Volume 63, Issue 3

Abstract: This commentary emphasizes the significance of conceptually biofunctional polymeric dental restorations in promoting improved periodontal health. Advances in periodontal and restorative dentistry suggest that conceptual biofunctional polymeric restorations could achieve controlled, sustained release of therapeutic ions, anti-inflammatory agents, and growth factors. The targeted release of agents (e.g., VEGF, BMPs, PDGF) could then support fibroblast proliferation, promote mineralization, and enhance cellular activity and tissue regeneration. However, their successful translation requires designing materials that provide stable, long-term release of bioactive substances and modulate the immune response. They must also present bioadhesive and cell-compatible surfaces and maintain mechanical durability within the oral environment. Successful translation requires interdisciplinary collaboration, standardized metrics for bioactivity, and advanced in vitro and in vivo validation.

Abstract: Background: Maxillary expansion is the action exerted on the maxillary bones to obtain an expansion of the maxillary arch, necessary for a correct and functional alignment of the teeth. The devices used in this process are called expanders and have undergone improvements over time to increase efficiency and patient comfort. Classic forms of maxillary expansion involve the use of expanders attached exclusively to the existing teeth with relatively low efficiency. The major upgrade has been the introduction of hybrid expanders consisting of anchorage on teeth and Temporary Anchorage Devices (TADs), resulting in significant improvement in clinical outcomes. However, the use of hybrid systems involves considerable risks related to damaging neighboring anatomical elements during the insertion of TADs using the free-hand technique, risks that can be avoided by using surgical guides. Methods: The employment of surgical guides for TADs, as well as digital technological flows, results in increased safety in use. Based on a Cone Beam Computed Tomography investigation (CBCT), all the surrounding anatomical elements are identified, and the position and insertion axis of the TADs can be accurately established. The procedure is combined with the use of modern, biocompatible, and sterilizable resins to reduce infectious risks. The result of this process is a high-precision (50 μm) surgical guide, which considerably reduces intraoperative risks and increases the efficiency of orthodontic maxillary expansion treatment. Conclusion: Combining several modern technologies, such as computer tomography, computer-assisted design, and 3D resin printing, leads to improved medical outcomes and thus considerably increases patient comfort.

Abstract: Background: Oxidative stress is a major contributor to granulosa cell dysfunction and follicular atresia, with excessive reactive oxygen species (ROS) impairing mitochondrial activity and cell survival. Hydrogels based on gelatin methacryloyl (GelMA) are biocompatible and easily photocrosslinked, but they lack intrinsic antioxidant function. Methods: A GelMA–tannic acid (TA) hydrogel was synthesized by visible light curing in the presence of TA. Structural features were confirmed by FT-IR and ¹H NMR. Photorheology was used to determine gelation kinetics, and scanning electron microscopy assessed morphology. Antioxidant performance was evaluated by DPPH, ABTS, FRAP, and H₂O₂ assays. The protective effect on human granulosa-like KGN cells under H₂O₂ stress was examined by CCK-8 viability, DCFH-DA ROS detection, JC-1 mitochondrial membrane potential, and Live/Dead staining. Results: GelMA–TA exhibited a rapid gelation time of 8.5 s and a plateau modulus of 1.8 kPa, higher than the 1.5 kPa modulus of GelMA alone. In antioxidant assays, GelMA–TA showed significant radical scavenging activity with DPPH (86.1%), ABTS (91.4%), and FRAP (1.15 mmol Fe²⁺ equivalent), as well as nearly complete H₂O₂ removal (94.8%). In KGN cells, GelMA–TA reduced intracellular ROS by 60%, restored mitochondrial membrane potential (Δψm) to 0.9 (compared to 0.5 for H₂O₂ treatment), and improved cell viability by 30%. Conclusion: These findings demonstrate that GelMA–TA forms a fast-curing, antioxidant hydrogel capable of maintaining a low-ROS microenvironment and protecting granulosa cells, offering a promising platform for ovarian tissue engineering and related regenerative applications.

Abstract: To address the challenge of balancing flame retardancy and thermal energy storage performance of rigid polyurethane foam (RPUF), flame-retardant RPUF composites with efficient thermal energy storage functionality were successfully prepared in this study by incorporating microencapsulated phase change materials (MEPCMs; n-octadecane within polyurethane shells) into a flame-retardant RPUF matrix. At an MEPCMs loading of 6 wt%, the resulting composite achieved a limiting oxygen index (LOI) of 26.3%, achieving a Class B2 flammability rating, while delivering a phase change enthalpy of 10.8 J/g. Thermogravimetric (TG) and leakage analyses revealed that the incorporation of MEPCMs did not significantly alter the final residue yield after high-temperature decomposition, and that the RPUF markedly suppressed microcapsule leakage. Scanning electron microscope (SEM) and mechanical performance analysis further demonstrated uniform dispersion of MEPCMs within the RPUF interior, although the specific compressive strength of the composites decreased progressively with increasing MEPCM content. Collectively, an MEPCM content of 6 wt% was identified as optimal, offering a well-balanced combination of flame retardancy, mechanical properties, and thermal performance.

Abstract: Antioxidants may improve the biocompatibility of resin-based materials, while adhesive interface durability is essential for clinical success. This study evaluated the effect of an antioxidant Resveratrol (RES) incorporation on adhesive agents’ microtensile bond strength (μTBS) after 2 years. Five different adhesive agents (G-aenial Bond (GC)/G, Optibond All-in-One (Kerr)/O, Gluma Self Etch (Kulzer)/Gl, Clearfil S3 Bond (Kuraray)/C, and Nova Compo-B Plus (Imicryl)/N) were used. In the experimental groups, 0.5 μM RES was added. Caries-free human third molars were used for the μTBS test. Occlusal enamel was removed, and dentin surfaces were abraded with silicon carbide paper to standardize the smear layer. RES was incorporated into adhesives in test groups, and adhesive systems were applied per manufacturers’ instructions. A composite build-up was created (n = 6). Samples were stored in distilled water for 2 years and stick-shaped specimens were prepared. The μTBS testing was performed and the failure patterns were evaluated under stereomicroscopic examination. Differences among groups were analyzed using ANOVA and Tukey’s multiple comparison test (p < 0.05). Adhesive failure was identified as the dominant failure type in every group. Compared to baseline measurements, RES incorporation did not result in a reduction in μTBS values for any of the tested adhesive agents (p > 0.05). The highest μTBS values after RES addition were recorded in the O and C groups. No significant differences were found between O and C, or among Gl, G, and N; however, the differences between these two subgroups were statistically significant. The incorporation of RES may be used to enhance the biocompatibility of adhesive agents without exerting a negative effect on their bond strength in long-term. Further studies on additional material properties are required.

Abstract: Background: Reactive oxygen species (ROS)–induced oxidative stress contributes to neuronal injury during ischemic conditions, creating a need for delivery systems that can release therapeutic molecules in response to oxidative cues. Incorporating thioketal linkages into polymeric materials provides a feasible strategy to construct ROS-degradable carriers. Methods: In this study, a triblock copolymer poly(ε-caprolactone)–thioketal–poly(ε-caprolactone) (PCL–PTK–PCL) was synthesized via ring-opening polymerization using thioketal diol as the initiator. The polymer self-assembled into nanocarriers capable of encapsulating nerve growth factor (NGF). The structural characteristics were analyzed by FTIR and TEM, while the degradation and release behaviors were evaluated under various H₂O₂ concentrations. Cytocompatibility and neuronal viability were assessed using PC12 cells. Results: The PCL–PTK–PCL nanocarriers exhibited uniform spherical morphology with an average size of ~100 nm. The presence of thioketal bonds conferred clear ROS sensitivity, as evidenced by H₂O₂-triggered swelling and accelerated NGF release. The carriers remained stable under non-oxidative conditions and showed good cytocompatibility, maintaining high neuronal cell viability after incubation. Conclusion: The synthesized PCL–PTK–PCL nanocarriers achieved ROS-triggered degradation and controlled NGF release while exhibiting minimal cytotoxicity. These findings confirm their suitability as a basic oxidation-responsive platform for further exploration in oxidative stress–related neuronal studies.

Abstract: Background: The liver tumor microenvironment is characterized by elevated reactive oxygen species (ROS), high glutathione (GSH) levels, and acidic pH, which limits the selectivity and efficacy of conventional chemotherapy. Microenvironment-responsive drug delivery systems offer a promising strategy to address these challenges. Methods: A redox-responsive thioketal-crosslinked gelatin hydrogel (TK-Gel) was prepared via dynamic covalent crosslinking and used to encapsulate doxorubicin (DOX). The rheological properties, swelling and degradation behaviors, redox responsiveness, and microenvironment-dependent drug release were systematically evaluated. In vitro antitumor performance was assessed using HepG2 liver cancer cells. Results: The TK-Gel hydrogel formed a stable and highly hydrated network under physiological conditions, while exhibiting accelerated degradation and enhanced DOX release under tumor-mimicking environments with elevated ROS and GSH. Cellular studies demonstrated good biocompatibility of the blank hydrogel and significantly enhanced cytotoxicity of DOX@TK-Gel under redox-activated conditions, accompanied by partial intracellular ROS consumption. Conclusions: Thioketal-crosslinked gelatin hydrogels enable tumor-selective drug release and redox modulation, providing a promising platform for liver cancer therapy.

Abstract: Background: Thermosensitive hydrogels have been widely investigated for localized drug delivery; however, their in vitro physicochemical stability, degradation behavior, and cell-level anti-inflammatory performance require systematic evaluation before further translational studies. In particular, prostate epithelial inflammation remains an underexplored application scenario for such delivery platforms. Methods: In this study, a PLGA–PEG–PLGA thermosensitive hydrogel was evaluated as a sustained delivery system for dexamethasone. The copolymer was characterized by GPC, FTIR, and ¹H NMR. Sol–gel transition behavior and viscoelastic properties were assessed using micro-DSC and rheological analysis. The microstructure of the drug-loaded hydrogel was examined by SEM. Degradation behavior was investigated under physiological (PBS, 37°C) and accelerated alkaline conditions. Cytocompatibility and anti-inflammatory effects were evaluated in RWPE-1 prostate epithelial cells. Results: SEM revealed an interconnected porous network structure in the drug-loaded hydrogel. Degradation studies showed high structural stability in PBS with minimal mass loss over 14 days, while rapid degradation occurred under alkaline conditions, confirming hydrolytic degradability. The hydrogel enabled sustained dexamethasone release and maintained good cytocompatibility. Notably, dexamethasone-loaded hydrogels significantly reduced IL-6 and IL-8 secretion, whereas blank hydrogels showed no intrinsic anti-inflammatory effect. Conclusion: This work provides a comprehensive in vitro evaluation of a thermosensitive PLGA–PEG–PLGA hydrogel for sustained dexamethasone delivery at the cellular level. The results clarify the relationship between hydrogel microstructure, degradation behavior, and diffusion-dominated drug release, establishing a solid foundation for future in vivo investigations.

Abstract: Polymer recycling from end-of-life vehicles (ELVs) represents a cost-effective and environmentally sound approach for managing polymer waste. Tribo-charging separation has been identified as an effective approach for achieving polymer recovery, whose performance largely depends on the charge acquired during tribo-charging. In this study, the tribo-charging and electrostatic separation of Polyamide (PA)/Polypropylene (PP)/Acrylonitrile-Butadiene-Styrene (ABS) mixed particles of three components of vehicle polymer were investigated using spiral tube tribo-charging and free-falling electrostatic separation test platforms developed. In this paper, a systematic investigation was conducted on the factors influencing electrostatic separation, including the rotation speed, inclination angle and tube length of the spiral tube in the charging mechanism, as well as electrostatic field voltage, electrode spacing and electrode inclination angle. Results indicated that purities exceeding 94% for PA and ABS, and over 84% for PP, were achieved. This study provides a reference for the single-stage electrostatic separation of three-component vehicle polymer mixed particles.

Abstract: To address the deformation monitoring challenge of sand-lime-gypsum-based brittle low-tensile-strength similar material physical models for simulating mining-induced overlying strata and slope instability, this paper adopts a low-modulus and high-elongation silicone polymer flexible strain gauge. Using silicone polymer as the substrate and encapsulation layer, the strain gauge effectively mitigates the local constraint strengthening effect of conventional strain gauges due to its favorable rigid-flexible interface compatibility with brittle similar materials. Relying on its fracture-bridging capability, it continuously outputs reliable signals even after fractures penetrate the physical model, enabling continuous monitoring of the entire deformation and failure process and ensuring complete acquisition of dynamic signals. In-situ comparative calibration within the same model shows that the sensitivity coefficient deviation between the silicone polymer flexible strain gauges and the conventional strain gauges is approximately −2%, which falls within the allowable error range for geotechnical engineering physical model tests. Taking underground coal mining on overlying strata and slope instability as the validation scenario, physical and mechanical models are established to monitor internal strain and surface failure processes during excavation. Continuous strain monitoring covering the entire process of the physical model from initial deformation, fracture initiation and propagation to overall instability is realized, and the mechanical responses of rock masses in different areas are clearly captured. This study provides a flexible strain gauge based on silicone polymer encapsulation for whole process deformation monitoring of brittle similar material physical model experiments, revealing the mechanisms of overlying strata and slope by progressive excavation, and providing a reference for the application of flexible polymer-based sensing materials in geotechnical engineering experiments.