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Nano‐hydroxyapatite (nano‐HAP)/poly (l‐lactic acid) (PLLA) bone scaffold is expected to overcome the deficiencies and achieve the complementary advantages of individual constituents, but the weak interfacial bonding due to their thermodynamic incompatibility is detrimental to the mechanical properties. Herein, the PLLA chains were grafted onto nano‐HAP with 3‐aminopropyltriethoxysilane (KH550) as a coupling reagent to enhance the interfacial bonding with PLLA. Specifically, the silicon hydroxyl group produced by KH550 hydrolysis could form covalent bonding with the hydroxyl group of nano‐HAP, and the amino group of KH550 initiated the ring‐opening polymerization of l‐lactide monomers to graft PLLA chains onto nano‐HAP more effectively, leading to a higher grafting ratio of 16.7% compared with 7.2% in direct grafting without KH550 modification. Consequently, the tensile and compressive strength of the modified nano‐HAP/PLLA scaffold were improved by 40.8% and 59.5% enhancement due to the enhanced interfacial bonding in the composite scaffold, respectively, compared to the original nano‐HAP/PLLA scaffold. Additionally, the bone scaffold was conducive to cell adhesion and proliferation, making it an ideal candidate for bone defect repair. Highlights: Amino‐functionalized nano‐HAP boosted the grafting efficiency of PLLA chains.Interfacial bonding between nano‐HAP and matrix was enhanced.Bone scaffold showed better mechanical properties and benign cytocompatibility. [ABSTRACT FROM AUTHOR]

In the recent years, electroconductive scaffolds have shown promising capabilities in guided regeneration of electroactive tissues including nerve, heart muscle, bone, cartilage, and skin. Herein, the fabrication of a novel electroconductive poly (L‐lactic acid) (PLLA)/polyamidoamine (PAMAM) dendrimer nanofibrous scaffold containing graphene oxide (GO) nanosheets is described. The presence of PAMAM with amine terminal groups successfully aminolyzed PLLA. Interestingly, both PAMAM (5% w/w) and GO (0.5, 1, 2% w/w) not only contributed to reducing the fiber diameter, increasing the hydrophilicity and degradation rate, but also provided a nanocomposite scaffold with enhancement in electrical conductivity. By incorporating 1% w/w of GO, the nanocomposite scaffold exhibited optimized properties, including electrical conductivity (≈3.09 × 10−5 S m−1), crystallinity (≈ 47%), Young's modulus (≈16.95 MPa), as well as strength (≈1.58 MPa). This nanocomposite also demonstrated significant antibacterial activity of ≥ 90% against both gram‐positive and gram‐negative bacteria. Cellular assays confirmed acceptable cytocompatibility of the nanocomposite scaffolds containing GO and PAMAM, which can support the viability and proliferation of PC‐12 cells. In conclusion, the presence of GO nanosheets alongside PAMAM dendrimers can synergically promote the properties of the prepared nanofibrous mats which can be used as potential electroconductive scaffolds for guided tissue regeneration. [ABSTRACT FROM AUTHOR]

While bone tissue allograft and autograft are commonly used in bone healing, their application is limited by factors such as availability, donor site morbidity, and immune response to the grafted tissue. Tissue-engineered implants, such as acellular or cellular polymeric structures, offer a promising alternative, and are a current trend in tissue engineering. Leveraging recent advancements in bone tissue engineering (BTE), we utilize 3D printing to develop biodegradable scaffolds that combine mechanical strength and bioactivity to facilitate bone repair and regeneration. This study focuses on the design and fabrication of mechanically competent 3D printed poly (L-lactic acid) (PLLA) micro-structured scaffolds. These scaffolds are enhanced with collagen type I nanofibrils to create bioactive scaffolds that promote tissue regeneration. The performance of these mechanically competent, micro-nanostructured polymeric matrices, in combination with bone marrow stromal cells (BMSCs), is evaluated in PLLA and PLLA-collagen scaffolds. The resulting micro-nanostructured PLLA-Collagen scaffolds mimic trabecular bone architecture, mechanical strength, and the extracellular matrix environment found in native bone tissue. The composite PLLA-collagen scaffolds exhibit mechanical properties in the mid-range of human trabecular bone. Both PLLA and PLLA-Collagen scaffolds support human BMSCs adhesion, proliferation, and osteogenic differentiation. A significantly higher number of implanted host cells are distributed in the PLLA-Collagen scaffolds with greater bone density, more uniform cell distribution, and attachment compared to the PLLA microstructure. Additionally, the biomimetic collagen nanostructure potently induces osteogenic transcription evidenced by increased alkaline phosphatase activity and upregulation of bone markers such as sialoprotein and collagen type I, ultimately guiding stem cell-mediated formation of a mature, mineralized bone matrix throughout the interconnected scaffold pores. This study underscores the benefits of micro-nanostructured scaffolds in successfully generating the inductive microenvironment of native bone extracellular matrix, triggering the cascade of cellular events required for functional bone regeneration, repairing critical-sized bone defects, and ultimately serving as an alternative material platform for bone regeneration, thereby instilling confidence in the potential of our research. [ABSTRACT FROM AUTHOR]

An efficient and scalable method to prepare oligolactic acid stereocomplex microplates (SC‐OLA‐MPs) is developed. Oligolactic acid was firstly synthesized via the melt polycondensation of lactic acid. Then, the oligo (L‐lactic acid) and oligo (D‐lactic acid) were crystallized with a mixture of dichloromethane and acetone, and consequently the stereocomplex microparticles were obtained in the form of circular microplates with a diameter of approximately 2 μm. As an eco‐friendly nucleating agent, SC‐OLA‐MPs were introduced into poly (L‐lactic acid) (PLLA) via melt blending. The nonisothermal and isothermal crystallization of the SC‐OLA‐MPs/PLLA composites were investigated, and the crystal morphology and heterogeneous nucleation phenomena during the isothermal crystallization process were photographed with POM. SC‐OLA‐MPs show excellent nucleating effects on PLLA crystallization. With the incorporation of 10% SC‐OLA‐MPs, the crystallization half‐time of the SC‐OLA‐MPs/PLLA composite decreased from 7.18 to 0.45 min at 100°C, compared to the neat PLLA. Through a short‐time molding procedure, the thermal deformation temperature of PLLA is improved by the addition of SC‐OLA‐MPs. Highlights: Polylactic acid stereocomplex microplates were fabricated by solution crystallization.This method is easy and scalable.This microplate is an effective nucleating agent for PLLA. [ABSTRACT FROM AUTHOR]

A series of nano-hydroxyapatite/polyl-lactic acid (n-HA/PLLA) three-dimensional nanofibrous composite scaffolds were synthesized by a new in-situ precipitation method combined with the frozen extraction using Ca(NO3)2·4H2O and (NH4)2HPO4 as the hydroxyapatite precursor. Combining SEM and XRD results showed that the HA nanoparticles were generated on the surface of the scaffolds and uniformly distributed throughout the material. The effects of the aging temperature and the amount of calcium phosphate solution on the morphology of resulting nanofiber composite scaffolds and fiber diameters were investigated. The results showed that uniform nanofibers were formed at low aging temperatures (−10 °C or less), while the fibers tended to flake and the support structure was more compact at high aging temperatures (5 °C or higher). The amount of added (NH4)2HPO4 had a similar effect on the nanofiber structure. The volume of the (NH4)2HPO4 solution and aging temperature used to prepare the composites also influenced the porosity, crystallinity, and mechanical properties of the final materials. In vitro bioactivity assays using simulated body fluid (SBF) showed that large amounts of low crystallinity carbonate hydroxyapatite (CHA) formed on the scaffolds after 14 days, indicating that the n-HA/PLLA nanofiber composite scaffolds have good bioactivity. This study shows that nHA effectively improved the biological activity of composite scaffolds. [ABSTRACT FROM AUTHOR]

For the design of polymer stents, supportability and flexibility are two important indexes, but they are often difficult to balance. The mixed braiding of monofilaments with different diameters provides a potential solution to balance these two indices. In this study, the influence of mixed braiding on the mechanical properties of the stent was further explored by adjusting the knitting ratio of thick and thin monofilaments. By replacing the monofilaments in the stent with monofilaments with smaller diameters in turn, the changing trend of supportability and flexibility is obtained. The results show that, when the number of thick monofilaments is greater than or equal to that of thin monofilaments, the supportability of the stent can not only be maintained but also the flexibility can be greatly improved. Therefore, mixed braiding has the function of adjusting supportability and flexibility. [ABSTRACT FROM AUTHOR]

Porous nanofibrous poly (L-lactic acid) (PLLA) scaffolds were fabricated in combination with a thermally induced phase separation technique using a dioxane/polyethylene glycol (PEG) system. The effect of factors such as molecular weight of PEG, aging treatment, aging or gelation temperature, and the ratio of PEG to dioxane were investigated. The results revealed that all scaffolds had high porosity, and had a significant impact on the formation of nanofibrous structures. The decrease in the molecular weight and aging or gelation temperature leads to a thinner and more uniform fibrous structure.

Porous nanofibrous poly (L-lactic acid) (PLLA) scaffolds were fabricated in combination with a thermally induced phase separation technique using a dioxane/polyethylene glycol (PEG) system. The effect of factors such as molecular weight of PEG, aging treatment, aging or gelation temperature, and the ratio of PEG to dioxane were investigated. The results revealed that all scaffolds had high porosity, and had a significant impact on the formation of nanofibrous structures. The decrease in the molecular weight and aging or gelation temperature leads to a thinner and more uniform fibrous structure. [ABSTRACT FROM AUTHOR]

Biliary stricture is defined as the reduction and narrowing of the bile duct lumen, which can be caused by many factors such as cancer and inflammation. Biliary stent placement can effectively alleviate benign and malignant biliary strictures. However, the commonly used plastic or metallic biliary stents are far from ideal and do not satisfy all clinical requirements，although several types of biodegradable biliary stents have been developed and used clinically. In this review, we summarized current development status of biodegradable stents with the emphasis on the stent materials. We also presented the future development trends based on the published literature.

Thermal analysis is an effective mean to study the crystallization of polymers. Fast scanning chip calorimetry (FSC) has ultra-high cooling and heating rate and plays an important role in the study of crystallization behavior. The crystallization kinetics of poly (l-lactic acid) (PLLA) with amino polyhedral oligomeric silsesquioxane (POSS-NH2) and polyethylene glycol-grafted POSS (POSS-PEG) was investigated by traditional differential scanning calorimetry (DSC) and FSC. The results show that the addition of POSS-PEG has a better promoting effect on the crystallization rate of PLLA than POSS-NH2. And there are two differences between the results of FSC and DSC: firstly, FSC can effectively avoid the nucleation and crystallization behavior in the cooling process and ensure that the crystallization process occurs completely in the isothermal stage, while DSC cannot; second, the measured crystallization rate by FSC is lower than the traditional DSC data. In a word, POSS plays a role of nucleation agent in PLLA crystallization, and PEG as nucleation accelerator further improves the crystallization rate; FSC can effectively avoid the nucleation and crystallization in the cooling and heating process. [ABSTRACT FROM AUTHOR]

Proper packaging can extend the shelf life and maintain the quality of mushrooms during storage. The purpose of this study is to investigate the preservation of Agaricus bisporus using copolymer-modified poly (L-lactide-co-butylene fumarate) and poly (L-lactide-co-glycolic acid) (PLBF and PLGA) packaging. Shelf life and quality were evaluated over 15 days of storage of Agaricus bisporus at 4 ± 1 °C and 90% relative humidity, including weight loss, browning index (BI), total phenolics (TP), ascorbic acid (AA), malondialdehyde content (MDA), electrolyte leakage rate (EC), and superoxide dismutase (SOD) and catalase (CAT). The results showed that mushrooms packaged in PLBF films exhibited better retention in BI, TP, and AA than those with PLLA, PLGA, or polyethylene (PE) films. They can reduce the rate of weight loss, EC, and MDA, which in turn increases the activity of SOD and CAT. PLBF and PLGA have substantially improved flexibility in comparison with PLLA. They also significantly reduced oxygen (O2) and carbon dioxide (CO2) permeability and changed the gas permeability ratio. These positive effects resulted in the effective restriction of O2 and CO2 in these packages, extending the post-harvest storage period of white mushrooms. [ABSTRACT FROM AUTHOR]

Bone defects cause serious psychological and economic burden to patients. Artificially bone repairing materials bring hope to the treatment of bone defects. Electrospun technique has attracted great attention since it can fabricate fibers from nano- to micro- scale continuously. Scaffolds fabricated by electrospun can mimic the structure of extracellular matrix which is beneficial to cell adhesion and migration. Researches have showed that bioactive ions (such as silicon and calcium ions) can promote bone regeneration. In addition, physical cues can affect cellular behavior such as cell adhesion and differentiation. In this study, two kinds of calcium silicate – adopted poly (L-lactic acid) (CS-PLLA) electrospun scaffolds with random/aligned structures were prepared by electrospun to promote bone regeneration. The integration of CS nanowires improved the biological property of PLLA electrospun scaffolds. Furthermore, in vitro results indicated that aligned 1 wt% CS adopted PLLA (PCA1) electrospun scaffolds with better physical properties and facilitated cell adhesion, improved alkaline phosphate (ALP) activity and the expression of osteogenic genes (Osteopontin (OPN), Collagen type 1 (Col-1) and Bone morphogenetic protein-2 (BMP-2)) compared with random 1 wt% CS adopted PLLA (PCR1) electrospun scaffolds. In conclusion, the prepared PCA1 electrospun scaffolds might be a potential candidate for bone regeneration in defect areas. [ABSTRACT FROM AUTHOR]

Poly (L‐lactic acid) (PLLA) vascular stents are promising to be used to treat vascular stenosis. However, the degradation of these implanted stents has a great influence on the mechanical properties. In this work, we studied the factors that can influence the mechanical properties by accelerating the degradation of PLLA stents with crimping and expansion in phosphate buffer solution (PBS) at 70°C. The typical influence factors such as the real‐time weight‐average molecular weight (Mw), crystallinity, surface morphologies, and mass loss of these samples were analyzed in detail. Results showed that radial strength of the stents increased from 877 to 1204 mmHg after accelerated degradation for 2 days and then decreased to almost 0 mmHg after 10 days. Meanwhile, radial stiffness showed an upward trend which is caused by the decrease in Mw, increase in crystallinity and local damage during the crimping and expansion process. Moreover, negligible mass loss of stents was observed in this period and the bulk degradation behavior predominated in the whole process. [ABSTRACT FROM AUTHOR]

Glucocorticoids inhibit angiogenesis in the femoral head, which fails to nourish the bone tissue and leads to osteonecrosis. Restoring angiogenesis is not only essential for vessel formation, but also crucial for osteogenesis. Poly (L-lactic acid) (PLLA) is commonly used in the bone tissue engineering field. Panax notoginseng saponins (PNS) and osteopractic total flavone (OTF) promote angiogenesis and osteogenesis, respectively. We designed a sequentially releasing PLLA scaffold including PLLA loaded with OTF (inner layer) and PLLA loaded with PNS (outer layer). We assessed the osteogenic effect of angiogenesis in this scaffold by comparing it with the one-layered scaffold (PLLA embedded with OTF and PNS) in vivo. Results from the micro-CT showed that the data of bone mineral density (BMD), bone volume (BV), and percent bone volume (BV/TV) in the PO-PP group were significantly higher than those in the POP group (p < 0.01). Histological analyses show that the PO-PP scaffold exhibits better angiogenic and osteogenic effects compared with the one-layered scaffold. These might result from the different structures between them, where the sequential release of a bi-layer scaffold achieves the osteogenic effect of vascularization by initially releasing PNS in the outer layer. We further explored the possible mechanism by an immunohistochemistry analysis and an immunofluorescence assay. The results showed that the protein expressions of vascular endothelial growth factor (VEGF) and platelet endothelial cell adhesion molecule-1(CD31) in the PO-PP scaffold were significantly higher than those in the POP scaffold (p < 0.01); the protein expressions of osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP) in the PO-PP scaffold were significantly higher than those in the POP scaffold (p < 0.05). Upregulating the expressions of angiogenic and osteogenic proteins might be the possible mechanism. [ABSTRACT FROM AUTHOR]

Poly (l-lactic acid) (PLLA) and polycarbonate (PCL) grafted Monoamino-Polyhedral oligomeric silsesquioxane (POSS-NH2) (POSS-PLLA and POSS-PCL) by ring-opening polymerization of L-lactide (L-LA) and caprolactone (ε-CL) from POSS-NH2 were obtained in this work. The fourier transform infrared spectrometer (FTIR) results show that the stretching vibration peaks of -C(O)-NH- of POSS-PLLA and POSS-PCL appears at 1650 cm−1 and 1645 cm−1. The crystal diffraction peaks of POSS-PLLA at 22°, 16.7° and 19° are same as the peak positions of PLLA; POSS-PCL at 21.7° 23.7° are same as the peak positions of PCL by X-Ray diffraction (XRD). Both FTIR and XRD results indicate that the grafted products are synthesized successfully. Then, the different contents of POSS-PLLA, POSS-PCL and purchased POSS-polyethylene glycol (POSS-PEG) were blended with PLLA/Poly (d-lactic acid) (PDLA) (with the mass ratio of 1:1) to prepare ternary blends with different contents of polymer grafted POSS. The effects of POSS-PLLA, POSS-PCL and POSS-PEG on the crystallization behavior of PLLA/PDLA were investigated. The results show that compared with POSS-PCL and POSS-PLLA, POSS-PEG enhances the crystallization ability of PLLA/PDLA, and promotes the formation of stereocomplex (SC); on the contrary, POSS-PCL and POSS-PLLA inhibit the formation of SC. [ABSTRACT FROM AUTHOR]

Biodegradable PLLA/SBA-15 mixtures and PLLA/SBA-15-g-OLLA grafted composites were prepared by solution blending. The purpose was to determine the effect of the SBA-15 additives on the PLLA hydrolytic degradation and systematically characterize the degraded products. Before hydrolysis, all the composites were crystalline with defined crystal periodicity. In particular, there was a slight increase in the SBA-15 crystalline reflections with increasing SBA-15-g-OLLA concentration in PLLA/SBA-15-g-OLLA composites. Molecular contact (through C–O–C bonds) and miscibility enhancements were determined in proportion with the OLLA segment concentration in SBA-15-g-OLLA samples. The highest concentration of SBA-15-g-OLLA rendered the most hydrolysis and pH decrement. Specifically, hydrolytic degradation in buffer and body tempered conditions increased up to 13 wt % in the grafted PLLA/SBA-15-g-OLLA (10 wt%). Non-isothermal crystallization from the melt of the degraded products indicated heterogeneous nucleation using both SBA-15 and SBA-15-g-OLLA additives, and crystallization enhancement was observed using the degraded PLLA/SBA-15-g-OLLA (10 wt%). Depending on the SBA-15-g-OLLA concentration of the degraded samples, there was a gradual decrease in the intensity of the PLLA melt-recrystallization, which continued until the formation of a new melting endotherm. Two crystal habits and a morphological explanation were given to explain these results. Although unexpected, due to the lower molecular weight of the hydrolyzed products, isothermal crystallization experiments showed the enhancement of the first melting endotherm as a function of SBA-15-g-OLLA with 70 days degraded samples. This effect was demonstrated as related to the PLLA molecular weight. Isothermal bulk crystallization experiments of the hydrolyzed samples showed acceleration of the crystallization rate and changes in the crystal's geometry as a function of SBA-15-g-OLLA. The corresponding isothermal crystallization optical micrographs indicated highly nucleated patterns of such samples. [ABSTRACT FROM AUTHOR]

In the recent years, bone tissue engineering is regarded as the promising solution for treatment of bone defects which arises due to trauma, infection and surgical intervention. In view of this, several polymer or ceramic based constructs are envisaged for bone tissue engineering potential. However, scaffolds based on pure polymeric materials suffer from slow bioactivity characteristics. On the other hand, scaffolds based on ceramic materials do not offer sufficient strength for load bearing applications. In order to overcome these drawbacks, the current work aims to develop mixed matrix scaffolds based on poly (L-lactic acid)/mesoporous bioactive glass composite with the formulation of 30:70 weight ratio, which mimics the natural bone composition. In the current work, PLA/MBG (30:70) composite based bioink suitable for 3D bioprinting is indigenously developed and its rheological characteristics are evaluated. The 3D architecture for PLA/MBG composite scaffold is designed using Solidworks CAD 2015 and the scaffolds are fabricated using pneumatic based 3D bioprinting technology, which has not been documented earlier for this formulation in view of bone tissue engineering in the best of our knowledge. Followed by this, optimization of printing parameters in order to develop 3D PLA/MBG composite constructs with hierarchical pore architecture suitable for bone tissue engineering is performed. The SEM analysis confirmed that the pore size of the 3D printed PLA/MBG composite scaffolds falls in the range of 500–700 μm, which corresponds to the macroporous nature of the scaffolds useful for bone cell growth. The mechanical analysis confirmed the superior compressive modulus and yield strength for PLA/MBG composite scaffold in comparison with neat PLA. The in-vitro bioactivity assessment showed rapid apatite crystallization by attaining Ca/P ratio of 1.66 equivalent to natural bone mineral within 3rd day of SBF treatment for PLA/MBG composite scaffold, thus indicating the excellent bioactivity behaviour. The 3D bioprinted PLA/MBG composite scaffold showed promising response in terms of cell attachment and proliferation, mineralization as well as gene expression characteristics while assessed through of in-vitro biological assessment using MG-63 osteosarcoma cells. In this regard, the 3D bioprinted PLA/MBG scaffold could be applied as potential implant for bone tissue engineering application. [Display omitted] • Tailoring of novel organic (PLA)/inorganic (MBG) composite based 3D bioprinted scaffold mimicking natural bone. • Optimization of 3D bioprinting parameters for fabrication of PLA30:MBG70 using pneumatic extrusion approach. • In-vitro bioactivity assessment reveals rapid apatite crystallization with Ca/P ratio of 1.66 during 3rd day of SBF treatment. • Overexpression of osteogenic markers proves the potential of PLA30:MBG70 scaffold in terms of osteoinduction and oestointegration. [ABSTRACT FROM AUTHOR]

High-performance microcellular polymer foams have been widely used all over the world, while the excessive usage of petroleum-based polymers caused serious environmental problems. As the eco-friendly awareness is increasing significantly, poly (L-lactic acid) (PLLA), as a typical biomass polymer, has gradually attracted widespread attention. However, the slow crystallization and poor melt strength of PLLA lead to low foaming ability and thus limiting its industrial applications. Herein, a novel and scalable strategy by coupling in-situ fibrillation and mold-opening microcellular injection molding (MOMIM) was developed to fabricate lightweight and tough PLLA/polytetrafluoroethylene (PTFE) foams. Thanks to the reticulated in-situ PTFE nanofibrils with a diameter of 100–200 nm, the crystallization and viscoelasticity of PLLA were dramatically promoted, and further contributing to its foaming ability. The expansion ratio of the MOMIM PLLA/PTFE foam was increased by 86 % compared with the regular microcellular injection molded (RMIM) PLLA foam. Moreover, the lower foam density and the toughening effect of PTFE nanofibrils resulted in the outstanding ductility of the PLLA/PTFE foams, whose tensile elongation, flexural strength, and impact strength were maximally increased by 52 %, 28 %, and 48 %, compared with PLLA foams. More importantly, the thermally-insulating performance and surface quality of PLLA/PTFE foams were also greatly improved. [Display omitted] • In-situ polytetrafluoroethylene (PTFE) fibril was achieved in polylactic acid (PLA). • Good surface-quality PLA/PTFE foam was prepared by microcellular injection molding. • PTFE nanofibrils enhanced foamability of PLA and mechanical property of PLA foams. • PLA/PTFE foams with large expansion ratios showed outstanding thermal insulation. [ABSTRACT FROM AUTHOR]

Designing high-performance flame retardants for poly (L-lactic acid) (PLA) materials and exploring a simple and scalable strategy have been hot topics in research. In this work, a novel and highly efficient flame retardant, that is, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) decorated urchin-like NiCo-based bimetallic hydroxide (NiCo-BH@DOPO), was synthesized and incorporated into PLA to prepare PLA and NiCo-BH@DOPO (PLA/NiCo-BH@DOPO) composite. Benefiting from the DOPO organic modification, NiCo-BH@DOPO had superb hydrophobicity and presented excellent dispersion in the PLA matrix. When 20 wt% NiCo-BH@DOPO was added, the LOI value of PLA/NiCo-BH@DOPO composites reached 33.2 %, passed the V-0 level of UL-94 grade, and its maximum peak heat release rate (PHRR) and total heat release (THR) were reduced by 13.2 % and 17.3 %, respectively, compared with PLA/NiCo-BH composites. Furthermore, the residue of PLA/NiCo-BH@DOPO at 800 °C reached 19.8 wt% and the T 10% (temperature at 10 % weight loss) increased by 33 °C. More importantly, the residual PLA/NiCo-BH@DOPO char exhibits a significantly reduced presence of large cracks compared to PLA/NiCo-BH, indicating a more compact formation of residual char. NiCo-BH@DOPO endowed PLA with outstanding flame retardancy, thermal stability and carbonization properties, which were owing to the multi-coordinating effect transition metal (NiCo-BH) catalyzed the char formation to form a char layer barrier and DOPO free radicals captured to inhibit the combustion reaction chain. This investigation provided a facile strategy for the novel multi-function NiCo-based bimetallic hydroxide flame retardant, expanding NiCo-BH potential applications in PLA., Competing Interests: Declaration of competing interest We would like to submit the enclosed manuscript entitled “Urchin-like NiCo-based bimetallic hydroxide decorated with DOPO as highly hydrophobic flame retardant for remarkably reducing fire hazard of polylactic acid”, which we wish to be considered for publication in “International Journal of Biological Macromolecules”. No conflict of interest exists in the submission of this manuscript, and manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Herein, poly(L-lactic acid) (PLA) and poly(vinyl acetate) (PVAc) with high molecular weight were melt compounded to prepare blends with improved mechanical and rheological properties. Dynamic mechanical analysis (DMA) suggested that PLA and PVAc were miscible. Rheological properties indicated that the addition of PVAc improved the viscoelasticity of PLA melt, resulting in the suppression of cold crystallization of the blends. Isothermal melt crystallization behaviors revealed the addition of PVAc decreased crystallization rate, whereas did not change the crystallization mechanism. Unexpectedly, increases of 38%, 21%, and 55% were achieved in the modulus, yield strength, and elongation at break of blend with 20 wt % PVAc content compared to neat PLA. What is more practical is that the PLA/PVAc blends prepared by simple melt blending process showed the combination of improved stiffness, strength, ductility, and melt strength, which helps to meet the performance and process requirements of PLA in various fields. [ABSTRACT FROM AUTHOR]

Proper packaging can extend the shelf life and maintain the quality of mushrooms during storage. The purpose of this study is to investigate the preservation of Agaricus bisporus using copolymer-modified poly (L-lactide-co-butylene fumarate) and poly (L-lactide-co-glycolic acid) (PLBF and PLGA) packaging. Shelf life and quality were evaluated over 15 days of storage of Agaricus bisporus at 4 ± 1 °C and 90% relative humidity, including weight loss, browning index (BI), total phenolics (TP), ascorbic acid (AA), malondialdehyde content (MDA), electrolyte leakage rate (EC), and superoxide dismutase (SOD) and catalase (CAT). The results showed that mushrooms packaged in PLBF films exhibited better retention in BI, TP, and AA than those with PLLA, PLGA, or polyethylene (PE) films. They can reduce the rate of weight loss, EC, and MDA, which in turn increases the activity of SOD and CAT. PLBF and PLGA have substantially improved flexibility in comparison with PLLA. They also significantly reduced oxygen (O2) and carbon dioxide (CO2) permeability and changed the gas permeability ratio. These positive effects resulted in the effective restriction of O2 and CO2 in these packages, extending the post-harvest storage period of white mushrooms.

Glucocorticoids inhibit angiogenesis in the femoral head, which fails to nourish the bone tissue and leads to osteonecrosis. Restoring angiogenesis is not only essential for vessel formation, but also crucial for osteogenesis. Poly (L-lactic acid) (PLLA) is commonly used in the bone tissue engineering field. Panax notoginseng saponins (PNS) and osteopractic total flavone (OTF) promote angiogenesis and osteogenesis, respectively. We designed a sequentially releasing PLLA scaffold including PLLA loaded with OTF (inner layer) and PLLA loaded with PNS (outer layer). We assessed the osteogenic effect of angiogenesis in this scaffold by comparing it with the one-layered scaffold (PLLA embedded with OTF and PNS) in vivo. Results from the micro-CT showed that the data of bone mineral density (BMD), bone volume (BV), and percent bone volume (BV/TV) in the PO-PP group were significantly higher than those in the POP group (p < 0.01). Histological analyses show that the PO-PP scaffold exhibits better angiogenic and osteogenic effects compared with the one-layered scaffold. These might result from the different structures between them, where the sequential release of a bi-layer scaffold achieves the osteogenic effect of vascularization by initially releasing PNS in the outer layer. We further explored the possible mechanism by an immunohistochemistry analysis and an immunofluorescence assay. The results showed that the protein expressions of vascular endothelial growth factor (VEGF) and platelet endothelial cell adhesion molecule-1(CD31) in the PO-PP scaffold were significantly higher than those in the POP scaffold (p < 0.01); the protein expressions of osteocalcin (OCN), osteopontin (OPN), and alkaline phosphatase (ALP) in the PO-PP scaffold were significantly higher than those in the POP scaffold (p < 0.05). Upregulating the expressions of angiogenic and osteogenic proteins might be the possible mechanism.

The thermally sensitive polymer, poly (l-lactic acid) PLLA, is first printed to a high-resolution object using an advanced 3D printing technology, called melt electrowriting (MEW). The MEW processing conditions are systematically investigated to manufacture PLLA scaffolds with adjustable filament diameter and pore size for the application of bone tissue engineering. To this end, the relationships among the rheological behavior of the molten polymer, the electro-hydrodynamics of the jet, and the processing parameters (applied voltage, collection speed, and flow rate) are illuminated. The scaffold with relatively high deposition accuracy and crystallinity of PLLA is achieved when the printing speed was set slightly above the critical translation speed. The MEW PLLA scaffold with filament diameter of 40 μm and pore size of 200 μm is evaluated with KUSA-A1 cells to prove its in vitro potential. This is a milestone work for MEW since it supplies one of the best strategies to design and manufacture an essential biobased polymer for tissue engineering.

Here, the poly (l-lactic acid) (PLLA) membrane with multi-structured networks (MSN) is successfully prepared by electrospinning technology for the first time. It is composed of micron-sized ribbon-structured fibers and ultrafine nanofibers with a diameter of tens of nanometers, and they are connected to form the new network structure. Thanks to the special fiber morphology and structure, the interception and electrostatic adsorption ability for against atmospheric particulate matter (PM) are significantly enhanced, and the resistance to airflow is reduced due to the "slip effect" caused by ultrafine nanofibers. The PLLA MSN membrane shows excellent filtration performance with ultra-high filtration efficiency (>99.9% for PM 2.5 and >99.5% for PM 0.3 ) and ultra-low pressure drop (≈20 Pa). It has demonstrated filtration performance that even exceeds current non-biodegradable polymer materials, laying the foundation for future applications of biodegradable PLLA in the field of air filtration. In addition, this new structure also provides a new idea for optimizing the performance of other polymer materials., (© 2024 Wiley‐VCH GmbH.)

The insect repellent ethyl butylacetylaminopropionate (IR3535) was used as a functional additive for poly (l-lactic acid) (PLLA) to modify its structure and mechanical properties and achieve insect repellency. PLLA/IR3535 mixtures at various compositions were prepared via melt extrusion. In the analyzed composition range of 0 to 23 m% IR3535, PLLA and IR3535 were miscible at the length scale represented by the glass transition temperature. Addition of IR3535 resulted in a significant decrease in the glass transition temperature of PLLA, as well as in the elastic modulus, indicating its efficiency as a plasticizer. All mixtures were amorphous after extrusion, though PLLA/IR3535 extrudates with an IR3535 content between 18 and 23 m% crystallized during long-term storage at ambient temperature, due to their low glass transition temperature. Quantification of the release of IR3535 into the environment by thermogravimetric analysis at different temperatures between 50 and 100 °C allowed the estimation of the evaporation rate at lower temperatures, suggesting an extremely low release rate with a time constant of the order of magnitude of 1–2 years at body temperature.

Fabrication method is one of the essential factors which directly affect on the properties of scaffold. Several techniques have been well established to fabricate nanofibrous scaffolds such as electrospinning. However, preparing a three-dimensional (3-D) interconnected macro-pore scaffold essential for transporting the cell metabolites and nutrients is difficult using the electrospinning method. The main aim of this study was developing a highly porous scaffold by poly (L-lactic acid) (PLLA)/chitosan blend using liquid–liquid phase separation (LLPS) technique, a fast and cost–benefit method, in order to use in nerve tissue engineering. In addition, the effect of different polymeric concentrations on morphology, mechanical properties, hydrophilicity, in vitro degradation rate and pH alteration of the scaffolds were evaluated. Moreover, cell attachment, cell viability and cell proliferation of scaffolds as candidates for nerve tissue engineering was investigated. PLLA/chitosan blend not only had desirable structural properties, porosity, hydrophilicity, mechanical properties, degradation rate and pH alteration but also provided a favorable environment for attachment, viability, and proliferation of human neuroblastoma cells, exhibiting significant potential for nerve tissue engineering applications. However, the polymeric concentration in blend fabrication had influence on both characteristics and cell responses. It concluded that PLLA/chitosan nanofibrous 3-D scaffold fabricated by LLPS method as a suitable candidate for nerve tissue engineering. [ABSTRACT FROM AUTHOR]

In order to solve the problem of uneven microporous structure of Poly(L-lactic acid) (PLLA) bulk orientation by using biological safety multi-functional plant oil as chain extenders (CE), multi-armed flexible chains were introduced into PLLA through reactive processing to prepare long chain branched PLLA (LCB-PLLA). When the total content of the CE was 6.15 wt%, PLLA and the CE reacted most fully, while maintaining the tensile strength of PLLA and improving toughness. After introducing the LCB structure, the presence of multi-armed flexible chains increased the mobility of the molecular chains, resulting in a significantly lower degree of crystallinity. When the draw ratio up to 900 %, the crystallinity of LCB-PLLA-F-900 % was only 45.15 %, lower than that of PLLA-F-900 %. Thanks to the mobility of polymer chains can be enhanced, which reduces the degree of crystallinity while promoting the uniform growth of oriented microporous structures. Finally, an oriented micro-porous biomimetic LCB-PLLA material with an average cell diameter of 540 nm was prepared, and the results of in vitro cell culture showed that the oriented micro-porous LCB-PLLA biomimetic material was more conducive to cell proliferation. [ABSTRACT FROM AUTHOR]

With the application of bioresorbable materials in self-expandable braided stent, current analytical model for radial compression property of the stent is not applicative if considering the constraint between the polymeric filaments. Poly (l-lactic acid) (PLLA) is one of the broadly used bioresorbable materials in stents due to its superior biocompatibility and mechanical properties. The radial compression properties of PLLA braided stents were investigated by considering two types of constraints between filaments in this work. Weak constraint indicates the friction between filaments of PLLA stents and strong constraint indicates the close looped end (extremity configuration) of PLLA stents. It is found that the radial stiffness can be enhanced by two types of constraints, and strong constraint improves the peak compression force slightly in the radial compression behavior of PLLA braided stents. This work provides suggestions for the study of PLLA braided stents theoretical development.

Xeroderma pigmentosum (XP) is a rare autosomal recessive hereditary disorder. As patients with XP are deficient in nucleotide excision repair, they show severe photosensitivity symptoms. Although skin protection from ultraviolet (UV) radiation is essential to improve the life expectancy of such patients, the optimal protective effect is not achieved even with sunscreen application, owing to the low usability of the preparations. Nanosheets are two-dimensional nanostructures with a thickness in the nanometer range. The extremely large aspect ratios of the nanosheets result in high transparency, flexibility, and adhesiveness. Moreover, their high moisture permeability enables their application to any area of the skin for a long time. We fabricated preparations containing avobenzone (BMDBM) based on freestanding poly (L-lactic acid) (PLLA) nanosheets through a spin-coating process. Although monolayered PLLA nanosheets did not contain enough BMDBM to protect against UV radiation, the layered nanosheets, consisting of five discrete BMDBM nanosheets, showed high UV absorbance without lowering the adhesive strength against skin. Inflammatory reactions in XPA-deficient mice after UV radiation were completely suppressed by the application of BMDBM-layered nanosheets to the skin. Thus, the BMDBM layered nanosheet could serve as a potential sunscreen preparation to improve the quality of life of patients with XP.

Polymer materials have found extensive applications in the clinical and medical domains due to their exceptional biocompatibility and biodegradability. Compared to metallic counterparts, polymers, particularly Poly (L-lactic acid) (PLLA), are more suitable for fabricating biodegradable stents. As a viscoelastic material, PLLA monofilaments exhibit a creep phenomenon under sustained tensile stress. This study explores the use of creep to enhance the mechanical attributes of PLLA monofilaments. By subjecting the highly oriented monofilaments to controlled, constant force stretching, we achieved notable improvements in their mechanical characteristics. The results, as confirmed by tensile testing and dynamic mechanical analysis, revealed a remarkable 67 % increase in total elongation and over a 20 % rise in storage modulus post-mechanical training. Further microscopic analyses, including Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM), revealed enhanced spacing and cavity formation. These mechanical advancements are attributed to the unraveling and a more orderly arrangement of molecular chains in the amorphous regions. This investigation offers a promising approach for augmenting the mechanical properties of PLLA monofilaments, potentially benefiting their application in biomedical engineering., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Lecithin is a natural mixture of phospholipids and neutral lipids, and plays a vital role in the maintenance of cell-membrane integrity for all of the basic biological processes.This study aimed to evaluate the adhesion and growth of bone marrow-derived mesenchymal stem cells (BMSCs) on the three-dimensional (3D) electrospun lecithin-containing poly (L-lactic acid) (PLLA) fibrous scaffolds. In this study, PLLA and 0-15% of lecithin (wt.%) were dissolved in methylene chloride and thoroughly mixed to fabricate fibrous scaffolds by electrospinning technique. Surface morphology and hydrophilic properties of the scaffolds were characterized by scanning electron microscopy (SEM) and water uptake, respectively. The cytocompatibility of electrospun scaffolds and their potential cytotoxic effects on cells were studied over 8 days by seeding rat BMSCs on the scaffolds of PLLA containing 0-15% lecithin. Then cell proliferation was tested by CCK-8 assay and cell injury was assessed by measuring the release of intracellular lactate dehydrogenase (LDH). And cell morphology was studied by Toluidine blue staining, propidium iodide staining and SEM. The hydrophilicity was dramatically increased with an increase of lecithin content in the modified PLLA/lecithin scaffolds, as determined by rate of water uptake. In addition, the results obtained from in vitro assays suggested that the electrospun PLLA/5%lecithin scaffolds could possess the optimal hydrophilicity, higher adhesion and proliferation of BMSCs than PLLA, and they also did not lead to any significant toxic effects to cells. Moreover, BMSCs on PLLA/5%lecithin scaffolds tended to maintain their phenotypic shape and integrate with the microfibers to form a 3D cellular network, indicating a favorable interaction between this electrospun lecithin-based scaffolds and cells. The study demonstrated that the electrospun PLLA/lecithin fibrous scaffolds showed much better hydrophilicity and biocompatibility by introducing lecithin into the polymer in comparison with pure PLLA, which would offer a promising strategy for constructing tissue engnineered blood vessel. [ABSTRACT FROM AUTHOR]

Poly (ethylene glycol) (PEG) blended with poly (L-lactic acid) (PLLA) as novel green and sustainable shape-stabilized phase change materials (PCMs) were prepared and characterized in this study. The miscibility and morphology of the blends played an important role in the properties of the PCMs. The partial miscibility between PEG and PLLA resulted in suitable latent heat and a low leakage percentage of PCMs. The typical spherulite structure with a Maltese cross was examined in neat PLLA, as observed using polarized optical microscopy. However, the addition of PEG to PLLA led to the formation of ring-banded spherulites due to the presence of PEG altering the aggregation and twisting the PLLA lamellae. These PLLA crystalline structures can capture liquid (including molten PEG), stabilize the shape, and prevent leakage. The thermal mechanical analysis results indicated that the thickness of the PEG/PLLA blends was not significantly changed during the phase change process. The PEG/PLLA 75/25 blends exhibited appropriate film forming properties and mechanical strength. Moreover, differential scanning calorimetry analysis demonstrated the largest latent heat of melting (130.26 J/g), which could have great potential for developing novel phase change materials for thermal energy storage. Image, graphical abstract • The facile preparation of PEG-based PCMs with biodegradable PLLA. • The degree of miscibility leads to different properties of PCMs. • The TMA results indicate that the thickness of PCMs is not significantly changed until reaching 100 °C. [ABSTRACT FROM AUTHOR]

Peripheral nerve injury is a common clinical neurological disease. In our previous study, highly oriented poly (L-lactic acid) (PLLA)/soy protein isolate (SPI) nanofiber nerve conduits were constructed and exhibited a certain repair capacity for peripheral nerve injury. In order to further improve their nerve repairing efficiency, the bone mesenchymal stem cells (BMSCs) overexpressing brain derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF) were introduced into the conduits as seed cells and then were used to repair the 10-mm sciatic nerve defects in rats. The nerve repair efficiency of the functional nerve conduits was evaluated by gait experiment, electrophysiological test, and a series of assays such as hemotoxylin-eosin (HE) staining, immunofluorescence staining, toluidine blue (TB) staining, transmission electron microscopy (TEM) observation of regenerated nerve and Masson’s trichrome staining of gastrocnemius muscle. The results showed that the conduits containing BMSCs overexpressing BDNF and GDNF double-factors group had better nerve repairing efficiency than blank BMSCs and single BDNF or GDNF factor groups, and superior to autografts group in some aspects. These data demonstrated that BDNF and GDNF produced by BMSCs could synergistically promote peripheral nerve repair. This study shed a new light on the conduits and stem cells-based peripheral nerve repair.

This study makes use of polycondensation to produce poly (L-lactic acid)-(polyethylene glycols), a biodegradable copolymer, then puts it with organically modified montmorillonite (o-MMT) going through an intercalation process to produce a series of nanocomposites of PLLA-PEG/o-MMT. The exfoliation and intercalation of the montmorillonite-layered structure could be found through X-ray diffraction and transmission electron microscopy. The lower the molecular weight of poly (ethylene glycol), the more obvious the exfoliation and dispersion. The nanocomposites were investigated under non-isothermal crystallization and isothermal crystallization separately via differential scanning calorimetry (DSC). After the adding of o-MMT to PLLA-PEG copolymers, it was found that the PLLA-PEG nanocomposites crystallized slowly and the crystallization peak tended to become broader during the non-isothermal crystallization process. Furthermore, the thermal curve of the non-isothermal melt crystallization process of PLLA-PEG copolymers with different proportions of o-MMT showed that the melting point decreased gradually with the increase of o-MMT content. In the measurement of isothermal crystallization, increasing the o-MMT of the PLLA-PEG copolymers would increase the t1/2 (crystallization half time) for crystallization and decrease the value of ΔHc. However, the present study results suggest that adding o-MMT could affect the crystallization rate of PLLA-PEG copolymers. The o-MMT silicate layer was uniformly dispersed in the PLLA-PEG copolymers, forming a nucleating agent. The crystallization rate and the regularity of the crystals changed with the increase of the o-MMT content, which further affected the crystallization enthalpies.

Biodegradable scaffolds based on biomedical polymeric materials have attracted wide interest in bone transplantation for clinical treatment for bone defects without a second operation. The composite materials of poly(trimethylene carbonate), poly(L-lactic acid), and hydroxyapatite (PTMC/PLA/HA and PTMC/HA) were prepared by the modification and blending of PTMC with PLA and HA, respectively. The PTMC/PLA/HA and PTMC/HA scaffolds were further prepared by additive manufacturing using the biological 3D printing method using the PTMC/PLA/HA and PTMC/HA composite materials, respectively. These scaffolds were also characterized by Fourier transform infrared spectroscopy (FT-IR), gel permeation chromatography (GPC), automatic contact-angle, scanning electronic micrographs (SEM), diffraction of X-rays (XRD), differential scanning calorimetry (DSC), and thermogravimetry (TG). Subsequently, their properties, such as mechanical, biodegradation, cell cytotoxicity, cell compatibility in vitro, and proliferation/differentiation assay in vivo, were also investigated. Experiment results indicated that PTMC/PLA/HA and PTMC/HA scaffolds possessed low toxicity, good biodegradability, and good biocompatibility and then enhanced the cell multiplication ability of osteoblast cells (MC3T3-E1). Moreover, PTMC/PLA/HA and PTMC/HA scaffolds enhanced the adhesion and proliferation of MC3T3-E1 cells and enabled the bone cell proliferation and induction of bone tissue formation. Therefore, these composite materials can be used as potential biomaterials for bone repatriation and tissue engineering.

In the present study the development of novel polymer-supported nanocomposite graphene oxide (GO)–TiO2 films, based on poly(L-lactic acid), one of the most exploited bioplastics worldwide, was explored for photocatalytic applications. The nanocomposites were synthesized and evaluated as photocatalysts for the removal of a mixture of nine antibiotics, consisting of two sulphonamides (sulfamethoxazole, sulfadiazine), three fluoroquinolones (levofloxacin, norfloxacin, moxifloxacin), one anti-TB agent (isoniazid), one nitroimidazole (metronidazole), one lincosamide (lincomycin) and one diaminopyrimidine (trimethoprim), which are commonly found in wastewaters. The films were synthesized using 1 wt% GO and different TiO2 content (10, 25, and 50 wt%) and characterized using Fourier transform infrared spectroscopy (FTIR), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Findings confirmed the successful immobilization of GO/TiO2 in all cases. The PLLA–GO–TiO2 50 wt% composite film demonstrated higher photocatalytic efficiency and, thus, was further investigated demonstrating excellent photostability and reusability even after four cycles. Overall, PLLA–GO–TiO2 50 wt% nanocomposite demonstrated high efficiency in the photocatalytic degradation of the antibiotics in various matrices including pure water and wastewater. [ABSTRACT FROM AUTHOR]

The effect of the post-annealing process on different properties of poly (L-lactic acid) (PLLA) nanofibers has been investigated in view of their use in energy-harvesting devices. Polymeric PLLA nanofibers were prepared by using electrospinning and then were thermally treated above their glass transition. A detailed comparison between as-spun (amorphous) and annealed (semi-crystalline) samples was performed in terms of the crystallinity, morphology and mechanical as well as piezoelectric properties using a multi-technique approach combining DSC, XRD, FTIR, and AFM measurements. A significant increase in the crystallinity of PLLA nanofibers has been observed after the post-annealing process, together with a major improvement of the mechanical and piezoelectric properties. [ABSTRACT FROM AUTHOR]

The use of targeted chemotherapy is a promising solution to mitigate the side effects and dosage of drugs. This research focuses on the development of magnetic microspheres (MMS) based drug carriers for targeted chemotherapy, formulated with iron oxide nanoparticles (Fe 3 O 4 NPs) and poly (l-lactic acid) (PLA) loaded with the antibiotic drug Ciprofloxacin (CIF). In this study, Fe 3 O 4 NPs were synthesized using pomegranate peel extract as a natural reducing and stabilizing agent. The double emulsification method (W 1 /O/W 2) was employed to produce Fe 3 O 4 @LEC-CIF-PLA-MMS, which were characterized using various spectral and microscopic techniques. The drug encapsulation efficiency for Fe 3 O 4 @LEC-CIF-PLA-MMS was found to be 80.7 %. The in vitro drug release of CIF from Fe 3 O 4 @LEC-CIF-PLA-MMS induced by H 2 O 2 and GSH- stimuli was found to be 87.55 % and 82.32 %, respectively in acidic pH 4.5. Notably, the magnetically triggered drug release behaviour of Fe 3 O 4 @LEC-CIF-PLA-MMS (93.56 %) was assessed in acidic pH environment upon exposure to low-frequency alternating magnetic field (LF-AMF). Fe 3 O 4 @LEC-CIF-PLA-MMS demonstrated significantly enhanced in vitro cytotoxicity (IC 50 = 0.8 ± 0.03 μg/mL) against the HeLa-S3 cancer cell lines. Nevertheless, these research findings highlight the potential of Fe 3 O 4 @LEC-CIF-PLA-MMS for further development as a chemotherapeutic agent and hold promise for the future of targeted cancer treatment. • Cancer site targeted chemotherapeutic magnetic microspheres produced with Fe3O4 nanoparticles and poly(l-lactic acid). • The double emulsification method (W 1 /O/W 2) was utilized to produce Fe3O4@LEC-CIF-PLA-MMS. • Physicochemical properties of Fe3O4@LEC-CIF-PLA-MMS were characterized by spectroscopic and microscopic techniques. • Fe 3 O 4 @LEC-CIF-PLA-MMS showed significant pH, ROS, GSH-stimuli and magnetic field responsive drug release efficacy. • Fe 3 O 4 @LEC-CIF-PLA-MMS showed significant cytotoxicity against HeLa S3 cancer cells, with an IC50 of 0.8 ± 0.03 μg/mL. [ABSTRACT FROM AUTHOR]

The physical properties and non-isothermal melt- and cold-crystallisation kinetics of poly (l-lactic acid) (PLLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biobased polymers reprocessed by mechanical milling of moulded specimens and followed injection moulding with up to seven recycling cycles are investigated. Non-isothermal crystallisation kinetics are evaluated by the half-time of crystallisation and a procedure based on the mathematical treatment of DSC cumulative crystallisation curves at their inflection point (Kratochvil-Kelnar method). Thermomechanical recycling of PLLA raised structural changes that resulted in an increase in melt flow properties by up to six times, a decrease in the thermal stability by up to 80 °C, a reduction in the melt half-time crystallisation by up to about 40%, an increase in the melt crystallisation start temperature, and an increase in the maximum melt crystallisation rate (up to 2.7 times). Furthermore, reprocessing after the first recycling cycle caused the elimination of cold crystallisation when cooling at a slow rate. These structural changes also lowered the cold crystallisation temperature without impacting the maximum cold crystallisation rate. The structural changes of reprocessed PHBV had no significant effect on the non-isothermal crystallisation kinetics of this material. Additionally, the thermomechanical behaviour of reprocessed PHBV indicates that the technological waste of this biopolymer is suitable for recycling as a reusable additive to the virgin polymer matrix. In the case of reprocessed PLLA, on the other hand, a significant decrease in tensile and flexural strength (by 22% and 46%, respectively) was detected, which reflected changes within the biobased polymer structure. Apart from the elastic modulus, all the other thermomechanical properties of PLLA dropped down with an increasing level of recycling.

Carbon nanostructures application, such as graphene (Gr) and graphene oxide (GO), provides suitable efforts for new material acquirement in biomedical areas. By aiming to combine the unique physicochemical properties of GO to Poly L-lactic acid (PLLA), PLLA-GO filaments were produced and characterized by X-ray diffraction (XRD). The in vivo biocompatibility of these nanocomposites was performed by subcutaneous and intramuscular implantation in adult Wistar rats. Evaluation of the implantation inflammatory response (21 days) and mesenchymal stem cells (MSCs) with PLLA-GO took place in culture for 7 days. Through XRD, new crystallographic planes were formed by mixing GO with PLLA (PLLA-GO). Using macroscopic analysis, GO implanted in the subcutaneous region showed particles’ organization, forming a structure similar to a ribbon, without tissue invasion. Histologically, no tissue architecture changes were observed, and PLLA-GO cell adhesion was demonstrated by scanning electron microscopy (SEM). Finally, PLLA-GO nanocomposites showed promising results due to the in vivo biocompatibility test, which demonstrated effective integration and absence of inflammation after 21 days of implantation. These results indicate the future use of PLLA-GO nanocomposites as a new effort for tissue engineering (TE) application, although further analysis is required to evaluate their proliferative capacity and viability.

The concept of specific work of flow has been applied for the analysis of critical shearing conditions for the formation of crystal nuclei in poly (l-lactic acid) (PLLA). Systematic variation in both time and rate of shearing the melt in a parallel-plate rheometer revealed that these parameters are interconvertible regarding the shear-induced formation of crystal nuclei; that is, low shear rate can be compensated for by increasing the shear time and vice versa. This result supports the view that critical shearing conditions can be expressed by a single quantity, providing additional options for tailoring polymer processing routes when enhanced nuclei formation is desired/unwanted. Analysis of PLLA of different mass-average molar masses of 70, 90, 120, and 576 kDa confirmed improved shear-induced crystal nucleation for materials of higher molar mass, with critical specific works of flow, above which shear-induced nuclei formation occurs, of 550, 60, 25, and 5 kPa, respectively.

• Effect of GONS and crystallinity on the barrier properties of PLLA was investigated. • PLLA/GONS nanocomposite films were prepared by the solution coagulation method. • Changing the form of crystals from α′ to α, led to decrease in permeability. • Presence of crystals and GONS resulted in a significant prolongation of gas pathway. In this study, the effects of crystallinity, crystal polymorphism, and graphene oxide nanosheets (GONS) on the oxygen and water vapor permeability of PLLA were investigated. It was revealed that for the pristine PLLA with a crystallinity degree of 40%, the oxygen and water vapor permeability decreased by about 48% and 30%, respectively. Also, by changing the crystal form from α′ to α in a constant crystallinity ratio, the oxygen and water vapor permeability decreased by about 10% and 28%, respectively. PLLA/GO nanocomposites with various compositions were prepared by solution coagulation. Results of the permeability analysis on nanocomposites showed that in the presence of 1 wt% GONS, the oxygen and water vapor permeability of PLLA films decreased by about 80% and 30% respectively. In addition, the simultaneous effect of crystallinity and the presence of GONS was investigated, demonstrating that the simultaneous presence of crystalline structures with nanosheets caused the gas pathways to prolong immensely, and for the sample containing 1 wt% nanosheets with about 35% of crystallinity, the rate of oxygen permeation and water vapor transmission decreases by about 90% and 60%, respectively. The Nielsen, Bharadwaj, Duan & Thomas, and Tan & Thomas models were used for comparing these results. [ABSTRACT FROM AUTHOR]

The aim of the present study was to assess the potential of biocompatible polymeric nanosheets as topical and transdermal drug-delivery devices. Nanosheets are two-dimensional nanostructures with a thickness in the nanometer order, and their extremely large aspect ratios result in unique properties, including high transparency, flexibility, and adhesiveness. Nanosheet formulations containing betamethasone valerate (BV) as a model drug and consisting of poly (L -lactic acid) or poly (lactic-co-glycolic) acid were fabricated through a spin-coating-assisted layer-by-layer method using a water-soluble sacrificial membrane. The fabricated formulations could incorporate and release higher amounts of BV compared with a commercial ointment, and the amounts could be controlled by the polymers used, the amount of BV added, and the use of controlled-release membranes. The presence of BV had a minimal effect on thickness, transparency, adhesiveness, and moisture permeability of nanosheets, permitting their application to any area of skin for a long period of time. Therefore, this biocompatible polymeric nanosheet formulation represents a novel and promising topical and transdermal drug delivery device, which has potential to deliver drugs regardless of the area of skin. [ABSTRACT FROM AUTHOR]

Novel biodegradable Poly (L-lactic acid) (PLLA) microspheres containing ytterbium were designed for intra-tumoral radiotherapy, especially for radioembolization. 175Yb possess both therapeutic beta and diagnostic gamma radiations. In this work, a process of making ready radiomicrospheres 175Yb (acac)3-loaded PLLA for more consideration has been investigated. The radiomicrospheres were prepared with approximate size of 20-40 μm, and radionuclidic purity > 92%. The radiomicrospheres were stable in-vitro for up to 72 h in normal saline, and also in human serum albumin (HSA). Biodistribution in mice bearing 4T1 tumor showed specific radionuclide uptake over 48 h. Tumor necrosis was also observed at the injection site up to 12 days after injection. These data indicated that 175Yb-PLLA microspheres could be prepared and considered further for radiomicrospheres tumor therapy. [ABSTRACT FROM AUTHOR]