Hydrolytically synthesized chlorinated bioactive glasses: Structural reticulation and controlled ion release without alkaline shift

Bioactive glasses are recognized for their ability to release ions and induce apatite formation in physiological media. However, conventional glasses often cause a marked increase in pH during dissolution, which may lead to cytotoxic effects. In this study, chlorinated bioactive glasses were synthesized via a hydrolytic sol–gel route using tetraethyl orthosilicate (TEOS) and calcium chloride, aiming to obtain materials with efficient ionic release and controlled pH response. Samples were thermally treated at 500 ◦C, 600 ◦C, and 700 ◦C and characterized by FTIR, Raman spectroscopy, specific surface area (BET), scanning electron microscopy (SEM), and ionic release tests. The chlorinated bioactive glass calcined at 500 ◦C exhibited the most promising combination of charac- teristics: presence of hydroxyl groups (–OH), a structure predominantly composed of Q2 units, high specific surface area (31.75 m2 g−1), well-defined mesoporosity, high ionic release (~2000 μS cm−1), and effective control of pH increase in aqueous media. These properties directly contribute to bioactivity and indicate that this ma- terial can be incorporated into biomedical formulations without the need for prior neutralization steps, in contrast to many conventional bioactive glasses. The results also demonstrate that the hydrolytic sol–gel route enables the synthesis of chlorinated bioactive glasses with tunable structure and dissolution profiles, overcoming limitations associated with more complex routes, such as those based on ion-exchange resins or precursors like metasilicate. The ability to combine high ionic release with low impact on pH represents a relevant advance in the design of bioceramics for regenerative and dental applications.