In the oral mechanical environment, periodontal ligament cells (PDL cells) contribute to maintaining periodontal tissue homeostasis. Recent studies showed that exosomes, which are small vesicles secreted by various types of cells, play a pivotal role in cell-to-cell communication in biological processes. We examined the secretion of exosomes from PDL cells stimulated with cyclic stretch and their role in the inflammatory response of macrophages using the human macrophage cell line THP-1 and human primary monocytes/macrophages. We prepared supernatants from human PDL cells (PDL-sup) stimulated with cyclic stretch. The treatment of macrophages with PDL-sup, but not PDL-sup from unstimulated PDL cells, inhibited the production of IL-1β in LPS/nigericin-stimulated macrophages. The pretreatment of PDL cells with GW4869, an inhibitor of exosome secretion, or siRNA for Rab27B, which controls exosome secretion, abrogated the inhibitory effects of PDL-sup. A transmission electron microscopy analysis demonstrated the existence of exosomes with diameters ranging between 30 and 100 nm in PDL-sup, suggesting that exosomes in PDL-sup contribute to this inhibition. An immunofluorescence microscopy analysis revealed that exosomes labeled with PKH67, a fluorescent dye, were incorporated by macrophages as early as 2 h after the addition of exosomes. Purified exosomes inhibited IL-1β production in LPS/nigericin-stimulated macrophages and the nuclear translocation of NF-κB as well as NF-κB p65 DNA-binding activity in LPS-stimulated macrophages, suggesting that exosomes suppress IL-1β production by inhibiting the NF-κB signaling pathway. Our results indicate that PDL cells in mechanical environments contribute to the maintenance of periodontal immune/inflammatory homeostasis by releasing exosomes.

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In principle, supercapacitors may store electrical energy through the electrical double-layer capacitance (EDLC), pseudocapacitance, or a mix of the above two. [3f ] EDLC stems from the electrostatically reversible electrolyte ion adsorption and desorption on electrode surfaces. [4] Therefore, electrodes with a large specific surface area and good electrical conductivity are essential to obtain a high EDLC. Carbon materials, such as activated carbon, [5] graphene, [6] and carbon nanotubes (CNTs), [7] are common EDLC materials due to their large specific surface area, high electrical conductivity, good cycling stability, and reasonably low cost. On the other hand, pseudocapacitance originates from rapid and reversible Faradaic reactions occurring on the surfaces of redox-active electrodes. [8] Common pseudocapacitive materials include transition metal oxides and conducting polymers. [9] Further, asymmetric hybrid capacitors combine electrodes with EDLC and pseudocapacitance to obtain broader operating potential windows and substantially higher energy density. [10] The properties of capacitive electrode materials govern the energy storage performance of supercapacitors. Extensive research efforts have been devoted to developing novel capacitive materials. These efforts have focused on two main strategies: 1) increasing the ion-accessible surface area of capacitive materials and 2) incorporating redox-active species to increase pseudocapacitance, achieving significant progress. For instance, a 3D graphene framework prepared by thermal decomposition exhibited a large specific surface area of 1018 m 2 g −1 and a high specific capacitance of 266 F g −1 at a current density of 0.5 A g −1 . [11] A nanoporous carbon sphere with an exceptional specific surface area of 3357 m 2 g −1 showed a specific capacitance of 405 F g −1 at 0.5 A g −1 . [12] Many studies have optimized the crystallinity, pore structure, and redox-active species of metal oxides/hydroxides and polymeric materials. [13] However, irregular pore structures, low electrical conductivity, uneven distribution of redox-active species in capacitive materials, and uncontrollable agglomeration of their nanoparticles often increase the mass transfer resistance of electrolyte ions and reduce their accessible surface areas, resulting in deteriorated energy storage performance. Further, metal dissolution and crystal structure transformation of metal oxides/hydroxides and fast degradation of polymeric materials also shorten the cycling life of supercapacitors fabricated using these materials. [14] Therefore, developing novel capacitive materials with Covalent-organic frameworks (COFs) are emerging organic crystalline materials with a porous framework that extends into two or three dimensions. Originating from their versatile and rigorous synthesis conditions, COFs have abundant and tunable pores, large and easily accessible surfaces, and plenty of redox-active sites, making them promising material candidates for various energy storage applications. One important area...

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ObjectivesTo evaluate the cyclic fatigue resistance and the force generated by OneShape files during preparation of simulated curved canals.MethodsSix OneShape files (the test) and six ProTaper F2 files (the control) were subject to the bending ability test. Another thirty files of each type were used to prepare artificial canals (n = 60), which were divided into 3 groups according to respective curvatures of the canals (30°, 60°, and 90°). The numbers of cycles to fatigue (NCF) as well as the positive and negative forces that were generated by files during canal preparation were recorded. The scanning electron microscopy was applied to detect the fracture surfaces.ResultsCompared with ProTaper F2 files, the bending loads of OneShape files were significantly lower at deflections of 45°(P < .05), 60° (P < .05) and 75° (P < .01). No significant difference was found at 30°. OneShape files presented a higher NCF in both 60° and 90° canals than the control (P < .01). No significant difference of NCF was found between OneShape and ProTaper files in 30° canals. During the preparation of 30° canals by both files, the negative forces were dominant. With the increase of the curvature, more positive forces were observed. When the OneShape Files were compared with the control, significant different forces were found at D3 and D2 (P < .05) in 30° canals, at D2 (P < .05), D1 (P < .01) and D0 (P < .01) in 60° canals, and at D4 and D3 (P < .01) in 90° canals.ConclusionsOneShape files possessed a reliable flexibility and cyclic fatigue resistance. According to the assessments of the forces generated by files, OneShape instruments performed in a more fatigue-resistant way during curved canal preparation, compared with the ProTaper F2 files.