Effect of zinc oxide micro- and nanoparticles on cytotoxicity, antimicrobial activity and mechanical properties of apatite-polymer osteoplastic material

Abstract

This work is devoted to the comparison of the physical and biological properties of synthesized osteoplastic composites with an experimentally determined content (375 μg/g) of the micro (ZnO_MPs) and nano (ZnO_NPs) particles, immobilized in Hydroxyapatite-Alginate-Chitosan matrix (HA-Alg-CS). ZnO_NPs show pronounced antimicrobial activity against E.coli ATCC 25922 and S. aureus ATCC 25923, while ZnO_MPs only in the CS presence. Composites containing ZnO_NPs/MPs do not have a toxic effect on bone-forming cells - osteoblasts, preserving their ability to biomineralization. ZnO_MPs and ZnO_NPs to varying degrees, but significantly affect composites' swelling, porosity, shape stability, and prolong vitamin D3 release for 120h, compared to Control. Composites do not demonstrate unwanted "burst release." ZnO_NPs/MPs increase Youngs' modulus of the HA-Alg matrix, namely 348 → 419 MPa (ZnO_MPs), 348 → 646 MPa (ZnO_NPs), and weaken the plastic (irreversible) deformations. The compressive strength of HA-Alg and HA-Alg/CS matrixes containing ZnO_NPs (178 MPa and 251 MPa, respectively) is in the range of values for native cortical bone (170-193 MPa). Biocompatibility and lack of toxic effect give both composites a perspective for osteoplastic application, but composites doped with ZnO_NPs are more attractive.

Keywords: Compressive strength; Cytotoxicity; Drug release; Osteoplastic material; ZnO-Nano/microparticles.