| Various of natural biominerals are composed of inorganic and organic matrix, whichorderly assemble and endow the minerals with varied morphology, fine structure and excellentproperties. Hence, it is a hot topicfor how to control the assembling of colloid andnano-particles accurately, that’s closely related to the complex structure and composition ofthe materials. In particular, the shape and composition regulation of the materials is animportant issue in biomimetic chemistry. Because of the composition similarity with naturalbone tissues, hydroxyapatite (HA) materials have excellent biocompatibility, bioactivityosteoconductivity and promoting osteoblast differentiation properties. With the application ofHA micro-/nano-particles in the field of bone tissue engineering, these particles mightinfluence the viability, proliferation, differentiation and internalization behavior of thesurrounding cells, therefore, a thoroughly investigate the interaction between HA particles andcells is crucial for their further widely application.In this study, sodium citrate and dodecyltrimethylammonium bromide (CTAB) were usedas a template for modifying the crystalline behavior of HA. Through investigating therelationship between the Ct/CTAB ratio, Ct/Ca ratio, pH value of the solution, reaction timeand reaction temperature with crystalline behavior, we controlled the microstructure and sizeaccurately, and successfully synthesized microsphere, microrod, microflower, hollowmicrosphere, nanorod bundles HA micro-/nano-particles with hierarchical structure. At thesame time, we carefully studied the interaction mechanism between the template moleculesand HA crystals, at last we proposed a possible model for demonstrating this phenomenon,which can provide theoretical guidance for the design of materials.We successfully prepared HA hollow microsphere with hierarchical structure, themicrosphere was composed by HA nanorods, its size was about2.8μm, the length and widthof the cavity was about2.5μm and1.6μm, respectively, the size of the mesoporousdistributed in the range of1.7to9.69nm, and it had high specific surface area (about225m2g-1). The results showed that after the drug loaded microsphere immersed at acidic andneutral medium for46h, the drug released amounts was less than30%of its total amounts. Hence, it’s a potential candidate carrier for drug loading.We prepared HA microsphere and microrod through modifying the pH adjusting order,they had uniform structure and size, good distribution state and similar chemical and physicalproperties. The in vitro cellular experiments revealed that both of them impaired theosteogenic differentiation of mouse bone marrow mesenchymal stem cells (mBMSCs) at theinitial co-culture period. With the co-culture time prolonged, these particles promoted theproliferation and osteogenic differentiation of mBMSCs. Moreover, the performance of themicrosphere was better than the microrod, which means the shape of the particles was closelyrelated to the cellular behavior.The composition of HA was modified through ions doping. The trace element—gallium(Ga) not only influenced the crystalline behavior, but also affected the interaction between thecells and materials. Results showed Ga inhibited the oriented growth along the c axis of HAand reduced its dissolution rate, besides, the doping HA particles promoted proliferationprocess of mBMSCs, and played positive role in the osteogenic differentiation process ofmBMSCs.In this work, through investigating the interaction mechanism between templates and HAcrystals, we successfully modified the microstructure of the materials accurately. Thecomposition of HA was modified through chemical doping mode. This kind of biomimeticsynthesis and functionalization mode can provide new ideas of designing for the materialsused in bone tissue engineering area. Meanwhile, the HA particles with varied hierarchicalstructure and composition work well for drug loading and promoting the osteogenicdifferentiation process of BMSCs, hence, they have potential application prospect inbiomedical field. |
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