Vascularization is necessary in tissue engineering to keep adequate blood supply in order to maintain the survival and growth of new tissue. The synergy of biologically active ions with multi-target activity may lead to superior angiogenesis promotion in comparison to single-target approaches but it has been rarely investigated. In this study, polycaprolactone (PCL) fiber mats embedded with B and Co co-doped bioactive glass nanoparticles (BCo.BGNs) were fabricated as a tissue regeneration scaffold designed for promoting angiogenesis. BCo.NBGs were successfully prepared with well-defined spherical shape using a sol-gel method. The PCL fiber mats embedding co-doped bioactive glass nanoparticles were fabricated by electrospinning using benign solvents. The Young’s moduli of the nanoparticle containing PCL fiber mats were similar to those of the neat fiber mats and suitable for scaffolds utilized in soft tissue repair approaches. The mats also showed non-cytotoxicity to ST-2 cells. PCL fiber mats containing BCo.BGNs with a relatively high content of B and Co promoted the secretion of vascular endothelial growth factor to a greater extent than PCL fiber mats with a relatively low B and Co contents, which demonstrates the potential of dual ion release (B and Co) from bioactive glasses to enhance angiogenesis in soft tissue engineering.

Silicone resins, filled with phosphates and other oxide fillers, yield upon firing in air at 1100 °C, a product resembling Biosilicate^® glass-ceramics, one of the most promising systems for tissue engineering applications. The process requires no preliminary synthesis of parent glass, and the polymer route enables the application of direct ink writing (DIW) of silicone-based mixtures, for the manufacturing of reticulated scaffolds at room temperature. The thermal treatment is later applied for the conversion into ceramic scaffolds. The present paper further elucidates the flexibility of the approach. Changes in the reference silicone and firing atmosphere (from air to nitrogen) were studied to obtain functional composite biomaterials featuring a carbon phase embedded in a Biosilicate^®-like matrix. The microstructure was further modified either through a controlled gas release at a low temperature, or by the revision of the adopted additive manufacturing technology (from DIW to digital light processing).

In this study, binary SiO₂-CaO hollow mesoporous bioactive glass nanoparticles (HMBGNs) are prepared by combing selective etching and impregnation strategies. Spherical silica particles (SiO₂ NPs) are used as hard cores to assemble cetyltrimethylammonium bromide (CTAB)/silica shells, which are later removed by selective etching to generate a hollow structure. After the removal of CTAB by calcination, the mesoporous shell of particles is formed. Calcium (Ca) is incorporated into the particles using impregnation by soaking the etched SiO₂ NPs in calcium nitrate aqueous solution. The amount of incorporated Ca is tailorable by controlling the ratio of SiO₂ NPs:calcium nitrate in the soaking solution. The produced HMBGNs are bioactive, as indicated by the rapid formation of hydroxyapatite on their surfaces after immersion in simulated body fluid. In a direct culture with MC3T3-E1 cells, HMBGNs were shown to exhibit concentration-dependent cytotoxicity and can stimulate osteogenic differentiation of MC3T3-E1 cells at concentrations of 1, 0.5, and 0.25 mg/mL. Our results indicate that the combination of selective etching and impregnation is a feasible approach to produce hierarchical HMBGNs. The produced hollow particles have potential in drug delivery and bone tissue regeneration applications, and should be further investigated in detailed in vitro and in vivo studies.

This investigation presents a novel approach to engineering mesoporous bioactive glass nanoparticles (MBGNs) through selective ion doping. This method can significantly potentiate their physicochemical properties and biological performance. We elucidate the effects of boron (B) and cobalt (Co) doping, individually and in combination, on MBGNs’ structural, functional, and biocompatible characteristics. Using microemulsion-assisted sol–gel synthesis, we fabricated MBGNs with sizes ranging from 150 to 250 nm and shapes that shifted from spherical to more irregular shapes upon co-doping, as observed by SEM and TEM. We assessed the materials’ amorphous nature and molecular structure through XRD and FTIR, respectively, noting the preservation of bioactivity-associated Si–O–Si groups. This can influence the nucleation and growth of the mineral phases similar to those found in natural tissues, forming a bioactive coating on the material surface. Nitrogen adsorption–desorption isotherms confirmed a mesoporous structure with increased specific surface area upon co-doping. The release behavior of Ca and Si in simulated body fluids studied by ICP-OES indicated alterations after adding Co and B, modifying their release kinetics. Bone regeneration relies on osteogenesis and vascular network formation for nutrient and oxygen supply. This study highlights the synergistic effect of B and Co co-doping, enhancing both angiogenesis and osteogenesis beyond single-ion doping. Biocompatibility studies with MG-63 and HDFa cell lines indicated that B enhanced cell viability, while the viability effect of Co was concentration-dependent. Cytotoxicity was assessed through lactate dehydrogenase (LDH) assays and is shown in high concentrations in the case of reference and B-doped sample, which was significantly reduced in the case of co-doped material. The newly developed nanoparticles showed a 10-fold increase in vascular endothelial growth factor (VEGF) secretion compared to the control sample (p < 0.05, one-way ANOVA), as determined by enzyme-linked immunosorbent assay (ELISA) in treated cells. Based on present results, the co-doped system shows a strong potential impact on angiogenesis with no effect on cell cytotoxicity.