Extracellular vesicles (EVs), as nanometer-scale particles, include exosomes, microvesicles, and apoptotic bodies. EVs are released by most cell types, such as bone marrow stem cells, osteoblasts, osteoclasts, and immune cells. In bone-remodeling microenvironments, EVs deliver specific proteins (e.g., tenascin C and Sema4D), microRNAs (e.g., miR-214-3p, miR-183-5p, and miR-196a), and other growth factors (e.g., bone morphogenetic protein 1 to 7 and transforming growth factor β1) to osteoblasts and regulate bone formation. In addition, EVs can deliver cytokines, such as RANK (receptor activator of nuclear factor κB) and RANKL (RANK ligand), and microRNAs, such as miR-218 and miR-148a, to modulate osteoclast differentiation during bone resorption. EVs also transfer bioactive molecules and have targeted therapies in bone-related diseases. Moreover, bioactive molecules in EVs are biomarkers in bone-related diseases. We highlight the emerging role of EVs in bone remodeling during physiologic and pathologic conditions and summarize the role of EVs in tooth development and regeneration. At the end of this review, we discuss the challenges of EV application in the treatment of bone diseases.
The hypoxic microenvironment, continuous oxygen consumption, and poor excitation light penetration depth during antimicrobial photodynamic therapy (aPDT) tremendously hinder the effects on bacterial inactivation. Herein, a smart nanocomposite with oxygen‐self‐generation is presented for enhanced and selective antibacterial properties against anaerobe‐induced periodontal diseases. By encapsulating Fe3O4 nanoparticles, Chlorin e6 and Coumarin 6 in the amphiphilic silane, combined light (red and infrared) stimulated aPDT is realized due to the increased conjugate structure, the corresponding red‐shifted absorption, and the magnetic navigation performance. To address the hypoxic microenvironment problem, further modification of MnO2 nanolayer on the composites is carried out, and catalytical activity is involved for the decomposition of hydrogen peroxide produced in the metabolic processing, providing sufficient oxygen for aPDT in infection sites. Experiments in the cellular level and animal model proved that the rising oxygen content could effectively relieve the hypoxia in a periodontal pocket and enhance the ROS production, remarkably boosting aPDT efficacy. The increasing local level of oxygen also shows the selective inhibition of pathogenic and anaerobic bacteria, which determines the success of periodontitis treatment. Therefore, this finding is promising for combating anaerobic pathogens with enhanced and selective properties in periodontal diseases, even in other bacteria‐induced infections, for future clinical application.
This paper describes a simple, mild, and environmentally friendly approach to synthesize polystyrene/Ag (PS/Ag) nanocomposite spheres, which makes use of both reducing and stabilizing functions of polyvinylpyrrolidone (PVP) in aqueous media. In this approach, monodisperse polystyrene (PS) spheres, which are used as templates for the synthesis of core-shell nanocomposite spheres, are sulfonated first. Then, [Ag(NH(3))(2)](+) ions are adsorbed onto the surface of the PS template spheres via electrostatic attraction between -SO(3)H groups (grafted on the surface of the PS template spheres) and [Ag(NH(3))(2)](+) ions. [Ag(NH(3))(2)](+) ions are then reduced by and simultaneously protected by PVP. In this way, the PS/Ag nanocomposite spheres in aqueous media are obtained through a so-called one-pot method. Neither additional reducing agents nor toxic organic solvents are utilized during the synthesis process. Furthermore, the coverage degree and the particle size of Ag nanoparticles on PS/Ag nanocomposite spheres is easily tuned by changing the concentration of [Ag(NH(3))(2)](+) ions in aqueous media. Moreover, these PS/Ag nanocomposite spheres can be used as catalyst for the reduction of organic dyes and as antibacterial agents against Salmonella and Escherichia coli. In the present study, these PS/Ag nanocomposite spheres exhibit excellent catalytic properties (both in efficiency and recyclability) for the reduction of organic dyes, and the preliminary antibacterial assays indicate that these PS/Ag nanocomposite spheres also possess extraordinary antibacterial abilities against Salmonella and Escherichia coli.
Simultaneous photodynamic therapy (PDT) and photothermal therapy (PTT) can reduce the risks of drug leakage, body burden, and preparation complexity in traditional combination PDT/PTT. Here, a versatile nanoporphyrin (Pp18‐lipos) self‐assembled from lipid–purpurin 18 conjugates (Pp18‐lipids) and pure lipids is presented. The as‐prepared Pp18‐lipos with 2 mol% Pp18‐lipids can perform effective PDT and fluorescence imaging. The Pp18‐lipos with 65 mol% Pp18 can perform potent PTT and photoacoustic imaging. The chelation of Mn2+ endows the Pp18‐lipids‐Mn2+ a high T1‐weighted magnetic resonance imaging contrast. Notably, pretreatment of low‐dose PDT facilitates the endocytosis and tumor accumulation of Pp18‐lipos, thus achieving synergistic PDT/PTT. Upon exposure to a single 705 nm‐laser, the combination of PDT/PTT achieves a significantly higher tumor growth inhibition rate than PDT or PTT alone. In addition, it is found that the synergistic PDT/PTT triggers more potent anti‐tumor immune response including tumor infiltration of immune cells and release of related cytokines.
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