Tangeskesen3453

In order to obtain bioactive bone-implant interfaces with enhanced osteogenic capacity, various approaches have been developed to modify surface physicochemical properties of bio-inert titanium and titanium alloys. One promising strategy involves fabricating highly ordered nanotubes (NT) on implant surfaces via electrochemical anodization. However, few studies have applied this technique to Ti-6Al-4V alloys most commonly adopted for the fabrication of osteo-integrated surfaces on orthopedic implants. In this study, we investigated the influence of electrolyte hydrodynamics to NT fabrication on Ti-6Al-4V in ethylene glycol based electrolyte and evaluated the osteogenic differentiation capacity of human mesenchymal stromal cells (hMSCs) on different diameter NT surfaces. Computational Fluid Dynamics (CFD) analysis was used to simulate electrolyte flow profiles under various stirring conditions (e.g. stirrer bar location and flow direction) and their correlation to NT formation. Polished Ti-6Al-4V disks (240 gripect to the electrolyte hydrodynamic effects to NT growth on Ti-6Al-4V alloys, demonstrating the feasibility of a one-step anodization process for generating uniform NT under optimal hydrodynamics. Optimized wavy micro-/nano-topography with Ø 39 nm NT stimulated osteogenic differentiation capacity of hMSCs on Ti-6Al-4V alloys and confirmed the potential application of anodization to improve osteo-integrative surfaces in orthopedic implants. Due to their low cost and possible green synthesis, high stability and resistance to photobleaching, graphene quantum dots (GQDs) can be considered as one of the class of carbon nanomaterials which may have great potential as an agent for photosensitized oxygen activation. In such a way, GQDs can be used as a theranostic agent in photodynamic therapy. In this work pristine GQDs, GQDs irradiated with gamma rays and GQDs doped with N and N, S atoms are produced using a simple, green approach. By using different techniques (AFM, HR-TEM, SEM-EDS, FTIR, XRD, PL and UV-Vis) we investigated structural and optical properties of the new types of GQDs. We showed that GQDs functionalized with thiourea (GQDs-TU) completely lost the ability to produce singlet oxygen (1O2) upon photoexcitation while functionalization with urea (GQDs-U) improves the capability of GQDs to produce 1O2 upon the same conditions. Thus, presented GQDs modification with urea seems like a promising approach for the production of the efficient photosensitizer. On the opposite, GQDs-TU are efficient OH quencher. Due to high singlet oxygen production and low cytotoxicity below 100 μg/mL against HeLa cells, GQDs-U is a good candidate as an agent in photodynamic therapy at this concentration. This study demonstrates the efficacy of collagen/tussah silk fibroin (Col/TSF) hybrid scaffolds loaded with bone mesenchymal stem cells (BMSCs) in skin repair. Collagen (Col) and tussah silk fibroin (TSF) were extracted from bovine tendons and tussah cocoons, respectively. Col/TSF scaffolds were obtained using a freeze-drying method and were characterised using fourier transform infrared spectroscopy, scanning electron microscopy, porosity, water retention, thermal stability, and biocompatibility. The results revealed that addition of TSF to scaffolds could enhance their moisturising ability and cell infiltration. The antibacterial properties of Col/TSF scaffolds loaded with antibiotics were also excellent. BMSCs cultured in contact with developed Col/TSF scaffolds showed increased cell adhesion, viability, and differentiation. An in vivo study on rats showed that the Col/TSF scaffold seeded with BMSCs was more conducive to wound healing compared to the Col/TSF scaffold alone. The present study suggests that Col/TSF scaffold seeded with BMSCs could be a promising candidate for skin tissue engineering, due to its excellent skin affinity, good air and water permeability, and improved wound healing potential. In tissue engineering, the use of supercritical CO2 foaming is a valuable and widespread choice to design and fabricate porous bioactive scaffolds for cells culture and new tissue formation in three dimensions. Nevertheless, the control of scaffold pores size, shape and spatial distribution with foaming technique remains, to date, a critical limiting step. To mimic the biomimetic structure of tissues like bone, blood vessels and nerve tissues, we developed a novel supercritical CO2-foaming approach for the preparation of dual-scale, dual-shape porous polymeric scaffolds with pre-defined arrays of micro-channels within a foamed porosity. The scaffolds were prepared by foaming the polymer inside polytetrafluoroethylene moulds having precisely designed arrays of pillars and obtained by computer-aided micromachining technique. Polycaprolactone was chosen as model polymer for scaffolds fabrication and the effect of mould patterning and scCO2 foaming conditions on scaffolds morphology, structural properties and biocompatibility was addressed and discussed. The results reported in this study demonstrated that the proposed approach enabled the preparation of polycaprolactone scaffolds with dual-scale, dual-shape porosity. In particular, by saturating the polymer with CO2 at 38 °C, 10 MPa and 1 h and by selecting 2 s as the venting time, scaffolds with ordered arrays of aligned channels, diameters ranging from 500 to 1000 μm, were obtained. Furthermore, the channels spatial distribution was controlled by defining mould patterning while the size of foamed pores was modulated by saturation and foaming temperatures and venting time control. The prepared scaffolds evidenced overall porosity up to 95%, with 100% interconnectivity and compression moduli in the 4 to 5 MPa range. Finally, preliminary in vitro cell culture tests evidenced that the scaffolds were biocompatible and that the micro-channels promoted and guided cells adhesion and colonization into the scaffolds core. Solid solutions of sparingly water-soluble drugs and highly water-soluble excipients are widely used for enhancing the drug delivery rate into the blood stream. The basic physico-chemical mechanisms, however, are not well understood. To delineate the mechanisms, therefore, in this work solid-solution fibers are immersed in a small volume of dissolution fluid and the drug concentration is monitored versus time. Two formulations are considered ibuprofen drug and low-molecular-weight hydroxypropyl methyl cellulose (HPMC) excipient; and ibuprofen and HPMC and polyoxyl stearate (POS) excipients. The fibers dissolved in the dissolution fluid and the drug was released up to three orders of magnitude faster than by ibuprofen particles, yielding a maximum supersaturation in the fluid up to 6.5 in 10-15 minutes. Past the maximum, when the fiber was fully dissolved, the drug concentration gradually decreased to terminal solubility, up to a factor of 10 greater than that of pure ibuprofen. Models suggest that the drug release rate is proportional to the drug concentration at the fiber-fluid interface, which is enhanced due to both supersaturation and solubility-increase. The interface supersaturates because the drug-molecule release rate from the fast-eroding HPMC fibers is greater than the precipitation rate within; the solubility increases proportionally to the concentration of micelle-forming POS. Similarly, the dissolution fluid supersaturates, and due to the presence of POS in the solution the terminal solubility is increased. Thus the solid-solution fibers with dual, low-molecular-weight HPMC-POS excipient enhance the release rate, supersaturation, and solubility of sparingly-soluble drugs, and their delivery rate into the blood stream. V.The application of hollow nerve conduits in the repair of peripheral nerve defects is effected by inferior recovery, and nerve extension is hampered by the scar tissue generated during the repair process. In this study, the filler in hollow nerve conduit, chitosan/oxidized hydroxyethyl cellulose (CS/OHEC) hydrogel loaded asiaticoside liposome and the conductive reduced graphene oxide (rGO) were developed and used to reform the microenvironment for peripheral nerve regeneration. The physiochemical properties of CS/OHEC/rGO/asiaticoside liposome hydrogel were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and compressive modulus, porosity, swelling ratio, degradation and conductivity. In addition, the asiaticoside release profiles in vitro were investigated. The hydrogel had a continuous porous network structure with pore size distribution in the range of 50-250 μm. The majority of the hydrogels had porosities above 70%, and a compressive modulus of 0.45 MPa. The weight loss rate of hydrogel reached 76.14 ± 4.45% within 8 weeks. Chidamide The conductivity of the hydrogel was 5.27 ± 0.42 × 10-4 S/cm. The hydrogel was non-toxic and suitable for adhesion and proliferation of nerve cells in vitro. In addition, the application of electrical stimulation after the addition of rGO can promote the differentiation and proliferation of nerve cells, accelerating nerve regeneration. The asiaticoside released from the hydrogel had a significant inhibitory effect on the growth and collagen secretion of fibroblasts, eliminating scars for regenerative nerves, which can promote the function recovery of defected peripheral nerve. Together, these positive results indicate that the hydrogel would be a promising candidate for peripheral nerve regeneration. V.OBJECTIVE To compare the fatigue strength of lithium disilicate ceramic crowns when cemented as a compound structure, as a function of the manufacturing process and the type of ceramic variation. METHOD A typodont maxillary first premolar was prepared for an all-ceramic crown in accordance with the manufacturer's guidelines for monolithic ceramic crowns (IPS e. max®; Ivoclar-Vivadent, Liechtenstein). 60 dies were duplicated in a polymer with a Young's Modulus closely matched to dentine (Alpha die, Schütz GmbH). Three different crown fabrication techniques were used (n = 20) (i) Manually applied wax spacer and pressed-crown; (ii) digitally scanned preparation, CAD-printed wax-pattern (D76PLUS, Solidscape Inc.) and pressed-crown; (iii) digitally scanned preparation and machined-crown (CEREC-inLab® v3.6 Sirona GmbH). Resin-based cement (Variolink-II®, Ivoclar-Vivadent, Liechtenstein) was employed with a standardised mechanised cementation technique to apply a controlled axial cementation pressure [Universal testing machine (Lloyd LRX®, Lloyd Materials Testing Inc)]. The samples were subjected to fatigue life testing with a cyclic impact load of 453 N for 1.25 × 106cycles at 37C⁰ and 1 Hz frequency until the point of fracture. RESULT There was a significant difference in the resistance to fatigue loading between the three groups. Weibull probability analysis and the α and β Weibull parameters indicate that the teeth restored with a 'Manually-applied wax spacer and pressed-crown' are best able to resist cyclic fatigue loading. They also have the most uniform interface geometry. CONCLUSION Teeth restored with IPS e. max® crowns constructed by manually applied wax spacer and pressing, have a more uniform interface and a greater structural integrity than wax CAD-printed patterns or CAD-CAM crowns.