Volume 62, Issue 3

Abstract: Fused Filament Fabrication (FFF) is an additive manufacturing process with wide use. However, the optimization of certain parameters presents some uncertainties in the FFF process. In the present study, the effect of infill density (ID) on the flexural behavior of Polylactic Acid (PLA) parts printed by the FFF process was investigated. The experimental tests were performed on rectangular parts, according to the ISO 178 standard, with a test speed of 5 mm/min. Parts with several IDs in the 20–100% range were 3D printed, analyzed, and tested. Every sample was subjected to dimensional and mass analyses before the experimental tests. After testing, the failure mechanisms were highlighted depending on the ID. It was found that the ID of the printed parts strongly influences the flexural characteristics (elastic, strength, strain, and energy absorption). However, using the specific properties (specific modulus and specific strength), it was noted that 20%-ID is the optimal density for such AM structures. Slight dependencies on IDs were recorded for dimensional accuracy. It was obtained that at low IDs (⁢ [ 40%), the FFF-printed parts show a quasi-brittle fracture, and with its increase (IDs > 60%), a slight plastic deformation was observed.

Abstract: Flexible and acrylic resins are used as denture bases. Acrylic resins derived from polymethyl methacrylate are the conventional approach. Flexible thermoplastic resins are the alternative, and of these, polyamides with low flexibility and ethylene propylene resins are often used in current practice. The biocompatibility, flexibility, non-allergenic properties, and ease of denture insertion all highlight the suitability of these materials. This study aims to evaluate the behavior of low flexibility polyamide, ethylene propylene resin, and polymethyl methacrylate resin, used as partial denture bases, by monitoring the specific parameters obtained. The evaluation of the behavior of the materials was carried out by clinical examination. Additionally, a questionnaire was used. The results with both flexible resins are almost similar and superior to conventional resins, in partially edentulous patients, in difficult clinical situations, on undercut prosthetic areas, and in extended edentulous, tilted teeth, or when the patient has a limited mouth opening. The prognosis over time with polyamides with low flexibility and ethylene propylene resins is more advantageous than with classic acrylic resins.

Abstract: [b]Background:[/b] Barrier membranes prevent soft tissue invasion while promoting bone healing, suggesting a potential significance in guided bone regeneration (GBR). However, many resorbable membranes lack adequate mechanical strength and long-term stability. Polyethylene terephthalate (PET), a biostable polymer, exhibits promising properties for GBR but remains underexplored. [b]Methods:[/b] Electrospun PET nanofiber membranes (PET-1 to PET-4) were fabricated by systematically varying solution concentrations and processing conditions. Their morphology was analyzed by scanning electron microscopy (SEM), and mechanical properties were assessed via tensile testing. Surface wettability was reflected by the water contact angle. In vitro biocompatibility was evaluated using the CCK- 8 assay using L929 mouse fibroblasts. Barrier function was tested by Transwell and time-course fibroblast migration assays. [b]Results:[/b] All PET membranes exhibited uniform nanofiber structures with good mechanical integrity. PET-4 showed the highest tensile strength (13.5 MPa) and elastic modulus (190 MPa). Contact angles ranged from 85◦ to 93◦, which indicated moderate hydrophobicity. Cytocompatibility was high across all the groups, with PET-4 representing nearly 100% cell viability. In migration assays, PET-4 significantly suppressed fibroblast invasion over 48 h. [b]Conclusion:[/b] Electrospun PET nanofiber membranes demonstrated excellent mechanical performance, cytocompatibility, and barrier function. PET-4 emerged as a particularly promising candidate for GBR application, offering effective long-term soft tissue exclusion and bone regeneration support.

Abstract: Lithography is a core-pattern transfer technique in micro/nanofabrication, among which electron-beam lithography (EBL) is a representative example. Polymethyl methacrylate (PMMA) has been widely employed as an electron-beam resist due to its high sensitivity, high resolution, and excellent contrast. However, commercial PMMA resists are relatively expensive and have complex formulations, thereby limiting process flexibility and cost control. Here, we demonstrate a rapid, low-cost preparation method for a PMMA resist suitable for micrometer-scale EBL. PMMA powder was dissolved in anisole to obtain a 4 wt% solution, which was spin-coated onto substrates to form uniform and smooth thin films. To evaluate resist performance, a custom-designed 5 × 5 array pattern was used to systematically study the effect of exposure dose on pattern quality. Results show that doses below 200 μC/cm² fail to induce complete scission of the PMMA molecular chains. Thermal evaporation and a lift-off process were employed to verify the dimensional accuracy of fabricated electrodes. Within the exposure dose range of 240–270 μC/cm², the electrode patterns were complete and exhibited straight edges. The optimal pattern fidelity was achieved at 260 μC/cm², with an absolute dimensional error below 0.2 μm, meeting the precision requirements of most micro/nanofabrication applications. This work provides a practical process reference for the preparation of PMMA electron-beam resists and their application in nanodevice fabrication.

Abstract: [b]Background:[/b] Effective pain control is often limited by the short duration and systemic side effects of conventional lidocaine administration. Transdermal delivery systems offer a non-invasive alternative, but require materials that match skin mechanics and provide sustained drug release. [b]Methods:[/b] We designed a stretchable, biodegradable elastomer patch composed of a Poly(glycerol sebacate) (PGS) top layer and a lidocaine-loaded Poly(lactic-co-glycolic acid) (PLGA) reservoir. The patch’s mechanical properties, degradation behavior, drug release kinetics, transdermal permeation, and analgesic efficacy were systematically evaluated in vitro and in vivo. [b]Results:[/b] The patch exhibited a skin-like modulus and remained flexible during deformation. In vitro, it sustained lidocaine release over 48 h and degraded to ~20% mass over 30 days. Franz cell experiments confirmed effective skin permeation. In a rodent model, the patch significantly increased paw withdrawal thresholds compared to free drug. [b]Conclusion:[/b] This multilayer elastomer patch provides conformal adhesion, sustained lidocaine release, and enhanced local analgesia, offering a promising platform for non-invasive, long-acting pain management.

Abstract: [b]Objective:[/b] To investigate and optimize the alkaline extraction process of Ganoderma lucidum polysaccharides, and to preliminarily explore their immunological activity. [b]Methods:[/b] Ganoderma lucidum was used as the raw material for the extraction of polysaccharides. A single-factor experiment was conducted to examine the effects of NaOH concentration, temperature, and extraction time on the total sugar content of the polysaccharides. Based on these results, response surface methodology was applied to optimize the extraction process. The total polysaccharide content, uronic acid content, monosaccharide composition, molecular weight, and cell viability were measured. [b]Results:[/b] The optimal extraction conditions were found to be a temperature of 93◦C, NaOH concentration of 0.40 mol/L, and extraction time of 172 min, yielding a total polysaccharide content of 47.66%. The monosaccharide composition of the extracted polysaccharides included mannose, glucuronic acid, glucose, galactose, arabinose, and fucose. Molecular weight analysis revealed two average molecular weights, 3.15 × 104 Da and 1.014 × 104 Da, indicating the polysaccharides were relatively small. Infrared spectroscopy showed the presence of β-type glycosidic linkages in the polysaccharides. In the cell viability assay, GLCP-1 enhanced the viability of RAW264.7 cells and significantly inhibited the viability of HepG2 cells. However, the specific regulatory mechanism remains unclear. [b]Conclusion:[/b] The study successfully optimized the alkaline extraction of Ganoderma lucidum polysaccharides and demonstrated their potential immunological activity, providing a foundation for the future exploration of their bioactivity and industrial production.

Abstract: Clopidogrel is widely used for stroke prevention, but its oral administration is limited by poor patient adherence, gastrointestinal irritation, and hepatic first-pass metabolism. To address these limitations, we developed a biodegradable microneedle patch composed of poly(lactic-co-glycolic acid) (PLGA) and polyvinylpyrrolidone (PVP) for the transdermal delivery of clopidogrel. The patch exhibited sufficient mechanical strength to penetrate the skin simulant and fully dissolve within 6 h. Drug release was sustained over 48 h in vitro, and platelet aggregation was evaluated using a simulated human platelet-rich plasma (PRP) model. Compared to clopidogrel solution, the microneedle patch maintained longer antiplatelet activity, with significant inhibition observed up to 72 h. These findings suggest that dissolvable microneedle patches may serve as a non-invasive and sustained delivery strategy for clopidogrel, potentially improving therapeutic consistency and patient compliance in stroke prophylaxis.

Abstract: Polypropylene (PP) is a commonly used raw material for the production of 3D printing composite filament, which has many advantages, such as low density, insulation, chemical resistance, and environmental friendliness, but its mechanical strength is poor, which affects the comprehensive performance of the 3D printing PP model. In order to effectively improve the flexural strength of material-extrusion-based 3D printing (ME-3DP) PP model, this study investigated the influence of three printing parameters (infill rate, extrusion speed, platform temperature) on the flexural strength of the 3D printed PP model through the three-point support flexural test. The results show that the flexural strength of 3D printed PP model gradually increases with the increase of the infill rate, the decrease of the extrusion speed, and the increase of the platform temperature; the degree of influence of the three parameters on the flexural strength of the 3D printed PP model is as follows: infill rate ] extrusion speed ] platform temperature; the optimal combination of the printing parameters is as follows: infill rate (90%), extrusion speed (20 mm/s), and platform temperature (70°C). The flexural strength of the 3D printed PP model fabricated according to the optimal printing parameters is 41.7 MPa, which is the maximum value in the orthogonal experiment, verifying the reliability of the experiment results.