Synthetic Biodegradable Polymers Research Articles

Electrospun polycaprolactone/graphene oxide scaffolds with secondary surface porosity and gelatin-coating

Polycaprolactone (PCL) is a versatile and biodegradable synthetic polymer widely used in tissue regeneration applications owing to its versatility and mechanical properties. In this study, we employed a three-level strategy to develop innovative PCL-based scaffold biomaterials using electrospinning. First, we incorporated graphene oxide (GO); second, we introduced secondary surface porosity (SSP) through non-solvent induced phase separation (NIPS) with a diameter of approximately 2 um; and third, we applied a gelatin coating (Gt). The inclusion of GO resulted in both a reduction in fiber size and a decrease in the size of the secondary surface pores formed on the fibers. Additionally, the incorporation of GO led to a noteworthy 20-fold increase in gelatin adhesion compared to pure SSP-PCL scaffolds. However, the mechanical properties of the gelatin-coated scaffolds exhibited a decrease compared to the uncoated scaffolds. This reduction is primarily attributed to the decrease in crystallinity in coating gelatin scaffold. Furthermore, GO and gelatin played critical roles in enhancing biodegradation and bioactivity, promoting hydroxyapatite formation on the surface of SSP-PCL scaffolds. In vitro cell viability tests demonstrated the cytocompatibility of PCL, PCL/Gt, and PCL/Gt/GO electrospun SSP scaffolds, facilitating the adhesion of human mesenchymal stem cells. Our study introduces an innovative strategy for fabricating PCL scaffolds through electrospinning, incorporating SSP for improved gelatin adsorption, and holds great promise for tissue engineering applications.

A Technical Note: on Microspheres

Microspheres have become a center of research. Microspheres are an excellent way to deliver drugs to specific sites and control their effects. They are characterized by free-flowing spheres composed of biodegradable or non-biodegradable proteins or synthetic polymers, with an ideal particle size of 1-1000 microns. Microspheres encapsulate active pharmaceutical ingredients (APIs) in a polymer matrix that protects the API from environmental degradation. Pharmacokinetic limitations can be overcome by modifying the formulation to release the drug slowly during prolonged action. The purpose of this review is to list the different types of microspheres, their different preparations, limitations, advantages and disadvantages, characterization, applications, and recent developments in microspheres and various compatibility studies.

Bone-Regeneration Therapy Using Biodegradable Scaffolds: Calcium Phosphate Bioceramics and Biodegradable Polymers.

Calcium phosphate-based synthetic bone is broadly used for the clinical treatment of bone defects caused by trauma and bone tumors. Synthetic bone is easy to use; however, its effects depend on the size and location of the bone defect. Many alternative treatment options are available, such as joint arthroplasty, autologous bone grafting, and allogeneic bone grafting. Although various biodegradable polymers are also being developed as synthetic bone material in scaffolds for regenerative medicine, the clinical application of commercial synthetic bone products with comparable performance to that of calcium phosphate bioceramics have yet to be realized. This review discusses the status quo of bone-regeneration therapy using artificial bone composed of calcium phosphate bioceramics such as β-tricalcium phosphate (βTCP), carbonate apatite, and hydroxyapatite (HA), in addition to the recent use of calcium phosphate bioceramics, biodegradable polymers, and their composites. New research has introduced potential materials such as octacalcium phosphate (OCP), biologically derived polymers, and synthetic biodegradable polymers. The performance of artificial bone is intricately related to conditions such as the intrinsic material, degradability, composite materials, manufacturing method, structure, and signaling molecules such as growth factors and cells. The development of new scaffold materials may offer more efficient bone regeneration.

Development and Evaluation of Biodegradable Core-Shell Microfibrous and Nanofibrous Scaffolds for Tissue Engineering Applications

Tissue engineering scaffolds as three-dimensional substrates may serve as ideal templates for tissue regeneration by simulating the structure of the extracellular matrix (ECM). Many biodegradable synthetic polymers, either hydrophobic, like Poly-ε-caprolactone (PCL), or hydrophilic, like Poly(Vinyl Alcohol) (PVA), are widely used as candidate bioactive materials for fabricating tissue engineering scaffolds. However, a combination of good cytocompatibility of hydrophilic polymers with good biomechanical performance of hydrophobic polymers could be beneficial for the in vivo performance of the scaffolds. In this study, we aimed to fabricate biodegradable fibrous scaffolds by combining the properties of hydrophobic PCL with those of hydrophilic PVA and evaluate their properties in comparison with pristine PCL scaffolds. Therefore, single-layered PCL scaffolds, sequential tri-layered (PVA/PCL/PVA), and core-shell (PVA as shell and PCL as core) composite scaffolds were developed utilizing the electrospinning technique. The material structural and biomechanical properties of the electrospun scaffolds, before and after their hydrolytic degradation over a seven-month period following storage in phosphate-buffered saline (PBS) at 37 °C, were comprehensively compared. In addition, human embryonic kidney cells (HEK-293) were cultured on the scaffolds to investigate potential cell attachment, infiltration, and proliferation. The results demonstrated the long-term efficacy of core-shell biodegradable fibrous scaffolds in comparison to single-layers PCL and tri-layers PVA/PCL/PVA, not only due to its superior morphological characteristics and mechanical properties, but also due to its ability to promote homogeneous cell distribution and proliferation, without any external chemical or physical stimuli.Graphical

An efficient and eco-friendly approach for the sustainable recovery and properties characterization of polyhydroxyalkanoates produced by methanotrophs

Synthetic biodegradable and bio-based polymers have emerged as sustainable alternatives to nonrenewable petroleum-derived polymers which cause serious environmental issues. In particular, polyhydroxyalkanoates (PHA) are promising biopolymers owing to their outstanding biodegradability and biocompatibility. The production of the homopolymer poly(3-hydroxybutyrate) (PHB) and copolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) from type II methanotrophs via microbial fermentation was presented. For the efficient extraction and recovery of intracellular PHA from methanotrophs, different extraction approaches were investigated including solvent extraction using 1,3-dioxolane as a green solvent, integrated cell lysis and solvent extraction, and cell digestion without the use of organic solvents. Among various extraction approaches, the integrated method exhibited the highest extraction performance, with PHA recovery and purity exceeding 91 % and 93 %, respectively, even when the PHA content of the cells was low. Furthermore, the molecular weight, thermal stability, and mechanical properties of the recovered PHA were comprehensively analyzed to suggest its suitable practical applications. The obtained properties were comparable to that of the commercial PHA products and PHA produced from other microbial species, indicating an efficient recovery of high-quality PHA produced from methanotrophs.

Enabling Proregenerative Medical Devices via Citrate-Based Biomaterials: Transitioning from Inert to Regenerative Biomaterials.

Regenerative medicine aims to restore tissue and organ function without the use of prosthetics and permanent implants. However, achieving this goal has been elusive, and the field remains mostly an academic discipline with few products widely used in clinical practice. From a materials science perspective, barriers include the lack of proregenerative biomaterials, a complex regulatory process to demonstrate safety and efficacy, and user adoption challenges. Although biomaterials, particularly biodegradable polymers, can play a major role in regenerative medicine, their suboptimal mechanical and degradation properties often limit their use, and they do not support inherent biological processes that facilitate tissue regeneration. As of 2020, nine synthetic biodegradable polymers used in medical devices are cleared or approved for use in the United States of America. Despite the limitations in the design, production, and marketing of these devices, this small number of biodegradable polymers has dominated the resorbable medical device market for the past 50 years. This perspective will review the history and applications of biodegradable polymers used in medical devices, highlight the need and requirements for regenerative biomaterials, and discuss the path behind the recent successful introduction of citrate-based biomaterials for manufacturing innovative medical products aimed at improving the outcome of musculoskeletal surgeries.

Achieving ultrasensitivity and high breathability in biodegradable piezoresistive electronic skins

Nonbiodegradable components, such as synthetic polymers, have been widely used in the fabrication of flexible piezoresistive sensors and electronic skins (e-skins), resulting in the generation of electronic waste (e-waste) and toxic by-products. To overcome this issue, a wide range of biodegradable natural biopolymers and synthetic polymers have been employed. However, most of the current biodegradable e-skins demonstrate limitations such as low sensitivity, poor electrical conductivity, limited breathability, and low stability. To address these limitations, this study proposes a highly breathable and ultrasensitive piezoresistive e-skin based on the oxidized single-walled carbon nanotube (Ox-SWCNT)/silver nanowire (AgNW)-coated leaf skeletons. The developed disposable piezoresistive e-skin exhibits a remarkable performance including high sensitivity (19.75 ± 1.5 kPa−1, <3 kPa), sensing range of ≤42 kPa, ultralow limit of detection (∼0.27 Pa), linearity for low- and high-pressure regimes, high flexibility, high stability (3000 cycles), low weight, ultrahigh breathability, and biodegradability. In addition, the developed leaf-based e-skin demonstrates outstanding sensing performance in human-motion monitoring by detecting various motions such as subtle and vigorous flexions, airflow, and vocal-cord vibrations. The proposed piezoresistive e-skin is a promising platform for the development of various low-cost, biocompatible, fully biodegradable, and point-of-care (POC) e-skins for a wide range of subtle and vigorous pressure-monitoring applications including human–machine interfaces (HMIs), robotics, prosthesis, and flexible electronics.

Investigations into the characterization, degradation, and applications of biodegradable polymers by mass spectrometry.

Biodegradable polymers have been getting more and more attention because of their contribution to the plastic pollution environmental issues and to move towards a circular economy. Nevertheless, biodegradable materials still exhibit various disadvantages restraining a widespread use in the market. Therefore, additional research efforts are required to improve their performance. Mass spectrometry (MS) affords a relevant contribution to optimize biodegradable polymer synthesis, to confirm macromolecular structures, to examine along the time the progress of degradation processes and highlight advantages and drawbacks in the extensive applications. This review aims to provide an overview of the MS investigations carried out to support the synthesis of biodegradable polymers, with helpful information on undesirable products or polymerization mechanism, to understand deterioration pathways by the structure of degradation products and to follow drug release and pharmacokinetic. Additionally, it summarizes MS studies addressed on environmental and health issues related to the extensive use of plastic materials, that is, potential migration of additives or microplastics identification and quantification. The paper is focused on the most significant studies relating to synthetic and microbial biodegradable polymers published in the last 15 years, not including agro-polymers such as proteins and polysaccharides.

Comparative Study of Various Fibers in Concrete Subjected to Elevated Temperatures

In this paper fiber reinforced concrete is a two-phase material consisting of a matrix which is reinforced with randomly oriented small diameter fibers to improve the mechanical properties of the matrix. It increases the tensile strength of the concrete. Two types of fibers have been used in this paper i.e steel fiber and glass fiber. Steel fiber reinforced concrete is a homogeneous distribution of randomly oriented discontinuous and discrete steel fibers. It is available in the forms of Carbon steel or stainless steel. It has a high tensile and compressive strength. The Glass fibers are formed by drawing the molten material rapidly from a melted batch in a crucible or furnace. Glass fibers do not have a negative effect on the well-known high compressive strength of concrete. Thus, it shows that the fiber reinforced concrete is in good workable condition rather than without super plasticizer. The addition of 2% steel fiber and 0.5% -1% of glass fiber in concrete is found to be optimum as well as effective and economical as it gives good compression, tensile, and flexural strength for the concrete. Carbon fiber is composed of carbon atoms bonded together to form a long chain. The fibers are extremely stiff, strong, and light, and are used in many processes to create excellent building materials. Carbon fiber material comes in a variety of "raw" building-blocks, including yarns, uni-directional, weaves, braids, and several others, which are in turn used to create composite parts. The properties of a carbon fiber part are close to that of steel and the weight is close to that of plastic. Thus, the strength to weight of a carbon fiber part is much higher than either steel or plastic (Polyvinyl alcohol) (PVA) is well known as a synthetic biodegradable polymer and possesses excellent mechanical properties. PVA “displays strong interaction with carbon nanotubes” (CNTs), resulting in exceptional properties that are not found in another polymer

IMPACT OF GLUTARALDEHYDE CROSSLINKING AGENT ON THE PROPERTIES OF NONWOVEN VISCOSE FABRIC–POLYVINYL ALCOHOL FLEXIBLE COMPOSITES

In recent years, researchers and industries have made efforts to decrease the reliance on fossil fuel-based materials due to the rise in environmental consciousness. A potential environmentally friendly alternative to petroleum-based, non-biodegradable polymeric materials is known to be natural fiber-reinforced polymer composites. Polyvinyl alcohol (PVA) is a biodegradable synthetic polymer that is water-soluble, easy to use, having film-formation property and good potential as a biodegradable matrix in environmentally friendly composites. The objective of this work has been to create a versatile, lightweight, flexible bio-composite based on nonwoven viscose fabric using PVA and a crosslinking agent (glutaraldehyde), and to analyze the effects of the crosslinking agent and of the nonwoven viscose filler in the PVA matrix on the mechanical and UV properties of the composite. The structural, chemical and mechanical properties of the composite were investigated using FTIR, and tensile and UV testing. The results showed that the composite exhibited high tensile strength, but with a drop in elongation. FTIR verified the interaction of the two polymers in the composites. The flexible bio-composite can be potentially used for food packaging applications.

Polymer and composite materials used in medicine

The article is a review of the literature on the use of polymers in medicine as biomaterials.Examples of the preparation of the most commonly used synthetic polymers in medicine, such as: polylactide(PLA), polyglycolide (PGA), polyhydrobutyrate (PHB), polycaprolactone (PCL) are described.The characteristics of ceramic materials: hydroxyapatite (HAp) and tricalcium phosphate (TCP) are alsopresented in terms of the use of synthetic biodegradable polymers as biofillers. The last part of articleis devoted to the functional properties of composites based on PLA with the addition of HAp and TCP.

Polymer and composite materials used in medicine

The article is a review of the literature on the use of polymers in medicine as biomaterials.Examples of the preparation of the most commonly used synthetic polymers in medicine, such as: polylactide(PLA), polyglycolide (PGA), polyhydrobutyrate (PHB), polycaprolactone (PCL) are described.The characteristics of ceramic materials: hydroxyapatite (HAp) and tricalcium phosphate (TCP) are alsopresented in terms of the use of synthetic biodegradable polymers as biofillers. The last part of articleis devoted to the functional properties of composites based on PLA with the addition of HAp and TCP.

Biocatalytic synthesis of new polyesteramides from ε-caprolactam and hydroxy acids: Structural characterization, biodegradability, and suitability as drug nanocarriers

The synthesis of polyesters and polyamides by enzyme-catalyzed processes in vitro was developed in the last decades as a green alternative to obtain biodegradable synthetic polymers with various applications, such as nanoparticle-sized carriers for drug delivery. Polyesteramides were much less studied in this respect, although having the presumable advantage of increased mechanical and thermic resistance brought by the amide moieties. In this work, polyesteramides were synthesized for the first time employing as raw materials ε-caprolactam and a hydroxy acid. L-malic, 3-hydroxybutyric, 12-hydroxystearic and 16-hydroxyhexadecanoic acid, respectively, were investigated as co-monomers in solventless or organic medium, using the immobilized lipase Novozyme 435 as catalyst. The short chain hydroxy acids holding secondary hydroxyl groups yielded oligomers with average degree of polymerization no higher than 4, while in the case of the long-chain 12-hydroxystearic acid this value increased to 7. The best results were achieved by using 16-hydroxyhexadecanoic acid in 2:1 M excess at 80 °C, yielding a product with 75% copolymer content and average molecular weight higher than 3000 Da. The emulsion-solvent evaporation method allowed the efficient production of nanoparticles based on this copolymer, with sizes around 230 nm, used for the encapsulation of a model bioactive compound, the anticancer drug sorafenib. Production yields of >70% and encapsulation efficiencies of around 60% are very promising for further development of this approach.

Bioscaffolds of graphene based-polymeric hybrid materials for myocardial tissue engineering.

Biomaterials currently utilized for the regeneration of myocardial tissue seem to associate with certain restrictions, including deficiency of electrical conductivity and sufficient mechanical strength. These two factors play an important role in cardiac tissue engineering and regeneration. The contractile property of cardiomyocytes depends on directed signal transmission over the electroconductive systems that happen inside the innate myocardium. Because of their distinctive electrical behavior, electroactive materials such as graphene might be used for the regeneration of cardiac tissue. In this review, we aim to provide deep insight into the applications of graphene and graphene derivative-based hybrid polymeric scaffolds in cardiomyogenic differentiation and cardiac tissue regeneration. Synthetic biodegradable polymers are considered as a platform because their degradation can be controlled over time and easily functionalized. Therefore, graphene-polymeric hybrid scaffolds with anisotropic electrical behavior can be utilized to produce organizational and efficient constructs for macroscopic cardiac tissue engineering. In cardiac tissue regeneration, natural polymer based-scaffolds such as chitosan, gelatin, and cellulose can provide a permissive setting significantly supporting the differentiation and growth of the human induced pluripotent stem cells -derived cardiomyocytes, in large part due to their negligible immunogenicity and suitable biodegradability. Cardiac tissue regeneration characteristically utilizes an extracellular matrix (scaffold), cells, and growth factors that enhance cell adhesion, growth, and cardiogenic differentiation. From the various evaluated electroactive polymeric scaffolds for cardiac tissue regeneration in the past decade, graphene and its derivatives-based materials can be utilized efficiently for cardiac tissue engineering.

Recent Advances in Biodegradable and Biocompatible Synthetic Polymers Used in Skin Wound Healing.

The treatment of skin wounds caused by trauma and pathophysiological disorders has been a growing healthcare challenge, posing a great economic burden worldwide. The use of appropriate wound dressings can help to facilitate the repair and healing rate of defective skin. Natural polymer biomaterials such as collagen and hyaluronic acid with excellent biocompatibility have been shown to promote wound healing and the restoration of skin. However, the low mechanical properties and fast degradation rate have limited their applications. Skin wound dressings based on biodegradable and biocompatible synthetic polymers can not only overcome the shortcomings of natural polymer biomaterials but also possess favorable properties for applications in the treatment of skin wounds. Herein, we listed several biodegradable and biocompatible synthetic polymers used as wound dressing materials, such as PVA, PCL, PLA, PLGA, PU, and PEO/PEG, focusing on their composition, fabrication techniques, and functions promoting wound healing. Additionally, the future development prospects of synthetic biodegradable polymer-based wound dressings are put forward. Our review aims to provide new insights for the further development of wound dressings using synthetic biodegradable polymers.

Green electrospinning of sustainable nanofibers: a sustainable frontier for next-generation materials

To fulfil the demand for eco-friendly nanomaterials, electrospinning offers a viable method for creating sustainable nanofibers. This mini review focuses on environmentally friendly and sustainability aspect of nanofibers produced via electrospinning. It examines difficulties and possibilities in ecologically friendly electrospinning, such as selecting environmentally friendly materials, reusing solvents, and using environmentally friendly additives. The use of biodegradable synthetic polymers, hybrid/composite nanofibers for improved performance, and natural polymers from renewable resources are only a few of the green electrospinning approaches that are covered. The review emphasises on green practices and sustainable challenges and opportunities. This review gives insight into green electrospinning techniques and the applications are also highlighted in tissue engineering, environmental remediation, energy storage, and environmentally friendly packaging. Further, the scalability, interdisciplinary cooperation, and regulatory issues are only a few of the obstacles and future directions that are discussed. A greener and more sustainable future in materials science is possible thanks to green electrospinning.

The current state of electrospinning technology and its prospects for the future

With the development of nanotechnology and modern research methods, the use of biodegradable polymer materials in various sectors of human life is of interest not only to the scientific world community, but also i a way to solve one of the global problems related to resource conservation and environmental protection. Polyvinyl alcohol-based materials have been widely used in various fields due to their biological and physical properties, such as biocompatibility, biodegradability, antimicrobial ability, non-toxicity and the ability to easily form a film. One of the methods of obtaining polymer films that exist today is electrospinning, the advantages of which are the relative simplicity of the technological process and the possibility of obtaining continuous nanofibers from both synthetic and natural polymers. In this work, the influence of various process parameters on the formation of nanofiber mats from a biodegradable synthetic polymer by electrospinning was studied. The technology of wet spinning, melt spinning and dry spinning is discussed. A number of experimental studies have been carried out to identify optimal modes of obtaining nanofibers from polyvinyl alcohol with the most homogeneous structure without the formation of defects.

Polylactic Acid/Lignin Composites: A Review

With the gradual depletion of petroleum resources and the increasing global awareness of environmental protection, biodegradable plastics are receiving more and more attention as a green substitute for traditional petroleum-based plastics. Poly (lactic acid) is considered to be the most promising biodegradable material because of its excellent biodegradability, biocompatibility, and good processability. However, the brittleness and high cost limit its application in more fields. Lignin, as the second largest renewable biopolymer in nature after cellulose, is not only rich in reserves and low in cost, but it also has an excellent UV barrier, antioxidant activity, and rigidity. The molecular structure of lignin contains a large number of functional groups, which are easy to endow with new functions by chemical modification. Currently, lignin is mostly treated as waste in industry, and the value-added utilization is insufficient. The combination of lignin and poly (lactic acid) can on the one hand solve the problems of the high cost of PLA and less efficient utilization of lignin; on the other hand, the utilization of lignocellulosic biomass in compounding with biodegradable synthetic polymers is expected to afford high-performance wholly green polymer composites. This mini-review summarizes the latest research achievements of poly (lactic acid)/lignin composites. Emphasis was put on the influence of lignin on the mechanical properties of its composite with poly (lactic acid), as well as the compatibility of the two components. Future research on these green composites is also prospected.

Sustainable feedstocks for 4D printing: biodegradable polymers and natural resources

Additive manufacturing is an emerging technology supported by ‘Industry 4.0’. When combined with a stimulus-responsive behavior, incorporating the fourth dimension of time, it results in a manufacturing technique known as four-dimensional (4D) printing. 4D-printed entities have the distinctive characteristic of property transformation, under the influence of a drafted stimulus, which can be cleverly engineered for the desired application. The conventional stimulus-driven smart printing inks deployed in 4D printing are non-biodegradable polymers that pose a challenge to sustainability. Hence, it is imperative to appraise the utilization of sustainable raw materials, composed of natural and synthetic biodegradable polymers, as feedstocks for 4D printing. Natural resources have fluctuating properties, which make them receptive toward intelligent engineering. This review is an effort toward the implementation of sustainable feedstocks as printing inks for 4D printing, for eventual environmental benignity. It covers several sustainable raw materials for 4D printing and the strategies to use them in conjunction with conventional inks in order to bring down the volume of non-biodegradables. This review can serve as a reference for designers and engineers wishing to use sustainable inks for 4D printing, thereby boosting the momentum needed to consolidate this next-generation technology in line with the UN Sustainable Development Goals.

Biodegradable Piezoelectric Polymers: Recent Advancements in Materials and Applications.

Recent materials, microfabrication, and biotechnology improvements have introduced numerous exciting bioelectronic devices based on piezoelectric materials. There is an intriguing evolution from conventional unrecyclable materials to biodegradable, green, and biocompatible functional materials. As a fundamental electromechanical coupling material in numerous applications, novel piezoelectric materials with a feature of degradability and desired electrical and mechanical properties are being developed for future wearable and implantable bioelectronics. These bioelectronics can be easily integrated with biological systems for applications, including sensing physiological signals, diagnosing medical problems, opening the blood-brain barrier, and stimulating healing or tissue growth. Therefore, the generation of piezoelectricity from natural and synthetic bioresorbable polymers has drawn great attention in the research field. Herein, the significant and recent advancements in biodegradable piezoelectric materials, including natural and synthetic polymers, their principles, advanced applications, and challenges for medical uses, are reviewed thoroughly. The degradation methods of these piezoelectric materials through in vitro and in vivo studies are also investigated. These improvements in biodegradable piezoelectric materials and microsystems could enable new applications in the biomedical field. In the end, potential research opportunities regarding the practical applications are pointed out that might be significant for new materials research.