Non-degradable Polymers Research Articles

Biodegradable antimicrobial films prepared in a continuous way by melt extrusion using plant extracts as effective components

Packaging plays an important role in delaying food spoilage. However, conventional packaging films do not have antimicrobial properties. Films with antimicrobial components are receiving growing research interest. However, many of the reported studies use conventional non-degradable polymers during film preparation, posing a significant threat to the environment and sustainable development. Furthermore, conventional inorganic antibacterial agents are commonly used during film preparation, posing a risk to food safety. In this study, antibacterial compounds were extracted from diverse plants, and then biodegradable antimicrobial films were prepared in a continuous way via the melt extrusion method. Especially, films prepared using Vernicia fordii and Phyllanthus urinaria extracts showed effective antibacterial activities against common foodborne pathogens. This study is the first to prepare antibacterial films in a continuous way using natural plant extracts as the effective components, and may shed new light on future research in preparing green antibacterial films via environment-friendly approaches.

Animal Derived Bioplastic: An Environment Responsive Substitute to Combat Climate Change

Plastics derived from fossil fuels are an important part of modern life and it is the most commonly used material in every industrial sector. The use of plastics is increasing day by day and its degradation has become a great challenge. Moreover, non-degradable plastic polymers tend to accumulate as waste in the environment posing a major ecological threat and climate change issues. Therefore, the identification of microbes that can grow easily on plastic and the novel biological agents with exert degradative potential on plastic material have been reviewd herein. In light of these, the enzymatic process can lead to the conversion of plastic into water, carbon dioxide, and methane as a byproduct. Furthermore, fossil fuels utilized to make plastic items are going to be shortened, therefore scientists are finding novel biobased alternatives. In this regard, starch can be promising biopolymer for bioplastic synthesis after understanding underlysing the biological deterioration process and biotic as well as abiotic mechanisms. Hence, this review specifically presents an extensive evaluation of bioplastic from animal waste that can bring revolutionary changes in the environment to mitigate the climate changes.

Microplastic-Free Microcapsules Using Supramolecular Self-Assembly of Bis-Urea Molecules at an Emulsion Interface.

Encapsulation technology is well established for entrapping active ingredients within an outer shell for their protection and controlled release. However, many solutions employed industrially use nondegradable cross-linked synthetic polymers for shell formation. To curb rising microplastic pollution, regulatory policies are forcing industries to substitute the use of such intentionally added microplastics with environmentally friendly alternatives. This work demonstrates a one-pot process to make microplastic-free microcapsules using supramolecular self-assembly of bis-ureas. Molecular bis-urea species generated in-situ spontaneously self-assemble at the interface of an oil-in-water emulsion via hydrogen bonding to form a shell held together by noncovalent bonds. In addition, Laponite nanodiscs were introduced in the formulation to restrict aggregation observed during the self-assembly and to reduce the porosity of the shell, leading to well-dispersed microcapsules (mean Sauter diameter d [3,2] ∼ 5 μm) with high encapsulation efficiency (∼99%). Accelerated release tests revealed an increase in characteristic release time of the active by more than an order of magnitude after encapsulation. The mechanical strength parameters of these capsules were comparable to some of the commercial, nondegradable melamine-formaldehyde microcapsules. With mild operating conditions in an aqueous environment, this technology has real potential to offer an industrially viable method for producing microplastic-free microcapsules.

A fully degradable flexible membrane via green synthesis for highly effective separation of oil-water emulsions

Flexible membranes have attracted extensive attention in water treatment due to their outstanding plasticity, portability, and toughness. However, conventional flexible membranes are usually made from non-degradable polymers or hazardous reagents, posing threats to the environment. In this work, a flexible silica nanofiber-regenerated cellulose composite membrane was fabricated by “no polymer solvents electrospinning” with cellulose regeneration. The membrane was fully degradable and eco-friendly, and it exhibited low oil adhesion force and recyclable oil emulsion separation performance. It achieved removal rates of almost 100 % and up to 0.1 % residual oil rate for six different types of oil emulsions with the addition of surfactant, which represents the optimal level reported in the literature to date. The presence of these extremely water-attracting functional groups on the surface of the membrane allows them to bond with water molecules, creating a stable water layer held together by hydrogen bonds. This layer can reject oil compounds during the separation process due to the inherent immiscibility between water and oil. Importantly, this membrane has excellent degradability. The regenerated cellulose layer on its surface can undergo complete microbial degradation (activated sludge) within 7 days, while the remaining substrate can be degraded continuously in concentrated hydrochloric acid, thereby facilitating complete environmentally benign disposal and providing a new strategy for developing green flexible membranes, which holds promise for addressing water scarcity and water pollution issues.

From Green Synthesis to Diverse Applications: Exploring the Environmentally Viable Potential of Silver Nanocomposites with Biodegradable Polymers.

In the realm of environmentally conscious materials science, the integration of silver nanoparticles (AgNPs) with biodegradable polymers to form innovative nanocomposites has sparked notable discourse and research. This review delves comprehensively into the synthesis, properties, and environmental implications of said AgNPs/biodegradable polymer nanocomposites. Leveraging the unique physicochemical attributes of silver nanoparticles, these nanocomposites are portrayed as promising platforms for delivery, sensing, and antimicrobial applications. The nanocomposites made of AgNPs with biodegradable polymers, however, extend beyond utility, demonstrating a commitment to minimizing ecological impact. Contrary to traditional non-degradable polymers that litter our environments and oceans, these green alternatives yield lesser waste, reduce energy use, and limit the emission of volatile organic compounds, thereby aligning with global efforts towards sustainability. Our review strives to substantiate the environmental viability of these nanocomposites, whilst elaborating on their diverse commercial potential.

Degradable 4D-printed hydration-driven actuators from a single family of amphiphilic star-shaped copolymers

Actuators are largely used in biomedical applications in the presence of sensitive live cells or biomolecules, which makes actuators triggered by water uptake highly appealing. Dual-material printing and hydration driven expansion is a method of choice to produce such actuators, but mostly rely of non-degradable polymers or on the combination of polymers of different nature that may lead to interface incompatibilities. To overcome this challenge, we report here on two photocrosslinkable resins based on a single family of degradable hydrophilic or hydrophobic star-shaped poly(ethylene glycol)-poly(lactide) copolymers. The two materials are first printed individually and characterized to ensure that their properties enable the printing of dual material objects by stereolithographic digital-light processing. Dual-materials actuators are then printed by sequential switching of the hydrophobic and hydrophilic resin baths. Objects of simple and complex shapes are easily obtained and exhibit rapid actuation (<60 s) upon hydration. The swelling-induced shape changes are accurately reproduced by numerical modeling of the printed geometries using the obtained material swelling properties. This set of results offers new perspectives to develop 4D-printed temporary medical devices.

Ultrafast-degradable and super-elastic PBAT/polybutylene succinate foam with stable cellular structure and enhanced thermal insulation

PBAT is considered a leading eco-friendly polymer known for its exceptional biodegradability and mechanical properties. However, the production of high-performance PBAT foam remains challenging owing to poor foaming ability and intrinsic shrinkage. Herein, this study presents a flexible approach to prepare super-elastic and ultrafast-degradable PBAT/polybutylene succinate (PBS) foams achieved by microcellular foaming with CO2 & N2 as co-blowing agents. Firstly, the SEM, FTIR, as well as XPS spectra, confirmed a uniform and miscible distribution of PBS. Further, the crystallization kinetics and rheological analysis demonstrated that PBS effectively promoted crystallization and molecular chain entanglement. Thus, the PBAT/PBS foam exhibited significantly refined cellular structure, higher expansion ratio of 20.3, and restricted shrinkage of less than 4 %. More importantly, compared with neat PBAT foam, the compression strength of PBAT/PBS foam was dramatically enhanced by 47.7 %, and the energy loss coefficient was pronouncedly reduced by 58.8 % under the expansion ratio of 15.0. Meanwhile, the PBAT/PBS foam showed a thermal conductivity as low as 35.9 mW/m·K, enhanced hydrophobicity, and an exceptionally rapid degradation ratio. Considering the eco-friendly and flexible characteristics of this process, anti-shrinkage and ultrafast-degradable PBAT/PBS foams with improved mechanical and thermal insulation performance present promising prospects to replace the nondegradable polymer foams.

3D Printing Materials and Technologies for Orthopaedic Applications.

3D printing technologies have evolved tremendously over the last decade for uses in orthopaedic surgical applications, including being used to manufacture implants for spine, upper extremity, foot and ankle, oncologic, and traumatic reconstructions. Materials used for 3D-printed orthopaedic devices include metals, degradable and nondegradable polymers, and ceramic composites. There are 2 primary advantages for use of 3D printing technologies for orthopaedics: first, the ability to create complex porous lattices that allow for osseointegration and improved implant stability and second, the enablement of complex geometric designs allowing for patient-specific devices based on preoperative imaging. Given continually evolving technology, and the relatively early stage of the materials and 3D printers themselves, the possibilities for continued innovation in orthopaedics are great.

Silver Nanoparticles in Food Bio Packaging. A Short Review

Abstract For human survival, the agri-food sector is fundamental, starting from the cultivation of the land to the production of food that ends up on our tables. Unfortunately, over time, this sector has faced numerous challenges, such as the appearance of pests, environmental pollution, short shelf life and, last but not least, inadequate packaging materials. All these challenges have led researchers from all over the world to find new alternatives to guarantee food safety. The application of nanomaterials, i.e. nanoparticles, could be the solution sought by all scientists. In recent years, nanotechnology has made remarkable progress, especially regarding the application of metallic nanoparticles and their synthesis methods. In particular, silver nanoparticles have attracted attention, due to their special antimicrobial, electrical and optical properties, but also to the fact that they can be combined with nondegradable, biodegradable and edible polymers. However, there are many concerns regarding the toxicity of these nanoparticles. This article aims to present some recent findings regarding the application of silver nanoparticles in food bio packaging.

Designing Degradable Polymers from Tricycloalkenes via Complete Cascade Metathesis Polymerization.

Cascade metathesis polymerization has been developed as a promising method to synthesize complex but well-defined polymers from monomers containing multiple reactive functional groups. However, this approach has been limited to the monomers involving simple alkene/alkyne moieties or produced mainly non-degradable polymers. In this study, we demonstrate a complete cascade ring-opening/ring-closing metathesis polymerization (RORCMP) using various tricycloalkenes and two strategies for the efficient degradation. Through rational design of tricycloalkene monomers, the structure and reactivity relationship was explored. For example, tricycloalkenes with trans configuration in the central ring enabled faster and better selective cascade RORCMP than the corresponding cis isomers. Also, a 4-substituted cyclopentene moiety in the monomers significantly enhanced the overall cascade RORCMP performance, with the maximum turnover number (TON) reaching almost 10,000 and molecular weight up to 170 kg/mol using an amide-containing monomer. Furthermore, we achieved one-shot cascade multiple olefin metathesis polymerization using tricycloalkenes and a diacrylate, to produce new highly A,B-alternating copolymers with full degradability. Lastly, we successfully designed xylose-based tricycloalkenes to give well-defined polymers that underwent ultra-fast and complete degradation under mild conditions.

Biodegradable Polymers in Veterinary Medicine-A Review.

During the past two decades, tremendous progress has been made in the development of biodegradable polymeric materials for various industrial applications, including human and veterinary medicine. They are promising alternatives to commonly used non-degradable polymers to combat the global plastic waste crisis. Among biodegradable polymers used, or potentially applicable to, veterinary medicine are natural polysaccharides, such as chitin, chitosan, and cellulose as well as various polyesters, including poly(ε-caprolactone), polylactic acid, poly(lactic-co-glycolic acid), and polyhydroxyalkanoates produced by bacteria. They can be used as implants, drug carriers, or biomaterials in tissue engineering and wound management. Their use in veterinary practice depends on their biocompatibility, inertness to living tissue, mechanical resistance, and sorption characteristics. They must be designed specifically to fit their purpose, whether it be: (1) facilitating new tissue growth and allowing for controlled interactions with living cells or cell-growth factors, (2) having mechanical properties that address functionality when applied as implants, or (3) having controlled degradability to deliver drugs to their targeted location when applied as drug-delivery vehicles. This paper aims to present recent developments in the research on biodegradable polymers in veterinary medicine and highlight the challenges and future perspectives in this area.

Acid-labile and non-degradable cross-linked star polymer model networks by aqueous polymerization for in situ encapsulation and release

Biocompatible, acid-labile cross-linked star polymer model networks (CSPMNs) have a great potential for use in drug delivery. However, a primary complication of this research stems from the prevalence for their...

Evaluation of stress-controlled high-cycle fatigue characteristics in PLA-wood fused deposition modeling 3D-printed parts under bending loads.

PLA (Poly-lactic acid)-wood provides more biodegradability through natural fibers, a significant advantage of pure PLA. Nevertheless, these bio-composites may have inferior mechanical properties compared to non-degradable polymer composites, considering the lower strength of natural particles compared to synthetic fibers. This research examines the fatigue behavior of additive-manufactured biopolymer PLA-wood and assesses its comparability with pure PLA. Therefore, solid fatigue test samples were printed using the FDM (fused deposition modeling) method. Afterward, fully reversed rotary bending fatigue experiments were performed at 4 different stress levels (7.5 to 15 MPa) to extract the S-N curve of PLA-wood. Moreover, the fatigue fracture surfaces of the PLA-wood were investigated and compared at the highest and lowest stress levels using an FE-SEM (Field Emission Scanning Electron Microscopy), indicating more ductile fracture marks at higher stress levels. The fatigue lifetime of the PLA-wood decreased by 87.48% at the highest stress level (15 MPa), rather than the result at the lowest stress level (7.5 MPa). Additionally, the results demonstrated that the fatigue characteristics of the printed pure PLA and PLA-wood were comparable, suggesting that the 3D-printed PLA-wood with the used printing parameters can be an alternative choice.

Releasable, Immune-Instructive, Bioinspired Multilayer Coating Resists Implant-Induced Fibrosis while Accelerating Tissue Repair.

Implantable biomaterials trigger foreign body reactions (FBRs), which reduces the functional life of medical devices and prevents effective tissue regeneration. Although existing therapeutic approaches can circumvent collagen-rich fibrotic encapsulation secondary to FBRs, they disrupt native tissue repair. Herein, a new surface engineering strategy in which an apoptotic-mimetic, immunomodulatory, phosphatidylserine liposome (PSL) is released from an implant coating to induce the formation of a macrophage phenotype that mitigates FBRs and improves tissue healing is described. PSL-multilayers constructed on implant surfaces via the layer-by-layer method release PSLs over a 1-month period. In rat muscles, poly(etheretherketone) (PEEK), a nondegradable polymer implant model, induces FBRs with dense fibrotic scarring under an aberrant cellular profile that recruits high levels of inflammatory infiltrates, foreign body giant cells (FBGCs), scar-forming myofibroblasts, and inflammatory M1-like macrophages but negligible amounts of anti-inflammatory M2-like phenotypes. However, the PSL-multilayer coating markedly diminishes these detrimental signatures by shifting the macrophage phenotype. Unlike other therapeutics, PSL-multilayered coatings also stimulate muscle regeneration. This study demonstrates that PSL-multilayered coatings are effective in eliminating FBRs and promoting regeneration, hence offering potent and broad applications for implantable biomaterials.

Exploring the Role of Green Microbes in Sustainable Bioproduction of Biodegradable Polymers.

Research efforts have shifted to creating biodegradable polymers to offset the harmful environmental impacts associated with the accumulation of non-degradable synthetic polymers in the environment. This review presents a comprehensive examination of the role of green microbes in fostering sustainable bioproduction of these environment-friendly polymers. Green microbes, primarily algae and cyanobacteria, have emerged as promising bio-factories due to their ability to capture carbon dioxide and utilize solar energy efficiently. It further discusses the metabolic pathways harnessed for the synthesis of biopolymers such as polyhydroxyalkanoates (PHAs) and the potential for genetic engineering to augment their production yields. Additionally, the techno-economic feasibility of using green microbes, challenges associated with the up-scaling of biopolymer production, and potential solutions are elaborated upon. With the twin goals of environmental protection and economic viability, green microbes pave the way for a sustainable polymer industry.

Insights into biofilm development on polyhydroxyalkanoate biofilm carrier for anoxic azo dye decolourization of acid orange 7

Polyhydroxyalkanoates (PHAs) are promising alternatives to non-degradable polymers in various applications. This study explored the use of biologically recovered PHA as a biofilm carrier in a moving bed biofilm reactor for acid orange 7 treatment. The PHA was comprised of 86 ± 1 mol% of 3-hydroxybutyrate and 14 ± 1 mol% of 3-hydroxyhexanoate and was melt-fused at 140 °C into pellets. The net positive surface charge of the PHA biocarrier facilitated attachment of negatively charged activated sludge, promoting biofilm formation. A 236-µm mature biofilm developed after 26 days. The high polysaccharides-to-protein ratio (>1) in the biofilm’s extracellular polymeric substances indicated a stable biofilm structure. Four main microbial strains in the biofilm were identified as Leclercia adecarboxylata, Leuconostoc citreum, Bacillus cereus, and Rhodotorula mucilaginosa, all of which exhibited decolourization abilities. In conclusion, PHA holds promise as an effective biocarrier for biofilm development, offering a sustainable alternative in wastewater treatment applications.

Investigating the potential of degradable poly(vinyl acetate) copolymer microparticles for encapsulation and in vitro release studies

Poly(vinyl acetate) is a well-known polymer synthesized through the free radical polymerization of vinyl acetate (VAc) monomer. However, enhancing the degradability of this polymer is best achieved by copolymerizing cyclic ketene acetal (CKA) with VAc. Despite their potential, the practical use of these degradable polymers remains limited. Therefore, our study aimed to develop a sustainable technology encompassing the synthesis and application of poly(VAc-co-MDO), and environmental biodegradability of poly(vinyl alcohol (VA)). To achieve this, we synthesized a series of degradable copolymers, namely poly(VAc-co-MDO), via free radical ring-opening polymerization (rROP) of 2-methylene-1,3-dioxepane (MDO) with VAc. The number of degradable ester units in the polymer backbone was systematically controlled by varying the initial monomer feed compositions, resulting in a range of 8–85 mol%. To compare their properties, we also synthesized homopolymers, namely poly(VAc) and poly(MDO). Subsequently, we formulated the homo and copolymers into microparticles using the co-solvent evaporation method, which yielded spherical particles with a particle size distribution ranging from 5 to 10 µm. Furthermore, we demonstrated the applicability of these degradable copolymers, exemplified by a poly[VAc(0.92)-co-MDO(0.08)] with 8 mol% MDO in the polymer backbone, in an encapsulation modeling study using curcumin as the active molecule. Successful encapsulation of curcumin into degradable polymer particles was confirmed and quantified via HPLC analysis. The degradability of the copolymers was evaluated through accelerated alkali hydrolysis, resulting in the formation of oligomeric degradation products. Additionally, we investigated the environmental biodegradability of poly(VA-co-MDO) as a proof of concept, revealing a biodegradability of 89% within 28 days for this polymer consisting of 88 mol% poly(VA) and 12 mol% poly(MDO) in the backbone. Preparing stable formulation for applications and performing biodegradability tests for the copolymers or microparticles derived from random poly(VAc-co-MDO) was challenging due to the insolubility of the polymer or instability in the form of sedimentation of the microparticles in the inoculum. Hence, in order to achieve stable formulation, we synthesized random poly(VA-co-MDO) through the selective cleavage of chloroacetyl group (ClAc) from its precursor, poly(VClAc-co-MDO). This method was preferred because obtaining poly(VA-co-MDO) directly from poly(VAc-co-MDO) was hindered by significant ester backbone cleavage, even under mild conditions. Our research assumes significance in light of recent restrictions imposed by various chemical agencies on the use of non-degradable polymers and microparticles in formulations.

Immunobiology of foreign body response to composite PLACL/gelatin electrospun nanofiber meshes with mesenchymal stem/stromal cells in a mouse model: Implications in pelvic floor tissue engineering and regeneration

Pelvic Organ Prolapse (POP) is a common gynaecological disorder where pelvic organs protrude into the vagina. While transvaginal mesh surgery using non-degradable polymers was a commonly accepted treatment for POP, it has been associated with high rates of adverse events such as mesh erosion, exposure and inflammation due to serious foreign body response and therefore banned from clinical use after regulatory mandates. This study proposes a tissue engineering strategy using uterine endometrium-derived mesenchymal stem/stromal cells (eMSC) delivered with degradable poly L-lactic acid-co-poly ε-caprolactone (PLACL) and gelatin (G) in form of a composite electrospun nanofibrous mesh (P + G nanomesh) and evaluates the immunomodulatory mechanism at the material interfaces. The study highlights the critical acute and chronic inflammatory markers along with remodelling factors that determine the mesh surgery outcome. We hypothesise that such a bioengineered construct enhances mesh integration and mitigates the Foreign Body Response (FBR) at the host interface associated with mesh complications. Our results show that eMSC-based nanomesh significantly increased 7 genes associated with ECM synthesis and cell adhesion including, Itgb1, Itgb2, Vcam1, Cd44, Cdh2, Tgfb1, Tgfbr1, 6 genes related to angiogenesis including Ang1, Ang2, Vegfa, Pdgfa, Serpin1, Cxcl12, and 5 genes associated with collagen remodelling Col1a1, Col3a1, Col6a1, Col6a2, Col4a5 at six weeks post-implantation. Our findings suggest that cell-based tissue-engineered constructs potentially mitigate the FBR response elicited by biomaterial implants. From a clinical perspective, this construct provides an alternative to current inadequacies in surgical outcomes by modulating the immune response, inducing angiogenesis and ECM synthesis during the acute and chronic phases of the FBR.

Polyester Brush Coatings for Circularity: Grafting, Degradation, and Repeated Growth.

Polymer brushes are widely used as versatile surface modifications. However, most of them are designed to be long-lasting by using nonbiodegradable materials. This generates additional plastic waste and hinders the reusability of substrates. To address this, we present a synthetic strategy for grafting degradable polymer brushes via organocatalytic surface-initiated ring-opening polymerization (SI-ROP) from stable PGMA-based macroinitiators. This yields polyester brush coatings (up to 50 nm in thickness) that hydrolyze with controlled patterns and can be regrown on the same substrate after degradation. We chose polyesters of different hydrolytic stability and degradation mechanism, i.e., poly(lactic acid) (PLA), polycaprolactone (PCL), and polyhydroxybutyrate (PHB), which are grown from poly(glycidyl methacrylate) (PGMA)-based macroinitiators for strong surface binding and initiating site reuse. Brush degradation is monitored via thickness changes in pH-varied buffer solutions and seawater with PHB brushes showing rapid degradation in all solutions. PLA and PCL brushes show higher stability in solutions of up to pH 8, while all coatings fully degrade after 14 days in seawater. These brushes offer surface modifications with well-defined degradation patterns that can be regrown after degradation, making them an interesting alternative to (meth)acrylate-based, nondegradable polymers brushes.

Multifunctional Microneedle Patches via Direct Ink Drawing of Nanocomposite Inks for Personalized Transdermal Drug Delivery.

Additive manufacturing, commonly known as 3D printing, allows decentralized drug fabrication of orally administered tablets. Microneedles are comparatively favorable for self-administered transdermal drug delivery with improved absorption and bioavailability. Due to the cross-scale geometric characteristics, 3D-printed microneedles face a significant trade-off between the feature resolution and production speed in conventional layer-wise deposition sequences. In this study, we introduce an economical and scalable direct ink drawing strategy to create drug-loaded microneedles. A freestanding microneedle is efficiently generated upon each pneumatic extrusion and controlled drawing process. Sharp tips of ∼5 μm are formed with submillimeter nozzles, representing 2 orders of magnitude improved resolution. As the key enabler of this fabrication strategy, the yield-stress fluid inks are formulated by simply filling silica nanoparticles into regular polymer solutions. The approach is compatible with various microneedles based on dissolvable, biodegradable, and nondegradable polymers. Various matrices are readily adopted to adjust the release behaviors of the drug-loaded microneedles. Successful fabrication of multifunctional patches with heterogeneously integrated microneedles allows the treatment of melanoma via synergistic photothermal therapy and combination chemotherapy. The personalized patches are designed for cancer severity to achieve high therapeutic efficacy with minimal side effects. The direct ink drawing reported here provides a facile and low-cost fabrication strategy for multifunctional microneedle patches for self-administering transdermal drug delivery.