Endowing dental resin composites (DRCs) with suitable radiopacity is necessary for clinical diagnosis during treatment of caries. To reach this effect, ZrO2 nanoparticles were introduced into the DRCs in this work after modification with two different methods, one modified with 3-methacryloxypropyltrimethoxysilane (ZrO2@γ-MPS) and the other coated with mesoporous SiO2 and then modified with γ-MPS (ZrO2@m-SiO2@γ-MPS). These ZrO2 nanoparticles were used as functional additives, and the SiO2 nanoparticles were used as the fundamental filler in the preparation of DRCs to study the effects of the surface modification of ZrO2 nanoparticles and the amount of particles added (0, 3, 5, and 7 wt %) on the properties of the DRCs. The DRC containing ZrO2@m-SiO2@γ-MPS showed a higher transmittance, which may be attributed to the fact that the SiO2 coating reduced the refractive index of the nanoparticles and thus decreased the scattering of light within the DRC. The silane polymer film on the surface of ZrO2@γ-MPS nanoparticles acted as a lubricant and decreased the viscosity of DRC, but the DRC containing ZrO2@m-SiO2@γ-MPS showed a higher viscosity due to the presence of a mesoporous structure. The radiopacity value of the DRCs containing the functional additives was close to 1 mm Al, much higher than that of the DRC filled with SiO2 nanoparticles alone (0.74 ± 0.07 mm Al), meeting the requirement of ISO 4049:2009. The surface modification of ZrO2 nanoparticles had no significant influence on the mechanical properties, radiopacity, and cytotoxicity of DRCs (p > 0.05). This study provides useful insight into the design and development of radiopaque DRCs with excellent physical and mechanical properties.
Abstract Reconstructing the intricate biophysical microenvironment to provide multiple biologically beneficial stimulation is deemed a promising therapeutic strategy. However, developing multi‐biophysical stimuli with wireless integration and accurate management remains a formidable challenge. Herein, a novel design of a magneto‐mechano‐electric (MME) cascade stimulation system based on aligned magnetoelectric nanofibrous membranes (PLLA/CFO) is reported. Simply regulating the loading amount of CFO nanoparticles endows the PLLA/CFO membranes with excellent magnetism, enhanced crystallization, and resultant piezoelectric responsiveness, thus providing built‐in topographical guidance and nanoscale magnetic field as well as manageably remote stimulation. Specifically, assisted by an external magnetic field (EMF), the magnetic response in PLLA/CFO can be amplified to offer an apparent deformation, which then induces the output of mechanical and electrical cues. Benefiting from the slow degradability of PLLA and continuous EMF triggering, such a performance can be well modulated to match the practical wound healing process, demonstrated by the repair of a rat full‐thickness skin defect. More importantly, this work offers a new strategy to reconstruct the complex biophysical microenvironment in a wireless remote manner.
Porphyrin and its derivatives have become the second generation of photosensitizers for photodynamic therapy for cancers. 5,10,15,20-Tetrakis[4-(2-hydroxyethoxy)phenyl]porphyrin photosensitizer was modified into a porphyrin-based ATRP initiator, and it was further used to construct star-shaped glycopolymers bearing galactose residuals by using atom transfer radical polymerization. Four star-shaped glycopolymers were obtained with a porphyrin core bearing four glyco-arms of varying arm lengths. They can be dissolved in water and displayed good light absorption and fluorescent emission due to the presence of porphyrin core. They generated singlet oxygen which may photobleach the indicator 1,3-diphenylisobenzofuran. The galactose-containing polymers show Hep G2 cells (a human liver cancer cell line) affinity which was selected for the toxicity study. These polymers caused lower cell viability in phototoxicity (1 h light irradiation), indicating their effectiveness as photosensitizers. The fluorescence microscopy results are in good agreement with 1O2 generation and the toxicity study, which indicates their effectiveness for potential use in photodynamic therapy. The star polymers with shorter glyco-arms have higher porphyrin content per unit mass, leading more efficient 1O2 generation to cancer cell extermination, while the polymers with longer glyco-arms showed lower toxicity and better lectin recognition and affinity. It is important to balance the photodynamic therapy and cell targeting property for practical applications.
A cast PU elastomer was prepared with polyester g lycol,toluene diisocyanate (TDI) and chain extender.The influence of prepolymeri zation and one-step polymerization,80/20 TDI and 2,4-TDI,type and molecular we ight of polyester glycol,molecular weight between crosslinking sites and molecul ar weight of rigid segment on the mechanical properties of PU elastomer was inve stigated.The results showed that the PU elastomer made of ployester and 80/20 TD I by prepolymerization had the better comprehensive properties.Among three polye ster PU elastomers,the PU elastomer made of PBA had the best comprehensive prope rties.The PU elastomer had the greatest strength when the molecular weight betwe en crosslinking sites was 4 500.
Artificial cell spheroids are gaining importance in tissue engineering and regenerative medicine fields. Biomimetic construction of stem cell spheroids is nevertheless challenging, and bioplatforms permitting controllable and high-efficient fabrication of functional stem cell spheroids are needed. Here, a fractal nanofiber-based bioplatform is developed based on a tunable interfacial-induced crystallization approach, allowing a programmed culture of artificial stem cell spheroids under an ultralow cell seeding density. Specifically, starting with the nanofibers of poly(L-lactide) (PLLA) and gelatin (PmGn), an interfacial growth of PLLA nanocrystals is subsequently performed to construct the fractal nanofiber-based biotemplates (C-PmGn). Cell experiments with human dental pulp stem cells (hDPSCs) demonstrate that the fractal C-PmGn could effectively decrease cell-matrix interactions, thus facilitating spontaneous cell spheroid formation even under a low cell seeding density (1 × 104 cells/cm2). Nanotopological properties of the C-PmGn bioplatform can be tuned by adjusting the fractal degree, thus enabling its suitability for the 3D culture of diverse hDPSC spheroids. Such a strategy provides a relatively simple and low-cost option for formation, expansion, and utility of stem cell spheroids. It offers another promising pathway to advance the development of stem cell therapies.
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