In situ synthesis and characterization of hydroxyapatite/natural rubber composites for biomedical applications

In this work, a biomimetic synthesis reaction for the production of hydroxyapatite (HA)/natural rubber (NR) composites is presented. HA was synthesized in the presence of solubilized NR in tetrahydrofuran (THF), which permits that negatively charged domains in proteins and lipids in NR work as nucleation sites for hydroxyapatite. The mechanical and physicochemical properties of composites containing 10, 20 and 30 wt% HA were studied. NR influenced HA crystallite morphology, shape and size and was able to disperse the HA particles in THF. The dispersion of HA in the composites promoted the enhancement of mechanical properties and loss of solubility of composites, which is believed to be macroscopic manifestations of the physical adsorption of NR to HA particles, known as the bound rubber phenomenon. Preliminary cell studies indicated that HepG2 cells presented viabilities ranging from 71.6 to 91.3%, with cell proliferation positively influenced by HA content at shorter culture times. The good dispersion of HA in the composites is expected to improve NR bioactivity and direct its use towards bone applications. - Highlights: • A biomimetic synthesis reaction of hydroxyapatite is proposed. • The presence of natural rubber influences size, shape and dispersion of hydroxyapatite. • Evidence of physical adsorption of natural rubber to hydroxyapatite particles. • Hydroxyapatite improves cell viability in the first day of culture.