Preparation, Biocompatibility And Antibacterial Activity Of Polymeric Polymer / Apatite Composite Coatings

Hydroxyapatite(HA) has good biological activity and biodegradability, thus it becomes the first choice of materials for bone replacement implants such as natural tissue damage caused by diseases and accidents. However, high brittleness and low mechanical strength of HA severely hamper its wide application. Therefore, researchers have been focused on combining HA and biocompatible material with higher mechanical strength to form a kind of biological tissue engineering material which has mechanical propertie matching with the bone. In this paper, the surface deposition technology was used to construct bioactive polymer/apatite composite coatings on titanium alloy substrate. According to in-situ transformation theory, ethyl cellulose/apatite composite coatings(marked as LEHCs and HEHCs, respectively) and gelatin/apatite composite coatings(marked as LGHCs and HGHCs, respectively)were prepared at 37 ℃ and 160 ℃ temperature, respectively. We studyed the influence of different p H on the morphology and structure of the coating and discussed the biological activity of composite coatings by simulating body fluid(SBF) immersion experiment. Human bone marrow mesenchymal stem cells(h BMSCs) cultivation experiment was used to evaluate the biocompatible properties of composite coatings.The morphology and phase structure of composite coatings were characterized by SEM, XRD and FTIR.The results showed that the crystallinity of HA on the surface of composite coatings fabricated at 37 ℃is low,HA of composite coatings prepared by hudrothermal method at 160 ℃ has high crystallinity. Different p H has a great influence on surface morphology of composite coatingd, but does not affect the phase structure of coatings. Apatite of composite coatings are calcium-deficient apatite due to part of Ca2 + replaced by the Na+, some PO43-replaced by HPO42-and CO32-. The chemical composition and structure of calcium-deficient apatite and polymer composite coatings are similar to natural bone. The SBF immersion experiments show that the two composite coatings prepared at 37 ℃ or160 ℃ possess good activity of apatite formation in vitro. The cell culture experiments reveal that compared withTi6Al4 V, composite coatings have better biocompatibility, cells on the surface of composite coatings grow and spread with strong ability and composite coatings induce h BMSCs to differentiate into osteoblasts more easily than Ti6Al4 V.Bacterial infection is an important reason leading to the failure of clinical bone repair surgery. Silver is a kind of very strong antibacterial agent, which has a broad antibacterial spectrum, safe, non-toxic and very suitable for preparation of antibacterial materials. Therefore, in this article, we used silver mirror method to load silver nanoparticles on ethyl cellulose/apatite and gelatin/apatite composite coatings fabricated in the solution p H =14 at 37 ℃(marked as Ag NPs-LEHCs B and Ag NPs-LGHCs B, respectively) and conducted the morphology and composition of composite coatings through thecharacterization methods such as SEM and EDS. From the antibacterial experiment and in vitro cell culture experiment, the antibacterial and biological properties of Ag NPs-LEHCs B and Ag NPs-LGHCs B are discussed.The antibacterial tests show that Ag NPs-LEHCs B and Ag NPs-LGHCs B have strong antibacterial effect on escherichia coli and staphylococcus aureus.SEM and CLSM of the in vitro cell culture experiment reveal that silver nanoparticles of the composite coating have little influence on the growth and spreading of h BMSCs. Both antibacterial and cell culture experiments indicate that Ag NPs-LEHCs B and Ag NPs-LGHCs B have good biocompatibility and strong antimicrobial properties.