Surface modification of zirconium alloy implants by collagen encapsulated strontium ranelate@PCN-224 coating to improve biocompatibility and promote osseointegration

Abstract

Implant materials were extensively used in bone fracture and replacement therapies. However, implants gradually loosen and eventually fail over time. Therefore, the bone integration ability of bone-implant materials needs further study. There are many methods and materials for enhancing osseointegration properties of Zr alloy by surface loading of osteogenic drugs. Compared with the traditional porous drug loading materials (such as zeolite and molecular sieve), the metal-organic framework (MOFs) materials have the advantages of large specific surface area, easy adjustment of pore structure, more active adsorption sites and large adsorption capacity, so they had a wide range of applications in adsorption separation and controlled drug release. In this paper, the metal-organic skeleton PCN-224 with large porosity and specific surface area was synthesized by hydrothermal reaction with H2TCPP and zirconium salt as raw materials. In order to understand the microstructure and physical and chemical properties of the materials and explore their adsorption mechanism, the prepared materials were characterized by XRD, SEM, TEM, FTIR, TG-RSC, surface area analyzer and BET. The particle size of the synthesized PCN-224 was 209.67 ± 25.24nm. The surface area analyzer (BET) showed that the specific surface area of PCN-224 was 735.96cm3g-1, the pore size was 2.18 ± 0.12 nm, and the maximum pore volume was 1.47 cm3g−1nm−1. By comparing the changes of SEM, EDS and XRD before and after PCN-224 was immersed in strontium ranelate solution, the results show that strontium ranelate has been successfully loaded into the pore structure of PCN-224 without destroying the original crystal structure of PCN-224, and its adsorption process conforms to pseudo-second-order kinetics. The maximum adsorption capacity of SR was up to 112.67 ± 2.14 mg g−1. The SR@PCN-224 was mixed with type I collagen and adhered to the anodized Zr alloy surface with a crosslinking agent. The sustained release performance of coated strontium ranelate showed that the complete release time was 13 days. In vitro biological experiments confirmed that Zr-Col-SR@PCN-224 coating could promote osteoblast proliferation and osteogenic differentiation. Metal-organic frame materials loaded with osteogenic drugs can improve the osseointegration performance of bone-implant materials, providing a novel idea and strategy for improving the osseointegration performance of bone implant materials.