Polylactide Membranes Research Articles

Porous polylactide membranes with high piezo-catalytic efficiency for organic wastewater treatment

Piezo-catalysis has been emerged as a green and promising wastewater treatment technology for efficient removal of persistent organic pollutants (POPs), such as 4-nitrophenol (4-NP). However, it remains challenging to achieve advanced materials with combined advantages of high piezo-catalytic efficiency, good hydrophilicity, and environmental friendliness. In this work, highly crystalline porous polylactide (PLA) membranes possessing such exceptional advantages have been successfully prepared from biodegradable poly(L-lactide)/poly(D-lactide)/polyethylene glycol/polyoxyethylene-polyoxypropylene block copolymer (PLLA/PDLA/PEG/PEO-PPO-PEO) blends by melt processing and subsequent water etching. During the melt-processing, the two PLA enantiomers co-crystallize into stereocomplex (SC) crystals and simultaneously the PEG used as a porogen is expelled from the crystalline regions. The results show that the prepared PLA membranes have not only abundant micro-porous structures but also good hydrophilicity due to the preferential localization of PEO-PPO-PEO copolymer on the pore walls, thus giving rise to an extremely high water flux of 2400 L/m2h. More interestingly, the PLA membranes exhibit remarkable piezoelectric activity and the piezo-catalytic degradation efficiency of 4-NP can reach as high as 96 % under the triggering of water flow involved in vacuum filtration. In addition, the membranes show excellent reusability and the high catalytic efficiency can be well-maintained after five repeated uses. These findings suggest broad application prospects of our porous SC-PLA membranes in organic wastewater treatment.

Incorporating nano-ZnCo-ZIF particles in the electrospinning polylactide membranes to improve their filtration and antibacterial performances

Incorporating nano-ZnCo-ZIF particles in the electrospinning polylactide membranes to improve their filtration and antibacterial performances

Diamond-Like Carbon Depositing on the Surface of Polylactide Membrane for Prevention of Adhesion Formation During Tendon Repair

HighlightsThe anti-adhesion effect of polylactic acid (PLA) membrane with diamond-like carbon (DLC) depositing is 44.72%, enhanced by 23.11% compared to PLA.DLC deposited on PLA membranes has been shown to effectively reduce the levels of reactive oxygen species, leading to a decrease in the expression of pro-inflammatory cytokines within peritendinous adhesion tissue.DLC decelerates PLA biodegradation and lactic production, which reduces the number of CD68+CD206+ macrophages within peritendinous adhesion tissue.

Incorporating charged Ag@MOFs to boost the antibacterial and filtration properties of porous electrospinning polylactide films

Faced with the pollution caused by particulate matter (PM) in the air, the prevalence of infectious diseases, and the environmental burden by use of nondegradable polymers, the existing filter materials such as meltblown cloth of polypropylene cannot satisfactorily meet people's requirements. In this study, Ag nanoparticles were loaded onto ZIF-8 particles by impregnation reduction to prepare the positively charged Ag@ZIF-8. The porous fibrous membranes of Ag@ZIF-8 with polylactide (PLA) were manufactured by electrostatic spinning technology. Due to the inherently charged feature of Ag@ZIF-8 particles and the presence of pores on fibers, the prepared membranes showed a stable good filtration efficiency of over 97 % at different humidity (30–90%RH, relative humidity). Meanwhile, the presence of charge on Ag@ZIF-8 and the synergistic effects of Ag and ZIF-8 particles made the membranes exhibit good antibacterial effects. The width of the inhibition zone of 3 wt%Ag@ZIF-8/PLA membrane reached 1.33 mm for E. coli and 1.35 mm for S. aureus, respectively.

Facile Approach for the Potential Large-Scale Production of Polylactide Nanofiber Membranes with Enhanced Hydrophilic Properties

Polylactide (PLA) nanofiber membranes with enhanced hydrophilic properties were prepared through electrospinning. As a result of their poor hydrophilic properties, common PLA nanofibers have poor hygroscopicity and separation efficiency when used as oil-water separation materials. In this research, cellulose diacetate (CDA) was used to improve the hydrophilic properties of PLA. The PLA/CDA blends were successfully electrospun to obtain nanofiber membranes with excellent hydrophilic properties and biodegradability. The effects of the additional amount of CDA on the surface morphology, crystalline structure, and hydrophilic properties of the PLA nanofiber membranes were investigated. The water flux of the PLA nanofiber membranes modified with different CDA amounts was also analyzed. The addition of CDA improved the hygroscopicity of the blended PLA membranes; the water contact angle of the PLA/CDA (6/4) fiber membrane was 97.8°, whereas that of the pure PLA fiber membrane was 134.9°. The addition of CDA enhanced hydrophilicity because it tended to decrease the diameter of PLA fibers and thus increased the specific surface area of the membranes. Blending PLA with CDA had no significant effect on the crystalline structure of the PLA fiber membranes. However, the tensile properties of the PLA/CDA nanofiber membranes worsened due to the poor compatibility between PLA and CDA. Interestingly, CDA endowed the nanofiber membranes with improved water flux. The water flux of the PLA/CDA (8/2) nanofiber membrane was 28,540.81 L/m2·h, which was considerably higher than that of the pure PLA fiber membrane (387.47 L/m2·h). The PLA/CDA nanofiber membranes can be feasibly applied as an environmentally friendly oil-water separation material because of their improved hydrophilic properties and excellent biodegradability.

The Use of a Polylactic Membrane in Pediatric Burns Proves to be Successful Even After Late Application.

The Polylactide membrane (PLM) is a biosynthetic dressing that mimics properties of the human epithelium. Herein we describe our experience on the use of PLM in pediatric burns. All pediatric burn patients admitted to the Pediatric Surgery Department between November 2019 and November 2021 and submitted to PLM application were selected. Clinical and demographic data were collected retrospectively. Seventy-seven patients with a median age of 1.8 years were included. The median total body surface area was 6% (2-20%), and burns were mainly mixed-partial thickness. PLM was applied at a median of 5 days post-burn (IQR 3-6), usually under sedation (43/77). After PLM application, the median healing time (HT) was 10 days (IQR 8-14). HT was significantly higher in deep-partial thickness burns vs. mixed superficial-deep (P = .015) and superficial burn areas (P = .006). No correlation was found between HT and the timing of PLM application. The grafting rate due to clinical misevaluation was 2.7%, one infection was found. The PLM is a promising way for treating partial-thickness burns, even when applied later during treatment. Shorter HT, the decreased need for dressing changes, and the potential of sparing of donor sites and pain reduction are its main advantages.

Degradative polylactide nanofibers promote M2 macrophage polarization via STAT6 pathway in peritendinous adhesion

Biodegradability has been considered a future trend in the development of medical biomaterials, with polylactide (PLA) and its derivatives regarded as the essential representatives. However, along with post-implantation degradation, the complications, such as in-stent restenosis and postoperative adhesion, are increasingly evident, which can significantly hamper its clinical application. With high plasticity and heterogeneity, macrophages can switch from the pro-inflammatory to the anti-inflammatory microenvironment. Macrophage M2 polarization is closely related to postoperative adhesion and occurs mainly in the late stages of injury, which overlaps with the period of PLA degradation. The STAT6 pathway plays a regulatory role in this process. Therefore, we speculated that STAT6 participates in M2 polarization caused by PLA degradation. Macrophages were grown on esterase-degraded PLA membranes to mimic in vivo degradation. We identified that PLA degradation promotes STAT6 phosphorylation-mediated excessive M2 polarization in macrophages, resulting in a pro-adhesion microenvironment. Furthermore, the in vivo results revealed the dynamic changes in the macrophage status mediated by PLA degradation from proliferation to the remodeling phase. Consistent with the in vitro results, we demonstrated that STAT6 phosphorylation is the vital promoter of peritendinous M2 macrophages polarization promoted by PLA degradation. The released pro-adhesion cytokines, such as TGF-β, accelerate the myofibroblast state transition from rest-state to activation-state. Together with MMP2 and Col III release, they lead to peritendinous adhesion. Our study reveals the regulatory mechanisms underlying PLA degradation and reduced anti-adhesion efficacy and provides a novel direction for optimizing PLA anti-adhesion membranes.

İnsan Mesenkimal Kök Hücrelerinin Dental Bariyer Membran Üzerinde Osteojenik Farklılaşması

In the field of tissue engineering, there are biodegradable bone implants with biocompatible synthetic polymers that provide successful results in many areas. Dental barrier membranes are bioabsorbable polylactide (PLA) membranes designed for use in many applications of guided bone regeneration (GBR). It provides a structure designed to attract, capture and retain fibroblasts and epithelial cells while protecting the area around the tooth for the development of bone and periodontal supporting tissue. The aim of this study was to evaluate the properties of dental barrier membranes that inhibit cell migration and promote bone formation differentiation using bone marrow stem cells (BMSCs) with high differentiation and proliferation properties. As a result of the study, characterization studies and cell viability experiments of the Synthetic Barrier Membrane product were carried out, and it was observed that it had a positive effect on the adherence and viability of the BMSCs.

Macrophage Polarization Modulated by NF-κB in Polylactide Membranes-Treated Peritendinous Adhesion.

Foreign body reactions (FBR) to implants seriously impair tissue-implant integration and postoperative adhesion. The macrophage, owing to its phenotypic plasticity, is a major regulator in the formation of the inflammatory microenvironment; NF-κB signaling also plays a vital role in the process. It is hypothesized that NF-κB phosphorylation exerts a proinflammatory regulator in FBR to polylactide membranes (PLA-M) and adhesion. First, in vitro and in vivo experiments show that PLA-M induces NF-κB phosphorylation in macrophages, leading to M1 polarization and release of inflammatory factors. The inflammatory microenvironment formed due to PLA-M accelerates myofibroblast differentiation and release of collagen III and MMP2, jointly resulting in peritendinous adhesion. Therefore, JSH-23 (a selective NF-κB inhibitor)-loaded PLA membrane (JSH-23/PLA-M) is fabricated by blend electrospinning to regulate the associated M1 polarization for peritendinous anti-adhesion. JSH-23/PLA-M specifically inhibits NF-κB phosphorylation in macrophages and exhibits anti-inflammatory and anti-adhesion properties. The findings demonstrate that NF-κB phosphorylation has a critical role in PLA-induced M1 polarization and aggravating FBR to PLA-M. Additionally, JSH-23/PLA-M precisely targets modulation of NF-κB phosphorylation in FBR to break the vicious cycle in peritendinous adhesion therapy.

Resorbable polylactide membrane for the treatment of segmental bone defects

IntroductionSegmental bone defects are a challenging clinical problem. In animal studies and craniomaxillofacial surgery, resorbable polylactide membrane (OrthoMesh; DePuy Synthes, West Chester, PA) shows promise for treatment of bone defects. This study presents the results of the treatment of segmental bone defects with resorbable polylactide membrane, bone morphogenic protein-2 (BMP-2), and autograft. MethodsThis study was approved by the institutional review board. All patients with a segmental bone defect treated with a resorbable polylactide membrane by a single surgeon from 2010 to 2019 were retrospectively reviewed. Data related to demographic variables, surgical details, and union were collected. ResultsEleven patients with median age of 37 years (range 22–62 years) were included in the study with segmental bone defects in the tibia (n = 3), femur (n = 4), or forearm (n = 4). Median bone defect size was 6 cm (range 3–12 cm). Etiology of bone defects included osteomyelitis (n = 7), oncologic resection (n = 3), and post-traumatic aseptic nonunion (n = 1). Flap coverage was performed in two patients. Median radiographic follow-up was 24 months (range 5–75 months). Ten patients (10/11) achieved union at a median of 17 months (range 5–46 months). Seven patients required reoperation for any reason with six patients requiring repeat grafting. ConclusionsTo our knowledge, this study is the largest series of patients with segmental bone defects treated with resorbable polylactide membrane. Resorbable polylactide membrane in combination with BMP-2 and autograft represents a safe and effective method of bone graft containment in segmental bone defects measuring up to 12 cm in this series. Ten of 11 patients achieved union at a median time of 16 months with 6 patients requiring repeat grafting. These results compare favorably with the induced membrane technique. This study is limited by its retrospective design, absence of control and comparison groups, and low patient numbers. Future prospective randomized study of the induced membrane technique and resorbable polylactide membrane should be undertaken to determine preferred approaches for treatment of segmental bone defects.

Plasticized 3D-Printed Polymer Electrolytes for Lithium-Ion Batteries

In the current research, we developed and printed by fused-filament fabrication polylactide-polyethylene-oxide blended membranes. The influence of relative content of polymers on the ease of extrusion and printing processes was studied. Ionic liquid N-butyl-N-methylpyrrolidinium bis(trifluoromethane-sulfonyl)imide (Pyr14TFSI) with dissolved LiTFSI salt was infused into the membranes to produce free-standing films of quasi-solid polymer electrolytes. The printed membranes were characterized by ESEM, DSC, XPS, NMR and EIS methods. Neat-printed PLA (polylactide) membrane exhibited poor wetting and low uptake of ionic liquid. However, the XPS tests of 3D-printed PLA-PEO membrane infused with LiTFSI solvated ionic liquid show evidence of the interaction between lithium cations with both, PEO (polyethylene oxide) and PLA. The measurements of diffusion coefficients by PGSE-NMR suggest that the Li+ ions are coordinated by the PEO segments in the polymer blend. Increase of the PEO content at the expense of PLA polymer, leads to more than one order of magnitude improvement of bulk conductivity, approaching 0.2 mS cm−1 at 60

Constructing tubular/porous structures toward highly efficient oil/water separation in electrospun stereocomplex polylactide fibers via coaxial electrospinning technology

The wide application of biodegradable polymers in wastewater treatment is of great significance because it can greatly reduce the risk of secondary pollution during the employ of polymers. In this work, a coaxial electrospinning technology was applied to prepare the polylactide (PLA)-based fibers. The solution of poly(L-lactide) (PLLA), poly(D-lactide) (PDLA) and γ-Fe2O3 nanoparticles was used to construct the tube wall, while the mineral oil was used as the core. As a result, the PLA fibers exhibited the tubular hollow structure with extensive pores on the tube wall after mineral oil was removed by solvents. The prepared PLA membrane exhibited superhydrophobicity and high porosity due to the special porous structure of the fibers. The maximum adsorption capacity toward castor oil was 219.5 g g−1, exhibiting excellent oil adsorption ability. In addition, the membrane showed high oil flux of 57324.8 L m-2h−1 and good oil/water separation ability. The gravity-driven separation flux of emulsion achieved 3401.4 L m-2h−1, and it still remained high level during separating acidic, alkaline and hypersaline emulsions. Besides, the high mechanical property of the membrane endowed it with excellent cycling stability. This work paves the way for the practical applications of environmentally friendly adsorption/separation membranes in oil/water cycling separation.

Design of experiments‐based strategy for development and optimization of polylactide membranes preparation by wet inversion phase method

Cells‐containing scaffolds made of biomaterial are modern hybrid constructs which allow regeneration or reconstruction of damaged connective tissue, e.g. cartilage or bone. The basic aim of the study was to recognize the impact of the scaffold production parameters (i.e. type of applied pore precursor, its concentration) on morphology and mechanical properties of polylactide (PLLA) membrane‐based constructs, as well as their biocompatibility exhibited as cellular response. Design of experiments (DoE) strategy has been applied to quantitatively recognize the effects of synthesis parameters on PLLA‐membrane properties. Two independent correlations have been introduced to provide the influence of the synthesis parameters on the pore size, as well as the Young's modulus identifying the surface properties of scaffolds. PLLA membrane‐based scaffolds characterized by average pore diameter exceeded 100 microns and average Young's modulus exceeded 10 MPa have been obtained. The evaluation of scaffolds biocompatibility has been performed due to comprehensive analysis of proliferation effects and metabolic activity of mouse L929 fibroblasts maintained on the surface of developed PLLA‐membranes. The Application of PVP as the pore precursor positively impacted on the surface properties of the constructs. The lack of cytotoxicity of the developed PLLA membranes has been detected.

Modification of PLA Scaffold Surface for Medical Applications

Materials used for medical applications (e.g., the cellular scaffold) should have not only the specific chemical composition, but the surface layer properties as well. For this reason, a method which enables an increase in the number of pores, wettability of the surface, and improvement the conditions of nutrient transportation into the membrane is being studied. The plasma of a dielectric barrier discharge was applied for the surface modification of polylactide obtained by dry or wet phase inversion. The plasma-modified surface was analyzed by contact angle measurements with water and diiodomethane. The surface free energy (SFE) was calculated by the Owens–Wendt method. The highest SFE and its polar component (67.6 mJ/m2 and 39.5 mJ/m2, respectively) were received when the process was conducted in an Ar + CO2 gas mixture with a discharge power of 20 W. The purpose of this research was to increase the wettability and porosity of the membrane’s surface. It can be concluded that the dielectric barrier discharge can effectively change the surface of the polylactide membranes, and that the structure of the modified membranes was not damaged during modification. The process of modification was easier for the membranes made by dry phase inversion. These materials had higher SFE values after the modification.

Biocompatibility and Bioresorption of 3D-Printed Polylactide and Polyglycolide Tissue Membranes.

We studied biocompatibility and bioresorption of 3D-printed polylactide and polyglycolide tissue membranes. Ultrasound microscopy and histological examination showed that membranes fabricated of a copolymer of lactic and glycolic acids in a mass ratio of 1:9 are bioresorbed and have good biocompatibility with soft tissues (connective tissue, adipose tissue, and epithelium). An important feature of the copolymer membranes, which differs them from pure polylactide membranes, is the formation of a thin fibrous capsule that did not interfere its destruction by the mechanism of hydrolytic resorption.

Bioresorbable magnesium-reinforced PLA membrane for guided bone/tissue regeneration

Considering the inferior mechanical properties of the current bioresorbable polymers, a novel bioresorbable magnesium-reinforced polylactide (PLA) membrane was designed for the application in critical defect sites in guided bone/tissue regeneration. The PLA-FAZ91 membrane was fabricated by combining two PLA membranes with a fluoride-coated AZ91 (9 wt% Al, 1 wt% Zn) (FAZ91) magnesium alloy core by hot pressing. A combined double-layered PLA membrane was used as the control group. A three-point bending test was performed to compare their maximum load and stiffness. Samples were immersed in the HBSS for 20 weeks, and their weight loss percentages were recorded, and a three-point bending test was performed after immersion. An ion release test was performed by immersing samples in the HBSS for 4 weeks and determining the pH and ion concentrations of the HBSS. Cell viability was tested by culturing pre-osteoblast cells with sample extracts in the culture medium obtained from degraded samples. As a result, PLA-FAZ91 showed a significantly higher maximum load and stiffness than those of the non-reinforced PLA membrane. The weight loss of PLA-FAZ91 was much faster, as FAZ91 showed major degradation and was completely degraded after 16–20 weeks of immersion. The degradation of the PLA wrap was accelerated by FAZ91. The mechanical superiority of PLA-FAZ91 over PLA endured for at least 3 weeks during immersion. The pH, magnesium- and fluoride-ion concentration in the PLA-FAZ91 group increased at an appropriate rate. The cell viability was not adversely affected by the addition of FAZ91 to PLA. Therefore, the bioresorbable magnesium-reinforced PLA membrane has the potential to be used as a good alternative to pure PLA membrane in guided bone/tissue regeneration.

The influence of the molecular weight of polymer on the morphology, functional properties and L929 fibroblasts growth on polylactide membranes for tissue engineering

The main goal of tissue engineering (TE) is supporting the regeneration of damaged tissues that are difficult to regenerate. The experimental results of the preparation of semi-permeable membranes for cell cultures are presented. The effect of the PLA molecular weight and addition of pore precursors on the morphology of the membranes was studied. The pore precursor of choice was polyvinylpyrrolidone (PVP). It was found that semi-permeable membranes for application in tissue engineering can be prepared with polylactides of molecular weight more significant than 37,000 g/mol. Moreover, it was observed that the growth of the molecular weight of the polymer, the porosity, the size of the pores, the Young modulus and maximum tensile increased. Additionally, to obtain a better morphology of the membranes, PVP should be added to the polymeric solution. Positive growth of L929 fibroblast cells on the obtained scaffolds was shown.

Polylactide-based stent coatings: biodegradable polymeric coatings capable of maintaining sustained release of the thrombolytic enzyme streptokinase

Abstract The paper describes synthesis and testing of novel biodegradable polylactide-based polymer membranes with desired mechanical properties, which are capable of sustained and directed release of biomacromolecules with high molecular weight (in particular, streptokinase; m.w. 47 kDa). Streptokinase is a pharmaceutical agent, possessing a pronounced thrombolytic activity. The membranes synthesized had a percentage elongation of 2–11% and tensile strength of 25–85 MPa. They were biodegradable – yet being stored in aqueous media in the absence of biological objects, would be dissolved by no more than 10% in 6 months. The synthesized membranes were capable of controlled release of streptokinase into the intercellular space, with the enzyme retaining more than 90% of its initial activity. The rate of streptokinase release from the membranes varied from 0.01 to 0.04 mg/day per cm2 of membrane surface. The membrane samples tested in the work did not have any short-term toxic effects on the cells growing de novo on the membrane surface. The mitotic index of those cells was approximately 1.5%, and the number of non-viable cells on the surface of the polymer films did not exceed 3–4% of their total amount. The implantation of the synthesized polymers – as both individual films and coatings of nitinol stents – was not accompanied by any postoperative complications. The subsequent histological examination revealed no abnormalities. Two months after the implantation of polymer films, only traces of polylactide were found in the implant-surrounding tissues. The implantation of stents coated with streptokinase-containing polymers resulted in the formation of a mature and thick connective-tissue capsules. Thus, the polylactide membranes synthesized and tested in this work are biodegradable, possess the necessary mechanical properties and are capable of sustained and directed release of streptokinase macromolecules.

Sulfated chitosan coated polylactide membrane enhanced osteogenic and vascularization differentiation in MC3T3-E1s and HUVECs co-cultures system

This study aimed to compare the effects of the two type chitosan derivatives, sulfated chitosan (SCS) and phosphorylated chitosan (PCS), coated on poly(d,l-lactide) (PDLLA) membrane via polydopamine, respectively, on vascularization and osteogenesis in vitro. Mouse preosteoblast cells (MC3T3-E1s) and human umbilical vein endothelial cells (HUVECs) were used as co-cultures system. The effects of two type membranes on calcium deposition, alkaline phosphatase (ALP) activity, vascularization related factors nitric oxide (NO) and angiogenic growth factor vascular endothelial growth factor (VEGF) were assessed. The changes of osteogenic and angiogenic related gene, and protein expression were evaluated too. In fact, SCS modified PDLLA membrane had the highest related gene and protein expression than other PDLLA membranes. Our results demonstrated that the SCS maybe a promising matrix for bone regeneration by co-cultures of ECs and OCs than PCS.

Development of bacterial-resistant electrospun polylactide membrane for air filtration application: Effects of reduction methods and their loadings

The antimicrobial activity of fibrous membranes with electrospun polylactide (PLA)/silver nanoparticles (AgNPs) depends on the accessibility of the AgNPs, among other factors. The challenge is therefore to develop a suitable method for loading the AgNPs onto the fibers. In this study, different techniques for determining the efficacy of the membranes in rendering AgNPs available for antimicrobial activity against Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus bacteria are evaluated. Immersion coating, electrospray-coating, and in-situ loading techniques were used to load AgNPs onto hierarchical electrospun PLA fibers, and their antibacterial effect was evaluated based on a qualitative disc diffusion method. The reduction of AgNO3 (Ag+) to AgNPs was carried out through the use of UV irradiation and neem (Azadirachta indica) leaf extracts. The membranes were coated using an electrospray technique resulted in the best antibacterial activity owing to the uniform dispersion of the AgNPs. The AgNPs were also exposed on the surface of the membranes, as confirmed using scanning electron and transmission electron microscopes. An electrospray is, therefore, a promising technique for the preparation of antimicrobial nanofibrous membranes.