Various types of nanomaterials play currently important role in different fields of medicine. For example, silica–calcia system is a well-known basic composition of bioactive glass that is used in regenerative medicine. Glass nanostructures might show higher activity and broader range of applications in comparison to their well-known microsized counterparts. We present studies on nanoparticles (average diameter <100 nm) of bioactive glass showing photoluminescence due to a modified composition of silica–calcia system. The sol–gel route was used to fabricate the particles. To ensure photoactivity, the composition of glass was modified by addition of lanthanide ions, phthalocyanine complexes with metals, carbon structures, or zinc oxide. The optical properties (absorption and photoluminescence spectra) of the samples as well as their structural and morphological properties were examined. The results showed that glasses were active in different spectral ranges of electromagnetic spectrum – from ultraviolet to near infrared – depending on the activators. Photoactivity was presented as luminescent and photocatalytic properties as well as singlet oxygen generation. The bioactivity tests indicated that when particles were immersed in the simulated body fluid, ions release to the medium appeared and hydroxyapatite formation on the glass surface was observed. Described systems could be used, for example, for monitoring structural changes of the glass immersed in biological fluids, bioimaging, photodynamic therapy, or photocatalysis. Research was supported by the National Science Centre (Poland) grant No. 2016/22/E/ST5/00530.
This work focuses on the fabrication process of SiO2–CaO and SiO2–CaO–ZnO glasses. To obtain glass powders, modified Stöber sol–gel synthesis was used. The X-ray diffraction patterns and infrared absorption spectra were used to investigate the structure of materials showing that the binary system was fully amorphous while the ternary one showed partial crystallization of dicalcium silicate. The scanning electron microscopy imagining allowed to determine the morphology of glass particles as well as their composition and distribution of Si, Ca, and Zn elements in the tested samples. The final glass composition was slightly different from the assumed and was equal to 85SiO2–15CaO and 85SiO2–6.5CaO–8.5ZnO (in wt.%). The particles of both glasses were spherical, but the ones of the SiO2–CaO–ZnO sample were smaller (diameter around 100 nm) and had a narrow range of size distribution. Considering the photocatalytic properties of zinc oxide, the photocatalytic degradation of methylene blue was shown in an aqueous solution in the presence of SiO2–CaO–ZnO glass.
We present studies on bioactive silica-based glass nanoparticles showing photoluminescence. The sol–gel or solvothermal route was used for syntheses. Lanthanides, zinc oxide or phthalocyanine complexes ensured light emission. The structural, morphological, and optical properties were examined. During the bioactivity tests, when particles were immersed in SBF, ions release to the medium and hydroxyapatite formation were analyzed. Composites with graphite oxide were described as well. The systems are promissing for monitoring structural changes of the glass immersed in biological fluids, bioimaging or photodynamic therapy. Research was performed within Polish–Ukrainian Joint Exchange Project and NSC grants 2016/23/B/ST5/024830, 2016/22/E/ST5/00530.
To emphasize the scientific and technological interest in the silica-based glassy systems and the versatility of the sol-gel route, nano and micrometer scale structures are discussed focusing the attention mainly on the rare-earth-activated materials and their spectroscopic characterization. We have demonstrated that various SiO2-based binary systems can be successfully employed for the fabrication of amorphous planar waveguides, glass–ceramic waveguides, and tapered rib waveguide laser. Different technological processes allowed to realize Er3+ -activated microspheres that can be exploited as microresonator and it has been evidenced that through specific coating it is possible to modify modal free spectral range and/or modal dispersion of the microresonator and achieve laser action. In the case of rare-earth-doped 3-D colloidal crystals in different configurations (direct and inverse one), it has been shown that the relaxation dynamics of the electronic states can be engineered.
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