 3D-Printed Bone Scaffolds: PCLDMA and p-PLA Integration

In bone tissue engineering, scaffold attributes such as pore dimensions and mechanical strength are crucial. This study synthesized polycaprolactone dimethacrylate (PCLDMA) from polycaprolactone (PCL), incorporating epichlorohydrin (Epi-PCL) and methacryloyl chloride (Meth-Cl). PCLDMA was blended with polylactic acid (p-PLA) to 3D-print bone scaffolds using stereolithography (SLA). Analytical techniques included nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and compression testing. Degradation kinetics and cell viability were investigated using human osteoblast (HOB) cells. Findings revealed PCLDMA/p-PLA composite scaffold superiority over the original polymers. Notably, PCLDMA-60 (60% PCLDMA, 40% p-PLA) displayed optimal properties. Compressive strength varied from 0.019 to 16.185 MPa, porosity from 2% to 50%, and degradation rates from 0% to 0.4% over three days. Cell viability assays affirmed biocompatibility across various PCLDMA ratios. In conclusion, PCLDMA/p-PLA composite scaffolds, particularly PCLDMA-60, show great potential in bone tissue engineering.

A Novel Approach for Glycero-(9,10-trioxolane)-Trialeate Incorporation into Poly(lactic acid)/Poly(ɛ-caprolactone) Blends for Biomedicine and Packaging

The product of ozonolysis, glycero-(9,10-trioxolane)-trioleate (ozonide of oleic acid triglyceride, [OTOA]), was incorporated into polylactic acid/polycaprolactone (PLA/PCL) blend films in the amount of 1, 5, 10, 20, 30 and 40% w/w. The morphological, mechanical, thermal and antibacterial properties of the biodegradable PLA/PCL films after the OTOA addition were studied. According to DSC and XRD data, the degree of crystallinity of the PLA/PCL + OTOA films showed a general decreasing trend with an increase in OTOA content. Thus, a significant decrease from 34.0% for the reference PLA/PCL film to 15.7% for the PLA/PCL + 40% OTOA film was established using DSC. Observed results could be explained by the plasticizing effect of OTOA. On the other hand, the PLA/PCL film with 20% OTOA does not follow this trend, showing an increase in crystallinity both via DSC (20.3%) and XRD (34.6%). OTOA molecules, acting as a plasticizer, reduce the entropic barrier for nuclei formation, leading to large number of PLA spherulites in the plasticized PLA/PCL matrix. In addition, OTOA molecules could decrease the local melt viscosity at the vicinity of the growing lamellae, leading to faster crystal growth. Morphological analysis showed that the structure of the films with an OTOA concentration above 20% drastically changed. Specifically, an interface between the PLA/PCL matrix and OTOA was formed, thereby forming a capsule with the embedded antibacterial agent. The moisture permeability of the resulting PLA/PCL + OTOA films decreased due to the formation of uniformly distributed hydrophobic amorphous zones that prevented water penetration. This architecture affects the tensile characteristics of the films: strength decreases to 5.6 MPa, elastic modulus E by 40%. The behavior of film elasticity is associated with the redistribution of amorphous regions in the matrix. Additionally, PLA/PCL + OTOA films with 20, 30 and 40% of OTOA showed good antibacterial properties on Pseudomonas aeruginosa, Raoultella terrigena (Klebsiella terrigena) and Agrobacterium tumefaciens, making the developed films potentially promising materials for wound-dressing applications.

The structure and selected properties of poly(ε-caprolactone)-based biodegradable composites with high calcium carbonate concentration

The article refers to new polycaprolactone (PCL) composites with high concentration of calcium carbonate (CC). The objective of the present study was the manufacturing of PCL-based biodegradable composites, containing from 24 to 75 % of CC by mass, along with analyses of changes in selected properties of the obtained PCL composites, occurring upon various amounts of CC. Importantly, in the study relatively cheap and unmodified kind of CC has been used to determine the changeover cost of produced composites. Qualitative and quantitative analyses in addition to structure analysis of the obtained composites, including the distribution of the filler particles and their average dimensions were conducted. Furthermore, the mechanical and thermal properties, mass melt flow rate and the density have been determined. Finally, a commercially important economic analysis has been presented. A significant influence of CC on the mechanical properties of PCL was found. Specifically, the reduction of its relative elongation at break and impact strength, as well as the increase of its flexural modulus and bending strength. An increase in the thermal stability of the produced composites was also observed, however the characteristic temperatures of phase transitions as well as the degree of crystallinity did not change significantly. Considering the results of the density tests, an increase in the CC content resulted in a significant decrease in the unit price of the produced composites. This is of particular application importance, because a lower cost material with new properties could be obtained.

Thermal Stability and Dynamic Mechanical Properties of Poly(ε-caprolactone)/Chitosan Composite Membranes

Poly (ε-caprolactone) (PCL) and chitosan (CS) are widely used as biodegradable and biocompatible polymers with desirable properties for tissue engineering applications. Composite membranes (CS-PCL) with various blend ratios (CS:PCL, w/w) of 0:100, 5:95, 10:90, 15:85, 20:80, and 100:0 were successfully prepared by lyophilization. The thermal stabilities of the CS-PCL membranes were systematically characterized by thermogravimetric analysis (TG), dynamic thermogravimetry (DTG), and differential scanning calorimetry (DSC). It was shown that the blend ratio of PCL and CS had a significant effect on the thermal stability, hydrophilicity, and dynamic mechanical viscoelasticity of the CS-PCL membranes. All the samples in the experimental range exhibited high elasticity at low temperature and high viscosity at high temperatures by dynamic mechanical thermal analysis (DMTA). The performances of the CS-PCL membranes were at optimum levels when the blend ratio (w/w) was 10:90. The glass transition temperature of the CS-PCL membranes increased from 64.8 °C to 76.6 °C compared to that of the pure PCL, and the initial thermal decomposition temperature reached 86.7 °C. The crystallinity and porosity went up to 29.97% and 85.61%, respectively, while the tensile strength and elongation at the breakage were 20.036 MPa and 198.72%, respectively. Therefore, the 10:90 (w/w) blend ratio of CS/PCL is recommended to prepare CS-PCL membranes for tissue engineering applications.

The Structure and Mechanical Properties of Hemp Fibers-Reinforced Poly(ε-Caprolactone) Composites Modified by Electron Beam Irradiation

The need for the development of new biodegradable materials and modification of the properties the current ones possess has essentially increased in recent years. The aim of this study was the comparison of changes occurring in poly(ε-caprolactone) (PCL) due to its modification by high-energy electron beam derived from a linear electron accelerator, as well as the addition of natural fibers in the form of cut hemp fibers. Changes to the fibers structure in the obtained composites and the geometrical surface structure of sample fractures with the use of scanning electron microscopy were investigated. Moreover, the mechanical properties were examined, including tensile strength, elongation at break, flexural modulus and impact strength of the modified PCL. It was found that PCL, modified with hemp fibers and/or electron radiation, exhibited enhanced flexural modulus but the elongation at break and impact strength decreased. Depending on the electron radiation dose and the hemp fibers content, tensile strength decreased or increased. It was also found that hemp fibers caused greater changes to the mechanical properties of PCL than electron radiation. The prepared composites exhibited uniform distribution of the dispersed phase in the polymer matrix and adequate adhesion at the interface between the two components.

Fully Biobased Shape Memory Thermoplastic Vulcanizates from Poly(Lactic Acid) and Modified Natural Eucommia Ulmoides Gum with Co-Continuous Structure and Super Toughness

Novel, fully biobased shape memory thermoplastic vulcanizates (TPVs) were prepared using two sustainable biopolymers, poly(lactic acid) (PLA), and modified natural Eucommia ulmoides gum (EUG-g-GMA), via a dynamic vulcanization technique. Simultaneously, in situ compatibilization was achieved in the TPVs to improve interfacial adhesion and the crosslinked modified Eucommia ulmoides gum (EUG) was in "netlike" continuous state in the PLA matrix to form "sea-sea" phase structure. The promoted interface and co-continuous structure played critical roles in enhancing shape memory capacity and toughness of the TPVs. The TPV with 40 wt % modified EUG displayed the highest toughness with an impact strength of 54.8 kJ/m2 and the most excellent shape memory performances with a shape fixity ratio (Rf) of 99.83% and a shape recovery ratio (Rr) of 93.74%. The prepared shape memory TPVs would open up great potential applications in biobased shape memory materials for smart medical devices.

Biodegradable Polymer Films with a Natural Antibacterial Extract as Novel Periodontal Barrier Membranes

Biodegradable composite membranes containing propolis were produced from PCL/PLLA blends using a simple and low-cost solvent casting method, and subsequently their physicochemical, mechanical, and antibacterial properties were characterized. SEM analysis revealed that the addition of propolis has created honeycomb-like structures on the film surfaces. The flexibility of the films increased in the presence of propolis, which may provide ease of use during application. Propolis disrupted the organized structure of both polymers at the molecular level and caused decreases in the melting points. The films with propolis showed faster degradation in physiological conditions due to this molecular disruption. Moreover, the PLLA/PCL/propolis composite films exhibited remarkable antibacterial activities against S. aureus. Collectively, the data suggest that the produced films might be used as an alternative to exiting barrier membranes in guided tissue regeneration.

Threads Made with Blended Biopolymers: Mechanical, Physical and Biological Features

Poly (Lactic Acid), PLA, and Poly (ε-CaproLactone), PCL, compatibilized with Ethyl Ester l-Lysine Triisocyanate (LTI) can be employed as biomaterials. We mixed PLA with PCL and LTI in a twin extruder and by a melt spinning process obtained threads with an average diameter of about 0.3 mm. In order to study the possible application of these threads, mechanical tensile (with the calorimetric and morphological investigations) and biological tests were performed. The results highlighted these biopolymers as promising materials for sutures since they can be rigid and elastic (especially by increasing the PCL amount in the blend), and they are bioactive, able to inhibit bacterial growth. This paper represents a starting point to optimize the blend composition for biomedical suture application.

A versatile strategy for the synthesis and mechanical property manipulation of networked biodegradable polymeric materials composed of well-defined alternating hard and soft domains

Networked materials composed of well-defined alternating domains of two types of biodegradable polymers, hard poly(l-lactide) and soft poly(ε-caprolactone), were successfully synthesized.

Hydrolytic degradation of PCL-PLLA semi-IPNs exhibiting rapid, tunable degradation

Accelerating the rate of polyester hydrolytic degradation is of interest for numerous biomedical applications. Poly(ε-caprolactone) (PCL) and poly(L-lactic acid) (PLLA) have been extensively studied as thermoplastic homo- and copolymers as well as PCL-PLLA blends. PCL-PLLA semi-interpenetrating networks (semi-IPN) prepared with thermoplastic PLLA embedded in a cross-linked PCL diacrylate (PCL-DA) network were previously shown to exhibit uniquely accelerated degradation behavior that increased with PLLA content. Herein, their properties before and during degradation were further investigated to reveal the origin of this behavior and to better understand the semi-IPNs' degradation mechanism. Initially, semi-IPNs exhibited restricted spherulite size and irregularity, as well as a phase-separated morphology and PLLA-rich surface. Under accelerated conditions (1 M NaOH, 37 °C), degradation was revealed to be initiated in PLLA regions. It was also found that the PCL-DA crosslinking and PCL-PLLA phase separation played the largest roles in degradation rates and that semi-IPNs underwent faster rates of degradation than an analogous blend largely due to the reduced crystallinity of PCL-DA. Non-accelerated conditions (PBS [pH = 7.4], 37 °C) up to 56 weeks, which had never before been studied for polyester semi-IPNs, revealed similar trends in degradation rates.

Modulating matrix-multicellular response using polysucrose-blended with poly-L-lactide or polydioxanone in electrospun scaffolds for skin tissue regeneration

Polysucrose (PSuc) is hydrophilic, has excellent biocompatibility with cells as a density gradient and is resistant to enzymes. Its use in electrospun mats for tissue engineering applications has not been investigated due to its amorphous nature. For spinnability and robustness, polysucrose was blended with poly-L-lactide (PLLA) and polydioxanone (PDX) respectively and electrospun into nanofibrous mats. Interaction with cells was assessed using L929 mouse fibroblasts and HaCaT keratinocytes separately and in co-culture. Effect of parameters such as porosity, fiber diameter, surface wettability and mechanical properties of mats on cell-scaffold interactions was studied. Depending on nature and composition of mats, fibroblasts showed dendritic, spindle or round cell morphologies along with the formation of lamellipodia, filopodia, fibrillar or fiber-like projections of 100 nm and 200-300 nm in diameter respectively from the periphery or center of cells. Granular extracellular matrix was formed on both PLLA-PSuc and PDX-PSuc 50-50 seeded with keratinocytes. Growth of keratinocytes was enhanced in co-culture with fibroblasts with the formation of a skin-like layer. Both cells showed the ability to form multilayer structures. The mats maintained their physical integrity during the period of study. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3275-3291, 2018.

Hydrolytic Degradation and Erosion of Polyester Biomaterials

Strategies to refine the degradation behavior of polyester biomaterials, particularly to overcome the limitations of slow hydrolytic degradation, would broaden their utility. Herein, we examine the complexities of polyester degradation behavior, its assessment and strategies for refinement. The factors governing polyester degradation are strikingly complex. In addition to the half-life of the hydrolytically-labile bond, a series of interdependent material properties must be considered. Thus, methods used to characterize such material properties, both before and during degradation, must be carefully selected. Assessment of degradation behavior is further complicated by the variability of reported test protocols and the need for accelerated rather than real-time in vitro testing conditions. Ultimately, through better control of degradation behavior and correlation of in vitro, simulated degradation to that observed in vivo, the development of superior devices prepared with polyester biomaterials may be achieved.

Block-Stereoblock Copolymers of Poly(ϵ-Caprolactone) and Poly(Lactic Acid)

A magnesium complex of the type {ONNN}Mg-HMDS wherein {ONNN} is a sequential tetradentate monoanionic ligand is introduced. In the presence of an alcohol initiator this complex catalyzes the living and immortal homopolymerization of the lactide enantiomers and ϵ-caprolactone at room-temperature with exceptionally high activities, as well as the precise block copolymerization of these monomers in a one-pot synthesis by sequential monomer addition. Copolymers of unprecedented microstructures such as the PCL-b-PLLA-b-PDLA and PDLA-b-PLLA-b-PCL-b-PLLA-b-PDLA block-stereoblock microstructures that feature unique thermal properties are readily accessed.

Immiscible poly(lactic acid)/poly(ε-caprolactone) for temporary implants: Compatibility and cytotoxicity

This manuscript focuses on the effect of the addition of a low molecular weight triblock copolymer derived from ε-caprolactone and tetrahydrofuran (CT) on the compatibility and cytotoxicity of immiscible poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) blends. Binary and tertiary PLA/PCL blends were prepared by melt mixing in a twin-screw extruder and their morphological, mechanical and thermal behaviors were investigated by scanning electron microscopy (SEM), tensile and Izod impact test, dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). SEM micrographs showed the CT copolymer suppressed the coalescence phenomena and maintained the size of dispersed PCL domains at approximately 0.35µm. Bioresorbable PLA/PCL blends containing 5wt% of CT copolymer exhibited a remarkable increase in ductility and improved toughness at room temperature. Although the CT copolymer increased the interfacial adhesion, the DMA results suggest it also acts as a plasticizer exclusively for the PCL phase. The cell viability evaluated by the XTT assay confirmed PLA/PCL blends compatibilized by CT copolymer exerted no cytotoxic effect.

Poly (lactic acid)-based biomaterials for orthopaedic regenerative engineering

Regenerative engineering converges tissue engineering, advanced materials science, stem cell science, and developmental biology to regenerate complex tissues such as whole limbs. Regenerative engineering scaffolds provide mechanical support and nanoscale control over architecture, topography, and biochemical cues to influence cellular outcome. In this regard, poly (lactic acid) (PLA)-based biomaterials may be considered as a gold standard for many orthopaedic regenerative engineering applications because of their versatility in fabrication, biodegradability, and compatibility with biomolecules and cells. Here we discuss recent developments in PLA-based biomaterials with respect to processability and current applications in the clinical and research settings for bone, ligament, meniscus, and cartilage regeneration.

Lactoferrin-Immobilized Surfaces onto Functionalized PLA Assisted by the Gamma-Rays and Nitrogen Plasma to Create Materials with Multifunctional Properties

Both cold nitrogen radiofrequency plasma and gamma irradiation have been applied to activate and functionalize the polylactic acid (PLA) surface and the subsequent lactoferrin immobilization. Modified films were comparatively characterized with respect to the procedure of activation and also with unmodified sample by water contact angle measurements, mass loss, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), and chemiluminescence measurements. All modified samples exhibit enhanced surface properties mainly those concerning biocompatibility, antimicrobial, and antioxidant properties, and furthermore, they are biodegradable and environmentally friendly. Lactoferrin deposited layer by covalent coupling using carbodiimide chemistry showed a good stability. It was found that the lactoferrin-modified PLA materials present significantly increased oxidative stability. Gamma-irradiated samples and lactoferrin-functionalized samples show higher antioxidant, antimicrobial, and cell proliferation activity than plasma-activated and lactoferrin-functionalized ones. The multifunctional materials thus obtained could find application as biomaterials or as bioactive packaging films.