Biocompatibility evaluation of hydroxyapatite/collagen nanocomposites doped with Zn+2

In this work, novel composites based on calcium phosphates (CaP)/collagen (COL) doped with Zn+2 have been synthesized. They were characterized by SEM coupled to EDS microprobe in order to evaluate their morphology and chemical composition, respectively. The biocompatibility of these synthetic CaP/COL nanocomposites doped and undoped with Zn+2 was investigated through osteoblast cell culture assay. Calcium phosphates were produced via aqueous precipitation routes where two different phases were obtained, hydroxyapatite (HAP) and biphasic hydroxyapatite-βtricalcium phosphate (HAPβTCP). In the sequence, the type-I collagen (COL) was added to the inorganic phase based on calcium phosphate and the mixture was blended until a homogenous composite was obtained. Zn+2 aqueous solution (1.0 wt%) was used as the doping reagent. The cell viability and the alkaline phosphatase production of osteoblasts in the presence of the composites were evaluated and compared to control osteoblasts. Also, the biocompatibility of the composite was investigated through cell morphological analysis using optical microscopy of osteoblasts. All experiments were performed in triplicates (n = 3) from three different experiments. They were analyzed by variance test (ANOVA) and Bonferroni's post-test with differences statistically significant at p < 0.05. The results showed that the CaP/COL composites doped and undoped with Zn+2 did not present alterations in cell morphology in 72 h and had similar cell viability and alkaline phosphatase activity to the control. All the tested CaP/COL composites showed adequate biological properties with the potential to be used in bone tissue replacement applications.