Search Results (967)

This study investigates the relationship between microscale indentation creep and macroscale tensile creep of immiscible polymer blends. Micro- and macroscale creep were measured across the full composition range of model poly(lactic acid)/poly(caprolactone) blends (PLA/PCL), using indentation loadings of 50 and 300 gf and a tensile loading of 2 kg. The creep data were fitted with the empirical power law (PL) model and three phenomenological elasto-visco-plastic (EVP) models implemented in our open-source Python package MCREEP (version 1.1.6). Traditional creep descriptors, such as indentation creep (C_IT) defined by ISO standard or the creep exponent (n) from the well-established empirical PL model (deformation = C·tⁿ), yielded inconsistent or even misleading results. However, detailed analysis of the creep curves showed that alternative creep descriptors, such as the total deformation corrected for the initial deformation, exhibited the same trends at the micro- and macroscale and strong linear correlations (R² > 0.97). These findings demonstrate that short-term microindentation creep can predict the ranking of macroscale creep behavior in polymer blends, provided that suitable creep descriptors are employed. Full article

Spinal surgery involves highly complex procedures where the risk of severe complications, including postoperative infections, may compromise both surgical success and patient survival. In this study, functional coatings for spinal screws were developed to promote bone integration and simultaneously prevent infection. The coating design employed a multilayer architecture based on poly(ε-caprolactone) (PCL) as the main structural layer, covered with chitosan (CS), a biocompatible polymer that enhances surface interaction with both the metallic substrate and the active agents. To stimulate bone regeneration, calcium β-hydroxy-β-methylbutyrate (HMB) was incorporated, while antimicrobial efficacy was achieved by embedding PLGA-based polymeric microspheres encapsulating gentamicin sulfate, a broad-spectrum antibiotic. The obtained results confirmed the successful integration of all components, as evidenced by FTIR and Raman spectroscopy, along with homogeneous surface morphologies observed via SEM analysis. Biological assays demonstrated significant antimicrobial activity against Staphylococcus aureus and Escherichia coli. The developed coatings therefore exhibit strong potential as bioactive, dual-functional protective layers for spinal screws, providing both osteoconductive and antimicrobial properties. Full article

Background/Objectives: Shape-memory biodegradable scaffolds (4D scaffolds) represent promising platforms for minimally invasive tissue engineering and localized drug delivery. This study investigated how two different fabrication techniques, electrospinning (ES) and extrusion-based direct ink writing (DIW), influence the structural, thermal, mechanical, shape-memory, and drug-release properties of poly(L-lactide-co-caprolactone) (PLA/PCL 70:30) scaffolds loaded with dexamethasone (DXM). Methods: DXM-loaded PLA/PCL 70:30 scaffolds were fabricated by ES and DIW. The resulting matrices were characterized in terms of morphology, mass, thickness, drug-loading efficiency, thermal properties by differential scanning calorimetry, shape-memory performance, tensile mechanical properties, and in vitro DXM release. Results: Both fabrication techniques produced DXM-loaded matrices with comparable mass and thickness and high loading efficiencies (>82%). Glass transition temperatures ranged between 33 and 39 °C, supporting thermally induced shape recovery under physiologically relevant conditions, while ES processing was associated with higher polymer crystallinity. All scaffolds exhibited shape-memory behavior, with recovery ratios exceeding 90%. ES scaffolds displayed a microporous nanofibrous architecture, whereas DIW scaffolds showed a more open and highly porous structure. These morphological differences were reflected in their mechanical behavior: ES scaffolds exhibited higher tensile strength (up to 16.5 MPa vs. 1.9 MPa) and elongation at break (up to 320% vs. 243%). Drug-release profiles were also fabrication-dependent, with ES scaffolds reaching a plateau at approximately 80% DXM release, whereas DIW scaffolds showed near-complete release within 48 h. Conclusions: Both fabrication approaches preserved the thermoresponsive shape-memory behavior of PLA/PCL 70:30 but generated distinct scaffold architectures that strongly influenced mechanical performance and DXM-release kinetics. Full article

Background/Objectives: Multipurpose prevention technologies (MPTs) that combine protection against HIV and unintended pregnancy can improve women’s health outcomes by simplifying use and enhancing adherence. We developed a long-acting (LA) implant for the simultaneous and sustained delivery of the antiretroviral islatravir (ISL) and the contraceptive hormone etonogestrel (ENG). Methods: Using extruded poly-ε-caprolactone (PCL) tubing, reservoir-style implants were fabricated and evaluated in three configurations: (Group 1) a two-segment implant formed by joining separate ISL- and ENG-containing tubes; (Group 2) a single tube divided into two drug compartments by a heat-sealed PCL spacer; (Group 3) separate single-drug implants. In vitro release was assessed in phosphate-buffered saline at 37 °C, and safety and pharmacokinetic (PK) profiles were evaluated in New Zealand White rabbits (n = 4/group) over approximately 90 days. Results: The average ISL daily in vitro release rates for Groups 1, 2, and 3 were 29 ± 5 µg/day, 18 ± 5 µg/day, and 47 ± 8 µg/day, respectively, and ENG daily in vitro release rates were 39 ± 9 µg/day, 41 ± 8 µg/day, and 33 ± 7 µg/day. From day 28 through the end of the study, median (IQR) plasma concentrations were 0.22 (0.18–0.27) ng/mL, 0.28 (0.24–0.33) ng/mL, and 0.31 (0.28–0.33) ng/mL for ISL in Groups 1, 2, and 3, respectively, and 0.26 (0.21–0.31) ng/mL, 0.25 (0.16–0.47) ng/mL, and 0.30 (0.23–0.38) ng/mL for ENG in Groups 1, 2 and 3, respectively. Implants across all groups were well tolerated and demonstrated favorable local tolerability over the 90-day dosing period. Conclusions: Integration of multiple indications into a single platform capable of sustained release over an extended duration holds potential to address persistent gaps in women’s sexual and reproductive health needs. Full article

Flexible polymer–ferrite composites provide a route for lightweight functional materials with tunable surface and structural properties. Here, poly(ε-caprolactone) (PCL)/Ti⁴⁺-doped barium hexaferrite (BaMTi⁴⁺) films containing 10–50 wt.% ferrite were prepared by solvent casting and characterized by XRD, FTIR, SEM, AFM, and fractal analysis. XRD confirmed the coexistence of semicrystalline PCL and magnetoplumbite-type BaMTi⁴⁺, whereas FTIR indicated preservation of the polymer backbone and non-covalent interfacial interactions. Morphological and topographical analyses revealed a composition-dependent transition from compact polymer-rich surfaces to rougher ferrite-rich architectures. Surface roughness decreased at 10 wt.% BaMTi⁴⁺ and increased at higher loadings, reaching Sa = 33.10 nm and Sq = 42.54 nm at 50 wt.%. Power spectral density and fractal analyses showed enhanced spatial correlation, with the Hurst exponent increasing from 0.51 to 0.81 and the fractal dimension decreasing from 2.49 to 2.19. These results demonstrate that ferrite loading effectively controls the multiscale surface organization of magnetically active PCL films. Full article

The global threat of multidrug-resistant infections requires new approaches for its management. A blend of polymethyl methacrylate (PMMA) and poly(ε-caprolactone) (PCL) electrospun nanofibrous membrane was utilised as a scaffold to sustain the release of three broad-spectrum antiseptics to combat multidrug-resistant (MDR) microorganisms. The scaffold was characterised by Fourier transform infrared spectroscopy, contact angle, and scanning electron microscopy. The latter revealed a random and smooth structure. The contact angle value of 81.8 ± 1.8 confirmed the hydrophilic nature of the scaffold, which is important for wound healing. The high surface-to-volume ratio of the scaffolds was utilised for loading benzoic acid (BA), methylparaben (MPB), and propylparaben (PPB) which were released during 72 h concentrations ranging between 0.20 and 0.8 mg mL⁻¹. The initial release of antiseptics was high and was then sustained for over 72 h. After 8 h, the burst release was 61.64 ± 4.11% for BA, 41.11 ± 2.98% for MPB and 34.32 ± 3.13% for PPB. The release profile of BA was superior to that of the MPB and PPB. The loaded scaffolds inhibited MDR-resistant methicillin-resistant Staphylococcus aureus, Escherichia coli and Candida albicans and were not cytotoxic to a fibroblast cell line. They inhibited their colonisation by the tested microorganisms to non-detectable counts or at least reduced microbial counts by at least 6–7 logs (p ≤ 0.001) for 72 h. Crystal violet techniques and electron microscopy confirmed colonisation inhibition. Because of their non-cytotoxicity and broad-spectrum antimicrobial activity, the antiseptic-loaded PMMA/PCL nanofibrous scaffolds could be utilised as wound dressings, particularly in non-healing wounds. Full article

Chemical recycling of plastic waste into value-added chemicals represents a key strategy for advancing a circular plastics economy. Herein, we report the first systematic application of commercially available Florisil^® as an inexpensive, readily available heterogeneous catalyst for the alcoholysis of polyester and polycarbonate plastic waste. Under optimized conditions, poly(lactic acid) (PLA), poly(ε-caprolactone) (PCL), poly(4-hydroxybutyrate) (P4HB), poly(butylene succinate) (PBS), poly(ethylene succinate) (PES), and bisphenol A polycarbonate (PC-BPA) were efficiently depolymerized into valuable diesters and diols in good to excellent yields (up to ~90%). The catalytic system also maintained high performance on a larger reaction scale and proved effective for the selective depolymerization of mixed polyester waste streams, demonstrating its robustness and practical applicability. Unlike many previously reported catalytic systems that rely on metal salts or specially synthesized catalysts, Florisil^® requires no prior modification and combines operational simplicity with high catalytic efficiency. These findings establish Florisil^® as a sustainable and practical catalytic alternative for plastic waste valorization, broadening the range of accessible heterogeneous catalysts for chemical recycling. Full article

Chronic cutaneous ulcers pose a major clinical challenge due to persistent inflammation, impaired angiogenesis, and limited regenerative capacity, underscoring the need to develop bioactive scaffolds that mimic the extracellular matrix (ECM) and promote skin repair. In this study, electrospun Poly(ε-caprolactone) (PCL) scaffolds functionalized with 10% (PCLGLI10) and 20% (PCLGLI20) glycine were fabricated, physicochemically and mechanically characterized, and evaluated in combination with human Wharton’s jelly mesenchymal stromal cells (hWJ-MSCs). Glycine incorporation reduced fiber diameter to the nanoscale range (140–155 nm) and increased scaffold porosity (~71–72%) while preserving mechanical properties compatible with skin. FTIR and X-ray diffraction analyses confirmed glycine incorporation and a polymorphic transition from α- to γ-glycine during electrospinning. Cell viability remained above 95% in all scaffolds; however, PCLGLI10 significantly enhanced cell proliferation, metabolic activity, and the secretion of VEGF and HGF, mediators associated with angiogenesis and tissue repair. Furthermore, in a guinea pig full-thickness wound model, the PCLGLI10+hWJ-MSCs construct promoted a modulated inflammatory response and more organized collagen deposition. These findings support the potential of glycine-functionalized electrospun scaffolds as a promising strategy for chronic cutaneous ulcer regeneration. Full article

Poor adherence to prolonged antibiotic regimens remains a major challenge in the treatment and prevention of chronic infectious diseases such as tuberculosis. Transdermal drug delivery systems capable of sustained antibiotic release may improve therapeutic compliance while reducing the need for frequent oral administration. In this study, electrospun polymeric membranes based on poly(lactic acid) (PLA) and poly(ε-caprolactone) (PCL) were developed as transdermal rifampicin delivery platforms. Homogeneous nanofibrous membranes with average fiber diameters of approximately 250 nm were successfully fabricated and exhibited efficient drug incorporation while preserving the structural integrity of the polymeric matrix. The electrospun membranes retained sufficient tensile strength and dimensional stability after accelerated temperature–humidity aging, supporting their stability during storage, handling, and application. In vitro cytotoxicity and biocompatibility assays using primary human peripheral blood mononuclear cells (PBMCs) demonstrated that the developed systems did not induce significant cytotoxic or pro-inflammatory responses. Transdermal permeation studies using an in vitro mouse skin model demonstrated sustained rifampicin diffusion for at least 72 h. Importantly, the antibiotic recovered after skin permeation preserved antimycobacterial activity against Mycobacterium tuberculosis H37Ra and Mycobacterium bovis BCG, confirming that rifampicin maintained its biological functionality after electrospinning and transdermal migration. Overall, these findings demonstrate the potential of electrospun PLA/PCL membranes as stable and biocompatible transdermal antibiotic delivery systems capable of sustained release and preservation of antimicrobial activity. This proof-of-concept study supports the translational potential of electrospun polymeric platforms for controlled antibiotic delivery in long-term infectious disease therapies. Full article

Background/Objectives: Chronic wounds remain difficult to manage because persistent inflammation, microbial colonization, and excess exudate require dressings that combine structural integrity, bioactivity, antimicrobial performance, and cytocompatibility. This study aimed to develop electrospun nanofibrous mats based on gelatin, poly(vinyl alcohol) (PVA), and poly(ε-caprolactone) (PCL), with and without Brazilian red propolis extract (BRPE), and to evaluate how extract incorporation affects solution properties, fiber morphology, fluid interaction, antimicrobial activity, and cytocompatibility. Methods: BRPE was characterized in terms of solid content, total phenolic content, antioxidant activity, and HPLC-DAD marker profile. Polymeric solutions were evaluated for electrical conductivity and rheological behavior and then processed by electrospinning under fixed conditions. The resulting mats were characterized by scanning electron microscopy, surface porosity, FTIR, and HPLC-DAD. Their performance was further assessed by swelling-associated degradation in simulated wound fluids, agar diffusion antimicrobial assays, and MTT cytocompatibility assays using HaCaT cells. Results: BRPE showed a solid content of 3.88%, a total phenolic content of 8.79 ± 0.21 mg pyrogallol equivalents g⁻¹ extract, and an antioxidant activity of 75.32 ± 9.80 mg Trolox equivalents g⁻¹ extract. HPLC-DAD confirmed preservation of the BRPE chromatographic fingerprint after electrospinning, with high retention of marker peaks associated with liquiritigenin and a formononetin-related signal. Solution conductivity varied with polymer composition and BRPE incorporation; for example, the PVA:gelatin:PCL formulation A4/A4.1 at 70:20:10 decreased from 919.6 to 539.6 µS cm⁻¹ after BRPE loading. Electrospinning produced continuous, defect-free fibers with mean diameters ranging from 94 to 224 nm and surface porosity between 9.8 and 10.6%. Most hydrophilic systems showed rapid fluid interaction but limited wet-state structural stability; among the quantified formulations, A5 showed the lowest mass loss, indicating better structural preservation under simulated wound conditions. BRPE-loaded mats showed microorganism-dependent antimicrobial activity, with the strongest inhibition against Staphylococcus epidermidis and Klebsiella pneumoniae and no activity against Pseudomonas aeruginosa. Free BRPE showed marked cytotoxicity, whereas selected electrospun formulations, especially A1.1 and A3.1, improved HaCaT cell viability. Conclusions: Electrospinning was an effective strategy for incorporating BRPE into polymeric nanofibers and modulating the physicochemical and biological performance of the resulting mats. These findings support the potential of these materials as multifunctional wound-dressing platforms, although further optimization is needed to improve wet-state structural stability, mechanical performance, and bioactive release. Full article

The development of 3D printing high-impact denture bases is challenging, as materials exhibiting both high flexural strength/modulus and fracture toughness are required. Nowadays, most of the commercially available 3D printing denture bases contain significant amounts of crosslinking monomers and therefore behave as brittle materials. In this contribution, urethane dimethacrylate DMA1/(octahydro-4,7-methano-1H-indenyl)methyl acrylate (OMIMA) 1/1 (wt/wt) formulations containing a poly(ε-caprolactone)-polydimethylsiloxane-poly(ε-caprolactone) (PCL-PDMS-PCL) triblock copolymer (BCP1) and fumed silica SiO₂-NPs were evaluated for DLP 3D printing of fracture-tough denture bases. The post-curing step was performed at various temperatures (RT, 60 °C, 80 °C, 100 °C and 120 °C). This parameter was shown to strongly influence the T_g and mechanical properties of 3D printed materials. A post-curing temperature of 100 °C was found to be ideal. Under these conditions, 3D printed materials exhibiting excellent mechanical properties were successfully obtained. Furthermore, the amounts of BCP1 and SiO₂-NPs were varied. The formulation containing 8.0 wt% of BCP1 and 10.0 wt% of SiO₂-NPs (FS = 67.5 ± 1.3 MPa, FM = 2450 ± 71 MPa, K_max = 2.11 ± 0.06 MPa m^1/2, W_f = 1109 ± 19 J m⁻²) was able to fulfill the ISO 20795-1:2013 requirements in terms of flexural strength (FS)/modulus (FM) and fracture toughness for denture bases with improved impact resistance (FS > 65 MPa, FM > 2000 MPa, K_max > 1.9 MPa m^1/2, W_f > 900 J m⁻²). This material showed better performance than the commercially available formulations Printodent^® GR-14.2 denture HI (FS = 69.2 ± 1.8 MPa, FM = 2153 ± 76 MPa, K_max = 0.82 ± 0.04 MPa m^1/2, W_f = 79 ± 10 J m⁻²) and Lucitone Digital Print^TM 3D denture base (FS = 56.7 ± 1.9 MPa, FM = 2144 ± 12 MPa, K_max = 1.92 ± 0.09 MPa m^1/2, W_f = 1272 ± 177 J m⁻²). Full article

The long-term stability of biodegradable polymer coatings deposited by matrix-assisted pulsed laser evaporation (MAPLE) remains insufficiently understood, particularly under ultraviolet irradiation conditions where photochemical effects may accompany material transfer. In this work, thin films of poly(lactide-co-caprolactone)-block-poly(ethyleneglycol)-block-poly(lactide-co-caprolactone), also known as PLCL-PEG-PLCL, are deposited from chloroform solutions by UV-MAPLE using a nanosecond Nd:YAG laser operating at 266 nm over a wide laser fluence range (0.25–0.9 J/cm²). The effect of laser fluence on the morphological, structural, and chemical evolution of the coatings is investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), focused ion beam scanning electron microscopy (FIB-SEM), and X-ray diffraction (XRD). At low laser fluence, relatively homogeneous coatings are obtained while largely preserving the characteristic functional groups of the triblock copolymer. Increasing the laser fluence progressively induces surface restructuring phenomena, including droplets, wrinkles, and the appearance of highly symmetric faceted structures. These entities develop preferentially in samples deposited at elevated fluence and frequently appear only after prolonged aging under ambient conditions, revealing delayed recrystallization behaviour associated with metastable species generated during the deposition process. EDS analyses reveal localized chlorine enrichment within the faceted structures, while FIB-SEM investigations show porous internal morphologies. XRD confirms that the polymer matrix remains predominantly amorphous. The combined observations suggest that UV-MAPLE deposition from chloroform involves not only physical material transfer but also photochemical processes that promote decomposition, recombination, and delayed crystallization phenomena. A phenomenological model describing the successive stages of surface evolution, aging, and recrystallization is proposed. These results provide new insight into the long-term evolution of laser-deposited biodegradable polymer coatings and highlight the importance of solvent selection and processing conditions in determining their stability. Full article

Cartilage engineering is a new therapeutic approach in regenerative medicine. This study explored the chondrogenic potential of human dental pulp stem/stromal cells (hDPSCs) and adipose-derived stem/stromal cells (hAD-MSCs) grown on a hydrolytically modified poly(L-lactide-co-caprolactone) (PLCL) electrospun scaffold in relation to the phenotype of primary chondrocytes on PLCL. The effects of PLCL scaffold on the biological features of hDPSC, hAD-MSC, and their chondrogenic differentiation and chondrocytes biology were evaluated via flow cytometry, immunochemistry, biochemistry, and RT–PCR. The results demonstrated that PLCL supported hDPSC, hAD-MSC, and chondrocyte viability and cellular attachment. The chondrogenic potential of hDPSCs and hAD-MSCs on PLCL scaffold was evidenced by the mRNA expression of the cartilage-specific genes. Collagen type II (Col II) and aggrecan (Acan) gene expression and their proteins significantly increased in chondrogenically differentiated hDPSCs and hAD-MSCs on PLCL compared with undifferentiated stem/stromal cells on PLCL. The phenotype of differentiated hDPSCs and hAD-MSCs was comparable to primary chondrocytes grown on PLCL. The results of this study showed that PLCL scaffold promoted chondrogenic differentiation of hAD-MSCs and hDPSCs toward chondrocytes with phenotypic similarities to native chondrocytes. The PLCL scaffold composition has a positive effect on hDPSC, hAD-MSC, and chondrocyte behavior, chondrogenic gene expression, and matrix protein synthesis. Full article

Hydrophilic surface modification is widely investigated as a strategy to improve the hemocompatibility of small-diameter vascular grafts. We previously developed a polyvinyl alcohol-coated poly-ε-caprolactone nanofiber graft (PVA–PCL graft) and showed that the PVA coating improved graft hydrophilicity and mechanical properties. However, whether this coating provides an in vivo advantage over uncoated PCL grafts remains unclear. In addition, the influence of pre-implantation surface hydration on the function of hydrophilic grafts has not been fully examined. In this study, we first compared PVA–PCL and uncoated PCL grafts in a rat abdominal aorta implantation model and found no statistically significant difference in patency rate between the graft types. We then examined whether pre-wetting enhanced the anti-fouling function of the PVA coating. In vitro whole-blood flushing assays demonstrated that pre-wetting markedly reduced blood component deposition on PVA–PCL grafts, but this effect did not translate into detectable improvements in patency or tissue regeneration in the rat model. These findings indicate that pre-wetting effectively enhances the in vitro anti-fouling behavior of PVA–PCL grafts and may serve as a simple strategy to optimize the functional surface state of hydrophilic coatings. Further studies are needed to determine whether this in vitro improvement can be translated into meaningful enhancement in graft performance in vivo. Full article

This study evaluates the intrinsic osteogenic potential of β-tricalcium phosphate (β-TCP)-containing composite scaffolds (PLCL–TCP, PLGA–TCP, and ZnO–TCP) on chorion-derived mesenchymal stem cells (CMSCs) under non-osteogenic in vitro conditions. CMSCs were cultured on the three biomaterials for 35 days without osteogenic supplements to isolate the material-driven cellular response. Cell viability was assessed via MTT assay, while osteogenesis-associated markers (alkaline phosphatase, type I collagen, and osteocalcin) were quantified using ELISA. Scaffold surface morphology and elemental composition were characterized before and after cultivation utilizing SEM and EDX. All investigated scaffolds supported long-term CMSC viability and induced measurable osteogenic responses. PLCL–TCP demonstrated a consistently strong biological response, characterized by sustained metabolic activity, elevated ALP and COL I production, and increased osteocalcin levels at later stages of cultivation. ZnO–TCP also exhibited favorable osteogenesis-associated responses, particularly with respect to late-stage osteocalcin production, while maintaining high structural stability. In conclusion, β-TCP composites can intrinsically modulate CMSC behavior without biochemical supplements. Osteogenic outcomes depend on a complex interplay of surface chemistry, scaffold architecture, and degradation profiles, with PLCL–TCP demonstrating favorable overall performance among the investigated biomaterials. Full article