Biodegradable Polymeric Materials Research Articles

Modification of Polyhydroxyalkanoates Polymer Films Surface of Various Compositions by Laser Processing.

The results of surface modification of solvent casting films made from polyhydroxyalkanoates (PHAs) of various compositions are presented: homopolymer poly-3-hydroxybutyrate P(3HB) and copolymers comprising various combinations of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 4-hydroxybutyrate(4HB), and 3-hydroxyhexanoate (3HHx) monomers treated with a CO2 laser in continuous and quasi-pulsed radiation modes. The effects of PHAs film surface modification, depending on the composition and ratio of monomers according to the results of the study of SEM and AFM, contact angles of wetting with water, adhesion and growth of fibroblasts have been revealed for the laser radiation regime used. Under continuous irradiation with vector lines, melted regions in the form of grooves are formed on the surface of the films, in which most of the samples have increased values of the contact angle and a decrease in roughness. The quasi-pulse mode by the raster method causes the formation of holes without pronounced melted zones, the total area of which is lower by 20% compared to the area of melted grooves. The number of viable fibroblasts NIH 3T3 on the films after the quasi-pulse mode is 1.5-2.0 times higher compared to the continuous mode, and depends to a greater extent on the laser treatment mode than on the PHAs' composition. The use of various modes of laser modification on the surface of PHAs with different compositions makes it possible to influence the morphology and properties of polymer films in a targeted manner. The results that have been obtained contribute to solving the critical issue of functional biodegradable polymeric materials.

Electrospun silk fibroin/polyethylene oxide composite scaffolds with strontium or copper-doped hollow bioactive glass nanospheres for pH-triggered sustained drug release

Organic/inorganic hybrid biomaterials based on polymeric nano-composites constructed from mixture of biodegradable polymeric matrices and bioactive inorganic substrates have been highly attractive owing to their efficient tissue engineering applications. Herein we reported, for the first time, electrospun silk fibroin/polyethylene oxide (SF/PEO) scaffolds incorporated with appropriate strontium or copper-doped hollow bioactive glass nanospheres (Sr/Cu-HBGNs) loading with vancomycin hydrochloride (VAN) were prepared and their use as pH-sensitive drug nano-carriers to extend the duration of drug release were reported as well. In addition, the excellent apatite-formation ability of Sr/Cu-introduced nanocomposites improved the bioactivity of the related scaffolds.

CHARACTERIZATION OF BICOMPONENT 3D PRINTING TECHNOLOGIES OF BIODEGRADABLE MATERIALS

Reducing the effect of human activities on the environment, natural resources and public health has become one of the essential concerns of researchers around the world. Biodegradable materials are suitable alternatives to petrochemical-derived materials and have essential roles in environmental protection due to reduced use of fossil-based raw materials and decreased carbon dioxide emissions. Therefore, there is a growing interest in biodegradable materials, which degrade faster than conventional materials. The current study aims to analyze the use of biodegradable polymer materials in Additive Manufacturing, through bi-component 3D printing. In Additive Manufacturing-AM, parts are manufactured layer by layer with minimal allocation for finishing operations. Because AM enables greater material savings than traditional processes, 3D printing can be considered a distributed manufacturing technology to improve sustainability and the circular economy worldwide.

Aliphatic polycarbonate-based hydrogel dressing for wound healing

In addition to various functions, hydrogels used to promote wound healing should also have good biocompatibility, stability and mild degradability. Therefore, we designed and synthesized aldehyde modified aliphatic cyclic carbonate monomer (MTC-Ba). Then the hydrogel matrix (MTC-Ban-b-PEG6k-b-MTC-Ban, MBP) was prepared by ring opening polymerization using polyethylene glycol (PEG) as the initiator and hydrophilicity enhancer. The matrix was covalently linked with the crosslinker adipic acid dihydrazide (ADH) through dynamic hydrazide bond to form a self-healing hydrogel (SH-Gel). At the same time, curcumin was loaded into the hydrogel as a functional model drug. The resulting hydrogel has porosity, injectability, appropriate swelling rate, friendly cell compatibility and safe degradability. In addition, in vivo wound healing evaluation, histological evaluation and immunofluorescence staining showed that this gel could the wound closure, re-epithelium and collagen regeneration. In conclusion, this study provides a new choice for the application of synthetic biodegradable polymer materials in promoting skin wound healing.

Therapy of Extensive Chronic Skin Defects after a Traumatic Injury Due to Microbial Contamination Using a Surface Implant Made of a Biocompatible Polycaprolactone—A Pilot Case Study

This case study describes the use of additive manufacturing technology combining a biodegradable polymer material, polycaprolactone (PCL), and innovative procedures for creating superficial wound dressing, a scaffold in the therapy of extensive contaminated skin defects caused by a traumatic injury. Chronic and contaminated wounds represent a clinical problem and require intensive wound care. The application of a temporary scaffold-facilitated bridging of the wound edges resulted in faster tissue regeneration and a shorter defect closure time, compared to other conservative and surgical methods used in therapy of chronic wounds. Although this procedure has proven to be an optimal alternative to autologous transplants, further studies with a larger number of patients would be beneficial.

Electrospinning vs. Electro-Assisted Solution Blow Spinning for Fabrication of Fibrous Scaffolds for Tissue Engineering

Biodegradable polymeric fibrous non-woven materials are widely used type of scaffolds for tissue engineering. Their morphology and properties could be controlled by composition and fabrication technology. This work is aimed at development of fibrous scaffolds from a multicomponent polymeric system containing biodegradable synthetic (polylactide, polycaprolactone) and natural (gelatin, chitosan) components using different methods of non-woven mats fabrication: electrospinning and electro-assisted solution blow spinning. The effect of the fabrication technique of the fibrous materials onto their morphology and properties, including the ability to support adhesion and growth of cells, was evaluated. The mats fabricated using electrospinning technology consist of randomly oriented monofilament fibers, while application of solution blow spinning gave a rise to chaotically arranged multifilament fibers. Cytocompatibility of all fabricated fibrous mats was confirmed using in vitro analysis of metabolic activity, proliferative capacity and morphology of NIH 3T3 cell line. Live/Dead assay revealed the formation of the highest number of cell-cell contacts in the case of multifilament sample formed by electro-assisted solution blow spinning technology.

Chitosan/starch beads as bioinoculants carrier: long-term survival of bacteria and plant growth promotion.

Immobilization of microorganisms in biodegradable polymeric matrices constitutes a promising technology for plant growth promoting to overcome the challenging conditions of the rhizosphere. Previously, we demonstrated that beads prepared from blends of chitosan/starch of analytical grades ionically cross-linked are useful carriers for Azospirillum brasilense and Pseudomonas fluorescens. The aims of this work were to study A. brasilense Az39 and P. fluorescens ZME4 immobilization in industrial quality beads produced with a blend of chitosan/starch, to assess bacterial survival during long-term storage and biofilm distribution in the beads. We also proposed to analyze the consortia root colonization and its performance as plant growth-promoting bioinoculants compared to liquid counterpart. Our results revealed that A. brasilense Az39 and P. fluorescens ZME4 can coexist in industrial grade chitosan/starch beads, and this mixed immobilization benefits the survival rates of both species, even for more than a year under shelf storage. Confocal laser scanning microscopy with fluorescent dyed strains showed that both species remain mainly in different locations inside and over the beads. Additionally, maize seed treatment with beads-loaded bacteria resulted in growth promotion of roots in a similar manner than traditional liquid-based inoculation. The evidence collected here demonstrate that low-cost chitosan/starch beads are a suitable carrier for bacteria consortia and could be a reliable alternative to liquid inoculation in agronomic practices with additional benefits for industrial management. KEY POINTS: • Mixed immobilization increases bacterial survival in chitosan/starch industrial beads • Beads increase competence of bacteria in rhizosphere of maize • Inoculation mediated by beads promotes plant growth of maize.

Structure–mechanics relationship of hybrid polyvinyl alcohol-collagen composite by molecular dynamics simulations

Polyvinyl alcohol (PVA) is a water-soluble synthetic polymer that can be used to make hydrogels for biomedical applications as well as biodegradable bags and films; however, compared to other plastics currently used for containers, it lacks mechanical strength, thermal stability, and can easily absorb water from humid environments. Although mechanical improvement has been observed by blending PVA with collagen in a hybrid hydrogel, there is a lack of fundamental understanding of the molecular mechanism, and it is not clear whether the improvement is limited to a hydrated state. Here, using classical molecular dynamics simulations based on fully atomistic models, we develop the equilibrated molecular structure of PVA with collagen and characterize its mechanics. We show that by interacting with a collagen molecule, PVA is equilibrated to a more ordered structure with each residue interacting with the near neighbors by forming more hydrogen bonds locally, making the structure stiffer than pure PVA. The structure shows higher thermal stability before melting, as well as higher rigidity in water. Our results provide the mechanism of the mechanical advantages of hybrid PVA-collagen polymer. The study demonstrates that the structure and mechanics of a synthetic polymer can be tuned by a tiny amount of a natural polymer at the molecular interface. Moreover, it may shed light on identifying a way to improve the mechanics of biodegradable polymer materials without adding much cost, which is crucial for environmental safety.Impact statementBlending natural and synthetic polymers (e.g., polyvinyl alcohol [PVA] and collagen in a hybrid hydrogel) has shown advantages in polymer mechanics, but there is a lack of fundamental understanding. Using molecular dynamics (MD) simulations based on fully atomistic models, we develop the equilibrated structure of the PVA with collagen and characterize its mechanics. We show that by interacting with a collagen molecule, PVA is equilibrated to a more ordered structure with each residue interacting with the near neighbors by forming more H-bonds locally and the structure is stiffer than pure PVA. Moreover, the structure shows a higher thermal stability before the melting point of PVA, as well as higher rigidity in water. Our results demonstrate that the structure and mechanics of a synthetic polymer can be tuned by a tiny amount of a natural polymer at the molecular interface. It provides the mechanism of the mechanical advantages as experimentally observed. This study paves the way for the multiscale modeling and mechanical design of the hybrid polymer material. It sheds light on identifying a way to improve the mechanics of biodegradable materials without adding much cost for both material functionality and environmental safety.Graphical abstract

Development of high strength potato starch nanocomposite films with excellent UV-blocking performance: Effect of heat moisture treatment synergistic with ligninsulfonic acid

The preparation biodegradable polymeric materials with both high strength and toughness remain elusive. In this thesis, potato starch (PS) nanocomposite films were fabricated through heat moisture treatment (HMT) synergistic with lignosulfonic acid (LA) nanoparticles (HMT-PS/LA). The results of mechanical properties indicated the optimal heat moisture treatment conditions and LA content were 110 ℃, 25% and 7 wt%, respectively. The fabricated HMT-PS/LA nanocomposite films exhibited a high tensile strength (TS) of 53.6 ± 1.6 MPa and a large elongation at break (E%) of 80.25 ± 2.9%, respectively, which were 1478% and 43.6% higher than those of PS film. In addition, the water content (WC) and water vapor permeability (WVP) of the HMT-PS/LA film decreased by 28% and 47.23%, respectively. Moreover, the HMT-PS/LA film presented superior UV-blocking performance and good biodegradability in four normal environments. Thus, this paper provided an innovative design strategy to obtain an outstanding polymer material with integrated strength and toughness.

Antimicrobial Biodegradable Polymeric Materials for Food Packaging Applications: Current Status and Future Directions

The production and consumption of non-biodegradable, petroleum-based plastics had an enormous increase in the past few years. Majority of these are used for food packaging. Biodegradable plastics receive much more attraction because they undergo complete degradation without forming any toxic compounds. Nowadays spoilage of food is the main concern faced by food industry. As microbial activity on food surface is the main reason for food spoilage, the integration of antimicrobial agents in biodegradable polymers or the use of biopolymers with inherent antimicrobial property could improve its shelf life. Current review summarizes major findings in the field of antimicrobial polymers, polymer/antimicrobial inorganic composites and polymer/essential oil blends for food packaging applications. India is home to large number of plants having antimicrobial properties. This review also highlights different methods for synthesis of efficient antimicrobial polymer films from these plants in a cost-effective way.

The impact of thermomechanical and chemical treatment of waste Brewers’ spent grain and soil biodegradation of sustainable Mater-Bi-Based biocomposites

Due to the massive plastic pollution, development of sustainable and biodegradable polymer materials is crucial to reduce environmental burdens and support climate neutrality. Application of lignocellulosic wastes as fillers for polymer composites was broadly reported, but analysis of biodegradation behavior of resulting biocomposites was rarely examined. Herein, sustainable Mater-Bi-based biocomposites filled with thermomechanically- and chemically-modified brewers’ spent grain (BSG) were prepared and subjected to 12-week soil burial test simulating their biodegradation in natural environment. BSG stabilizing effect on polymer matrix affected by the content of melanoidins and antioxidant phytochemicals, along with the impact of diisocyanate applied to strengthen the interfacial adhesion. Biocomposites showed 25–35 wt% mass loss over 12 weeks resulting from swelling of BSG filler and sample microcracking, which increased surface roughness by 247–448 %. The degree of decomposition was partially reduced by BSG modifications pointing to the stabilizing effect of melanoidins and phytochemicals, and enhanced interfacial adhesion. Soil burial-induced structural changes enhanced biocomposites’ thermal stability determined by thermogravimetric analysis shifting decomposition onset by 14.4–32.0 °C due to the biodegradation of lower molecular weight starch macromolecules confirmed by differential scanning calorimetry. For unfilled Mater-Bi, it caused an average 32 % reduction in complex viscosity and storage modulus captured by oscillatory rheological measurements. Nonetheless, the inverse effect was noted for biocomposites where modulus increased even by one order of magnitude due to the swelling of BSG particles and amorphous phase decomposition. Presented results indicate that BSG promotes soil degradation of Mater-Bi and its rate can be engineered by biofiller treatment elaboration.

Enhanced antitumor effect of doxorubicin through active-targeted nanoparticles in doxorubicin-resistant triple-negative breast cancer

Breast cancer is the most common cancer in women worldwide, and the incidence and mortality rates have been increasing. Chemotherapy remains the main treatment strategy for triple-negative breast cancer (TNBC). However, multidrug resistance often affects the efficiency of chemotherapy and is the main reason for the failure of current clinical cancer treatments in patients with TNBC. Therefore, we developed a nanocarrier with biodegradable polymer materials and encapsulated a clinical chemotherapeutic drug to form an active targeting nanoparticle drug delivery system. In this study, the biopolymers fucoidan (FD) and arginine-gelatin (Arg-GL) were used to synthesize nanoparticles through electrostatic forces and to encapsulate the chemotherapeutic drug doxorubicin (Dox). Our study demonstrated that the Dox-loaded FD/Arg-GL nanoparticles exhibited high drug loading capacity and pH-responsive characteristics. The results of in vitro experiments showed that the nanoparticles actively targeted P-selectin expressed by cancer cells, thereby enhancing the anticancer effect and inhibiting the migration and invasion of Dox-resistant TNBC cells. Moreover, in vivo studies further confirmed the antitumor activity of the nanoparticles, as they enabled the drug to accumulate at the tumor site. In conclusion, Dox-loaded FD/Arg-GL nanoparticles offer a potential therapeutic strategy for drug-resistant TNBC.

Strength Characteristics of Electrospun Coconut Fibre Reinforced Polylactic Acid: Experimental and Representative Volume Element (RVE) Prediction.

Environmental conservation and waste control have informed and encouraged the use of biodegradable polymeric materials over synthetic non-biodegradable materials. It has been recognized that nano-sized biodegradable materials possess relatively good properties as compared to conventional micron-sized materials. However, the strength characteristics of these materials are inferior to fossil-based non-biodegradable materials. In this study, biodegradable polylactide (PLA), reinforced with treated coconut husk particulates (CCP) for improved mechanical properties, was fabricated using an electrospinning process and representative volume element (RVE) technique, and some of the obtained mechanical properties were compared. It was observed that the electrospun CCP-PLA nanofibre composites show improved mechanical properties, and some of these mechanical properties using both techniques compared favourably well. The electrospun fibres demonstrate superior properties, mostly at 4 wt.% reinforcement. Thus, achieving good mechanical properties utilising agro waste as reinforcement in PLA to manufacture nanocomposite materials by electrospinning method is feasible and provides insight into the development of biodegradable nanocomposite materials.

Sustainable Fiber‐Reinforced Composites: A Review

AbstractSustainable fiber reinforced polymer (FRP) composites from renewable and biodegradable fibrous materials and polymer matrices are of great interest, as they can potentially reduce environmental impacts. However, the overall properties of such composites are still far from the high‐performance conventional glass or carbon FRP composites. Therefore, a balance between composite performance and biodegradability is required with approaches to what one might call an eco‐friendly composite. This review provides an overview of sustainable FRP composites, their manufacturing techniques, and sustainability in general at materials, manufacturing, and end‐of‐life levels. Sustainable plant‐based natural fibers and polymer matrices are also summarized, followed by an overview of their modification techniques to obtain high‐performance, multifunctional, and sustainable FRP composites. Current state‐of‐the‐art mechanical and functional properties of such composites are then surveyed, and an overview of their potential applications in various industries, including automobile, aerospace, construction, medical, sports, and electronics is provided. Finally, future market trends, current challenges, and the future perspective on sustainable natural FRP composites are discussed.

One-step fabrication of self-healing poly(thioctic acid) coatings on ZE21B Mg alloys for enhancing corrosion resistance, anti-bacterial/oxidation, hemocompatibility and promoting re-endothelialization

Coating magnesium (Mg) alloy stents with biodegradable polymeric materials can address the problems of thrombosis, inflammation, and restenosis caused by poor corrosion resistance and delayed endothelialization; however, these commonly used polymer coatings and their degradation products have no therapeutic effect and sometimes bring extra-side effects. Herein, to develop a polymeric coating with an additional therapeutic effect from that of the polymer itself, a poly(thioctic acid)-based homopolymer was simply synthesized via solvent-free thermal polymerization (containing Zn2+ ions) of thioctic acid (TA), a bioactive ingredient originating from the human body. A Poly(TA-Zn) coating was fabricated on alkali-heat (Mg(OH)2) treated ZE21B alloys via a one-step method, followed by conjugating REDV peptides, to simultaneously enhance the corrosion resistance and re-endothelialization process. Surface characterization and performance were comprehensively investigated. Molecular dynamics (MD) simulations demonstrate that the Zn-O coordination bonds formed between Zn2+ ions and carboxylic groups can inhibit the depolymerization of the Poly(TA-Zn) polymer. SEM micrographs show that the Poly(TA-Zn) coating is homogeneous and has a thickness of 45.03 ± 4.85 μm, and this coating is sturdily bonded to the Mg(OH)2 modified ZE21B substrate. Electrochemical and immersion tests show that the Poly(TA-Zn) sample provides good corrosion protection for ZE21B substrates because of its excellent self-healing properties, and it exhibits superior anti-bacterial/oxidation properties. After immobilizing REDV peptides, Poly(TA-Zn)-REDV samples can substantially hinder platelet adhesion/activation, reduce hemolysis rate, selectively promote the proliferation of endothelial cells and inhibit the growth of smooth muscle cells, thereby improving the anti-coagulation and re-endothelialization ability of Mg substrates.

A Review: Sustainable development of Biodegradable Polymer Material

A Review: Sustainable development of Biodegradable Polymer Material

Synthesis, characterization, thermal stability, and in vitro and in vivo degradation study of polycaprolactone and polyglycolide block copolymers

Biodegradable polymer materials are attractive in various biomedical applications. Herein, we report a block aliphatic copolymer, polycaprolactone-block-polyglycolide (PCL-b-PGA, denoted as PCLGA), and explored the polymer composition effect on the thermal and degradation behaviors. Three copolymers with different PCL/PGA weight ratios were obtained by a two-step ring opening polymerization. The chemical structures and compositions of copolymers were studied by NMR and FT-IR. The thermal behaviors were investigated by DSC and TGA. The in vitro degradation in phosphate buffer saline and in vivo degradation as an implant in rats were evaluated and the hygroscopic rate and polymer weight loss changes were monitored in an eight-week period. PCLGA with a higher PCL composition showed a slower degradation in vitro and in vivo. These PCLGAs with different degradation rates could be used as biomedical implants for potential application in drug delivery and tissue repair.

Electrospun Polylactic Acid-Based Fibers Loaded with Multifunctional Antibacterial Biobased Polymers.

Here, we report the development of antibacterial and compostable electrospun polylactic acid (PLA) fibers by incorporation of a multifunctional biobased polymer in the process. The multifunctional polymer was synthesized from the bio-sourced itaconic acid building block by radical polymerization followed by click chemistry reaction with hydantoin groups. The resulting polymer possesses triazole and hydantoin groups available for further N-alkylation and chlorination reaction, which provide antibacterial activity. This polymer was added to the electrospinning PLA solution at 10 wt %, and fiber mats were successfully prepared. The obtained fibers were surface-modified through the accessible functional groups, leading to the corresponding cationic triazolium and N-halamine groups. The fibers with both antibacterial functionalities demonstrated high antibacterial activity against Gram-positive and Gram-negative bacteria. While the fibers with cationic surface groups are only effective against Gram-positive bacteria (Staphylococcus epidermidis and Staphylococcus aureus), upon chlorination, the activity against Gram-negative Escherichia coli and Pseudomonas aeruginosa is significantly improved. In addition, the compostability of the electrospun fibers was tested under industrial composting conditions, showing that the incorporation of the antibacterial polymer does not impede the disintegrability of the material. Overall, this study demonstrates the feasibility of this biobased multifunctional polymer as an antibacterial agent for biodegradable polymeric materials with potential application in medical uses.

Modifying Anti-Compression Property and Water-Soluble Ability of Polyglycolic Acid via Melt Blending with Polyvinyl Alcohol.

Biodegradable polymeric materials have become the most attractive research interest in recent years and are gradually widely used in various fields in the case of environmental pollution. In this paper, binary blends, mainly including varying contents of polyglycolic acid (PGA) and poly(vinyl alcohol) (PVA), were prepared via a melt compounding strategy. The ethylene-methyl acrylate-glycidyl methacrylate (EMA-GMA) was employed as the compatibilizer to improve the compatibility between the PGA and PVA and the polyolefin elastomer (POE) was used as toughening agent. The anti-compression property and water-soluble ability of the blends were particularly studied to explore their potential application in an oil/gas exploitation field. Special attentions were paid to the evolution of the water-soluble ability of PGAX with the PVA concentration. Furthermore, isothermal shear measurement and thermogravimetric analysis were performed to evaluate the thermal stability of PGA and PGA blends (PGAX) during melt processing. The results showed that the incompatibility between PGA and PVA largely deteriorated the mechanical property, i.e., anti-compression strength, leading to fragile characteristics under a lower compressive load for the PGAX samples with varied contents of PVA. The presence of PVA and EMA-GMA greatly enhanced the viscoelasticity of the PGA melt, showing an increased storage modulus and viscosity at a low shear frequency; however, the thermal instability of PGAX was intensified owing to the greater ease of thermal degradation of PVA than that of PGA. Meanwhile, the water-soluble ability of PGAX was improved due to the high water dissolution of PVA, which played the role as a sacrificial material. The purpose of this work is to pursue an effective modification for PGA processing and application via melt blending.

Thiol-Based Three-Dimensional Printing of Fully Degradable Poly(propylene fumarate) Star Polymers.

Poly(propylene fumarate) star polymers photochemically 3D printed with degradable thiol cross-linkers yielded highly tunable biodegradable polymeric materials. Tailoring the alkene:thiol ratio (5:1, 10:1, 20:1 and 30:1) and thus the cross-link density within the PPF star systems yielded a wide variation of both the mechanical and degradation properties of the printed materials. Fundamental trends were established between the polymer network cross-link density, glass transition temperature, and tensile and thermomechanical properties of the materials. The tensile properties of the PPF star-based systems were compared to commercial state-of-the-art non-degradable polymer resins. The thiolene-cross-linked materials are fully degradable and possess properties over a wide range of mechanical properties relevant to regenerative medicine applications.