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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]

Within this work, the influence of recovery temperature on thermal induced shape recovery behaviour of injection molded biodegradable poly-(L-lactide) (PLLA) was investigated. Shape retention, shape recovery and shape recovery rate were determined for high molecular weight (HMW) PLLA (320 kDa) and very high molecular weight (VHMW) PLLA (700 kDa) at recovery temperatures of 50, 60, 70, 80 and 90 °C, respectively, using DMA experiments. It was found that for both polymers, shape recovery reached a plateau of around ~70% at 80 °C, which could not be increased at higher temperatures. However, shape recovery rate did show to be affected by higher temperatures. Moreover, it was found that the polymer with the higher molecular mass exhibited a higher shape recovery rate. [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]

In this research, the synthesis of new nanocomposites based on Poly (L-lactic acid)/ poly (L-lactide- ɛ-caprolactone) PLLA/PLCL with a ratio of 90/10 and different amounts of graphene oxide (GO) (0.1-1%) was put on the agenda. The poly (ethylene glycol)-block-poly (propylene glycol), PEG-PPG, as a compatibilizer was used in each compound to increase the compatibility of the two phases. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were applied to study the structure of the obtained samples. Also, morphology, mechanical properties, rheological behavior, thermal stability, dynamic mechanical thermal analysis (DMTA), contact angle, and hydro-catalytic degradation were investigated. The results showed that using the GO, and PEG-PPG compatibilizer significantly decreased the average diameter of the dispersed phase of PLCL in the PLLA matrix. In addition, with the increase of GO contents, the mechanical properties, thermal stability contact angle, storage modulus increased, but hydro-catalytic degradation decreased. The results of scanning electron microscope (SEM) and transmission electron microscopy (TEM) approved that the presence of PEG-PPG compatibilizer significantly affects the dispersion of GO in the PLLA/PLCL matrix. So, the synthesized nanocomposite is a good candidate for mechanical and biomedical applications. [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]

Advanced nurse practitioner Michelle McLean delves into the benefits of poly-L-lactic acid filler (PLLA) for skin rejuvenation and restoration as patients demand a 'less is more' approach to facial aesthetics. A recent surge in patients wanting to restore or preserve a youthful appearance has seen a surge in popularity for collagen stimulators due to their association with high levels of patient satisfaction, long-lasting efficiency, minor adverse events and sound safety profile (Christen, 2022). Patients are increasingly opting for a 'less is more' visual aesthetic, hoping to achieve subtle, natural-looking, undetectable results. To meet patient goals, clinicians are utilising combination approaches in facial aesthetics, utilising products with PLLA because of its desirable results. PLLA is a powerful, well-tolerated tool for clinicians to employ for the non-surgical augmentation of the ageing face. [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]

The in vitro evaluation of 3D scaffolds for bone tissue engineering in mono-cultures is a common practice; however, it does not represent the native complex nature of bone tissue. Co-cultures of osteoblasts and osteoclasts, without the addition of stimulating agents for monitoring cellular cross-talk, remains a challenge. In this study, a growth factor-free co-culture of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and human peripheral blood mononuclear cells (hPBMCs) has been established and used for the evaluation of 3D-printed scaffolds for bone tissue engineering. The scaffolds were produced from PLLA/PCL/PHBV polymeric blends, with two composite materials produced through the addition of 2.5% w/v nanohydroxyapatite (nHA) or strontium-substituted nanohydroxyapatite (Sr-nHA). Cell morphology data showed that hPBMCs remained undifferentiated in co-culture, while no obvious differences were observed in the mono- and co-cultures of hBM-MSCs. A significantly increased alkaline phosphatase (ALP) activity and osteogenic gene expression was observed in co-culture on Sr-nHA-containing scaffolds. Tartrate-resistant acid phosphatase (TRAP) activity and osteoclastogenic gene expression displayed significantly suppressed levels in co-culture on Sr-nHA-containing scaffolds. Interestingly, mono-cultures of hPBMCs on Sr-nHA-containing scaffolds indicated a delay in osteoclasts formation, as evidenced from TRAP activity and gene expression, demonstrating that strontium acts as an osteoclastogenesis inhibitor. This co-culture study presents an effective 3D model to evaluate the regenerative capacity of scaffolds for bone tissue engineering, thus minimizing time-consuming and costly in vivo experiments. [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]

Commonly used as a stent-based material, cobalt-chromium (Co-Cr) alloy requires drug coating on its surface for prevention of restenosis risk; this is known as the drug-eluting stent (DES). In this research, curcumin was investigated as a drug coating material with biodegradable polymer PLLA (poly-L lactic acid) as a drug carrier and mildly fabricated on the surface of Co-Cr alloy by using an ultrasonic spraying method. Three kinds of concentrations were equipped — low (~62.5 µg), moderate (~125 µg), and high (~250 µg) concentration. This study also investigated the coating with curcumin only that may be used as the exploration to develop the drug coating stent without using polymer. The characterization of the coating specimens was analyzed by Fourier-transform infrared spectroscopy (FT-IR), analytical scanning electron microscope (SEM) together with energy dispersive X-Ray spectroscopy (EDS). Results showed that curcumin and PLLA were relatively homogeneous blended in order to be formulated as the coating material. Further, the curcumin/PLLA and the curcumin only were also affecting the topography of the surfaces on the specimens coated. Moreover, the in vitro study result showed that the drug release of all curcumin concentrations indicated a mildly sustained release profile without any apparent burst release within the period of the measurements.

Poly-L-lactic acid (PLLA) mesh implants containing collagen sponge (CS) were replaced with autologous adipose tissue regeneration in vivo. Herein, we investigated the optimal external frames and internal fillings using poly (lactic-co-ε-caprolactone) (P (LA/CL)), PLLA, and low-molecular-weight PLLA (LMW-PLLA) as the external frame and polyglycolic acid (PGA) nanosheets and CS as the internal filling. We prepared six implants: P (LA/CL) with PGA nano, PLLA with PGA nano, PLLA with CS, PLLA with 1/2 CS, PLLA with 1/4 CS, and LMW-PLLA with CS, and evaluated adipogenesis at 6 and 12 months using a rat inguinal model. The internal spaces in the P (LA/CL) and LMW-PLLA implants collapsed at 6 months, whereas those in the other four implants collapsed at 12 months. Adipose tissue regeneration was not significantly different between the PLLA-implanted groups at 6 and 12 months and was greater than that in the P (LA/CL) with PGA nano and LMW-PLLA with CS groups. The PGA nanosheet inside PLLA was comparable to the CS inside PLLA in the regeneration of adipose tissue and macrophage infiltration. In summary, PLLA is a promising external frame material in which the internal space can be replaced with adipose tissue. Thus, PGA nanosheets are an alternative internal filling material for adipose tissue regeneration.

Dynamic mechanical properties of polymers for biomedical applications are crucial parameters for development and engineering of new medical devices. Here, the time-dependent material behavior is a key factor for durability. Varying the strain rate is a convenient implementation of time-dependency for uniaxial testing. This study investigates time-dependence of Poly(L-Lactide) (PLLA) through uniaxial testing with different strain rates and PLLA with different molecular weight. The results show strain dependence for elongation at break and yield stress, Young’s modulus however is not rate dependent. An increase in elongation at break is also seen with increasing molecular weight of PLLA. Plastic strain increases significantly only for PLLA with an intermediate inherent viscosity. Results show distinct time dependencies regarding strain rate for PLLA with slightly different inherent viscosities. For stent-related mechanical material characteristics, higher molecular weight PLLA seems to be advantageous. This study only considers base materials, although appropriate thermal, mechanical as well as chemical post processing approaches for further adjustment of different properties have already been shown. A combination of the best possible base material and a suitable post-processing should be targeted.

Various manufacturing techniques are available for polymer stent fabrication. Polymer semi-finished products can be prepared using solvent based methods, e.g. dip coating, as well as thermal processes, e.g. extrusion. These different methods may lead to an altered polymer crystal structure, resulting in a different deformation mechanism during mechanical stress. For the material property characterization needed for implant development, the test specimens usually are prepared using laser-cut or die-cut methods. Due to these different preparation protocols, a change in polymer microstructure, causing a material property variation, may also result. For this purpose, comparison of laser-cut versus die-cut of PLLA films has been performed. PLLA films have been prepared by dip-coating and were evaluated with respect to structural, thermal, and mechanical properties. In this study, a combination of uniaxial tensile tests, SEM and DSC studies was used. The results of the mechanical tests showed drastic differences in the elongations at break of die-cut specimens compared to laser-cut ones. The results point out formation of complex crystal structures during the manufacturing process. By the use of SEM imaging and DSC measurements, we were able to attribute these changes to the different plastic deformation mechanisms.

Minimally invasive surgery procedures are of utmost relevance in clinical practice. However, the associated mechanical stress on the material poses a challenge for new implant developments. In particular PLLA, one of the most widely used polymeric biomaterials, is limited in its application due to its high brittleness and low elasticity. In this context, blending is a conventional method of improving the performance of polymer materials. However, in implant applications and development, material selection is usually limited to the use of medical grade polymers. The focus of this work was to investigate the extent to which blending poly-l-lactide (PLLA) with low contents of a selection of five commercially available medical grade polyurethanes leads to enhanced material properties. The materials obtained by melt blending were characterized in terms of their morphology and thermal properties, and the mechanical performance of the blends was evaluated taking into account physiological conditions. From these data, we found that mixing PLLA with Pellethane 80A is a promising approach to improve the material's performance, particularly for stent applications. It was found that PLLA/Pellethane blend with 10% polyurethane exhibits considerable plastic deformation before fracture, while pure PLLA fractures with almost no deformation. Furthermore, the addition of Pellethane only leads to a moderate reduction in elongation at yield and yield stress. In addition, dynamic mechanical analysis for three different PLLA/Pellethane ratios was performed to investigate thermally induced shape retention and shape recovery of the blends.

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]

Commonly used as a stent-based material, cobalt-chromium (Co-Cr) alloy requires drug coating on its surface for prevention of restenosis risk; this is known as the drug-eluting stent (DES). In this research, curcumin was investigated as a drug coating material with biodegradable polymer PLLA (poly-L lactic acid) as a drug carrier and mildly fabricated on the surface of Co-Cr alloy by using an ultrasonic spraying method. Three kinds of concentrations were equipped -- low (~62.5 µg), moderate (~125 µg), and high (~250 µg) concentration. This study also investigated the coating with curcumin only that may be used as the exploration to develop the drug coating stent without using polymer. The characterization of the coating specimens was analyzed by Fourier-transform infrared spectroscopy (FT-IR), analytical scanning electron microscope (SEM) together with energy dispersive X-Ray spectroscopy (EDS). Results showed that curcumin and PLLA were relatively homogeneous blended in order to be formulated as the coating material. Further, the curcumin/PLLA and the curcumin only were also affecting the topography of the surfaces on the specimens coated. Moreover, the in vitro study result showed that the drug release of all curcumin concentrations indicated a mildly sustained release profile without any apparent burst release within the period of the measurements. [ABSTRACT FROM AUTHOR]

For many years, we have been developing flexible sensors made of braided piezoelectric poly-l-lactic acid (PLLA) fibers that can be tied and untied for practical applications in society. To ensure good quality of sleep, the occurrence of bruxism has been attracting attention in recent years. Currently, there is a need for a system that can easily and accurately measure the frequency of bruxism at home. Therefore, taking advantage of the braided piezoelectric PLLA cord sensor's unique characteristic of being sewable, we aimed to provide a system that can measure the frequency of bruxism using the braided piezoelectric PLLA cord sensor simply sewn onto a bed sheet on which the subject lies down. After many tests using trial and error, the sheet sensor was completed with zigzag stitching. Twenty subjects slept overnight in a hospital room on sheets integrated with a braided piezoelectric PLLA cord. Polysomnography (PSG) was simultaneously performed on these subjects. The results showed that their bruxism could be detected with an accuracy of more than 95% compared with PSG measurements, which can only be performed in a hospital by a physician and are more burdensome for the subjects, with the subjects simply lying on the bed sheet with a braided piezoelectric PLLA cord sensor sewn into it. [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]

Physical vapor deposition (PVD) sputtering is a promising technique for the generation of electrically conductive coatings on complex structured biomaterials, such as nonwovens, that can be used in implants. The ultra-thin coatings can fulfil a variety of purposes, such as drug depot or biosensor. The aim of our studies was to determine the feasibility of generating thin silver (Ag) coatings on complex structured poly-L-lactide (PLLA) nonwovens by sputtering and their morphological characterization. PVD sputter process was performed using a customized plasma chamber and a complex rotation of the tender electrospun PLLA nonwovens. Morphological analysis revealed a promising homogenous Ag coating, representing the structure of the nonwovens.

Poly(l-lactic) acid (PLLA) is commonly used in bioabsorbable medical implants, but it suffers from slow degradation rate and rapid decline in mechanical properties for orthopedic applications. To address this drawback, recent research has explored the use of Mg as a filler for PLLA, resulting in composites with improved degradation rate and cytocompatibility compared to neat PLLA. In this study, FeMg powder particles were proposed as fillers for PLLA to investigate the potential of PLLA/FeMg composites for bioabsorbable implants. Cylinder specimens of PLLA, PLLA/Fe, PLLA/Mg and PLLA/FeMg were prepared using solvent casting followed by thermo-molding. The microstructure, thermal behavior, in vitro degradation behavior in simulated body fluid, mechanical properties and cytocompatibility of these composites were examined. The results indicate that the presence of FeMg particles prevents the deterioration of the composite mechanical properties, at least up to 14 days. Once a certain amount of degradation of the composite is reached, the degradation is faster than that of PLLA. Direct cytotoxicity assays revealed that pre-osteoblast MC3T3-E1 cells successfully adhered to and proliferated on the PLLA/FeMg surface. The inclusion of a low percentage of Mg into the Fe lattice not only accelerated the degradation rate of Fe but also improved its cytocompatibility. The enhanced degradation rate, mechanical properties, and osteoconductive properties of this composite make it a promising option for temporary orthopedic biomedical devices.

En este artículo se describen, de manera resumida, algunos trabajos realizados en el laboratorio de polímeros de la Universidad del Valle sobre ácido polil-L-láctico (PLLA), un compuesto biodegradable. Específicamente se describe la síntesis de PLLA de alto y bajo peso molecular y su aplicación en la fabricación de dispositivos o de andamios (scaffolds) para el crecimiento de células óseas, ya sea en forma de bloques blandos, películas, bloques porosos y tornillos. La caracterización de los diferentes materiales se realizó por espectroscopia (resonancia magnética, RMN, e infrarrojo, IR), análisis térmico, y microscopía, por determinación de sus pesos moleculares (viscosimetría, cromatografía) y de sus propiedades mecánicas. Los implantes, las pruebas de biocompatibilidad y de crecimiento celular se realizaron en conejos y se evaluaron de forma macroscópica, y mediante pruebas histológicas.

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]

Background: Infection of orthopaedic implants after internal fixation of bone fractures remains a major complication with occasionally devastating consequences. Recent studies have reported that the use of absorbable materials, instead of metallic ones, may lead to a lower incidence of postoperative infection. In this experimental pre-clinical animal study, we compared the infection rate between absorbable implants consisting of copolymers composed from trimethylene carbonate, L-polylactic acid, and D, L-polylactic acid monomers, and titanium implants after the inoculation of a pathogenic microorganism. Material and Methods: We used an experimental implant-related infection model in rabbits. Sixty animals were randomly and equally divided into two groups. In all animals, the right femur was exposed via a lateral approach and a 2.5 mm two-hole titanium plate with screws (Group A), or a two-hole absorbable plate and screws (Group B), were applied in the femoral shaft. Afterwards, the implant surface was inoculated with Pseudomonas Aeruginosa at a concentration of 2 × 108 CFU/mL. The primary outcome was the comparison of the incidence of developed infection between the two groups. The wound condition was monitored on a daily basis and radiographies were obtained at 12 weeks postoperatively. Infection-related laboratory markers (white blood cell count, erythrocyte sedimentation rate, and C-reactive protein values) were assessed at 3, 6, and 16 weeks postoperatively. Histologic analysis and cultures of tissue samples were also performed to evaluate the presence of infection. Results: Clinical and laboratory signs of infection were evident in 11 rabbits in Group A (36.7%), and 4 in Group B (13.3%). The difference between the groups was statistically significant (p = 0.04). Five animals in Group B (16.7%) had clinical and histologic signs of a foreign-body reaction with significantly elevated CRP and ESR values but no simultaneous presence of infection was identified (p = 0.04). Bone remodelling with thickening of the periosteum and surrounding sclerosis was demonstrated radiologically in animals developing infection or foreign-body reactions. Conclusions: Absorbable plates and screws show lower susceptibility to infection compared to titanium ones. However, their application is associated with foreign-body reaction and the potential need for a second surgical intervention. [ABSTRACT FROM AUTHOR]

Abstract 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.

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]

Bioplastics are frequently utilized in daily life, particularly for food packaging and carrier bags. They can be delivered to biogas plants through a separate collection of the organic fraction of municipal waste (OFMSW). The increased demand for and use of bioplastics aimed at mitigating plastic pollution raises significant questions concerning their life cycle and compatibility with waste management units. Anaerobic digestion (AD) in OFMSW is a valuable resource for biogas production. In this work, the valorization of poly-L-lactic acid (PLLA) composed of food waste within the Biowaste to Bioplastic (B2B) Project framework was studied in laboratory and pilot-scale anaerobic liquid conditions. Taking into account that the addition of PLLA to biowaste can increase biogas production, we performed laboratory-scale anaerobic tests on food waste enriched with different molecular-weight PLLAs produced from food waste or commercial PLLA at a mesophilic temperature of 37 °C. PLLA with the highest molecular weight was subjected to AD on the pilot scale to further validate our findings. The addition of PLLA increased biogas production and had no apparent negative impact on the operation of the reactors used in the laboratory or on the pilot scale. Biogas production was higher when using PLLA with the lowest molecular weight. In the pilot-scale experiments, co-digestion of FW with PLLA increased biogas production by 1.1 times. When PLLA was added to the feed, biomethane was 8% higher, while volatile solids (VS) and total chemical oxygen demand (TCOD) removal were almost the same. Importantly, no effect was observed in the operation of the digesters. [ABSTRACT FROM AUTHOR]

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Poly(l‐lactic acid) (PLLA) films have excellent piezoelectric properties, but the strong hydrophobicity of the surface makes it difficult for cells to attach there. PLLA nanofibers have good biocompatibility, but the weak piezoelectric coefficient limits the ability of the nanofibers to stimulate cell growth. Therefore, the PLLA piezoelectric film is combined with the PLLA nanofibers to make a multilayer film. In our tests, the piezoelectric output of the multilayer film ≈260 mV. In the biological experiments section, without piezoelectric stimulation, the cell length on the nanofibers is approximately twice that of the cells in the blank control group. The length of cells cultured on piezoelectric‐based stimulated nanofibers is more than twice that of cells cultured on nanofibers without piezoelectric stimulation. Therefore, it is confirmed that under the dual action of nanofiber guidance and piezoelectric stimulation, the growth rate of cells is four times faster than that in ordinary Petri dishes. Intracellular calcium imaging experiments confirmed that the concentration of Ca2+ in electrically stimulated cells is approximately twice that of ordinary cells. It is also confirmed that piezoelectric materials can complete electrical stimulation of cells in indirect contact with cells. [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]

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.

The in vitro evaluation of 3D scaffolds for bone tissue engineering in mono-cultures is a common practice; however, it does not represent the native complex nature of bone tissue. Co-cultures of osteoblasts and osteoclasts, without the addition of stimulating agents for monitoring cellular cross-talk, remains a challenge. In this study, a growth factor-free co-culture of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and human peripheral blood mononuclear cells (hPBMCs) has been established and used for the evaluation of 3D-printed scaffolds for bone tissue engineering. The scaffolds were produced from PLLA/PCL/PHBV polymeric blends, with two composite materials produced through the addition of 2.5% w/v nanohydroxyapatite (nHA) or strontium-substituted nanohydroxyapatite (Sr-nHA). Cell morphology data showed that hPBMCs remained undifferentiated in co-culture, while no obvious differences were observed in the mono- and co-cultures of hBM-MSCs. A significantly increased alkaline phosphatase (ALP) activity and osteogenic gene expression was observed in co-culture on Sr-nHA-containing scaffolds. Tartrate-resistant acid phosphatase (TRAP) activity and osteoclastogenic gene expression displayed significantly suppressed levels in co-culture on Sr-nHA-containing scaffolds. Interestingly, mono-cultures of hPBMCs on Sr-nHA-containing scaffolds indicated a delay in osteoclasts formation, as evidenced from TRAP activity and gene expression, demonstrating that strontium acts as an osteoclastogenesis inhibitor. This co-culture study presents an effective 3D model to evaluate the regenerative capacity of scaffolds for bone tissue engineering, thus minimizing time-consuming and costly in vivo experiments.

The effect of molecular weight Mwon the polymorphous crystallization and melting behavior of poly(Llactide) PLLA (L206, L210 and L214) were systemically studied by differential scanning calorimetry (DSC). Melting and reorganization of conformationally disordered crystals (α′-phase) of PLLA are analyzed with respect to the cooling rate qcin a range between about 4 and 50 K/min and the heating rate qhin a range between about 5 and 200 K/min. It was shown that the α′- to α-crystalline phase transition prior to the dominant melting depends on cooling rate qcand Mw. Unlike very high-MwPLLA L214, for low-MwPLLA L206 crystallized at high qc, the α′-form crystals only partially transformed into the α-modification, and certain amounts of α′-form crystals melted directly without α′- to α-transition during the heating process. With increasing qc, the melting of PLLA L210 changed from phase-transition- and -melting mechanism to the common melt-recrystallization mechanism. It was also found that the polymorphism of PLLA significantly affected the crystallization kinetics. Consequently, the reorganization of α′-crystals into stable α- crystals could be inhibited by fast heating (qh> 150 K/min).