Preparation and characterization of cobalt-60 glass microspheres for radioactive particle tracking applications.

The current work describes development and optimization of a process for preparation of cobalt-60 glass microspheres. These microspheres have potential for applications in radioactive particle tracking (RPT) studies in multiphase flow systems. In the first step of preparation, soda lime glass containing 5-10 wt% cobalt oxide was produced through melt-quench method. Subsequently, cobalt glass microspheres (CMSs) were prepared by microwave heating of tiny glass grains in presence of graphite. In the final step, radioactive cobalt-60 microspheres (RMSs) were produced by neutron irradiation of the CMSs in a nuclear reactor. The CMSs were characterized for surface morphology, elemental composition, homogeneity, crystalinity using SEM, EDX and XRD, respectively. The thermal behaviour of the microspheres was characterized by TG and DSC analysis. The size distribution of CMSs analyzed by SEM was found to be in the range 500-2000 µm. The preparation step was optimized to produce adequate activity in a single microsphere, so that they can be utilized for RPT applications.

The use of bioactive glass (BAG) in dental composites: A critical review.

OBJECTIVE: In recent years, numerous studies have analyzed the role of bioactive glass (BAG) as remineralizing additives in dental restorative composites. This current review provides a critical analysis of the existing literature, particularly focusing on BAGs prepared via the melt-quench route that form an "apatite-like" phase when immersed in physiological-like solutions. METHODS: Online databases (Science Direct, PubMed and Google Scholar) were used to collect data published from 1962 to 2020. The research papers were analyzed and the relevant papers were selected for this review. Sol-gel BAGs were not included in this review since it is not a cost-effective manufacturing technique that can be upscaled and is difficult to incorporate fluoride. RESULTS: BAGs release Ca2+, PO43- and F- ions, raise the pH and form apatite. There are numerous published papers on the bioactivity of BAGs, but the different glass compositions, volume fractions, particle sizes, immersion media, time points, and the characterization techniques used, make comparison difficult. Several papers only use certain characterization techniques that do not provide a full picture of the behavior of the glass. It was noted that in most studies, mechanical properties were measured on dry samples, which does not replicate the conditions in the oral environment. Therefore, it is recommended that samples should be immersed for longer time periods in physiological solutions to mimic clinical environments. SIGNIFICANCE: BAGs present major benefits in dentistry, especially their capacity to form apatite, which could potentially fill any marginal gaps produced due to polymerization shrinkage.

Review and the state of the art: Sol-gel and melt quenched bioactive glasses for tissue engineering.

Biomaterial development is currently the most active research area in the field of biomedical engineering. The bioglasses possess immense potential for being the ideal biomaterials due to their high adaptiveness to the biological environment as well as tunable properties. Bioglasses like 45S5 has shown great clinical success over the past 10 years. The bioglasses like 45S5 were prepared using melt-quenching techniques but recently porous bioactive glasses have been derived through sol-gel process. The synthesis route exhibits marked effect on the specific surface area, as well as degradability of the material. This article is an attempt to provide state of the art of the sol-gel and melt quenched bioactive bioglasses for tissue regeneration. Fabrication routes for bioglasses suitable for bone tissue engineering are highlighted and the effect of these fabrication techniques on the porosity, pore-volume, mechanical properties, cytocompatibilty and especially apatite layer formation on the surface of bioglasses is analyzed in detail. Drug delivery capability of bioglasses is addressed shortly along with the bioactivity of mesoporous glasses. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1248-1275, 2016.

Composition dependent structural and optical properties of PbF2-TeO2-B2O3-Eu2O3 glasses.

Boric oxide based quaternary glasses in the system PbF2-TeO2-B2O3-Eu2O3 have been prepared by melt quenching technique. Density, molar volume, FTIR, UV-Vis techniques were used to probe the structural modifications with incorporation of europium ions in the glass network. An increase in glass density & decrease in molar volume (Vm) values proved the structural changes occurring in coordination of boron atom [conversion of BO3 units to BO4]. This resulted in the increase of the compaction of the prepared glasses with increase in Eu2O3 contents. The amorphous natures of the samples were ascertained by XRD and metallization criterion (M) studies. XPS study showed the values of core-level binding energy [O1s, Eu3d, Eu4d, Te3d, Te4d, Pd4f, Pb5d, O1s, and F1s] of (PbF2-TeO2-B2O3-Eu2O3) the glass matrix. The frequency and temperature dependence of dielectric properties of present glasses were investigated in the frequency range of 1 Hz-10 MHz and temperature range of 313-773K. The study of dielectric measurements proved good insulating and thermal stability of the prepared glasses. At room temperature, dielectric loss [tanδ] values were negligibly small for prepared glasses and increased with increase in temperature. FTIR spectroscopy results were in good agreement with optical band energy gap, density, molar volume and hardness values revealing network modifications caused by europium ions in the glass structure.

Nano-amorphous spray dried powder to improve oral bioavailability of itraconazole.

The objective of this study was to formulate nano-amorphous spray-dried powders of itraconazole to enhance its oral bioavailability. A combination approach of solvent-antisolvent precipitation followed by spray drying was used. DoE studies were utilized to understand the critical processing parameters: antisolvent-to-solvent ratio, drug concentration and stabilizer concentration. Particle size was the critical quality attribute. Spray drying of the nano-precipitated formulation was performed with several auxiliary excipients to obtain nano-sized amorphous powder formulations. PLM, DSC and PXRD were utilized to characterize the spray-dried powders. In vitro dissolution and in vivo bioavailability studies of the nano-amorphous powders were performed. The particle size of the nano-formulations was dependent on the drug concentration. The smallest size precipitates were obtained with low drug concentration. All high molecular weight auxiliary excipients and mannitol containing formulations were unstable and crystallized during spray drying. Formulations containing disaccharides were amorphous and non-aggregating. In vitro dissolution testing and in vivo studies showed the superior performance of nano-amorphous formulations compared to melt-quench amorphous and crystalline itraconazole formulations. This study shows superior oral bioavailability of nano-amorphous powders compared to macro-amorphous powders. The nano-amorphous formulation showed similar bioavailability to the nano-crystalline formulation but with a faster absorption profile.