Effect of molecular weight of polyethylene glycol on crystallization behaviors, thermal properties and tensile performance of polylactic acid stereocomplexes

Optimizing lornoxicam-loaded poly(lactic-co-glycolic acid) and (polyethylene glycol) nanoparticles for transdermal delivery: ex vivo/in vivo inflammation evaluation

Aim: This study focused on developing a topical gel incorporating lornoxicam-loaded poly(lactic-co-glycolic acid) and polyethylene glycol (PLGA-PEG) blend nanoparticles to mitigate gastrointestinal (GIT) side effects and enhance therapeutic efficacy. Materials & methods: Synthesized nanoparticles were subjected to in vitro characterization, ex vivo permeation studies, and acute oral toxicity analysis post-incorporation into the gel using a S/O/W double emulsion solvent. Results & conclusion: The nanoparticles displayed a smooth, spherical morphology (170-321 nm) with increased entrapment efficiency (96.2%). LOX exhibited a permeation rate of 70-94% from the nanoparticle-infused gel, demonstrating favorable biocompatibility at the cellular level. The formulated gel, enriched with nanoparticles, holds promising prospects for drug-delivery systems and promising improved therapeutic outcomes for LOX.

Ring-opening polymerization of emulsion-templated deep eutectic system monomer for macroporous polyesters with controlled degradability

Biodegradable polyesters with interconnected macroporosity, such as poly(l-lactide) (PLLA) and poly(ε-caprolactone) (PCL), have gained significant importance in the fields of tissue engineering and separation. This study introduces functional macroinitiators, specifically polycaprolactone triol (PCLT) and polyethylene glycol (PEG), both OH-terminated, in the solventless ring-opening polymerization (ROP) of a liquid deep eutectic system monomer (DESm) composed of LLA and CL at a 30 : 70 molar ratio, respectively. The macroinitiators selectively initiate the organocatalyzed ROP of LLA in the DESm during the first polymerization stage, thereby modifying the PLLA architecture. This results in the formation of either branched or linear PLLA copolymers depending on the macroinitiator, PCLT and PEG, respectively. In the second stage, the ROP of the CL, which is a counterpart of the DESm, produces PCL that blends with the previously formed PLLA. The insights gained into the PLLA architectures during the first stage of the DESm ROP, along with the overall molecular weight and hydrophobicity of the resulting PLLA/PCL blend in bulk, were advantageously used to design polymerizable high internal phase emulsions (HIPEs) oil-in-DESm. By incorporating a liquid mixture of DESm and macroinitiators (PCLT or PEG), stable HIPE formulations were achieved. These emulsions sustained the efficient organocatalyzed ROP of the continuous phase at 37 °C with high conversions. The resulting polymer replicas of the HIPEs, characterized by macroporous and interconnected structures, were subjected to a degradation assay in PBS at pH 7.4 and 37 °C and remained mechanically stable for at least 30 days. Notably, they exhibited the capability to sorb crude oil in a proof-of-concept test, with a rate of 2 g g-1. The macroporous and interconnected features of the polyHIPEs, combined with their inherent degradation properties, position them as promising degradable polymeric sorbents for efficient separation of hydrophobic fluids from water.

Synthesis of MPEG-b-PLLA Diblock Copolymers and Their Crystallization Performance with PDLA and PLLA Composite Films

Methoxy poly(ethylene glycol)-block-poly(L-lactide) (MPEG-b-PLLA) has a wide range of applications in pharmaceuticals and biology, and its structure and morphology have been thoroughly studied. In the experiment, we synthesized MPEG-b-PLLA with different block lengths using the principle of ring-opening polymerization by controlling the amount of lactic acid added. The thermodynamic properties of copolymers and the crystallization properties of blends were studied separately. The crystallization kinetics of PDLA/MPEG-b-PLA and PLLA/MPEG-b-PLA composite films were studied using differential scanning calorimetry (DSC). The results indicate that the crystallization kinetics of composite films are closely related to the amount of block addition. The crystallinity of the sample first increases and then decreases with an increase in MPEG-b-PLLA content. These results were also confirmed in polarized optical microscope (POM) and wide-angle X-ray diffraction (WAXD) tests. When 3% MPEG-b-PLLA was added to the PDLA matrix, the blend exhibited the strongest crystallization performance.

Polyethylene Glycol/Rice Husk Ash Shape-Stabilized Phase Change Materials: Recovery of Thermal Energy Storage Efficacy via Engineering Porous Support Structure

This study focuses on modifying the porous structure of acid-treated rice husk ash (ARHA) to enhance the thermal energy storage capacity of poly(ethylene glycol) (PEG) confined within shape-stabilized phase change materials. The modification process involved a cost-effective sol-gel method in which ARHA was initially dissolved in an alkaline solution and subsequently precipitated in an acidic environment. ARHA, being a mesoporous SiO2-based material with a high surface area but low pore volume, had limited capacity to adsorb PEG (50%). Furthermore, it hindered the crystallinity of impregnated PEG by fostering abundant interfacial hydrogen bonds (H-bonds), resulting in a diminished thermal energy storage efficiency. Following modification of the porous structure, the resulting material, termed mARHA, featured a three-dimensional macroporous network, providing ample space to stabilize a significant amount of PEG (70%) without any leakage. Notably, mARHA, with a reduced surface area, effectively mitigated interfacial H-bonds, consequently enhancing the crystallinity of impregnated PEG. This modification led to the recovery of thermal energy storage efficacy from 0 J/g for PEG/ARHA to 109.3 J/g for PEG/mARHA. Additionally, the PEG/mARHA composite displayed improved thermal conductivity, reliable thermal performance, and effective thermal management when used as construction materials. This work introduces a straightforward and economical strategy for revitalizing thermal energy storage in PEG composites confined within RHA-based porous supports, offering promising prospects for large-scale applications in building energy conservation.

Porous and Meltable Metal-Organic Polyhedra for the Generation and Shaping of Porous Mixed-Matrix Composites

Here, we report the synthesis of BCN-93, a meltable, functionalized, and permanently porous metal-organic polyhedron (MOP) and its subsequent transformation into amorphous or crystalline, shaped, self-standing, transparent porous films via melting and subsequent cooling. The synthesis entails the outer functionalization of a MOP with meltable polymer chains: in our model case, we functionalized a Rh(II)-based cuboctahedral MOP with poly(ethylene glycol). Finally, we demonstrate that once melted, BCN-93 can serve as a porous matrix into which other materials or molecules can be dispersed to form mixed-matrix composites. To illustrate this, we combined BCN-93 with one of various additives (either two MOF crystals, a porous cage, or a linear polymer) to generate a series of mixed-matrix films, each of which exhibited greater CO2 uptake relative to the parent film.

177Lu-Labeled Iron Oxide Nanoparticles Functionalized with Doxorubicin and Bevacizumab as Nanobrachytherapy Agents against Breast Cancer

The use of conventional methods for the treatment of cancer, such as chemotherapy or radiotherapy, and approaches such as brachytherapy in conjunction with the unique properties of nanoparticles could enable the development of novel theranostic agents. The aim of our current study was to evaluate the potential of iron oxide nanoparticles, coated with alginic acid and polyethylene glycol, functionalized with the chemotherapeutic agent doxorubicin and the monoclonal antibody bevacizumab, to serve as a nanoradiopharmaceutical agent against breast cancer. Direct radiolabeling with the therapeutic isotope Lutetium-177 (177Lu) resulted in an additional therapeutic effect. Functionalization was accomplished at high percentages and radiolabeling was robust. The high cytotoxic effect of our radiolabeled and non-radiolabeled nanostructures was proven in vitro against five different breast cancer cell lines. The ex vivo biodistribution in tumor-bearing mice was investigated with three different ways of administration. The intratumoral administration of our functionalized radionanoconjugates showed high tumor accumulation and retention at the tumor site. Finally, our therapeutic efficacy study performed over a 50-day period against an aggressive triple-negative breast cancer cell line (4T1) demonstrated enhanced tumor growth retention, thus identifying the developed nanoparticles as a promising nanobrachytherapy agent against breast cancer.

Electrospun PEO/PEG fibers as potential flexible phase change materials for thermal energy regulation

Polyethylene glycol (PEG) is widely used as phase change materials (PCM) due to their versatile working temperature and high latent heat. However, the low molecular weight of PEG prevents from the formation of flexible microfibers, and the common leakage problem associated with solid-liquid PCM further hinders their applications in various fields. To address these challenges, polyethylene oxide (PEO) is incorporated as the supporting matrix for PEG, leading to a successful electrospinning of fibrous mats. Due to the similar chemical nature of both PEG and PEO, the blended composites show great compatibility and produce uniform electrospun fibers. The thermal properties of these fibers are characterized by DSC and TGA, and supercooling for the PEG(1050) component is effectively reduced by 75-85%. The morphology changes before and after leakage test are analyzed by SEM. Tensile and DMA tests show that the presence of PEG(1050) component contributes to plasticization effect, improving mechanical and thermomechanical strength. The ratio of PEO(600K):PEG(1050) at 7:3 affords the optimal performance with good chemical and form-stability, least shrinkage, and uniformity. These fibrous mats have potential applications in areas of food packaging, flexible wearable devices, or textiles to aid in thermal regulation.

Synthesis and Characteristic Valuation of a Thermoplastic Polyurethane Electrode Binder for In-Mold Coating

A polyurethane series (PHEI-PU) was prepared via a one-shot bulk polymerization method using hexamethylene diisocyanate (HDI), polycarbonate diol (PCD), and isosorbide derivatives (ISBD) as chain extenders. The mechanical properties were evaluated using a universal testing machine (UTM), and the thermal properties were evaluated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The PHEI-PU series exhibited excellent mechanical properties with an average tensile strength of 44.71 MPa and an elongation at break of 190%. To verify the applicability of different proportions of PU as an electrode binder, PU and Ag flakes were mixed (30/70 wt%) and coated on PCT substrates, the electrodes were evaluated by four-point probe before and after 50% elongation, and the dispersion was evaluated by scanning electron microscopy (SEM). The electrical resistance change rate of PHEI-PU series was less than 20%, and a coating layer with well-dispersed silver flakes was confirmed even after stretching. Therefore, it exhibited excellent physical properties, heat resistance, and electrical resistance change rate, confirming its applicability as an electrode binder for in-mold coating.

Crystallization-driven formation poly (l-lactic acid)/poly (d-lactic acid)-polyethylene glycol-poly (l-lactic acid) small-sized microsphere structures by solvent-induced self-assembly

Improving hydrophobicity through the regulation of surface microstructures has attracted significant interest in various applications. This research successfully prepared a surface with microsphere structures using the Non-solvent induced phase separation method (NIPS). Poly(D-Lactic acid)-block-poly(ethylene glycol)-block-poly(D-Lactic acid) (PDLA-PEG-PDLA) block polymers were synthesized by ring-opening polymerization of D-Lactic acid (D-LA) using polyethylene glycol (PEG) as initiator. PLLA/PDLA-PEG-PDLA membrane with microscale microsphere morphology was fabricated using a nonsolvent-induced self-assembly method by blending the triblock copolymer with a poly(L-lactic acid) (PLLA) solution. In phase separation processes, the amphiphilic block copolymers self-assemble into micellar structures to minimize the Gibbs free energy, and the hydrophilic segments (PEG) aggregate to form the core of the micelles, while the hydrophobic segments (PDLA) are exposed on the outer corona resulting in a core-shell structure. The Stereocomplex Crystalline (SC), formed by the hydrogen bonding between PLLA and PDLA, can facilitate the transition from liquid-liquid phase separation to solid-liquid phase separation, and the PEG chain segments can enhance the formation of SC. The membrane, prepared by adjusting the copolymer content and PEG chain length, exhibited adjustable microsphere quantity, diameter, and surface roughness, enabling excellent hydrophobicity and controlled release of oil-soluble substances.

Enhancing interfacial interaction and crystallization in polylactic acid-based biocomposites via synergistic effect of wood fiber and self-assembly nucleating agent

Incorporation of natural fibers into polylactic acid (PLA) provides a feasible pathway to improve the performance of PLA with a low environmental impact. However, the insufficient interfacial adhesion between fiber and matrix limits the reinforcement efficiency of fiber and final mechanical properties of the biocomposites. Herein we reported an efficient method to simultaneously enhance interfacial interaction, crystallization and mechanical performance of PLA-based biocomposites via combination of wood fiber (WF) and a self-assembly nucleating agent (TMC-300). The interactions between WF and TMC-300 and its influence on PLA, including interfacial crystal morphology, crystallization behavior, and mechanical performance were studied. The results showed that TMC-300 could self-assemble into dendritic-like structure on WF surface driven by hydrogen bonding, inducing the epitaxial crystallization of PLA. This unique interfacial crystallization integrated PLA matrix with WF, resulting in better interfacial adhesion. Under the optimal TMC-300 content (0.5 wt%), the flexural strength and notched impact strength of PLA composites increased by 10 % and 69 % compared with neat PLA, respectively. Additionally, TMC-300 and WF synergistically functioned as effective nucleating agents, which significantly accelerated the crystallization rate and improved the crystallinity of PLA. This work provides a new insight into the enhancement of interfacial bonding in natural fiber/PLA biocomposites.

Preparation of nanofibrous poly (L-lactic acid) scaffolds using the thermally induced phase separation technique in dioxane/polyethylene glycol solution

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

Thiol-Ene Click Cross-linking of Starch Oleate Films for Enhanced Properties

Biobased films were synthesized from starch oleate (DS = 2.2) cross-linked with polyethylene glycol with Mn = 2000 and 1000 g · mol-1, and ethylene glycol, all of which were esterified with either lipoic acid (LA) or 3-mercaptopropionic acid (MPA). Cross-linking was achieved through a UV-initiated thiol-ene click, and confirmed by Fourier transform infrared spectroscopy and rheometry. The films exhibit higher degradation temperatures, and an increased degree of crystallinity as cross-linker length increased. The introduction of MPA-based cross-linkers resulted in hydrophilic films, while the contact angle was barely affected by the addition of LA-based cross-linkers. A reduction in maximum strength upon introducing the cross-linkers was observed, while an increase in elongation was observed for most of the LA-based cross-linkers. Our results demonstrate the potential for tuning the mechanical and thermal properties of starch-based films through the cross-linker choice, with some formulations exhibiting increased flexibility that may be well suited for packaging applications.

Study on aging behavior of polyethylene glycol under three wavelengths of ultraviolet light irradiation

PEG2000 (polyethylene glycol, molecular weight: 2000) is commonly used for the dehydration and reinforcement of waterlogged wooden cultural relics, but its photo-aging degradation will seriously affect the long-term conservation of the wooden cultural relics. In this study, the photo-aging characteristics and mechanisms of PEG2000 under UV (ultraviolet) irradiations of three wavelengths were comprehensively investigated, and the surface morphology, crystal structure, and relative molecular weight of PEG2000 were systematically characterized. The results showed that PEG2000 showed a higher gloss loss rate, carbonyl index and crystallinity, and a wider molecular weight distribution with increasing aging time, especially under the irradiation of 313 nm ultraviolet light. The evolution of the PEG2000 from surface to interior during photoaging was elucidated by SEM (scanning electron microscopy) and FTIR (Fourier transform infrared spectroscopy), and it was determined that photodegradation not only occurs on the surface of PEG2000 but also gradually extends to the interior of the sample with the prolongation of irradiation time, resulting in the transformation of the basic component unit of spherical crystals in PEG2000 from fibrous crystals to spherical particles. Based on 1H-NMR (nuclear magnetic resonance spectroscopy), the photochemical reactions for the generation of degradation products were proposed, and it was found that the degradation occurred at the C-H and C-O-C bonds on the main chain, forming a large number of ester and ethoxy structures. The aging degree of PEG2000 was evaluated from the perspective of surface morphology and chemical structure by gloss and FTIR spectroscopy, and it was found that the combination of gloss loss rate and carbonyl index was more suitable to evaluate the aging degree of the sample. The relevant theoretical research will provide reliable guidance for the preservation of polyethylene glycol in waterlogged wooden cultural relics.

Preparation of hydroxyapatite coated porous carbon nanofibres for DEX loading and enhancing differentiation of BMSCs

The proliferation and differentiation of bone mesenchymal stem cells (BMSCs) in vitro are the key properties of bone tissue engineering for biomaterials. In this study, hydroxyapatite (HA) coated porous carbon nanofibres (PCNFs) were prepared to load dexamethasone (DEX) and further improve the differentiation ability of the BMSCs. Various characterisations were applied to reveal the DEX loading efficacy and biocompatibility, especially the differentiation strength. The results showed that HA could be successfully coated on the PCNFs by pretreating the surface using PEG conjugation. With an increase of HA, the particle diameter increased and the DEX loading decreased. In vitro experiments proved higher cell viability, alkaline phosphatase (ALP) activity, calcium nodule secretion ability and the RUNX2 protein expression, indicating that the as-prepared was of great biocompatibility and optimised osteoconductivity, which was attributed to the componential imitation to natural bone and the accelerated BMSCs differentiation. Consequently, the novel DEX loaded and HA coated PCNFs can provide potential applications in bone tissue regeneration.

Cellulose-Reinforced Polylactic Acid Composites for Three-Dimensional Printing Using Polyethylene Glycol as an Additive: A Comprehensive Review

Growing concerns about environmental issues and global warming have garnered increased attention in recent decades. Consequently, the use of materials sourced from renewable and biodegradable origins, produced sustainably, has piqued the interest of scientific researchers. Biodegradable and naturally derived polymers, such as cellulose and polylactic acid (PLA), have consistently been the focus of scientific investigation. The objective is to develop novel materials that could potentially replace conventional petroleum-based polymers, offering specific properties tailored for diverse applications while upholding principles of sustainability and technology as well as economic viability. Against this backdrop, the aim of this review is to provide a comprehensive overview of recent advancements in research concerning the use of polylactic acid (PLA) and the incorporation of cellulose as a reinforcing agent within this polymeric matrix, alongside the application of 3D printing technology. Additionally, a pivotal additive in the combination of PLA and cellulose, polyethylene glycol (PEG), is explored. A systematic review of the existing literature related to the combination of these materials (PLA, cellulose, and PEG) and 3D printing was conducted using the Web of Science and Scopus databases. The outcomes of this search are presented through a comparative analysis of diverse studies, encompassing aspects such as the scale and cellulose amount added into the PLA matrix, modifications applied to cellulose surfaces, the incorporation of additives or compatibilizing agents, variations in molecular weight and in the quantity of PEG introduced into the PLA/cellulose (nano)composites, and the resulting impact of these variables on the properties of these materials.

Thermo-responsive Diels-Alder stabilized hydrogels for ocular drug delivery of a corticosteroid and an anti-VEGF fab fragment

In the present study, a novel in situ forming thermosensitive hydrogel system was investigated as a versatile drug delivery system for ocular therapy. For this purpose, two thermosensitive ABA triblock copolymers bearing either furan or maleimide moieties were synthesized, named respectively poly(NIPAM-co-HEA/Furan)-PEG6K-P(NIPAM-co-HEA/Furan) (PNF) and poly(NIPAM-co-HEA/Maleimide)-PEG6K-P(NIPAM-co-HEA/-Maleimide) (PNM). Hydrogels were obtained upon mixing aqueous PNF and PNM solutions followed by incubation at 37 °C. The hydrogel undergoes an immediate (<1 min) sol-gel transition at 37 °C. In situ hydrogel formation at 37 °C was also observed after intravitreal injection of the formulation into an ex vivo rabbit eye. The hydrogel network formation was due to physical self-assembly of the PNIPAM blocks and a catalyst-free furan-maleimide Diels-Alder (DA) chemical crosslinking in the hydrophobic domains of the polymer network. Rheological studies demonstrated sol-gel transition at 23 °C, and DA crosslinks were formed in time within 60 min by increasing the temperature from 4 to 37 °C. When incubated at 37 °C, these hydrogels were stable for at least one year in phosphate buffer of pH 7.4. However, the gels degraded at basic pH 10 and 11 after 13 and 3 days, respectively, due to hydrolysis of ester bonds in the crosslinks of the hydrogel network. The hydrogel was loaded with an anti-VEGF antibody fragment (FAB; 48.4 kDa) or with corticosteroid dexamethasone (dex) by dissolving (FAB) or dispersing (DEX) in the hydrogel precursor solution. The FAB fragment in unmodified form was quantitatively released over 13 days after an initial burst release of 46, 45 and 28 % of the loading for the 5, 10 and 20 wt% hydrogel, respectively, due to gel dehydration during formation. The low molecular weight drug dexamethasone was almost quantitively released in 35 days. The slower release of dexamethasone compared to the FAB fragment can likely be explained by the solubilization of this hydrophobic drug in the hydrophobic domains of the gel. The thermosensitive gels showed good cytocompatibility when brought in contact with macrophage-like mural cells (RAW 264.7) and human retinal pigment epithelium-derived (ARPE-19) cells. This study demonstrates that PNF-PNM thermogel may be a suitable formulation for sustained release of bioactive agents into the eye for treating posterior segment eye diseases.

Efficiency Encapsulation of FK506 with New Dual Self-Assembly Multi-Hydrophobic-Core Nanoparticles for Preventing Keratoplasty Rejection

Nanoparticles self-assembled by amphiphilic copolymers for loading hydrophobic molecules are intensively investigated. However, their hydrophobic molecule-loading capacity is low due to the limitation of hydrophobic groups in these copolymers. In this regard, new lysine oligomer-based multi-hydrophobic side chain polymers (MHCPs) are synthesized by polymerization of γ-benzyl-l glutamate N-carboxy anhydride initiated by side-chain primary amino groups in lysine oligomer. Each hydrophobic side chain in MHCPs can be self-assembled by hydrophobic interaction to form multi-hydrophobic-core nanoparticles (MHC-NPs) with silkworm cocoon-, grape cluster-, and butterfly-like shapes (depending on hydrophobic-side-chains lengths). To increase their stability, MHC-NPs are dually self-assembled with polyethylene glycol-polyglutamic acid through charge interaction. Each hydrophobic core in MHC-NPs serves as a carrier for hydrophobic molecules, endowing their nanostructure with high loading capacity. MHC-NPs are employed to load tacrolimus (also known as FK506), and the loading amount is 18% and the loading efficiency is 80%, which are higher than those of previously reported nanomicelles self-assembled by linear amphiphilic copolymers. Topical administration of FK506-loaded nanoparticle (FK506-NP) can significantly prolong retention of FK506 on the eye surface. FK506-NP exhibits higher in vivo immunosuppressive effects than free FK506 and commercial FK506 eye drop, as well as a better protective effect against immunotoxicity in the corneal grafts after keratoplasty.

Melt Processible Biodegradable Blends of Polyethylene Glycol Plasticized Cellulose Diacetate with Polylactic Acid and Polybutylene Adipate-Co-Terephthalate

Enhancing the melt processability of cellulose is key to broadening its applications. This is done via derivatization of cellulose, and subsequent plasticization and/or blending with other biopolymers, such as polylactic acid (PLA) and polybutylene adipate terephthalate (PBAT). However, derivatization of cellulose tends to reduce its biodegradability. Moreover, traditional plasticizers are non-biodegradable. In this study, we report the influence of polyethylene glycol (PEG) plasticizer on the melt processibility and biodegradability of cellulose diacetate (CD) and its blends with PLA and PBAT. CD was first plasticized with PEG (PEG-200) at 35 wt%, and then blended with PLA and PBAT using a twin-screw extruder. Blends of the PEG plasticized CD with PLA at 40 wt% and with PBAT at 60 wt% were studied in detail. Dynamic mechanical analysis (DMA) showed that PEG reduced the glass transition of the CD from ca. 220 °C to less than 100 °C, indicating effective plasticization. Scanning electron microscopy revealed that the CD/PEG-PBAT blend had a smoother morphology implying some miscibility. The CD/PEG-PBAT blend at 60 wt% PBAT had an elongation-to-break of 734%, whereas the CD/PEG-PLA blend had a tensile strength of 20.6 MPa, comparable to that of the PEG plasticized CD. After a 108-day incubation period under simulated aerobic composting, the CD/PEG-PBAT blend at 60 wt% PBAT exhibited a biodegradation of 41%, whereas that of the CD/PEG-PLA at 40 wt% PLA was 107%. This study showed that melt processible, biodegradable CD blends can be synthesized through plasticization with PEG and blending with PBAT or PLA.

Investigation on Filaments for 3D Printing of Nasal Septum Cartilage Implant

Septoplasty is a widely used method in treating deviated septum. Although it is successfully implemented, there are problems with excessive bleeding, septal perforation, or infections. The use of anatomically shaped implants could help overcome these problems. This paper focuses on assessing the possibility of the usage of a nasal septum cartilage implant 3D printed from various market-available filaments. Five different types of laments were used, two of which claim to be suitable for medical use. A combination of modeling, mechanical (bending, compression), structural (FTIR), thermal (DSC, MFR), surface (contact angle), microscopic (optical), degradation (2 M HCl, 5 M NaOH, and 0.01 M PBS), printability, and cell viability (MTT) analyses allowed us to assess the suitability of materials for manufacturing implants. Bioflex had the most applicable properties among the tested materials, but despite the overall good performance, cell viability studies showed toxicity of the material in MTT test. The results of the study show that selected filaments were not suitable for nasal cartilage implants. The poor cell viability of Bioflex could be improved by surface modification. Further research on biocompatible elastic materials for 3D printing is needed either by the synthesis of new materials or by modifying existing ones.

Titanium Dioxide Thin Films Produced on FTO Substrate Using the Sol-Gel Process: The Effect of the Dispersant on Optical, Surface and Electrochemical Features

In this study, TiO₂ thin films formed by dip-coating on an FTO substrate were obtained and characterized using surface, optical and electrochemical techniques. The impact of the dispersant (polyethylene glycol-PEG) on the surface (morphology, wettability, surface energy), optical (band gap and Urbach energy) and electrochemical (charge-transfer resistance, flat band potential) properties were investigated. When PEG was added to the sol-gel solution, the optical gap energy of the resultant films was reduced from 3.25 to 3.12 eV, and the Urbach energy increased from 646 to 709 meV. The dispersant addition in the sol-gel process influences surface features, as evidenced by lower contact-angle values and higher surface energy achieved for a compact film with a homogenous nanoparticle structure and larger crystallinity size. Electrochemical measurements (cycle voltammetry, electrochemical impedance spectroscopy and the Mott-Schottky technique) revealed improved catalytic properties of the TiO₂ film, due to a higher insertion/extraction rate of protons into the TiO₂ nanostructure, as well as a decrease in charge-transfer resistance from 418 k to 23.4 k and a decrease in flat band potential from 0.055 eV to -0.019 eV. The obtained TiO₂ films are a promising alternative for technological applications, due to their advantageous surface, optical and electrochemical features.

Perivascular patch using biodegradable polymers: Investigation of mechanical and drug elution characteristics

Intimal hyperplasia (IH) is the primary cause for the vascular graft stenosis. Perivascular devices offer a potential treatment option to reduce the impact of intimal hyperplasia by providing mechanical support and local administration of therapeutic agents to control cellular overgrowth. In the present study, a perivascular patch primarily made up of biodegradable polymer, Poly L-Lactide, has been designed with adequate mechanical strength and ability for sustained drug elution of anti-proliferative drug (Paclitaxel). The elastic modulus of the polymeric film has been optimized by blending the base polymer with different grades of biocompatible polyethylene glycols. Using design of experiments, the optimized parameters were obtained as PLLA with 2.5% PEG-6000 and have shown 3.14 MPa elastic modulus. The film prepared based on optimum conditions has been employed for prolonged drug delivery (about four months) under simulated physiological conditions. The addition of drug release rate enhancer (polyvinyl pyrrolidone K90F) has improved the drug elution rate and ∼83% drug was released over entire study period. The molecular weight of the base biodegradable polymer was estimated by gel permeation chromatography (GPC) which remained unchanged during the drug release study duration. Evidences of Paclitaxel drug crystallization were found to contribute to the sustained drug elution. The SEM examination of the surface morphology post-incubation revealed micropores on the surface, contributing to the overall drug release rate. The study concluded that perivascular biodegradable films could be tailored for their mechanical properties, and sustained drug elution could also be formulated with reasonable choices of biodegradable polymer and biocompatible additives.

Functional Filaments: Creating and Degrading pH-Indicating PLA Filaments for 3D Printing

With the rapid pace of advancements in additive manufacturing and techniques such as fused filament fabrication (FFF), the feedstocks used in these techniques should advance as well. While available filaments can be used to print highly customizable parts, the creation of the end part is often the only function of a given feedstock. In this study, novel FFF filaments with inherent environmental sensing functionalities were created by melt-blending poly(lactic acid) (PLA), poly(ethylene glycol) (PEG), and pH indicator powders (bromothymol blue, phenolphthalein, and thymol blue). The new PLA-PEG-indicator filaments were universally more crystalline than the PLA-only filaments (33-41% vs. 19% crystallinity), but changes in thermal stability and mechanical characteristics depended upon the indicator used; filaments containing bromothymol blue and thymol blue were more thermally stable, had higher tensile strength, and were less ductile than PLA-only filaments, while filaments containing phenolphthalein were less thermally stable, had lower tensile strength, and were more ductile. When the indicator-filled filaments were exposed to acidic, neutral, and basic solutions, all filaments functioned as effective pH sensors, though the bromothymol blue-containing filament was only successful as a base indicator. The biodegradability of the new filaments was evaluated by characterizing filament samples after aging in soil and soil slurry mixtures; the amount of physical deterioration and changes in filament crystallinity suggested that the bromothymol blue filament degraded faster than PLA-only filaments, while the phenolphthalein and thymol blue filaments saw decreases in degradation rates.

Preparation and Characterization of Electrospun Poly(lactic acid)/Poly(ethylene glycol)-b-poly(propylene glycol)-b-poly(ethylene glycol)/Silicon Dioxide Nanofibrous Adsorbents for Selective Copper (II) Ions Removal from Wastewater

The problem of industrial wastewater containing heavy metals is always a big concern, especially Cu²⁺, which interprets the soil activity in farmland and leaves a negative impact on the environment by damaging the health of animals. Various methods have been proposed as countermeasures against heavy-metal contaminations, and, as a part of this, an electrospun nanofibrous adsorption method for wastewater treatment is presented as an alternative. Poly(lactic acid) (PLA) is a biopolymer with an intrinsic hydrophobic property that has been considered one of the sustainable nanofibrous adsorbents for carrying adsorbate. Due to the hydrophobic nature of PLA, it is difficult to adsorb Cu²⁺ contained in wastewater. In this study, the hydrophilic PLA/poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) (PEG-PPG-PEG) nanofibrous adsorbents with different silicon dioxide (SiO₂) concentrations were successfully prepared by electrospinning. A hydrophilic group of PEG-PPG-PEG was imparted in PLA by the blending method. The prepared PLA/PEG-PPG-PEG/SiO₂ nanofibrous adsorbents were analyzed with their morphological, contact angle analysis, and chemical structure. The Cu²⁺ adsorption capacities of the different PLA/PEG-PPG-PEG/SiO₂ nanofibrous adsorbents were also investigated. The adsorption results indicated that the Cu²⁺ removal capacity of PLA/PEG-PPG-PEG/SiO₂ nanofibrous adsorbents was higher than that of pure ones. Additionally, as an affinity nanofibrous adsorbent, its adsorption capacity was maintained after multiple recycling processes (desorption and re-adsorption). It is expected to be a promising nanofibrous adsorbents that will adsorb Cu²⁺ for wastewater treatment.

Core/Double-Sheath Composite Fibers from Poly(ethylene oxide), Poly(L-lactide) and Beeswax by Single-Spinneret Electrospinning

The conventional approach for preparation of core-sheath fibers is coaxial electrospinning. Single-spinneret electrospinning of emulsions is a much less common method to obtain core-sheath fibers. Core-sheath structure may be generated by electrospinning of homogeneous blend solutions; however, reports on such cases are still scarce. Herein, the preparation of nanofibrous composites from poly(ethylene oxide) (PEO), poly(L-lactide) (PLA) and beeswax (BW) by single-spinneret electrospinning of their homogeneous blend solutions in chloroform is reported. The produced fibers had core/double-sheath structure with a PEO core, PLA inner sheath and BW outer sheath. This original fiber structure was evidenced by transmission electron microscopy, selective extraction of BW or PEO, and X-ray photoelectron spectroscopy. The PLA/BW double sheath led to hydrophobicity of the PEO/PLA/BW mats. The tensile tests revealed that PEO/PLA/BW mats had substantially improved mechanical behavior as compared to PEO, PLA and PEO/BW mats. PEO/PLA/BW mats can be used as drug carriers as evidenced by the one-pot incorporation of the model drug 5-nitro-8-hydroxyquinoline (NQ) into the fibrous materials. Microbiological tests showed that PEO/PLA/BW/NQ had antimicrobial activity. Therefore, the new materials are promising for wound healing applications.

Loading and Release of Phenolic Compounds Present in Mexican Oregano (Lippia graveolens) in Different Chitosan Bio-Polymeric Cationic Matrixes

Mexican oregano (Lippia graveolens) polyphenols have antioxidant and anti-inflammatory potential, but low bioaccessibility. Therefore, in the present work the micro/nano-encapsulation of these compounds in two different matrixes of chitosan (CS) and chitosan-b-poly(PEGMA2000) (CS-b-PPEGMA) is described and assessed. The particle sizes of matrixes of CS (~955 nm) and CS-b-PPEGMA (~190 nm) increased by 10% and 50%, respectively, when the phenolic compounds were encapsulated, yielding loading efficiencies (LE) between 90–99% and 50–60%, correspondingly. The release profiles in simulated fluids revealed a better control of host–guest interactions by using the CS-b-PPEGMA matrix, reaching phenolic compounds release of 80% after 24 h, while single CS retained the guest compounds. The total reducing capacity (TRC) and Trolox equivalent antioxidant capacity (TEAC) of the phenolic compounds (PPHs) are protected and increased (more than five times) when they are encapsulated. Thus, this investigation provides a standard encapsulation strategy and relevant results regarding nutraceuticals stabilization and their improved bioaccessibility.

Highly efficient green up-conversion emission from fluoroindate glass nanoparticles functionalized with a biocompatible polymer

Up-conversion nanoparticles have garnered lots of attention due to their ability to transform low energy light (near-infrared) into high-energy (visible) light, enabling their potential use as remote visible light nano-transducers. However, their low efficiency restricts their full potential. To overcome this disadvantage, fluoroindate glasses (InF3) doped at different molar concentrations of Yb3+ and Er3+ were obtained using the melting-quenching technique, reaching the highest green emission at 1.4Yb and 1.75Er (mol%), which corresponds to the 4S3/2 → 4I15/2 (540-552 nm) transition. The particles possess the amorphous nature of the glass and have a high thermostability, as corroborated by thermogravimetric assay. Furthermore, the spectral decay curve analysis showed efficient energy transfer as the rare-earth ions varied. This was corroborated with the absolute quantum yield (QY) obtained (85%) upon excitation at 385 nm with QYEr = 17% and QYYb = 68%. Additionally, InF3-1.4Yb-1.75Er was milled and functionalized using poly(ethylene glycol) to impart biocompatibility, which is essential for biomedical applications. Such functionalization was verified using FTIR, TG/DSC, and XRD.

Hypoxia-Responsive Stereocomplex Polymeric Micelles with Improved Drug Loading Inhibit Breast Cancer Metastasis in an Orthotopic Murine Model

Tumor metastasis is a leading cause of breast cancer-related death. Taxane-loaded polymeric formulations, such as Genexol PM and Nanoxel M using poly(ethylene glycol)-poly(d,l-lactide) (PEG-PLA) micelles as drug carriers, have been approved for the treatment of metastatic breast cancer. Unfortunately, the physical instability of PEG-PLA micelles, leading to poor drug loading, premature drug leakage, and consequently limited drug delivery to tumors, largely hinders their therapeutic outcome. Inspired by the enantiomeric nature of PLA, this work developed stereocomplex PEG-PLA micelles through stereoselective interactions of enantiomeric PLA, which are further incorporated with a hypoxia-responsive moiety used as a hypoxia-cleavable linker of PEG and PLA, to maximize therapeutic outcomes. The results showed that the obtained micelles had high structural stability, showing improved drug loading for effective drug delivery to tumors as well as other tissues. Especially, they were capable of sensitively responding to the hypoxic tumor environment for drug release, reversing hypoxia-induced drug resistance and hypoxia-promoted cell migration for enhanced bioavailability under hypoxia. In vivo results further showed that the micelles, especially at a high dose, inhibited the growth of the primary tumor and improved tumor pathological conditions, consequently remarkably inhibiting its metastasis to the lungs and liver, while not causing any systemic toxicity. Hypoxia-responsive stereocomplex micelles thus emerge as a reliable drug delivery system to treat breast cancer metastasis.

Access to high-molecular-weight poly(γ-butyrolactone) by using simple commercial catalysts

The simple commercial organomagnesium catalysts were utilized for efficient access to high-molecular-weight poly(γ-butyrolactone) and facile manipulation of the reaction conditions enabled the polymer topology controlled.

Surface coating prolongs the degradation and maintains the mechanical strength of surgical suture in vivo

Biodegradable and absorbable sutures have been widely used in surgical procedures. However, for the repair of ligament and tendon injures, the biodegradable suture cannot provide sufficient mechanical support to close the wound for a long period of time which is important to completely heal the tissue. Herein, we develop a simple method that makes a surface coating to prolong the degradation of the suture in vivo. Polylactic acid (PLLA) and Polycaprolactone (PCL) were successfully coated to a commercial degradable polydioxanone (PDO) suture in this study, which was confirmed by Fourier transform infrared spectra (FTIR). Scanning electron microscopy (SEM) was used to observe the smooth surface of the coated sutures. Moreover, live/dead assay of human fibroblasts after co-culturing with the modified/unmodified sutures showed fairly good cellular activity. In vivo study demonstrates the degradation properties of sutures were significantly changed after the surface coating. The raw suture exhibited the fastest degradation in 12 weeks, showing significantly decline in mechanical strength. Interestingly, the PCL-coated suture was able to maintain more than 20% of its original tensile strength after 12 weeks' implantation. In addition, in vivo results of PCL-coated sutures also showed less inflammatory cell infiltration and less surface inflammation. These findings indicate the one step suture-coating method could be feasibly for the development of clinical equipment.

Toughened PLA-b-PCL-b-PLA triblock copolymer based biomaterials: effect of self-assembled nanostructure and stereocomplexation on the mechanical properties

The current research unfolds the effect of block lengths, microdomain morphology and stereocomplexation on the mechanical properties of PLA-b-PCL-b-PLA triblock copolymers where PCL is involved to improve the poor extensibility of PLA.