Polymers Based on PLA from Synthesis Using D,L-Lactic Acid (or Racemic Lactide) and Some Biomedical Applications: A Short Review

Synthesis and use of thermoplastic polymers for tissue engineering purposes

Thermoplastic polymers provide a versatile platform to mimic various aspects of physiological extracellular matrix properties such as chemical composition, stiffness, and topography for use in cell and tissue engineering applications. In this review, we provide a brief overview of the most promising thermoplastic polymers, and in particular the thermoplastic polyesters, such as poly(lactic acid), poly(glycolic acid), and polycaprolactone, and the thermoplastic elastomers, such as polyurethanes, polyhydroxyalkanoates, and poly(butyl cyanoacrylate). A particular focus has been made on the synthesis processes, the processability and the biocompatibility. We also discuss how these materials can be applied in tissue engineering, mimicking tissues' structure and function, and stimulate mesenchymal stem cells differentiation and mechanotransduction.

Controlling Oligomer Chain Length via Ultrasonic Pretreatment in Lactic Acid Polycondensation for Enhanced Poly(lactic acid) ROP

Controlling oligomer chain length in lactic acid (LA) polycondensation is crucial for producing good properties of poly(lactic acid) (PLA). This study explores the use of ultrasonic pretreatment to reduce the water content of LA, aiming to optimize the polycondensation process and enhance the quality of PLA through ring-opening polymerization (ROP). The methodology involved varying ultrasonic treatment time and power during LA pretreatment, followed by polycondensation at the optimized temperature. The study results indicate that ultrasonic pretreatment effectively reduces the water content in LA, with optimal conditions found at 90 min and 75 W, yielding the lowest water content. The polycondensation process, conducted at a gradual temperature of 150 °C followed by 180 °C, resulted in the highest yield of 92.75% and a molecular weight of 25,126 g/mol for the oligomers. Ultrasonic pretreatment enhances water removal efficiency, reduces byproduct formation, and increases oligomer reactivity, resulting in higher-purity oligomers and improved chain length control. During the ROP stage, oligomers prepared through ultrasonic pretreatment produced PLA with a higher molecular weight and crystallinity.

PLA/PMMA Reactive Blending in the Presence of MgO as an Exchange Reaction Catalyst

To address the limitations of poly (lactic acid) (PLA), it was blended with poly (methyl methacrylate) (PMMA) as a toughening component, using MgO nanoparticles (NPs, 0.075-0.15 wt%) as a catalyst. SEM pictures confirmed the good miscibility of the blends. Mechanical tests showed a slight decrease in elastic modulus and tensile strength for the PLA/PMMA125 sample containing 0.125% MgO. Yet, elongation at break rose by over 60% and impact strength increased by over 400% compared to pure PLA. Also, MgO facilitated the shifting of the glass transition temperature (Tg) of both polymers in DSC curves. Additionally, the absence of cold crystallization in PLA, coupled with reductions in its melting temperature (Tm) and crystallinity, were identified as critical factors contributing to improved miscibility within the reactive blend. Melt flow index (MFI) evaluation indicated a decrease in viscosity, while water contact angle measurements revealed an increase in polar groups on the surfaces of the MgO-containing samples. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses confirmed the effective distribution and dispersion of NPs throughout the blend, along with a significant decrease in crystallinity. Moreover, DFT calculations were performed to better understand the role of MgO in the reaction. The findings offered key insights into the reaction mechanism, confirming that MgO plays a crucial role in facilitating the transesterification between PLA and PMMA. These findings underscore the enhanced performance of exchange reactions between the active groups of both polymers in the presence of MgO, leading to the formation of PLA-PMMA copolymers with superior miscibility and mechanical properties. Finally, a cell culture assay confirmed the blend's non-toxicity, showing its versatile potential.

Exploring the Catalytic Efficiency of Lithium Bis(trimethylsilyl)amide (LiHMDS) in Lactide Polymerization

The exploration of efficient catalysts for the ring-opening polymerization of cyclic esters has significant implications for the synthesis of biocompatible and biodegradable polymers. In this work, the simple catalyst lithium bis(trimethylsilyl)amide (LiHMDS) with high activity was explored in detail for the synthesis of polylactide (PLA). Using LiHMDS as the catalyst, various cyclic esters were polymerized to obtain diverse sustainable polyesters, such as poly(lactide), poly(δ-valerolactone), and poly(caprolactone), with controlled molecular weights and narrow molecular weight distributions. PLA synthesis was accomplished in just a few minutes at room temperature, contributing to the sustainable advancement of this polymer.

Inside out: Exploring edible biocatalytic biosensors for health monitoring

Edible biosensors can measure a wide range of physiological and biochemical parameters, including temperature, pH, gases, gastrointestinal biomarkers, enzymes, hormones, glucose, and drug levels, providing real-time data. Edible biocatalytic biosensors represent a new frontier within healthcare technology available for remote medical diagnosis. The main challenges to develop edible biosensors are: i) finding edible materials (i.e. redox mediators, conductive materials, binders and biorecognition elements such as enzymes) complying with Food and Drug Administration (FDA), European Food Safety Authority (EFSA) and European Medicines Agency (EMEA) regulations; ii) developing bioelectronics able to operate in extreme working conditions such as low pH (∼pH 1.5 gastric fluids etc.), body temperature (between 37 °C and 40 °C) and highly viscous bodily fluids that may cause surface biofouling issues. Nowadays, advanced printing techniques can revolutionize the design and manufacturing of edible biocatalytic biosensors. This review outlines recent research on biomaterials suitable for creating edible biocatalytic biosensors, focusing on their electrochemical properties such as electrical conductivity and redox potential. It also examines biomaterials as substrates for printing and discusses various printing methods, highlighting challenges and perspectives for edible biocatalytic biosensors.

Advances in L-Lactic Acid Production from Lignocellulose Using Genetically Modified Microbial Systems

Lactic acid is a vital organic acid with a wide range of industrial applications, particularly in the food, pharmaceutical, cosmetic, and biomedical sectors. The conventional production of lactic acid from refined sugars poses high costs and significant environmental impacts, leading to the exploration of alternative raw materials and more sustainable processes. Lignocellulosic biomass, particularly agro-industrial residues such as agave bagasse, represents a promising substrate for lactic acid production. Agave bagasse, a by-product of the tequila and mezcal industries, is rich in fermentable carbohydrates, making it an ideal raw material for biotechnological processes. The use of lactic acid bacteria (LAB), particularly genetically modified microorganisms (GMMs), has been shown to enhance fermentation efficiency and lactic acid yield. This review explores the potential of lignocellulosic biomass as a substrate for microbial fermentation to produce lactic acid and other high-value products. It covers the composition and pretreatment of some agricultural residues, the selection of suitable microorganisms, and the optimization of fermentation conditions. The paper highlights the promising future of agro-industrial residue valorization through biotechnological processes and the sustainable production of lactic acid as an alternative to conventional methods.

Epoxidized Soybean Oil Toughened Poly(lactic acid)/Lignin-g-Poly(lauryl methacrylate) Bio-Composite Films with Potential Food Packaging Application

The application of lignin as a filler for poly (lactic acid) (PLA) is limited by their poor interfacial adhesion. To address this challenge, lignin-graft-poly(lauryl methacrylate) (LG-g-PLMA) was first blended with poly (lactic acid), and then epoxidized soybean oil (ESO) was also added to prepare PLA/LG-g-PLMA/ESO composite, which was subsequently hot pressed to prepare the composite films. The effect of ESO as a plasticizer on the thermal, mechanical, and rheological properties, as well as the fracture surface morphology of the PLA/LG-g-PLMA composite films, were investigated. It was found that the compatibility and toughness of the composites were improved by the addition of ESO. The elongation at break of the composites with an ESO content of 5 phr was increased from 5.6% to 104.6%, and the tensile toughness was increased from 4.1 MJ/m3 to 44.7 MJ/m3, as compared with the PLA/LG-g-PLMA composite without ESO addition. The toughening effect of ESO on composites is generally attributed to the plasticization effect of ESO, and the interaction between the epoxy groups of ESO and the terminal carboxyl groups of PLA. Furthermore, PLA/LG-g-PLMA/ESO composite films exhibited excellent UV barrier properties and an overall migration value below the permitted limit (10 mg/dm2), indicating that the thus-prepared biocomposite films might potentially be applied to environmentally friendly food packaging.

Bone Incorporation of a Poly (L-Lactide-Co-D, L-Lactide) Internal Fixation Device in a Rat's Tibia: Microtomographic, Confocal LASER, and Histomorphometric Analysis

This study evaluated the bone incorporation process of a screw-shaped internal fixation device made of poly (L-lactide-co-D, L-lactide) (PLDLLA). Thirty-two male Wistar rats received 32 fixation devices (2 mm × 6 mm) randomly assigned to either the right or left tibia and one implant in each animal. After 7, 14, 28, and 42 days, the rats were euthanized and the specimens were subjected to microtomographic computed tomography (microCT) and histomorphometric analyses to evaluate bone interface contact (BIC%) and new bone formation (NBF%) in cortical and cancellous bone areas. The animals euthanized on days 28 and 42 were treated with calcein and alizarin red, and confocal LASER microscopy was performed to determine the mineral apposition rate (MAR). Micro-CT revealed a higher percentage of bone volume (p < 0.006), trabecular separation (p < 0.001), and BIC in the cortical (p < 0.001) and cancellous (p = 0.003) areas at 28 and 42 days than at 7 and 14 days. The cortical NBF at 42 days was greater than that at 7 and 14 days (p = 0.022). No statistically significant differences were observed in cancellous NBF or MAR at 28 and 42 days. Based on these results, it can be seen that the PLDLLA internal fixation device is biocompatible and allows new bone formation around the screw thread.

Forefront Research of Foaming Strategies on Biodegradable Polymers and Their Composites by Thermal or Melt-Based Processing Technologies: Advances and Perspectives

The last few decades have witnessed significant advances in the development of polymeric-based foam materials. These materials find several practical applications in our daily lives due to their characteristic properties such as low density, thermal insulation, and porosity, which are important in packaging, in building construction, and in biomedical applications, respectively. The first foams with practical applications used polymeric materials of petrochemical origin. However, due to growing environmental concerns, considerable efforts have been made to replace some of these materials with biodegradable polymers. Foam processing has evolved greatly in recent years due to improvements in existing techniques, such as the use of supercritical fluids in extrusion foaming and foam injection moulding, as well as the advent or adaptation of existing techniques to produce foams, as in the case of the combination between additive manufacturing and foam technology. The use of supercritical CO2 is especially advantageous in the production of porous structures for biomedical applications, as CO2 is chemically inert and non-toxic; in addition, it allows for an easy tailoring of the pore structure through processing conditions. Biodegradable polymeric materials, despite their enormous advantages over petroleum-based materials, present some difficulties regarding their potential use in foaming, such as poor melt strength, slow crystallization rate, poor processability, low service temperature, low toughness, and high brittleness, which limits their field of application. Several strategies were developed to improve the melt strength, including the change in monomer composition and the use of chemical modifiers and chain extenders to extend the chain length or create a branched molecular structure, to increase the molecular weight and the viscosity of the polymer. The use of additives or fillers is also commonly used, as fillers can improve crystallization kinetics by acting as crystal-nucleating agents. Alternatively, biodegradable polymers can be blended with other biodegradable polymers to combine certain properties and to counteract certain limitations. This work therefore aims to provide the latest advances regarding the foaming of biodegradable polymers. It covers the main foaming techniques and their advances and reviews the uses of biodegradable polymers in foaming, focusing on the chemical changes of polymers that improve their foaming ability. Finally, the challenges as well as the main opportunities presented reinforce the market potential of the biodegradable polymer foam materials.

Applications and advancements of nanoparticle-based drug delivery in alleviating lung cancer and chronic obstructive pulmonary disease

Lung cancer (LC) and chronic obstructive pulmonary disease (COPD) are among the leading causes of mortality worldwide. Cigarette smoking is among the main aetiologic factors for both ailments. These diseases share common pathogenetic mechanisms including inflammation, oxidative stress, and tissue remodelling. Current therapeutic approaches are limited by low efficacy and adverse effects. Consequentially, LC has a 5-year survival of < 20%, while COPD is incurable, underlining the necessity for innovative treatment strategies. Two promising emerging classes of therapy against these diseases include plant-derived molecules (phytoceuticals) and nucleic acid-based therapies. The clinical application of both is limited by issues including poor solubility, poor permeability, and, in the case of nucleic acids, susceptibility to enzymatic degradation, large size, and electrostatic charge density. Nanoparticle-based advanced drug delivery systems are currently being explored as flexible systems allowing to overcome these limitations. In this review, an updated summary of the most recent studies using nanoparticle-based advanced drug delivery systems to improve the delivery of nucleic acids and phytoceuticals for the treatment of LC and COPD is provided. This review highlights the enormous relevance of these delivery systems as tools that are set to facilitate the clinical application of novel categories of therapeutics with poor pharmacokinetic properties.

Harnessing the dual nature of Bacillus (Weizmannia) coagulans for sustainable production of biomaterials and development of functional food

Bacillus coagulans, recently renamed Weizmannia coagulans, is a spore-forming bacterium that has garnered significant interest across various research fields, ranging from health to industrial applications. The probiotic properties of W. coagulans enhance intestinal digestion, by releasing prebiotic molecules including enzymes that facilitate the breakdown of not-digestible carbohydrates. Notably, some enzymes from W. coagulans extend beyond digestive functions, serving as valuable biotechnological tools and contributing to more sustainable and efficient manufacturing processes. Furthermore, the homofermentative thermophilic nature of W. coagulans renders it an exceptional candidate for fermenting foods and lignocellulosic residues into L-(+)-lactic acid. In this review, we provide an overview of the dual nature of W. coagulans, in functional foods and for the development of bio-based materials.

Improvement of Osteogenic Differentiation of Mouse Pre-Osteoblastic MC3T3-E1 Cells on Core-Shell Polylactic Acid/Chitosan Electrospun Scaffolds for Bone Defect Repair

Electrospun hybrid scaffolds composed of synthetic and natural polymers have gained increasing interest in tissue engineering applications over the last decade. In this work, scaffolds composed of polylactic acid electrospun fibers, either treated (P-PLA) or non-treated (PLA) with air-plasma, were coated with high molecular weight chitosan to create a core-shell microfibrous structure. The effective thickness control of the chitosan layer was confirmed by gravimetric, spectroscopic (FTIR-ATR) and morphological (SEM) investigations. The chitosan coating increased the fiber diameter of the microfibrous scaffolds while the tensile mechanical tests, conducted in dry and wet environments, showed a reinforcing action of the coating layer on the scaffolds, in particular when deposited on P-PLA samples. The stability of the Chi coating on both PLA and P-PLA substrates was confirmed by gravimetric analysis, while their mineralization capacity was evaluated though scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) after immersing the scaffolds in simulated body fluids (SBF) at 37 °C for 1 week. Sample biocompatibility was investigated through cell viability assay and SEM analysis on mouse pre-osteoblastic MC3T3-E1 cells grown on scaffolds at different times (1, 7, 14 and 21 days). Finally, Alizarin Red assay and qPCR analysis suggested that the combination of plasma treatment and chitosan coating on PLA electrospun scaffolds influences the osteoblastic differentiation of MC3T3-E1 cells, thus demonstrating the great potential of P-PLA/chitosan hybrid scaffolds for bone tissue engineering applications.

Exploiting Multimetallic Cooperativity in the Ring-Opening Polymerization of Cyclic Esters and Ethers

The use of multimetallic complexes is a rapidly advancing route to enhance catalyst performance in the ring-opening polymerization of cyclic esters and ethers. Multimetallic catalysts often outperform their monometallic analogues in terms of reactivity and/or polymerization control, and these improvements are typically attributed to "multimetallic cooperativity". Yet the origins of multimetallic cooperativity often remain unclear. This review explores the key factors underpinning multimetallic cooperativity, including metal-metal distances, the flexibility, electronics and conformation of the ligand framework, and the coordination environment of the metal centers. Emerging trends are discussed to provide insights into why cooperativity occurs and how to harness cooperativity for the development of highly efficient multimetallic catalysts.

Progress of biodegradable polymer application in cardiac occluders

Cardiac septal defect is the most prevalent congenital heart disease and is typically treated with open-heart surgery under cardiopulmonary bypass. Since the 1990s, with the advancement of interventional techniques and minimally invasive transthoracic closure techniques, cardiac occluder implantation represented by the Amplazter products has been the preferred treatment option. Currently, most occlusion devices used in clinical settings are primarily composed of Nitinol as the skeleton. Nevertheless, long-term follow-up studies have revealed various complications related to metal skeletons, including hemolysis, thrombus, metal allergy, cardiac erosion, and even severe atrioventricular block. Thus, occlusion devices made of biodegradable materials have become the focus of research. Over the past two decades, several bioabsorbable cardiac occluders for ventricular septal defect and atrial septal defect have been designed and trialed on animals or humans. This review summarizes the research progress of bioabsorbable cardiac occluders, the advantages and disadvantages of different biodegradable polymers used to fabricate occluders, and discusses future research directions concerning the structures and materials of bioabsorbable cardiac occluders.

Titanium and Vanadium Complexes of Tridentate Phenoxy-Imine and Phenoxy-Amine Ligands and Their Application in the Ring-Opening Polymerization of Cyclic Esters

Phenoxy-imine and phenoxy-amine proligands, with the additional OH donor groups 2,4-tBu2-6-(2-CH2(OH)-C6H4N=CH)C6H3OH (L1H2), 6-(2-CH2(OH)-C6H4N=CH)C6H3OH (L2H2), and 2,4-tBu2-6-(2-CH2(OH)-C6H4NH-CH)C6H3OH (L3H2), were synthesized and their titanium (Ti-L1-Ti-L3) and vanadium (V-L1-V-L2) complexes were prepared in reactions with Ti(OiPr)4 and VO(OiPr)3, respectively. All new compounds were characterized with the use of FTIR, 1H, and 13C NMR spectroscopy; X-ray crystallography was also used to study proligands. All the complexes proved to be active catalysts in the ring-opening polymerization (ROP) of ε-caprolactone, rac-lactide, and L-lactide in the melt. The effects of the complex structure (transition metal type, presence of tBu substituents, and type of nitrogen donor group), as well as the polymerization time and temperature, on the monomer conversion and polymer properties were investigated in detail.

Sonochemical Synthesis of Magnetite/Poly(lactic acid) Nanocomposites

Nanocomposites based on poly(lactic acid) (PLA) and magnetite nanoparticles (MNP-Fe3O4) show promise for applications in biomedical treatments. One key challenge is to improve the stabilization and dispersion of MNP-Fe3O4. To address this, we synthesized MNP-Fe3O4/PLA nanocomposites using ultrasound mediation and a single iron(II) precursor, eliminating the need for surfactants or organic solvents, and conducted the process under ambient conditions. The resulting materials, containing 18 and 33 wt.% Fe3O4, exhibited unique thermal behavior characterized by two mass losses: one at a lower degradation temperature (Td) and another at a higher Td compared to pure PLA. This suggests that the interaction between PLA and MNP-Fe3O4 occurs through hydrogen bonds, enhancing the thermal stability of a portion of the polymer. Fourier Transform Infrared (FT-IR) analysis supported this finding, revealing shifts in bands related to the terminal -OH groups of the polymer and the Fe-O bonds, thereby confirming the interaction between the groups. Raman spectroscopy demonstrated that the PLA serves as a protective layer against the oxidation of MNP-Fe3O4 in the 18% MNP-Fe3O4/PLA nanocomposite when exposed to a high-power laser (90 mW). Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) analyses confirmed that the synthetic procedure yields materials with dispersed nanoparticles within the PLA matrix without the need for additional reactants.

Engineering yeast cell factories to produce biodegradable plastics and their monomers: Current status and prospects

Traditional plastic products have caused serious environmental pollution due to difficulty to be degraded in the natural environment. In the recent years, biodegradable plastics are receiving increasing attention due to advantages in natural degradability and environmental friendliness. Biodegradable plastics have potential to be used in food, agriculture, industry, medicine and other fields. However, the high production cost of such plastics is the bottleneck that limits their commercialization and application. Yeasts, including budding yeast and non-conventional yeasts, are widely studied to produce biodegradable plastics and their organic acid monomers. Compared to bacteria, yeast strains are more tolerable to multiple stress conditions including low pH and high temperature, and also have other advantages such as generally regarded as safe, and no phage infection. In addition, synthetic biology and metabolic engineering of yeast have enabled its rapid and efficient engineering for bioproduction using various renewable feedstocks, especially lignocellulosic biomass. This review focuses on the recent progress in biosynthesis technology and strategies of monomeric organic acids for biodegradable polymers, including polylactic acid (PLA), polyhydroxyalkanoate (PHA), polybutylene succinate (PBS), and polybutylene adipate terephthalate (PBAT) using yeast cell factories. Improving the performance of yeast as a cell factory and strategies to improve yeast acid stress tolerance are also discussed. In addition, the critical challenges and future prospects for the production of biodegradable plastic monomer using yeast are also discussed.

Bifunctional thiourea-based organocatalyst promoted kinetic resolution polymerization of racemic lactide to isotactic polylactide

Here, we prepared a series of thiourea-based organocatalysts 1-7 by combining two stereogenic elements: binaphthyl-amine and cyclohexyl diamine moieties. Catalyst (R,S)-1 facilitated a stereoselective polymerization of rac-LA to afford iso-enriched PDLA with Pm of 0.96 while its enantiomer (S,R)-1 produced PLLA with Pm of 0.96. These iso-enriched PLA contributed to forming a stereocomplexed PLA with a significantly increased Tm of 196 °C.

Development of PLA/Lignin Bio-Composites Compatibilized by Ethylene Glycol Diglycidyl Ether and Poly (ethylene glycol) Diglycidyl Ether

Poly (lactic acid) (PLA) is a promising green substitute for conventional petroleum-based plastics in a variety of applications. However, the wide application of PLA is still limited by its disadvantages, such as slow crystallization rate, inadequate gas barrier, thermal degradation, etc. In this study, lignin (1, 3, 5 PHR) was incorporated into PLA to improve the thermal, mechanical, and barrier properties of PLA. Two low-viscosity epoxy resins, ethylene glycol diglycidyl ether (EGDE) and poly (ethylene glycol) diglycidyl ether (PEGDE), were used as compatibilizers to enhance the performance of the composites. The addition of lignin improved the onset degradation temperature of PLA by up to 15 °C, increased PLA crystallinity, improved PLA tensile strength by approximately 15%, and improved PLA oxygen barrier by up to 58.3%. The addition of EGDE and PEGDE both decreased the glass transition, crystallization, and melting temperatures of the PLA/lignin composites, suggesting their compatabilizing and plasticizing effects, which contributed to improved oxygen barrier properties of the PLA/lignin composites. The developed PLA/lignin composites with improved thermal, mechanical, and gas barrier properties can potentially be used for green packaging applications.

Development of Polyhydroxybutyrate-Based Packaging Films and Methods to Their Ultrasonic Welding

This study developed a technical task associated with the formation of welded joints based on biodegradable polymers and their subsequent physicochemical characterization. The primary objective was to establish the effect of the welding process and modification of natural poly(3-hydroxybutyrate) (PHB) with N,N-dibutylundecenoylamide (DBUA) as a plasticizing agent on the structure and properties of PHB-based biopolymer materials as well as the process and structure of welded joints formation using ultrasonic welding technique. The weldability of biodegradable layers based on PHB and PHB/DBUA mixture was ultrasonically welded and optimized using a standard Branson press-type installation. The effect of the DBUA plasticizer and welding process on the structure of PHB-based biodegradable material was investigated using scanning electron microscopy, X-ray diffraction, FT-IR spectroscopy, differential scanning calorimetry, and thermomechanical analysis. The results confirmed that the DBUA acted as an effective plasticizer of PHB, contributing to lower crystallinity of the PHB/DBUA mixture (63%) in relation to the crystallinity degree of pure PHB film (69%). Ultrasonic welding resulted in an additional increase (approximately 8.5%) in the degree of crystallinity in the PHB/DBUA in relation to the initial PHB/DBUA mixture. The significant shift toward lower temperatures of the crystallization and melting peaks of PHB modified with DBUA were observed using DSC concerning pure PHB. The melt crystallization process of PHB was affected by welding treatment, and a shift toward higher temperature was observed compared with the unwelded PHB/DBUA sample. The butt-welded joints of biodegradable PHB/DBUA materials made using the ultrasonic method tested for tensile strength have damaged the area immediately outside the joining surface.

A critical review on biodegradable food packaging for meat: Materials, sustainability, regulations, and perspectives in the EU

The development of biodegradable packaging is a challenge, as conventional plastics have many advantages in terms of high flexibility, transparency, low cost, strong mechanical characteristics, and high resistance to heat compared with most biodegradable plastics. The quality of biodegradable materials and the research needed for their improvement for meat packaging were critically evaluated in this study. In terms of sustainability, biodegradable packagings are more sustainable than conventional plastics; however, most of them contain unsustainable chemical additives. Cellulose showed a high potential for meat preservation due to high moisture control. Polyhydroxyalkanoates and polylactic acid (PLA) are renewable materials that have been recently introduced to the market, but their application in meat products is still limited. To be classified as an edible film, the mechanical properties and acceptable control over gas and moisture exchange need to be improved. PLA and cellulose-based films possess the advantage of protection against oxygen and water permeation; however, the addition of functional substances plays an important role in their effects on the foods. Furthermore, the use of packaging materials is increasing due to consumer demand for natural high-quality food packaging that serves functions such as extended shelf-life and contamination protection. To support the importance moving toward biodegradable packaging for meat, this review presented novel perspectives regarding ecological impacts, commercial status, and consumer perspectives. Those aspects are then evaluated with the specific consideration of regulations and perspective in the European Union (EU) for employing renewable and ecological meat packaging materials. This review also helps to highlight the situation regarding biodegradable food packaging for meat in the EU specifically.

Investigating the Mechanical Properties of Annealed 3D-Printed PLA-Date Pits Composite

Biomedical applications are crucial in rehabilitation medicine, assisting individuals with disabilities. Nevertheless, materials failure can sometimes result in inconvenience for users. Polylactic Acid (PLA) is a popular 3D-printed material that offers design flexibility. However, it is limited in use because its mechanical properties are inadequate. Thus, this study introduces an artificial intelligence model that utilizes ANFIS to estimate the mechanical properties of PLA composites. The model was developed based on an actual data set collected from experiments. The experimental results were obtained by preparing samples of PLA green composites with different weight fractions of date pits, which were then annealed for varying durations to remove residual stresses resulting from 3D printing. The mechanical characteristics of the produced PLA composite specimens were measured experimentally, while the ANSYS model was established to identify the composites' load-carrying capacity. The results showed that ANFIS models are exceptionally robust and compatible and possess good predictive capabilities for estimating the hardness, strength, and Young's modulus of the 3D-printed PLA composites. The model results and experimental outcomes were nearly identical.

Bioplastic production in terms of life cycle assessment: A state-of-the-art review

The current transition to sustainability and the circular economy can be viewed as a socio-technical response to environmental impacts and the need to enhance the overall performance of the linear production and consumption paradigm. The concept of biowaste refineries as a feasible alternative to petroleum refineries has gained popularity. Biowaste has become an important raw material source for developing bioproducts and biofuels. Therefore, effective environmental biowaste management systems for the production of bioproducts and biofuels are crucial and can be employed as pillars of a circular economy. Bioplastics, typically plastics manufactured from bio-based polymers, stand to contribute to more sustainable commercial plastic life cycles as part of a circular economy in which virgin polymers are made from renewable or recycled raw materials. Various frameworks and strategies are utilized to model and illustrate additional patterns in fossil fuel and bioplastic feedstock prices for various governments' long-term policies. This review paper highlights the harmful impacts of fossil-based plastic on the environment and human health, as well as the mass need for eco-friendly alternatives such as biodegradable bioplastics. Utilizing new types of bioplastics derived from renewable resources (e.g., biowastes, agricultural wastes, or microalgae) and choosing the appropriate end-of-life option (e.g., anaerobic digestion) may be the right direction to ensure the sustainability of bioplastic production. Clear regulation and financial incentives are still required to scale from niche polymers to large-scale bioplastic market applications with a truly sustainable impact.

Synthesis and Characterization of Poly(DL-lactide) Containing Fluorene Structures

9,9-bis[4-(2-hydroxy-3-acryloyloxypropoxy)phenyl]fluorene (BPF) hydroxyl groups (-OH) were used as initiators in the ring-opening polymerization reaction with DL-lactide monomers at different molar ratios to synthesize a Poly(DL-lactide) polymer containing bisphenol fluorene structure and acrylate functional groups (DL-BPF). The polymer's structure and molecular weight range were analyzed using NMR (¹H, ¹³C) and gel permeation chromatography. DL-BPF was then subjected to photocrosslinking using the photoinitiator Omnirad 1173, resulting in the formation of an optically transparent crosslinked polymer. Characterization of the crosslinked polymer involved analyzing its gel content, refractive index, thermal stability (via differential scanning thermometry (DSC) and thermogravimetric analysis (TGA)), as well as conducting cytotoxicity tests. The crosslinked copolymer exhibited a maximum refractive index of 1.5276, a maximum glass transition temperature of 61.1 °C, and cell survival rates higher than 83% in the cytotoxicity tests.

Thiophene End-Functionalized Oligo-(D,L-Lactide) as a New Electroactive Macromonomer for the "Hairy-Rod" Type Conjugated Polymers Synthesis

The development of the modern society imposes a fast-growing demand for new advanced functional polymer materials. To this aim, one of the most plausible current methodologies is the end-group functionalization of existing conventional polymers. If the end functional group is able to polymerize, this method enables the synthesis of a molecularly complex, grafted architecture that opens the access to a wider range of material properties, as well as tailoring the special functions required for certain applications. In this context, the present paper reports on α-thienyl-ω-hydroxyl-end-groups functionalized oligo-(D,L-lactide) (Th-PDLLA), which was designed to combine the polymerizability and photophysical properties of thiophene with the biocompatibility and biodegradability of poly-(D,L-lactide). Th-PDLLA was synthesized using the path of "functional initiator" in the ring-opening polymerization (ROP) of (D,L)-lactide, assisted by stannous 2-ethyl hexanoate (Sn(oct)₂). The results of NMR and FT-IR spectroscopic methods confirmed the Th-PDLLA's expected structure, while the oligomeric nature of Th-PDLLA, as resulting from the calculations based on ¹H-NMR data, is supported by the findings from gel permeation chromatography (GPC) and by the results of the thermal analyses. The behavior of Th-PDLLA in different organic solvents, evaluated by UV-vis and fluorescence spectroscopy, but also by dynamic light scattering (DLS), suggested the presence of colloidal supramolecular structures, underlining the nature of the macromonomer Th-PDLLA as an "shape amphiphile". To test its functionality, the ability of Th-PDLLA to work as a building block for the synthesis of molecular composites was demonstrated by photoinduced oxidative homopolymerization in the presence of diphenyliodonium salt (DPI). The occurrence of a polymerization process, with the formation of a thiophene-conjugated oligomeric main chain grafted with oligomeric PDLLA, was proven, in addition to the visual changes, by the results of GPC, ¹H-NMR, FT-IR, UV-vis and fluorescence measurements.

Surface grafting of sericin onto thermoplastic polyurethanes to improve cell adhesion and function

Thermoplastic polyurethane (TPU) membrane has super physical-mechanical properties and biocompatibility, but the surface is inert and lack of active groups which limit its application in cell culture. Silk sericin (SS) can improve cell adhesion, proliferation, growth and metabolism. In this paper, SS was grafted onto the surface of TPU membrane by -NH₂ bridge to build a high efficiency cell culture membrane. The FT-IR spectrum results indicated SS was grafted by chemical bond. According to the SEM and AFM results, we found that the grafting of SS reduced the water contact angle by 43.31% and increased the surface roughness by about four times. When TPU-SS was used for HepG2 cell culture, the cell adhesion rate of TPU-SS was significantly higher than that of the general TCPS cell culture plate, and the cell proliferation rate was close to that of TCPS. FDA/EB staining showed that HepG2 cells remained a better cellular growth behavior. HepG2 cells had higher cell vitality including the albumin secretion and the intracellular total protein synthesis. Grafting SS maintained the stability of cell and significantly decreased the cytotoxicity by decreased LDH release. In conclusion, SS grafting is beneficial to cell culture in vitro, and provides a key material for bioartificial liver culture system.

A comprehensive review on fused deposition modelling of polylactic acid

Fused Deposition Modelling (FDM) is one of the additive manufacturing (AM) techniques that have emerged as the most feasible and prevalent approach for generating functional parts due to its ability to produce neat and intricate parts. FDM mainly utilises one of the widely used polymers, polylactic acid, also known as polylactide (PLA). It is an aliphatic polyester material and biocompatible thermoplastic, with the best design prospects due to its eco-friendly properties; when PLA degrades, it breaks down into water and carbon dioxide, neither of which are hazardous to the environment. However, PLA has its limitations of poor mechanical properties. Therefore, a filler reinforcement may enhance the characteristics of PLA and produce higher-quality FDM-printed parts. The processing parameters also play a significant role in the final result of the printed parts. This review aims to study and discover the properties of PLA and the optimum processing parameters. This review covers PLA in FDM, encompassing its mechanical properties, processing parameters, characterisation, and applications. A comprehensive description of FDM processing parameters is outlined as it plays a vital role in determining the quality of a printed product. In addition, PLA polymer is highly desirable for various field industrial applications such as in a medical, automobile, and electronic, given its excellent thermoplastic and biodegradability properties.

Evaluating the Performance of 3D-Printed PLA Reinforced with Date Pit Particles for Its Suitability as an Acetabular Liner in Artificial Hip Joints

Off-the-shelf hip joints are considered essential parts in rehabilitation medicine that can help the disabled. However, the failure of the materials used in such joints can cause individual discomfort. In support of the various motor conditions of the influenced individuals, the aim of the current research is to develop a new composite that can be used as an acetabular liner inside the hip joint. Polylactic acid (PLA) can provide the advantage of design flexibility owing to its well-known applicability as a 3D printed material. However, using PLA as an acetabular liner is subject to limitations concerning mechanical properties. We developed a complete production process of a natural filler, i.e., date pits. Then, the PLA and date pit particles were extruded for homogenous mixing, producing a composite filament that can be used in 3D printing. Date pit particles with loading fractions of 0, 2, 4, 6, 8, and 10 wt.% are dispersed in the PLA. The thermal, physical, and mechanical properties of the PLA–date pit composites were estimated experimentally. The incorporation of date pit particles into PLA enhanced the compressive strength and stiffness but resulted in a reduction in the elongation and toughness. A finite element model (FEM) for hip joints was constructed, and the contact stresses on the surface of the acetabular liner were evaluated. The FEM results showed an enhancement in the composite load carrying capacity, in agreement with the experimental results.