Biomimetic and mesoporous nano-hydroxyapatite for bone tissue application: a short review.

In the last decades, many research groups have experimented the synthesis of hydroxyapatite (HA) for bone tissue application obtaining products with different shapes and dimensions. This review aims to summarise and critically analyse the most used methods to prepare physiologic-like nano-HA, in the form of plates or rods, similar to the HA present in the human bones. Moreover, mesoporous HA has gained increasing interest in the biomedical field due its pecualiar structural features, such as high surface area and accessible mesoporous volume, which is known to confer enhanced biological behaviour and the possibility to act as nanocarriers of functional agents for bone-related therapies. For this reason, more recent studies related to the synthesis of mesoporous HA, with physiological-like morphology, are also considered in this review. Since a wide class of surfactant molecules plays an essential role both in the shape and size control of HA crystals and in the formation of mesoporosity, a section devoted to the mechanisms of action of several surfactants is also provided.