Chitosan/PVA reinforced boron/strontium multi-substituted hydroxyapatite-based biocomposites: Effects of synthesis pH and coating on the physicochemical, mechanical, and in vitro biological properties of scaffolds

Abstract

Bioceramics are used in hard tissue applications to repair and replace damaged parts inside the human body. Hydroxyapatite (HAp) is the most widely used bioceramic due to its ability to bind to hard tissues. Furthermore, enhancing the bioactivity of HAp in hard tissue applications through co-substituted particles is of great interest. In this study, different types of HAp microparticles, including unsubstituted, boron-substituted (B-HAp), strontium-substituted (Sr-HAp), boron and strontium co-substituted HAp (B–Sr-HAp) were synthesized at pH 9 and 11 using the wet precipitation method. The impact of synthesis pH on the chemical composition and crystalline structure of the microparticles was investigated. Sintered porous three-dimensional ceramic scaffolds were prepared, polyvinyl alcohol (PVA) and chitosan (Chi) were chosen to improve the mechanical properties of the ceramic scaffolds owing to their biocompatibility and functional groups. In vitro cytotoxicity and in vitro hemocompatibility studies were conducted to evaluate the biocompatibility of the constructs. The results revealed that synthesis pH of 11 yielded the highest substitution without altering the crystalline phase. Also, the PVA/Chi coating improved the compressive strength of all scaffolds, with the most significant improvement observed in Br-HAp due to borate-diol complexation at the ceramic-polymer interface. Preliminary in vitro studies revealed that scaffolds were non-cytotoxic and hemocompatible.