Table 1.

Summary of the reported biological functions of Sr-doped bioactive glasses.

Composition of Bioactive Glass (mol%)	Concentration (mol%)	Precursor ion Sr	Process	Sr Function in Bioactive Glass	Reference
45SiO2–24.5Na2O–24.5CaO–6P2O5	1	SrO	Hydrothermal	Improves the osteogenic ability and stimulates new blood vessel formation in critical-sized rat calvarial defects.	[93]
46SiO2–24.5Na2O–26.9(CaO + SrO)–2.6P2O5	50 and 100	SrO	Melt quench	Stimulates genes associated with osteoblastic differentiation (including Alpl e Bglap) and promotes osteogenesis in a differentiating model of bone cells culture.	[99]
(59 − x)B2O3–3P2O5–13CaCO3–15Na2CO3–10TiO2–xSrCO3	5–25	SrCO3	Sol–gel	Promotes osteoblastic cells (MC3T3-E1) proliferation (in concentrations of 20 and 25 mol%) and exhibits antibacterial effects against S. aureus in the short term (1–7 days).	[17]
60SiO2–36CaO–4P2O5	5 and 10	Sr(NO3)2	Sol–gel	Increases MC3T3-E1 differentiation, proliferation and ALP activity. Promotes the formation of hydroxycarbonate apatite on the BG surfaces and exhibits antibacterial effect against S. aureus.	[100]
18SiO2–36B2O3–22CaO–6Na2O–8K2O–8MgO–2P2O5	3, 6 and 9	SrO	Melt quench	Suppresses the fast release of boron and minimizes cytotoxicity. Also improves MG-63 cell proliferation.	[101]
SiO2–CaO	2 and 4	SrCl2	Aerosol-Assisted Spray Drying and Sol–gel	Stimulates the expression of pro-osteogenic genes, like COLL1A1, SPARC and OPG. Promotes apatite layer formation after 1 day of SBF immersion and does not significantly affect the surface ion-exchange kinetics.	[102]
55SiO2–40CaO–(5 − x)SrO–xAg2O	1, 3 and 5	_	Sol–gel	Positive effect on the materials’ bioactivity, promoting hydroxyapatite layer formation after 7 days of immersion in SBF.	[16]
53.85SiO2–1.72P2O5–21.77Na2O–(22.65 − x)CaO–1Al2O3–xSrO	3	Sr(NO3)2	Sol–gel	Formation of high density of needlelike shape HAp crystals 7 days after immersion in SBF. Increases MC3T3-E1 osteoblast-like cell proliferation, ALP activity and bone nodule formation.	[103]
45SiO2–6P2O5–24.5Na2O–(24.5 − x)CaO–xSrO	5, 10 and 20	SrO	Melt quench	Promotes the regeneration of osteoporotic bone defects via early improvement in autophagy and late activation of the Akt/mTOR signaling pathway.	[104]
45.2SiO2–2.5P2O5–23.9Na2O–26.4CaO–2Al2O3–2SrO	2	Sr(NO3)2	Melt quench	Inhibitory effects on E. coli and cell viability greater than 90% by using the NCTC clone 929.	[105]
60SiO2–35CaO–5P2O5	1, 3 and 5	Sr(NO3)2	Spray drying	Positive effect on the bioactivity and significant increase in osteoblast cell viability.	[95]
46.1SiO2–26.9CaO–2.6P2O5–24.35Na2O	1 and 2	Sr(NO3)2	Melt quench	Antibacterial activity against E. coli and a positive effect on the viability of Saos-2 cells (ATCC ® HTB-85™ human osteosarcoma cell line).	[98]
74SiO2–(26 − x) CaO–xSrO	1, 3 and 5	Sr(NO3)2	Sol–gel	Affects the microstructure of nanoparticles, resulting in a decrease in specific surface area on the pore size of nanoparticles and reduced polymerization of the glass network.	[106]