Bioactive glasses (BGs) of silicate, phosphate or borate compositions are materials of choice for several advanced biomedical applications, including tissue engineering (TE), drug delivery and biofabrication. Such applications are based on the surface bioreactivity of BGs. It is well known that interactions of bioactive (bioreactive) surfaces with the biological environment lead to specific cell biology effects, which can be exploited in several applications. In this context, different compositions of BGs doped with one or more biologically active ions have been developed over the last years. Such ions, released in a controlled manner when the glass surface is in contact with an aqueous environment, have profound effects on cell behavior and on the tissue formation processes, for example inducing osteogenesis and local mineralization in the case of bone tissue engineering [1]. One important effect of such ion doping of BGs is the increase of angiogenesis, e.g. the secretion of vascular endothelial growth factor (VEGF) from stem cells is affected by the (controlled) release of certain ions (e.g. Cu, B) from BGs. In addition, recent studies have confirmed the immunomodulatory effects of ion releasing BGs in the framework of bone regeneration and wound healing [2]. The general field of BGs in TE approaches will be discussed first, especially considering the interaction of biologically active ions (released from BGs) and stem cells to achieve osteogenic and angiogenic effects. Due to its relevance in TE, both for hard and soft tissue repair, the angiogenic effect of specific ions released from both silicate and borate glasses will be discussed. The increasing trend of doping with less common or exotic elements, e.g. rare earth elements [3], will be also discussed. A special class of BGs, namely mesoporous bioactive glass nanoparticles (MBGNs), will be introduced, which have the capability of releasing simultaneously biomolecules or drugs (loaded into the mesopores) and ions to achieve synergistic effects. Applications of such MBGNs in biofabrication (or 3D bioprinting) approaches will be presented [4]. Here MBGNs are added to printable hydrogels to develop functional bioinks, e.g. cell laden hydrogel-bioactive glass systems capable of forming 3D scaffolds of increasing complexity for example by extrusion 3D printing [4]. The challenges and opportunities for further research in the field will be discussed.
 
References
 
[1] A. Hoppe, et al., A review of the biological response to ionic dissolution products from bioactive glasses and glass-ceramics, Biomaterials 32 (2011) 2757-2774.
 
[2] K. Zheng, et al., Immunomodulatory bioactive glasses for tissue regeneration, Acta Biomater.133 (2021) 168-186.
 
[3] U. Pantulap, et al., Bioactive glasses incorporating less-common ions to improve biological and physical properties, J. Mater. Sci. Mater. Med. 33 (2022) article number: 3.
 
[4] H. Zhu, et al., 3D Bioprinting of Multifunctional Dynamic Nanocomposite Bioinks Incorporating Cu?Doped Mesoporous Bioactive Glass Nanoparticles for Bone Tissue Engineering, Small 18 (2022) 2104996.