Mesoporous silica with monodispersed pores synthesized from the controlled self-assembly of silica nanoparticles

In-Bath 3D Printing of Anisotropic Shape-Memory Cryogels Functionalized with Bone-Bioactive Nanoparticles

Cryogels exhibit unique shape memory with full recovery and structural stability features after multiple injections. These constructs also possess enhanced cell permeability and nutrient diffusion when compared to typical bulk hydrogels. Volumetric processing of cryogels functionalized with nanosized units has potential to widen their biomedical applications, however this has remained challenging and relatively underexplored. In this study, we report a novel methodology that combines suspension 3D printing with directional freezing for the fabrication of nanocomposite cryogels with configurable anisotropy. When compared to conventional bulk or freeze-dried hydrogels, nanocomposite cryogel formulations exhibit excellent shape recovery (>95%) and higher pore connectivity. Suspension printing, assisted with a prechilled metal grid, was optimized to induce anisotropy. The addition of calcium- and phosphate-doped mesoporous silica nanoparticles into the cryogel matrix enhanced bioactivity toward orthopedic applications without hindering the printing process. Notably, the nanocomposite 3D printed cryogels exhibit injectable shape memory while also featuring a lamellar topography. The fabrication of these constructs was highly reproducible and exhibited potential for a cell-delivery injectable cryogel with no cytotoxicity to human-derived adipose stem cells. Hence, in this work, it was possible to combine a gravity defying 3D printed methodology with injectable and controlled anisotropic macroporous structures containing bioactive nanoparticles. This methodology ameliorates highly tunable injectable 3D printed anisotropic nanocomposite cryogels with a user-programmable degree of structural complexity.

Adsorption studies of molybdate(VI)-99Mo onto nano zirconium hydroxide gel

Zr(OH)₄ gels have been prepared by sol-gel method using isoamyl alcohol/ammonia mixture of different concentrations. The nano Zr(OH)₄ gel obtained using 80% isoamyl alcohol and diluted ammonia (6%) gave the highest ⁹⁹Mo distribution coefficient. SEM images indicated a jelly-like appearance of the optimum Zr(OH)₄ gel. XRD analysis proved that Zr(OH)₄ gel is an amorphous material. HRTEM analysis indicated a particle size of ≤100 nm with the existence of particle aggregates. According to DLS studies, the hydrodynamic diameter was found to be 78.82 nm (with a mean number percentage of 21.1%), while zeta potential was found to be 29.2 mV N₂ adsorption/desorption chromatographic analysis calculations stated a BET surface area of 151 m²/g and an average pore diameter of 1.93 nm. Molybdate(VI)-⁹⁹Mo adsorption process onto the optimum Zr(OH)₄ gel was found to follow pseudo 2nd order and (to some extent) film diffusion mass transfer kinetic models. The adsorption isotherm was found to follow Langmuir model. From kinetic and adsorption isotherm studies it could be determined that the optimum Zr(OH)₄ gel has E_a, ΔH° and ΔS° values of 31.29, 50 and 0.185 kJ/mol, respectively, in addition to ΔG° values of -5.09, -7.86 and -11.56 kJ/mol at 25, 40 and 60 °C, respectively. Static molybdate(VI)-⁹⁹Mo capacity (determined from Langmuir adsorption model) was found to be 292.4, 333.3 and 357.1 mg/g at 25, 40 and 60 °C, respectively, while dynamic capacity was found to be 134.3 mg/g at 25 °C.

Effect of ethanol/TEOS ratios and amount of ammonia on the properties of copper-doped calcium silicate nanoceramics

Calcium magnesium silicate glasses could be suggested for the synthesis of scaffolds for hard tissue regeneration, as they present a high residual glassy phase, high hardness values and hydroxyapatite-forming ability. The use of trace elements in the human body, such as Cu, could improve the biological performance of such glasses, as Cu is known to play a significant role in angiogenesis. Nano-bioceramics are preferable compared to their micro-scale counterparts, because of their increased surface area, which improves both mechanical properties and apatite-forming ability due to the increased nucleation sites provided, their high diffusion rates, reduced sintering time or temperature, and high mechanical properties. The aim of the present work was the evaluation of the effect of different ratios of Ethanol/TEOS and total amount of the inserted ammonia to the particle size, morphology and bioactive, hemolytic and antibacterial behavior of nanoparticles in the quaternary system SiO₂-CaO-MgO-CuO. Different ratios of Ethanol/TEOS and ammonia amount affected the size and morphology of bioactive nanopowders. The optimum materials were synthesized with the highest ethanol/TEOS ratio and ammonia amount as verified by the enhanced apatite-forming ability and antibacterial and non-hemolytic properties.