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Lactic acid (LA) is a versatile, optically active compound with applications across the food, cosmetics, pharmaceutical, and chemical industries, largely driven by its role in producing biodegradable polylactic acid (PLA). Due to its abundance, lignocellulosic biomass is a promising and sustainable resource for LA production, although media derived from these matrices are often rich in xylose and contain growth inhibitors. This study investigates LA production using a xylose-rich medium derived from Cynara cardunculus L. altilis DC stalks treated through steam explosion and enzymatic hydrolysis. The lactic acid bacteria strains Lacticaseibacillus casei, Paucilactobacillus vaccinostercus, and Pediococcus pentosaceus were grown on natural media, achieving yields of 0.59, 0.57, and 0.58 g LA/g total carbon consumed, respectively. Remarkably, on xylose-rich media, all supplied sugar was consumed, with LA yields comparable to those on complex media. These findings highlight the adaptability of these strains in the presence of inhibitors and support the potential of lignocellulosic biomass as a low-cost and sustainable substrate for effective PLA production. [ABSTRACT FROM AUTHOR]

ABSTRACT Background Objective Methods Results Conclusion Esthetic medicine has shifted significantly toward non‐surgical procedures, with the collagen biostimulator poly‐l‐lactic acid (PLLA) becoming increasingly popular for facial rejuvenation. However, the safety and patient satisfaction associated with PLLA facial treatments remain largely unexplored.This study aimed to evaluate the safety profile of PLLA treatment and assess patient mid‐ and long‐term satisfaction with the outcome.This prospective single‐center study was conducted at Bravo Clinic in Rio de Janeiro from August 2023 to August 2024. The patients' mid and lower face was treated by injecting Rennova Elleva (a collagen biostimulator containing 210 mg of PLLA) into the zygomatic and pre‐masseteric regions. All patients underwent monthly clinical evaluations for the first 150 days and kept diaries to self‐record any adverse effects during the first 30 days. Patient satisfaction was measured using the Global Aesthetic Improvement Scale (GAIS) on days 90 and 150 post‐injection.The study included 52 female patients [mean age: 49.87 ± 10.7 years; mean body mass index (BMI): 23.99 ± 3.5 kg/m2]. Patients reported mild to moderate injection site reactions, including redness, pain, hardening, swelling, lumps, bruises, and skin discoloration, with most symptoms resolving within a few days. Clinically, no major adverse events were noted, except for one small, painless nodulation that resolved without intervention. On post‐injection Day 90, the average GAIS was rated at 2.32 ± 1.0. This rating remained stable at Day 150, with an average GAIS of 2.32 ± 0.8 (p = 0.862). Inverse correlations were identified between the duration of mild pain and GAIS (rs = −0.546, p = 0.035), as well as between the duration of mild bruises and GAIS (rs = −0.598, p = 0.019). The duration of moderate pain was significantly associated with age (rs = −0.894, p = 0.041).Rennova Elleva, a PLLA‐based collagen biostimulator, is safe and well‐tolerated with a low incidence of adverse effects. It provides long‐lasting, satisfactory results for patients with mild to moderate facial sagging, rendering it an effective non‐surgical option for enhancing facial esthetics. [ABSTRACT FROM AUTHOR]

This study investigates the crystallization behavior of electrospun coaxial fibers composed of crystalline poly(ethylene oxide) (PEO) in the core and crystalline poly(L‐lactide) (PLLA) in the sheath. The influence of cold crystallization temperature and premelting temperature on the crystallization of PEO and PLLA is investigated. At a cold crystallization temperature of ≤60 °C, PLLA remained immobile. PEO crystallization is hard‐confined, leading to a low degree of crystallinity. At a cold crystallization temperature of >60 °C, PEO melted, whereas PLLA crystallized. An increase in cold crystallization temperature results in an increase in the crystallite size and crystallinity of PLLA. Furthermore, the melt crystallization behavior of PEO in the coaxial fibers is strongly influenced by its premelting temperature and crystallization temperature. A higher premelting temperature leads to enhanced interdiffusion between PEO and PLLA. This increased confinement results in a decrease in PEO's crystallizability. Additionally, premelting relaxes the PEO chains, causing a shift in crystal orientation from parallel to the fiber axis (observed in as‐electrospun fibers) to perpendicular to the fiber axis (observed in melt‐crystallized fibers). Moreover, at a low melt crystallization temperature, demixing between PEO and PLLA is observed. This, coupled with a higher degree of supercooling, leads to an increase in PEO's crystallizability. [ABSTRACT FROM AUTHOR]

Highlights A detailed investigation was employed on the manufacturing process of Glass Fiber (GF) reinforced poly‐L‐lactide (PLLA) composites (GFRP) during in‐situ PLLA polymerization using Resin Transfer Molding (RTM). The lower viscosity of lactide, in comparison to PLLA, led to a strong interaction between PLLA and GF as a result of improved penetration into the fiber matrix, resulting in a high conversion rate of 100% for GFRP and 91.9% for PLLA. GF incorporation into the composite material resulted in an improved crystallinity of 55.65% for GFRP, where PLLA showed crystallinity of 36.5%. A GFRP composite with exceptional mechanical properties, including 122.3 MPa tensile strength and 4.485 GPa modulus, was achieved. Both surface and bulk erosion were seen during the breakdown of these composites. These composites seem to be a viable substitute for metallic implants in biological applications. In situ, resin transfer molding of poly‐l‐lactide and GF composite. Higher volume fraction such as 40% w/v loading of GF into composites. 1% conversion of GFRP is achieved. GFRP shows the machinal strength of 122 MPa and harness of 4.2 GPa. Biocompatibility of GFRP composites in body stimulated conditions. [ABSTRACT FROM AUTHOR]

Collagen regeneration is a complex biological process that involves a variety of cell types and growth factors. Pro-collagen regeneration materials are usually made of biological materials or synthetic substances, which can stimulate the proliferation and differentiation of skin cells. At present, there are many kinds of pro-collagen regeneration materials on the market, but the effects and safety of different materials are different. In this paper, the mechanism of action, application and adverse reactions of Calcium hydroxylapatite (CaHA), poly-L-lactic acid (PLLA) and poly-caprolactone (PCL), which promote collagen regeneration, are reviewed. [ABSTRACT FROM AUTHOR]

Bone repair and regeneration require physiological cues, including mechanical, electrical, and biochemical activity. Many biomaterials have been investigated as bioactive scaffolds with excellent electrical properties. Amongst biomaterials, piezoelectric materials (PMs) are gaining attention in biomedicine, power harvesting, biomedical devices, and structural health monitoring. PMs have unique properties, such as the ability to affect physiological movements and deliver electrical stimuli to damaged bone or cells without an external power source. The crucial bone property is its piezoelectricity. Bones can generate electrical charges and potential in response to mechanical stimuli, as they influence bone growth and regeneration. Piezoelectric materials respond to human microenvironment stimuli and are an important factor in bone regeneration and repair. This manuscript is an overview of the fundamentals of the materials generating the piezoelectric effect and their influence on bone repair and regeneration. This paper focuses on the state of the art of piezoelectric materials, such as polymers, ceramics, and composites, and their application in bone tissue engineering. We present important information from the point of view of bone tissue engineering. We highlight promising upcoming approaches and new generations of piezoelectric materials. [ABSTRACT FROM AUTHOR]

Prevention of aseptic loosening, the main reason for secondary surgery of bone implants, is of great crucial clinical importance. As a promising bioactive material to promote bone regeneration, the piezoelectric materials for preventing aseptic loosening has not been reported. Here, a surface coating is presented for implants based on piezoelectric poly(L‐lactic acid) (PLLA). The coating ingeniously utilizes zoledronic acid (ZA), a drug used to treat osteoporosis, as a nucleating agent to enhance the piezoelectricity of PLLA. The coating can not only provide a continuous porous piezoelectric environment to stimulate osteogenic differentiation without intervention, but also effectively inhibit the osteolytic activity of osteoclasts through the slow release of ZA, achieving long‐term effectiveness with a single implantation. The rat femur cavity implantation experiment suggests that, the PLLA/ZA coating can rapidly initiate osseointegration of the implant and effectively mitigate the risk of aseptic loosening, even in the presence of metal submicroscopic particles that induce aseptic loosening. This strategy of piezo‐enhanced PLLA drug‐loaded coating may provide a new idea for the surface modification of bone implants. [ABSTRACT FROM AUTHOR]

Electrospinning technology is widely used for preparing biological tissue engineering scaffolds because of its advantages of simple preparation, accurate process parameters, and easy control. Poly(L-lactide) (PLLA) is regarded as a promising biomass-based polymer for use in electrospinning. The incorporation of Fe3O4 nanoparticles (NPs) could improve the osteogenic differentiation and proliferation of cells in the presence or absence of a static magnetic field (SMF). In this work, these two materials were blended together to obtain electrospun samples with better dispersibility and improved magnetic properties. First, composite PLLA and Fe3O4 NP fibers were prepared by means of electrospinning. The influence of electrospinning conditions on the morphology of the composite fibers was then discussed. Changes in magnetic properties and thermal stability resulting from the use of different PLLA/Fe3O4 mass ratios were also considered. Next, the morphology, crystal state, thermodynamic properties, and magnetic properties of the electrospun samples were determined using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and vibration sample magnetization (VSM). The results showed that the fibers prepared using PLLA with Mn = 170,000 exhibited good morphology when electrospun at 12 KV. The magnetic properties of PLLA/Fe3O4 composite electrospun fibers increased with the NP content, with the exception of thermal stability. The results of the present study may help to promote the further development of PLLA/Fe3O4 composite materials in the biomedical field. [ABSTRACT FROM AUTHOR]

Injectable fillers, pivotal in aesthetic medicine, have evolved significantly with recent trends favoring biostimulators like calcium hydroxylapatite (CaHA‐CMC; Radiesse, Merz Aesthetics, Raleigh, NC) and poly‐l‐lactic acid (PLLA; Sculptra Aesthetics, Galderma, Dallas, TX). This study aims to compare the particle morphology of these two injectables and examine its potential clinical implications. Utilizing advanced light and scanning electron microscopy techniques, the physical characteristics of CaHA‐CMC and PLLA particles were analyzed, including shape, size, circularity, roundness, aspect ratio, and quantity of phagocytosable particles. The findings reveal several morphological contrasts: CaHA‐CMC particles exhibited a smooth, homogenous, spherical morphology with diameters predominantly ranging between 20 and 45 µm, while PLLA particles varied considerably in shape and size, appearing as micro flakes ranging from 2 to 150 µm in major axis length. The circularity and roundness of CaHA‐CMC particles were significantly higher compared to PLLA, indicating a more uniform shape. Aspect ratio analysis further underscored these differences, with CaHA‐CMC particles showing a closer resemblance to circles, unlike the more oblong PLLA particles. Quantification of the phagocytosable content of both injectables revealed a higher percentage of phagocytosable particles in PLLA. These morphological distinctions may influence the tissue response to each treatment. CaHA‐CMC's uniform, spherical particles may result in reduced inflammatory cell recruitment, whereas PLLA's heterogeneous particle morphology may evoke a more pronounced inflammatory response. [ABSTRACT FROM AUTHOR]

Bilayer electrospun fibers aimed to be used for skin tissue engineering applications were fabricated for enhanced cell attachment and proliferation. Different ratios of PHBV-PLLA (70:30, 80:20, and 90:10 w/w) blends were electrospun on previously formed electrospun PHBV membranes to produce their bilayers. The fabricated electrospun membranes were characterized with FTIR, which conformed to the characteristic peaks assigned for both PHBV and PLLA. The surface morphology was evaluated using SEM analysis that showed random fibers with porous morphology. The fiber diameter and pore size were measured in the range of 0.7 ± 0.1 µm and 1.9 ± 0.2 µm, respectively. The tensile properties of the bilayers were determined using an electrodynamic testing system. Bilayers had higher elongation at break (44.45%) compared to the monolayers (28.41%) and improved ultimate tensile strength (7.940 MPa) compared to the PHBV monolayer (2.450 MPa). In vitro cytotoxicity of each of the scaffolds was determined via culturing MC3T3 (pre-osteoblastic cell line) on the membranes. Proliferation was evaluated using the Alamar Blue assay on days 3, 7, and 14, respectively. SEM images of cells cultured on membranes were taken in addition to bright field imaging to visually show cell attachment. Fluorescent nuclear staining performed with DAPI was imaged with an inverted fluorescent microscope. The fabricated bilayer shows high mechanical strength as well as biocompatibility with good cell proliferation and cell attachment, showing potential for skin substitute applications. [ABSTRACT FROM AUTHOR]

To overcome the inherent brittleness of renewable poly(L-lactide) acid (PLLA) and enable it for use in a wide application, we successfully synthesized the toughening agent of ZnO nanoparticles grafted by poly(caprolactone-co-D-lactide) (ZnO-g-PCLDLA) via sequential open-loop polymerization. First, ZnO was silanized to produce hydroxyl groups on the surface of the nanoparticles. Initiated by hydroxyl groups on the ZnO core, the rubbery PCLDLA composed of caprolactone-D-lactide co-polymeric segments and D-lactide homo-polymeric segments was successively polymerized, forming ZnO core-shell nanoparticles. PLLA/ZnO-g-PCLDLA nanocomposites were prepared by solution blending. The nanocomposites with 10 wt% ZnO-g-PCLDLA exhibited superior ductility, whose elongation at break was about 54 times higher than that of neat PLLA. This considerable increment of toughness was attributed to the rubbery shell of PCLDLA and the enhanced interfacial interaction from the interfacial stereocomplex crystallites, formed by co-crystallization of the PLLA matrix and D-lactide homo-polymeric segments of the PCLDLA shell on ZnO. The PLLA/ZnO-g-PCLDLA nanocomposite films possessed outstanding antimicrobial properties against Staphylococcus aureus and Escherichia coli. Positive ZnO produces an electrostatic force to interact with the negatively charged membrane of bacteria, thereby damaging the cell membrane and achieving significant antibacterial effects. Highlights • ZnO-g-PCLDLA core-shell nanoparticles were constructed by sequential ROP. • The ZnO core provided high rigidity and antimicrobial properties. • The rubbery PCLDLA shell provided high elasticity and ductility. • Interfacial interaction was greatly enhanced by the SC crystallites. • The PLLA nanocomposite films exhibited outstanding antimicrobial activity. [ABSTRACT FROM AUTHOR]

The morphology and microstructure of crystalline blends of poly (ethylene glycol) (PEG) and poly (L-lactic acid) (PLLA) were examined using polarized optical microscopy (POM) and scanning electron microscopy (SEM). As PEG was in the melt state during PLLA crystallization, it was rejected from the PLLA bundles. The size of PEG inclusions determined by their extraction is around 1 μm. The PEG/PLLA blends exhibited not only spherulites with Maltese crosses but also distinct extinction rings. The formation of ring-banded spherulites and the periodic distance between the rings were related to the degree of supercooling of the polymer. The ring-banded structure was easily obtained at a high PEG content (70 wt%) and high PLLA crystallization temperature (120 °C). The end group of PEG significantly affected the morphology of PEG/PLLA blends. PLLA blended with PEG containing both end groups as CH3 exhibited the greatest melting temperature depression and lowest degree of supercooling of PLLA, implying the formation of ring-banded spherulites with the smallest PEG content (30 wt%) and lowest PLLA crystallization temperature (85 °C). PEG morphology was also observed using POM after the formation of PLLA crystals. Because PLLA crystals confined the formation of PEG crystals, the chain growth direction of PEG was in association with that of PLLA. Therefore, a brighter POM image was obtained on PEG crystallization. [ABSTRACT FROM AUTHOR]

Proven safe and effective for over 25 years, PLLA-SCA (Injectable poly-L-lactic acid, Sculptra®) boasts versatile applications for both facial and body indications. Increasing consumer demand emphasizes the necessity for clear and effective PLLA-SCA usage recommendations. With extensive experience gathered over the last 25 years, there is a heightened understanding of the clinical, technical, and mechanistic aspects of PLLA-SCA use, essential for optimizing patient outcomes. Dr. Luiz Avelar, a respected Plastic Surgeon from Brazil, imparts expert advice on patient selection, meticulous preparation, refined injection techniques, and practical considerations tailored to body indications. These recommendations align seamlessly with medical literature and Dr. Avelar's wealth of experience, encompassing various body areas, including the neck, décolletage, gluteal region, abdomen, arms, legs, hands, and knees. [ABSTRACT FROM AUTHOR]

Proven safe and effective for over 25 years, PLLA-SCA (Injectable poly-L-lactic acid, Sculptra®) boasts versatile applications for both facial and body indications. Increasing consumer demand emphasizes the necessity for clear and effective PLLA-SCA usage recommendations. With extensive experience gathered over the last 25 years, there is a heightened understanding of the clinical, technical, and mechanistic aspects of PLLA-SCA use, essential for optimizing patient outcomes. The author imparts expert advice on patient selection, meticulous preparation, refined injection techniques, and practical considerations tailored to body indications. These recommendations align seamlessly with medical literature and the authors wealth of experience, encompassing various body areas, including the neck, décolletage, gluteal region, abdomen, arms, legs, hands, and knees. [ABSTRACT FROM AUTHOR]

In this study, 3D printing of poly- l -lactic acid (PLLA) scaffolds reinforced with graphene oxide (GO) nanoparticles via Digital Light Processing (DLP) was investigated to mimic bone tissue. Stereolithography is one of the most accurate additive manufacturing methods, but the dominant available materials used in this method are toxic. In this research, a biocompatible resin (PLLA) was synthetized and functionalized to serve the purpose. Due to the low mechanical properties of the printed product with the neat resin, graphene oxide nanoparticles in three levels (0.5, 1, and 1.5 wt%) were added with the aim of enhancing the mechanical properties. At first, the optimum post cure time of the neat resin was investigated. Consequently, all the parts were post-cured for 3 h after printing. Due to the temperature-dependent structure of GO, all samples were placed in an oven at 85°C for different time periods of 0, 6, 12, and 18 h to increase mechanical properties. The compression test of heat-treated samples reveals that the compressive strength of the printed parts containing 0.5,1, and 1.5% of GO increased by 151,162 ad 235%, respectively. Scaffolds with the designed pore sizes of 750 microns and a porosity of 40% were printed. Surface hydrophilicity test was performed for all samples showing that the hydrophilicity of the samples increased with increasing GO percentage. The degradation behavior of the samples was evaluated in a PBS environment, and it revealed that by increasing GO, the rate of component degradation increased, but the heat treatment had the opposite effect and decreased the degradation rate. Finally, besides improving biological properties, a significant increase in mechanical properties under compression can introduce the printed scaffolds as a suitable option for bone implants. Graphical Abstract [ABSTRACT FROM AUTHOR]

The structure and properties of blends of a novel polyethylene terephthalate copolymer (COPET) obtained by chemical recycling of commercial PET with high-molar-mass poly-L-lactide (PLLA) are investigated and compared to corresponding composites with chopped flax fibres. The focus is on the morphology at nano- and micro-scales, on the thermal characteristics and on the mechanical behaviour. The blends are immiscible, as evidenced by virtually unchanged glass transition temperatures of the blend components compared to the neat polymers (49 °C for COPET and 63 °C for PLLA by DSC). At low PLLA content, the blends display a sea–island morphology with sub-micron to micron droplet sizes. As the composition approaches 50/50, the morphology transitions to a coarser co-continuous elongated structure. The blends and composites show strongly improved stiffness compared to COPET above its glass transition temperature, e.g., from melt behaviour at 60 °C for COPET alone to almost 600 MPa for the 50/50 blend and 500 MPa for the 20% flax composite of the 80/20 COPET/PLLA blend. The flax fibres increase the crystallisation rate of PLLA in blends with dispersed PLLA morphology. The evidence of cavitation on the fracture surfaces of blends shows that despite the immiscibility of the components, the interfacial adhesion between the phases is excellent. This is attributed to the presence of aliphatic ester spacers in COPET. The tensile strength of the 80/20 blend is around 50 MPa with a Young's modulus of 2250 MPa. The corresponding 20% flax composite has similar tensile strength but a high Young's modulus equal to 6400 MPa, which results from the individual dispersion and strong adhesion of the flax fibres and leads close to the maximum possible reinforcement of the composite, as demonstrated by tensile tests and nano-indentation. The Ashby approach to eco-selection relying on the embodied energy (EE) further clarifies the eco-friendliness of the blends and their composites, which are even better positioned than PLLA in a stiffness versus EE chart. [ABSTRACT FROM AUTHOR]

The application of mechanical stimulation on bone tissue engineering constructs aims to mimic the native dynamic nature of bone. Although many attempts have been made to evaluate the effect of applied mechanical stimuli on osteogenic differentiation, the conditions that govern this process have not yet been fully explored. In this study, pre-osteoblastic cells were seeded on PLLA/PCL/PHBV (90/5/5 wt.%) polymeric blend scaffolds. The constructs were subjected every day to cyclic uniaxial compression for 40 min at a displacement of 400 μm, using three frequency values, 0.5, 1, and 1.5 Hz, for up to 21 days, and their osteogenic response was compared to that of static cultures. Finite element simulation was performed to validate the scaffold design and the loading direction, and to assure that cells inside the scaffolds would be subjected to significant levels of strain during stimulation. None of the applied loading conditions negatively affected the cell viability. The alkaline phosphatase activity data indicated significantly higher values at all dynamic conditions compared to the static ones at day 7, with the highest response being observed at 0.5 Hz. Collagen and calcium production were significantly increased compared to static controls. These results indicate that all of the examined frequencies substantially promoted the osteogenic capacity. [ABSTRACT FROM AUTHOR]

Composites based on an L-rich poly(lactic acid) (PLLA) and MCM-41, either neat or modified with a silver (MCM-41@Ag), are achieved by solvent casting, being next processed by compression molding. Ag is mainly embedded as nanowires within the hybrid MCM-41@Ag particles, enabling its antimicrobial character. In these composites, the PLLA thermal stability, nucleation efficiency, and mechanical response are dependent on the MCM-41 nature and, to a lesser extent, on its content. Thus, differences in transitions of the PLLA matrix are noticed during cooling at 10 °C/min and in the subsequent heating when composites with neat or modified MCM-41 are compared. A very remarkable nucleation effect is played by pristine MCM-41, being inferior when MCM-41@Ag is incorporated into the PLLA. Wide angle X-ray scattering (WAXS) measurements using synchrotron radiation and performed under variable-temperature conditions in the composites containing MCM-41@Ag indicate that during cold crystallization, the disordered α′ polymorph is initially formed, but it rapidly transforms into ordered α crystals. A long spacing peak, clearly seen in pure PLLA, appears as a small shoulder in PLLAMCM@Ag4 and is undetectable in PLLAMCM@Ag9 and PLLAMCM@Ag20. Furthermore, an increase in MH with the silica content is found in the two sets of composites, the higher MH values being observed in the family of PLLA and MCM-41@Ag. Finally, remarkable antimicrobial features are noticeable in the composites with MCM-41@Ag since this modified silica transfers its biocidal characteristics into the PLLA composites. [ABSTRACT FROM AUTHOR]

Objective: Poly‐L‐Lactic Acid (PLLA) is a synthetic polymer which possesses biocompatible and biodegradable properties, and is widely used in the clinical filler material. This study focuses on the potential role of PLLA on the collagen production of dermal fibroblasts and its mechanism. Methods: The dermal fibroblast Hs60 was treated with different concentration of PLLA. RT‐qPCR was conducted for the determination of mRNA levels of collagen type I (COL1) alpha 1 (COL1A1), COL1 alpha 2 (COL1A2), elastin, matrix metalloproteinase 1 (MMP‐1), tissue inhibitor of metalloproteinase 1 (TIMP‐1), and TIMP‐2. Procollagen Type I C‐peptide (PIP) enzyme immunoassay (EIA) Kit assay was carried out to analyze procollagen production. Western Blot was employed to examine the effect of PLLA and transforming frown factor (TGF‐β) receptor‐specific inhibitor (SB431542) on protein levels of COL1A1 and TGF‐β/Smad signaling pathway related proteins. Results: With the increase of PLLA concentration, the production of procollagen gradually increased, and both protein and mRNA levels of COL1A1 and COL1A2 gradually increased (p < 0.001). Elevated PLLA concentrations increased elastin, TIMP‐1, and TIMP‐2 levels and attenuated MMP‐1 expression. PLLA increased TGF‐β levels in a dose‐dependently manner. p‐Smad2 and p‐Smad3 protein levels were also increased by PLLA, but the influences were reversed by SB431542 (p < 0.001). Similarly, increased levels of COL1A1, COL1A2, TIMP‐1, and TIMP‐2 caused by PLLA were significantly inhibited by SB431542, whereas MMP‐1 was typically elevated (p < 0.001). Conclusion: Poly‐L‐Lactic Acid promotes the collagen production of dermal fibroblasts by activating the TGF‐β/Smad signaling pathway. The findings may lay a foundation for clinical material applications of PLLA. [ABSTRACT FROM AUTHOR]

Background: 3D printing technology has become a research hotspot in the field of scientific research because of its personalized customization, maneuverability and the ability to achieve multiple material fabrications. The focus of this study is to use 3D printing technology to customize personalized poly L-lactic acid (PLLA) porous screws in orthopedic plants and to explore its effect on tendon-bone healing after anterior cruciate ligament (ACL) reconstruction. Methods: Preparation of PLLA porous screws with good orthogonal pore structure by 3D printer. The hydroxyapatite (HA) was adsorbed on porous screws by electrostatic layer-by-layer self-assembly (ELSA) technology, and PLLA-HA porous screws were prepared. The surface and spatial morphology of the modified screws were observed by scanning electron microscopy (SEM). The porosity of porous screw was measured by liquid displacement method. Thirty New Zealand male white rabbits were divided into two groups according to simple randomization. Autologous tendon was used for right ACL reconstruction, and porous screws were inserted into the femoral tunnel to fix the transplanted tendon. PLLA group was fixed with porous screws, PLLA-HA group was fixed with HA modified porous screws. At 6 weeks and 12 weeks after surgery, 5 animals in each group were sacrificed randomly for histological examination. The remaining 5 animals in each group underwent Micro-CT and biomechanical tests. Results: The pores of PLLA porous screws prepared by 3D printer were uniformly distributed and connected with each other, which meet the experimental requirements. HA was evenly distributed in the porous screw by ELSA technique. Histology showed that compared with PLLA group, mature bone trabeculae were integrated with grafted tendons in PLLA-HA group. Micro-CT showed that the bone formation index of PLLA-HA group was better than that of PLLA group. The new bone was uniformly distributed in the bone tunnel along the screw channel. Biomechanical experiments showed that the failure load and stiffness of PLLA-HA group were significantly higher than those of PLLA group. Conclusions: The 3D printed PLLA porous screw modified by HA can not only fix the grafted tendons, but also increase the inductivity of bone, promote bone growth in the bone tunnel and promote bone integration at the tendon-bone interface. The PLLA-HA porous screw is likely to be used in clinic in the future. [ABSTRACT FROM AUTHOR]

Bone tissue engineering has emerged as a promising strategy to overcome the limitations of current treatments for bone-related disorders, but the trade-off between mechanical properties and bioactivity remains a concern for many polymeric materials. To address this need, novel polymeric blends of poly-L-lactic acid (PLLA), polycaprolactone (PCL) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) have been explored. Blend filaments comprising PLLA/PCL/PHBV at a ratio of 90/5/5 wt% have been prepared using twin-screw extrusion. The PLLA/PCL/PHBV blends were enriched with nano-hydroxyapatite (nano-HA) and strontium-substituted nano-HA (Sr-nano-HA) to produce composite filaments. Three-dimensional scaffolds were printed by fused deposition modelling from PLLA/PCL/PHBV blend and composite filaments and evaluated mechanically and biologically for their capacity to support bone formation in vitro. The composite scaffolds had a mean porosity of 40%, mean pores of 800 µm, and an average compressive modulus of 32 MPa. Polymer blend and enriched scaffolds supported cell attachment and proliferation. The alkaline phosphatase activity and calcium production were significantly higher in composite scaffolds compared to the blends. These findings demonstrate that thermoplastic polyesters (PLLA and PCL) can be combined with polymers produced via a bacterial route (PHBV) to produce polymer blends with excellent biocompatibility, providing additional options for polymer blend optimization. The enrichment of the blend with nano-HA and Sr-nano-HA powders enhanced the osteogenic potential in vitro. [ABSTRACT FROM AUTHOR]

A highly oriented poly(l -lactic acid) (PLLA), with a blood vessel-like biomimetic structure, was fabricated using solid-phase hot drawing technology and homo-epitaxial crystallization to improve the mechanical properties and biocompatibility of PLLA. Long chain branched PLLA (LCB-PLLA) was prepared through a two-step ring-opening reaction, and a consequent draw as high as 1000 % was achieved during the hot drawing. The modulus and tensile strength were found to have increased through the formation of oriented shish-kebab like crystals along the drawing direction during processing. Furthermore, PLLA nano-lamellae were formed on the surface of the oriented plates via the introduction of homo-epitaxial crystallization. The high degree of orientation and epitaxial crystallization substantially enhanced the biocompatibility of the PLLA by prolonging clotting time, decreasing the rate of hemolysis, and increasing the cell growth and reproduction of the osteoblasts. [ABSTRACT FROM AUTHOR]

Sustainable cellulose- graft -diblock copolymers (cellulose- graft -polyisoprene- block -polylactide, MCC- g -PI- b -PLLA, MCC was chemically-modified microcrystalline cellulose) were designed and delicately synthesized for the first time by a mild and facile procedure via combining ring-opening polymerization and reversible addition-fragmentation chain transfer polymerization techniques, which conquered the difficulties in synthesis due to the distinct chemical properties among the MCC backbone, PI and PLLA blocks. Two separate glass transition temperatures were detected for MCC- g -PI- b -PLLA copolymers by differential scanning calorimetry, indicative of microphase separation, consistent with small-angle X-ray scattering and atomic force microscopy measurements. The α -form crystals of PLLA outer blocks were revealed by wide-angle X-ray diffraction measurement. The monotonic and step-cyclic tensile tests revealed that the mechanical property could be tuned by changing the molecular mass of PI midblock. The two ends of the soft PI midblock were anchored by rigid cellulose backbone and hard PLLA outer block, respectively, which served as physical crosslinking points. The rigid cellulose backbones brought the PI rubbery domains and PLLA hard domains together to form a whole hierarchical microstructure, endowing the copolymers with distinguished mechanical property. This work provided a feasible approach to producing environmental-friendly cellulose-based copolymers with fully biomass-derived feedstocks, having a profound impact on the development of sustainable polymer-based materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Blending chemically synthesized poly(4-hydroxybutyrate) (P4HB) with polylactide (PLLA) can overcome PLLA's brittleness, offering fully biobased blends. However, due to low compatibility between PLLA and P4HB, the influence of compatibilizers on the morphology, structure and tensile deformation of PLLA/P4HB blends remains to be unresolved. This article introduces reactive poly(methyl methacrylate- co -styrene-glycidyl methacrylate) (MSG) and non-reactive polyformaldehyde (POM) compatibilizers to improve the compatibility between P4HB and PLLA, achieving the maximal elongation at break exceeding 300 % at 2 wt% MSG or 3 wt% POM. MSG inhibits PLLA crystallization, extending stress stability in the silver streak stage, while POM enhances crystallization, prolonging the strain-hardening stage. Small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) analysis show that pristine PLLA forms voids before fracture, and PLLA/P4HB blends cavitate at the yield point and develop crazes in the silver streak stage. MSG effectively transmits stress and delays cavitation, extending the silver streak stage, whereas POM forms a microcrystalline network, lowering the energy barrier for stretching-induced recrystallization. These findings could provide theoretical guidelines on selecting compatibilizers for different PLLA based blends. [Display omitted] [ABSTRACT FROM AUTHOR]

Currently, numerous bone tumor patients undergo tumor recurrence after surgical resection, which seriously affects their quality of life. In this study, the ceria (CeO 2) nanoparticle was added to Poly-L-Lactic Acid (PLLA) bone implants endowing the bone implant with antitumor function. The results showed that the reactive oxygen species increased in U2OS cells while it dropped in HEK293 cells as the CeO 2 content increased. Meanwhile, the PLLA-8CeO 2 showed a high cell inhibition rate of 53.66 % for U2OS cells and possessed a high cell viability of 76.96 ± 2.20 % for HEK293 cells, meaning that the implant could kill bone tumor cells meanwhile show good cytocompatibility for normal cells. These were mainly due to the fact that the CeO 2 nanoparticles acted as a superoxide dismutase in tumor cells reducing superoxide to hydrogen peroxide, inducing an increase in reactive oxygen species levels. The excess reactive oxygen species could result in tumor cell apoptosis by disrupting mitochondrial structure, oxidizing proteins, and promoting DNA denaturation. Moreover, the compressive strength of PLLA was improved by the CeO 2 addition due to its particle dispersion strengthening. Besides, the PLLA-CeO 2 had a faster degradation rate compared to PLLA. Overall, the PLLA-CeO 2 is a promising implant material for bone tumor treatment. [ABSTRACT FROM AUTHOR]

Blending chemically synthesized poly(4-hydroxybutyrate) (P4HB) with polylactide (PLLA) can overcome PLLA's brittleness, offering fully biobased blends. However, due to low compatibility between PLLA and P4HB, the influence of compatibilizers on the morphology, structure and tensile deformation of PLLA/P4HB blends remains to be unresolved. This article introduces reactive poly(methyl methacrylate- co -styrene-glycidyl methacrylate) (MSG) and non-reactive polyformaldehyde (POM) compatibilizers to improve the compatibility between P4HB and PLLA, achieving the maximal elongation at break exceeding 300 % at 2 wt% MSG or 3 wt% POM. MSG inhibits PLLA crystallization, extending stress stability in the silver streak stage, while POM enhances crystallization, prolonging the strain-hardening stage. Small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) analysis show that pristine PLLA forms voids before fracture, and PLLA/P4HB blends cavitate at the yield point and develop crazes in the silver streak stage. MSG effectively transmits stress and delays cavitation, extending the silver streak stage, whereas POM forms a microcrystalline network, lowering the energy barrier for stretching-induced recrystallization. These findings could provide theoretical guidelines on selecting compatibilizers for different PLLA based blends. [Display omitted] [ABSTRACT FROM AUTHOR]

Poly(L-lactic acid) (PLLA) has been extensively used in tissue engineering, in which its surface hydrophilicity plays an important role. In this work, an efficient and green strategy has been developed to tailor surface hydrophilicity via alkali hydrolysis. On one hand, the ester bond in PLLA has been cleaved and generates carboxyl and hydroxyl groups, both of which are beneficial to the improvement of hydrophilicity. On the other hand, the degradation of PLLA increases the roughness on the film surface. The resultant surface wettability of PLLA exhibits crucial dependence on its crystallinity. In the specimen with high crystallinity, the local enrichment of terminal carboxyl and hydroxyl groups in amorphous regions accelerates the degradation of ester group, producing more hydrophilic groups and slit valleys on film surface. The enhanced contact between PLLA and water in aqueous solution (i.e., the Wenzel state) contributes to the synergistic effect between generated hydrophilic groups and surface roughness, facilitating further degradation. Consequently, the hydrophilicity has been improved significantly in the high crystalline case. On the contrary, the competition effect between them leads to the failure of this strategy in the case of low crystallinity. [ABSTRACT FROM AUTHOR]

PLLA, PCL and PHBV are aliphatic polyesters which have been researched and used in a wide range of medical devices, and all three have advantages and disadvantages for specific applications. Blending of these materials is an attractive way to make a material which overcomes the limitations of the individual polymers. Both PCL and PHBV have been evaluated in polymer blends with PLLA in order to provide enhanced properties for specific applications. This paper explores the use of PCL and PHBV together with PLLA in ternary blends with assessment of the thermal, mechanical and processing properties of the resultant polymer blends, with the aim of producing new biomaterials for orthopaedic applications. DSC characterisation is used to demonstrate that the materials can be effectively blended. Blending PCL and PHBV in concentrations of 5–10% with PLLA produces materials with average modulus improved by up to 25%, average strength improved by up to 50% and average elongation at break improved by 4000%, depending on the concentrations of each polymer used. PHBV impacts most on the modulus and strength of the blends, whilst PCL has a greater impact on creep behaviour and viscosity. Blending PCL and PHBV with PLLA offers an effective approach to the development of new polyester-based biomaterials with combinations of mechanical properties which cannot be provided by any of the materials individually. [ABSTRACT FROM AUTHOR]

Dermal fillers have become one of the main tools for soft tissue augmentation in the field of cosmetic dermatology. There are many types of fillers. While hyaluronic acid fillers are generally accepted as ones that fill in a space, they and other materials have been shown to have a biostimulatory effect on tissue through the process of a controlled foreign body reaction. Little research is available comparing their effects in terms of new collagen formation post administration. The goal of this review article is to evaluate the biostimulatory effects and the levels of neocollagenesis of poly‐l‐lactic acid (PLLA), calcium hydroxylapatite (CaHA), polycaprolactone (PCL), and hyaluronic acid (HA). A concise summary of the evidence is provided to assist clinicians in making informed decisions when deciding between the different types of widely available fillers. [ABSTRACT FROM AUTHOR]

Biodegradable shape-memory polymers (SMPs) which are functional materials with applicability for medicine devices are designed to acquire their therapeutically relevant shape and drug release after implantation. In the work, an amphiphilic polymer (PVAD) is synthesized by using polytetrahydrofuran (PTMG), vinyl acetate (VAc), acrylic acid (AA), tetramethyltetravinylcyclotetrasiloxane (D 4 vi) as raw materials. PVAD encapsulating hydrophilic drug as switching phase and poly(l -lactide) (PLLA) as fixing matrix construct an SM system with the characteristic of "reservoir-matrix" drug release. The shape recovery ratio (R r) of medicated PVAD/PLLA reaches 99 % by heat-water stimulation. The effects of release temperature and SM on drug release are investigated. With the release temperature increasing, the medicated PVAD/PLLA accelerates drug release and shows burst release initially, while the drug release for the medicated PLLA changes slightly. The drug release rate goes up after 3 rounds of SM. The mechanism of SM system controlling drug release is put forward based on structural changes. The yield strength and elongation at break of medicated PVAD/PLLA are 29.8 MPa and 44.6 %, respectively. It opens up new perspectives for drug carrier matrices in Pharmaceutical Sciences. [Display omitted] [ABSTRACT FROM AUTHOR]

Crude oil spills seriously harm the ocean environment and endanger the health of various animals and plants. In the present study, a totally biodegradable polymer, poly(L-lactic acid) (PLLA), was employed to fabricate highly porous oil absorbent nanofibrous materials by using a combination of electrospinning technique and subsequent acetone treatment. We systematically investigated how the electrospinning parameters affected formation of the porous structure of PLLA nanofibers and demonstrated that PLLA nanofibers with decreased and uniform diameter and improved porosity could be rapidly prepared by adjusting solution parameters and spinning parameters. We also demonstrated that the acetone treatment could obviously enhance the pore diameter and specific surface area of as-optimized electrospun PLLA nanofibers. The acetone treatment could also improve the hydrophobic property of as-treated PLLA nanofiber membranes. All these led to a significant increase in oil absorption performance. Through our research, it was found that the oil absorption of PLLA nanofiber membrane increased by more than double after being treated with acetone and the oil retention rate was also improved slightly. [ABSTRACT FROM AUTHOR]

Antimicrobial packaging can prolong the shelf life of fresh food, but those active antimicrobial substances may leach into the food and affect its quality. To avoid this phenome, the C C double bond was first incorporated into the chemical structure of polylactic acid (PLLA) and tannic acid (TA) to prepare poly(L-LA- co -butyrate itaconate) (PLBI) and photoactive tannic acid (pTA). Then pTA-grafted PLBI (pTA-g-PLBI) films were fabricated using UV curing technology. Results showed that pTA was successfully grafted onto the surface of PLBI film and formed a uniform layer. The pTA-g-PLBI films exhibited good bacteriostatic effects of 86 %, 90 %, and 96 % on E. coli, P. fluorescens, and S. aureus , respectively. Additionally, pTA-g-PLBI packaging reduced the relative abundance of Shewanella , Psychrobacter, and Pseudomonas in chilled pork and delayed the deterioration of pork for more than 5 days. • C C bonds were introduced in the PLLA and tannic acid (TA) chemical structures. • TA grafted on the surface of PLLA films (pTA-g-PLBI) using UV curing technology. • pTA-g-PLBI films inhibited the growth of S. aureus , E. coli , and P. fluorescens. • pTA-g-PLBI films extend the shelf life of chilled pork. • pTA-g-PLBI films changed the microbial diversity in chilled pork during storage. [ABSTRACT FROM AUTHOR]

Decreased collagen synthesis by fibroblasts is a key aspect of skin aging. Poly-L-Lactic Acid (PLLA) is a bioabsorbable material that can release lactate continuously, stimulating endogenous collagen synthesis in the skin. Herein, this study aimed to investigate the impact of PLLA-released lactate on collagen production in fibroblasts for skin rejuvenation. Human fibroblasts were exposed to varying concentrations of PLLA in vitro, while PLLA was injected into the back skin of aged mice in vivo. Safety and efficacy of PLLA on collagen synthesis and skin rejuvenation were evaluated through Calcein-AM/PI staining, EdU proliferation assay, and analysis of collagen I and collagen III expression in fibroblasts using western blotting and immunofluorescence. To elucidate the underlying mechanisms, lactate contents in cell-free supernatant and cell lysates from PLLA-treated fibroblasts, as well as total lysine lactylation (Pan Kla) levels were measured. Additionally, we found that fibroblasts can uptake extracellular lactate released from PLLA through monocarboxylate transporter-1 (MCT1) to facilitate latent-transforming growth factor beta-binding protein 1 (LTBP1) lactylation at lysine 752 (K752) via a KAT8-dependent mechanism, then increases the protein levels of collagen I and collagen III in fibroblasts. Overall, this study highlights a valuable insight into lactylation modification of non-histone protein for skin rejuvenation. [ABSTRACT FROM AUTHOR]

Poly-L-lactic acid (PLLA), recognized as a piezoelectric material, not only demonstrates exceptional piezoelectric properties but also exhibits commendable biocompatibility and biodegradability. These properties render PLLA highly promising for diverse applications, including sensors, wearable devices, biomedical engineering, and related domains. This review offers a comprehensive overview of the distinctive piezoelectric effect of PLLA-based material and delves into the latest advancements in its preparation strategies as a piezoelectric material. It further presents recent research progress in PLLA-based piezoelectric materials, particularly in the realms of health monitoring, skin repair, nerve regeneration, and tissue repair. The discourse extends to providing insights into potential future trajectories for the development of PLLA-based piezoelectric materials. [ABSTRACT FROM AUTHOR]

Microplastic accumulates in various habitats, posing a potential environmental threat. Biodegradable polymers like poly(L-lactide) (PLLA) is a possible eco-friendly alternative to conventional, non-biodegradable plastics. However, biodegradation of PLLA in soil is strongly limited, but is potentially enhanced by soil-dwelling organisms. We recently showed that PLLA exposure positively affected reproduction in the earthworm Eisenia fetida , and increased gut lactate concentrations, indicating the hypothesis of earthworm-enhanced PLLA biodegradation. Thus, 13C-labelled PLLA was used for a 13CO 2 -tracing approach to monitor PLLA mineralisation in presence and absence of the earthworm E. fetida. Mineralisation of 0.2% of initial PLLA was attributed to the activity of earthworms after two weeks of exposure. Extrapolation assuming zero-order kinetics and limitation of microbial growth suggested a substantially shorter half-life of PLLA in earthworm-amended soils. This finding provides strong evidence that conditions inside the earthworm gut are beneficial for PLLA degradation and provide a basis for the development of mitigation strategies for PLLA microplastic pollution. [Display omitted] • Synthesis of 13C-PLLA from 13C-lactide • Stable isotope tracing of 13C-PLLA mineralisation to 13CO 2 against a strong CO 2 background • PLLA is mineralised in soil and at higher rates inside the earthworm gut • Earthworms stimulate PLLA mineralisation in soil by 5 times [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermochromic poly(L-lactic acid) based materials have been produced and their printability on different substrates evaluated. • The materials morphology, physical–chemical, mechanical and electrical properties were determined. • The highest optical thermochromic response was observed for PLLA/[Bmim] 2 [NiCl 4 ] incorporating 40% wt. • Good ink printability, adhesion and thermochromic response was demonstrated on different substrates: paper, PET, wood and textile. Ionic liquids (ILs) have been combined with different polymer matrixes to develop smart and functional materials. Due to their versatility, hybrid materials with specific tailor made properties can be obtained, including printable thermochromic materials, with a strong potential for sensing applications. In this context, the thermochromic IL bis(1-butyl-3-methylimidazolium) tetrachloronickelate ([Bmim] 2 [NiCl 4 ]) was incorporated into a biopolymer derived matrix, poly(L-lactic acid) (PLLA) in distinct concentrations up to 40% wt. aiming to develop environmentally friendly screen-printable printable thermochromic materials. The addition of IL does not induce changes on the thermal properties of the material. On the other hand, the incorporation of the IL leads to the development of a porous structure in the films, a mechanical plasticizing effect in the polymer matrix, revealed by the decrease of the Young's Modulus from 1110 ± 66 MPa to 572 ± 41 MPa and a increase in the electrical conductivity from 2.89x10-14 S·cm−1 to 2.66x10-8 S·cm−1, for PLLA and the samples with 40 % wt. of IL, respectively. Finally, the thermochromic material was screen-printed on various substrates, including paper, polyethylene terephthalate (PET), textile and wood, opening the way for a wide range of applications. [ABSTRACT FROM AUTHOR]

The field of tissue engineering exploits living cells in a variety of ways to restore, maintain, or enhance tissues and organs. Between stem cells, human induced pluripotent stem cells (hiPSCs), are very important due to their wide abilities. Growth factors can support proliferation, differentiation, and migration of hiPSCs. Platelet-rich plasma (PRP) could be used as the source of growth factors for hiPSCs. In the present study, proliferation and neural differentiation of hiPSCs on surface-modified nanofibrous Poly-l-lactic acid (PLLA) coated with platelet-rich plasma was investigated. The results of in vitro analysis showed that on the surface, which was modified nanofibrous scaffolds coated with platelet-rich plasma, significantly enhanced hiPSCs proliferation and neural differentiation were observed. Whereas the MTT ([3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide]) results showed biocompatibility of surface-modified nanofibrous scaffolds coated with platelet-rich plasma and the usage of these modified nanoscaffolds in neural tissue engineering in vivo is promising for the future. [ABSTRACT FROM AUTHOR]

Present work attempted to manufacture kenaf/PLLA/HDPE blended composites using a novel technique of microwave-assisted compression molding (MACM). Since the manufacturing of pure PLLA composite is costly as well as its structural instability while manufacturing via MACM. Therefore, blending of HDPE in PLLA was done for structural stability as well as cost reduction purpose. Influence of microwave power and HDPE blend ratio on thermal and mechanical properties of 20 wt.% kenaf/PLLA/HDPE blended composites were investigated. Effect of various microwave power levels (i.e., 180 W, 360 W, and 540 W) and different HDPE blend percentages (i.e., 0%, 10%, 20%, 30%, and 40%) on mechanical properties of PLLA-based composites studied. Composites fabricated at 180 W and 30% HDPE blend exhibited the highest tensile strength. Elongation of composites decreased at higher microwave power due to decreased relaxation time of molecules. Furthermore, the crystallinity of the composites increased with increasing wt.% of the HDPE blend. [ABSTRACT FROM AUTHOR]

In this work, PLLA/TAIC has been taken as a model system to investigate the inclusion and exclusion of small molecules during the crystallization of polymers in their miscible blend. Our results indicate that it is the growth rate and diameter of PLLA spherulites that dominate the localization of TAIC. On the one hand, crystallization temperature plays an important role. Crystallization at higher temperature corresponds to higher growth rates and a greater diameter of PLLA spherulites. The former improves the ability of PLLA crystals to trap TAIC while the latter leads to a lower volume fraction of space among neighboring PLLA spherulites. The combination of the two contributes to the enhanced inclusion behaviors. On the other hand, when compared to melt crystallization, cold crystallization results in much smaller spherulites (from higher nucleation density) and sufficient space among spherulites, which accounts for the enrichment of TAIC in interspherulitic regions and for its enhanced exclusion. In the adopted polymer–small molecule blend, TAIC can enrich in interspherulitic regions even in its miscible blend with PLLA, which can be attributed to its stronger diffusion ability. [ABSTRACT FROM AUTHOR]

The aim of this work was to study the crystallization kinetics and melting behaviour of polymer blend nanocomposites based on poly (L-lactic acid) (PLLA), nylon 11 and tungsten disulfide nanotubes (INT-WS2), which are layered transition metal dichalcogenides (TMDCs), using non-isothermal differential scanning calorimetry (DSC). Blends containing different nylon 11 contents ranging from 20 to 80 wt.% with or without INT-WS2 were prepared by melt mixing. Evaluation of their morphology with high-resolution SEM imaging proved that the incorporation of inorganic nanotubes into the immiscible PLLA/nylon 11 mixtures led to an improvement in the dispersibility of the nylon 11 phase, a reduction in its average domain size and, consequently, an increase in its interfacial area. The crystallization temperatures of these PLLA/nylon 11-INT blends were influenced by the cooling rate and composition. In particular, the DSC results appear to demonstrate that the 1D-TMDCs WS2 within the PLLA/nylon 11-INT blend nanocomposites initiated nucleation in both polymeric components, with the effect being more pronounced for PLLA. Moreover, the nucleation activity and activation energy were calculated to support these findings. The nucleation effect of INT-WS2, which influences the melting behaviour of PLLA, is highly important, particularly when evaluating polymer crystallinity. This study opens up new perspectives for the development of advanced PLA-based nanomaterials that show great potential for ecological and biomedical applications. [ABSTRACT FROM AUTHOR]

Textile scaffolds that are either 2D or 3D with tunable shapes and pore sizes can be made through textile processing (weaving, knitting, braiding, nonwovens) using microfilaments. However, these filaments lack nano-topographical features to improve bone cell adhesion and proliferation. Moreover, the diameter of such filaments should be higher than that used for classical textiles (10–30 µm) to enable adhesion and the efficient spreading of the osteoblast cell (>30 µm diameter). We report, for the first time, the fabrication of biodegradable nanostructured cylindrical PLLA (poly-L-Lactic acid) microfilaments of diameters 100 µm and 230 µm, using a single step melt-spinning process for straightforward integration of nano-scale ridge-like structures oriented in the fiber length direction. Appropriate drawing speed and temperature used during the filament spinning allowed for the creation of instabilities giving rise to nanofibrillar ridges, as observed by AFM (Atomic Force Microscopy). These micro-filaments were hydrophobic, and had reduced crystallinity and mechanical strength, but could still be processed into 2D/3D textile scaffolds of various shapes. Biological tests carried out on the woven scaffolds made from these nano-structured micro filaments showed excellent human bone cell MG 63 adhesion and proliferation, better than on smooth 30 µm- diameter fibers. Elongated filopodia of the osteoblast, intimately anchored to the nano-structured filaments, was observed. The filaments also induced in vitro osteogenic expression, as shown by the expression of osteocalcin and bone sialoprotein after 21 days of culture. This work deals with the fabrication of a new generation of nano-structured micro-filament for use as scaffolds of different shapes suited for bone cell engineering. [ABSTRACT FROM AUTHOR]

Fungi constitute the largest number of plant pathogens and are responsible for a range of serious plant diseases. Phaeomoniella chlamydospora (P. chlamydospora) and Phaeoacremonium aleophilum (P. aleophilum) are the main fungal pathogens causing esca disease in grapevines. On the other hand, there are beneficial microorganisms such as Trichoderma spp., which are able to control the growth of many phytopathogens. In the present study, innovative, eco-friendly hybrid nanomaterials were created by electrospinning PLLA, followed by the formation of a film of chitosan/Trichoderma asperellum (T. asperellum) spores on the fibers. The polymer carrier used in this study plays an active role in ensuring the viability of the biological agent during storage and, when placed in contact with moisture, ensures the agent's normal development. Oligochitosan, as well as low molecular weight and high molecular weight chitosan, were used. The effects of chitosan molecular weight on the dynamic viscosity of chitosan solutions, film formation, mechanical properties, spore incorporation and growth were studied. The morphology of the prepared nanomaterials, and the presence of a film based on the formation of chitosan/T. asperellum spores on the PLLA fibers, were examined using scanning electron microscopy (SEM). The surface chemical compositions of the fibrous materials were studied using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The mechanical properties of the obtained materials were also tested. The microbiological screening that was performed revealed that the eco-friendly hybrid nanomaterials incorporated with the beneficial microorganism, T. asperellum, to hamper the growth of the pathogenic P. chlamydospora and P. aleophilum fungi. The suppression rate depended on the viscosity of the chitosan solution used for the film formation. The use of oligochitosan resulted in the most effective infection of the material with T. asperellum spores. The environmentally friendly hybrid nanomaterials obtained in this study—in which the bioagent was embedded—are promising bioactive dressings for protecting grapevines against esca disease. [ABSTRACT FROM AUTHOR]

Establishing drug release from shape memory polymers (SMPs) for biomedical applications will broaden the horizon of SMP applications from commercial medical device to scientific drug delivery system. Therefore, a strategy combining degradable SMP with drug release is put forward. However, there are few reports about the relevance between them so far. In the work, incorporations of three grafting tannins (TA) as switching phase into poly (l -lactide)(PLLA) construct different thermoresponsive SM composites. TA-PCL-COOH/PLLA exhibites good shape fixation (R f) and recovery rate (R r) at 55 °C, and its recovery time is 75 s. After loading lipophilic drug, SM capability of medicated TA-PCL-COOH/PLLA enhances, the R f and R r are 97.8% and 97.2%, in particular, its recovery time decreases to 32 s. The effect of SM on drug release is explored. After the first round of SM, the drug release accelerates obviously at body temperature; for example, the release amount of drug increases from 46.5% to 66.1% at initial 12 h due to change of microstructure and improvement of wettability. The drug release rate climbs only slightly as the SM round increases. [ABSTRACT FROM AUTHOR]

Poly-L-lactic acid (PLLA) is an environmentally friendly and renewable polymer material with excellent prospects, but its low crystallization rate greatly limits its application. Through the amidation reaction between amino hyperbranched polymer (HBP N103) and carboxylated carbon nanotubes (CNTs), CNTs-N103 was obtained. The modification was confirmed by Fourier-transform infrared (FTIR) spectroscopy, X-ray electron spectroscopy (XPS) and thermogravimetric analysis (TGA). Using transmission electron microscopy (TEM), we observed the changes on the surface of modified CNTs. PLLA/CNT composites were prepared, and differential scanning calorimetry (DSC) was used to investigate the crystallization behavior of the composites. The results showed that the addition of CNTs could greatly improve the crystallization properties of PLLA; at the same concentration, the modified CNTs had better regulation ability in PLLA crystallization than the unmodified CNTs. Moreover, in the concentration range of 0.1–1%, with the increase in HBP concentration, the ability of CNTs-N103 to regulate the crystallization of PLLA increased as well. Wide-angle X-ray diffraction (WAXD) once again proved the improvement of the crystallization ability. The results of polarized optical microscopy (PLOM) showed that the number of nucleation points increased and the crystal became smaller. [ABSTRACT FROM AUTHOR]

Poly (L-Lactide) (PLLA) and PLLA/Poly (D-Lactide) (PLLA/PDLA) blends were blended with different contents of multi-walled carbon nanotubes-graft-polyethylene glycol (PEG) (MWCNTs-g-PEG), which was synthesized by esterifying. The infrared peak of MWCNTs-g-PEG at 1730 cm−1 is caused by the carbonyl (C = O) stretching vibration, and the peak at 1109 cm−1 is attributed to the stretching vibration of C–O–C, confirming that the grafted product is successfully synthesized. When compared to MWCNTs-OH, the synergistically effects of heterogeneous nucleation of MWCNTs-g-PEG and plasticizing of PEG in MWCNTs-g-PEG strengthen the crystallization ability of PLLA matrix much more effectively. Furthermore, the addition of MWCNTs-g-PEG to PLLA/PDLA inhibits the formation of homopolymer crystals (HC), while promoting the formation of stereocomplex (SC). [ABSTRACT FROM AUTHOR]

Two L-rich polylactides (PLLA) with distinct contents in D isomer and their composites with an intermediate amount of mesoporous Santa Barbara Amorphous-15 (SBA-15) (about 9 wt.%) particles were attained by melt extrusion for the evaluation of the effect of content in D isomer and incorporation of mesoporous silica on the structural PLLA features and on their ultimate mechanical performance. For that, samples have been crystallized under dynamic and isothermal tests (from the melt and from the glassy states). The results from DSC and X-ray diffraction show obtainment of the pure α' and α modifications at different intervals of crystallization temperature depending on the D steroisomer amount of the PLLA used. Furthermore, several phase transitions are observed depending on the crystallinity reached and the polymorphs developed during the isothermal crystallization from the glass: an additional cold crystallization, the α'/α transformation and the subsequent melting process, appearing all of them at temperatures clearly dependent on the D content. Rigidity, measured through microhardness in amorphous samples, is also affected by the D isomer and the presence of SBA-15 particles. Reinforcement effect of mesoporous silica is relatively more important in the matrix with the highest D content. [ABSTRACT FROM AUTHOR]

Poly-L-lactic acid (PLLA) has been produced by ring-opening polymerization method. During the polymerization processes different temperatures and process times have been applied to reach an optimum setup that was used to produce sample. The sample was measured by Fourier-transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) methods to identify the structure, molar mass and define the glass transition temperatures of product and obtain general information about the physical and chemical properties of material. Based on the results of measures, the material's crystallinity was also investigated. The plasticization of PLLA has been also investigated. During the experiments, previously produced material (PLLA synthesized by polycondensation) was plasticised by adding of glycerol-dioleate. The plasticized material was also measured by FTIR, GPC and DSC methods to check the basic physical and chemical parameters of the material. According to the results of the measurements that were found, by this approach, the glass transition temperature of PLLA was reduced by 7 °C that indicated the glycerol-dioleate might act as a plasticizer for PLLA material without any deviation in the chemical structure of material. [ABSTRACT FROM AUTHOR]

The deoxyfluorouridine tagged poly(d,l-Lactide) was prepared by the ROP method using deoxyfluorouridine (DF) as an initiator and stannous octoate (SO) as a catalyst under N2 atmosphere at 160 °C for 2 h. ROP of d,l-Lactide was also achieved at various monomer to initiator [M/I] ratios whereas the ratio of monomer to catalyst [M/C] was kept at 1000. For polymer characterization, FT-IR, 1H-NMR, UV–visible, fluorescence emission spectra, SEM, GPC, DSC, TGA and POM were used. The FT-IR based RI[C=O/C–H] indicated a 0.23 order of ROP of d,l-Lactide. The increase in Tm of PLLA was observed while increasing the ratio of [M/I]. The GPC results declared the ring-opening activity of DF toward d,l-Lactide. The presence of microvoids made the PLLA as a suitable candidate for sustainable drug delivery applications. The release of DF from PLLA was examined to assess the drug release efficiency of the prepared polymer system at three different pH levels. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to present an approach for the development of multi-layered tissue engineering constructs by using cell sheet engineering. Briefly, MC3T3-E1 mouse pre-osteoblast cells were cultured in temperature-responsive plates (Nunc Upcell®) in the presence of osteogenic medium and the resulting cell sheets were laminated with electrospun poly(L-lactic acid) (PLLA) membranes to obtain viable three-dimensional, thick constructs. The constructs prepared without PLLA membranes were used as control. The cell viability and death in the resulting structures were investigated by microscopic and colorimetric methods. The in vitro performance of the structures was discussed comparatively. Alkaline phosphatase (ALP) activity, collagen and sulfated glycosaminoglycan (sGAG) content values were calculated. The presented approach shows potential for engineering applications of complex tissues with at least two or more microenvironments such as osteochondral, corneal or vascular tissues. [ABSTRACT FROM AUTHOR]

N, N'-oxalyl bis(piperonylic acid) dihydrazide (PAOD) was obtained through the amination of piperonylic acid chloride and its structure was characterized by Fourier transform infrared spectrometer and nuclear magnetic resonance. Melting blend technology was used to prepare the modified poly(L-lactic acid) (PLLA) containing the various loading PAOD as a new organic nucleating agent. The thermal performances including crystallization, melting behavior and thermal decomposition process, as well as the fluidity of PAOD-nucleated PLLA were investigated via a series of tests. The DSC results showed that, in comparison to DSC curve of the virgin PLLA, the DSC curves of all PLLA/PAOD appeared the sharp melt-crystallization peak, and a higher PAOD concentration caused the melt-crystallization to occur in the higher temperature region and reduced the negative effect of the high cooling rate on the melt-crystallization process. However, with increasing of PAOD concentration, the cold-crystallization enthalpy decreased from 24.4 J/g to 16.7 J/g. The melting peak after melt-crystallization depended on the heating rate and the PAOD concentration; and the double melting peaks appeared after isothermal crystallization in low temperature region was thought to be due to the melting-recrystallization. The addition of PAOD decreased the onset decomposition temperature of PLLA, but the onset decomposition temperature was determined by the PAOD concentration and the intermolecular interaction of PLLA and PAOD. Additionally, the PAOD could considerably improve the fluidity of PLLA. [ABSTRACT FROM AUTHOR]