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Phosphate invert glasses (PIGs) exhibit excellent biocompatibility because of their high chemical durability and controlled ion releasability. PIGs are composed of short phosphate units such as ortho‐ and pyrophosphate. This structure makes it difficult to obtain clear glass using the melt‐quenching method. Our previous work reported that intermediate oxides (such as TiO2 and Nb2O5)‐containing PIGs exhibit good glass‐forming ability and ion dissolution controllability. This work used a liquid‐phase method to prepare PIGs at room temperature and pressure. Furthermore, TiO2 was used to control ion releasability for biomedical applications. Titanium‐containing PIGs were successfully prepared using a liquid‐phase method. Pyrophosphate and titania formed P‐O‐Ti bonds with an increasing TiO2 content in the glass, forming chain‐like structural units such as (‐O‐P‐O‐P‐O‐Ti‐O‐)n. The number of chain‐like structures increased with an increasing TiO2 content in the glass, improving the chemical durability. Hence, the ion releasability of titanium‐containing PIGs prepared using the liquid‐phase method can be controlled by the glass structure. Additionally, the PIGs exhibited good cell viability. Therefore, the PIGs are candidates for carriers of therapeutic inorganic ions for biomedical applications. [ABSTRACT FROM AUTHOR]

Mg2+ and silicate ions are important ionic species in bone formation. Previously, the authors' group reported a 15MgO–15CaO–8P2O5–4SiO2 glass (silicophosphate invert glass [spIG]) containing orthophosphate and orthosilicate structures. Mg2+ and Ca2+ ions in the glass preferentially formed Si–O–Mg and P–O–Ca bonds, respectively, suppressing the release amount of silicate ions in a tris–HCl buffer solution (TBS). In this study, a new 15MgO–15CaO–5P2O5–10SiO2 invert glass without a silicate 3D‐network structure was prepared via a melt‐quenching method. The new glass exhibits an improved silicate‐ion release ability that promotes bone formation. The dissolution amounts of Ca2+ and phosphate ions from the glass into a TBS were similar to those of spIG, but the amounts of Mg2+ and silicate ions increased by ∼2 and ∼5 times, respectively. 31P and 29Si magic‐angle spinning nuclear magnetic resonance spectroscopic analyses showed that the glass was composed of orthophosphate and chain silicate structures. Even when the silica content exceeded that of spIG, the formation of a silicate 3D‐network was suppressed. The O1s X‐ray photoelectron spectra indicated that (Si, P)–O–Mg bonds contribute to the glass formation. In a glass model based on classical molecular dynamics, the oxygen coordination numbers of Mg and Ca were determined as 4–7 and 5–8, respectively. Mg2+ ions are predominantly responsible for bridging the silicate/phosphate structures in this glass and play an important role in tuning the glass formation and the release amount of silicate ions. [ABSTRACT FROM AUTHOR]