Synthesis, Characterization, and Biological Evaluation of Nanostructured Hydroxyapatite with Different Dimensions

Abstract

Nanosized hydroxyapatite (HA) is a promising candidate for a substitute for apatite in bone in biomedical applications. Furthermore, due to its excellent bone bioactivity, nanosized strontium-substituted HA (SrHA) has aroused intensive interest. However, the size effects of these nanoparticles on cellular bioactivity should be considered. In this study, nanosized HA and SrHA with different dimensions and crystallization were synthesized by hydrothermal methods. The phase, crystallization and chemical composition were analyzed by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR), respectively. The morphology was observed under field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The degradation behaviors of the samples were monitored by determining the ions release profile with inductively coupled plasma mass spectrometry (ICP-MS). The releasing behavior of Ca2+ and Sr2+ showed that the degradation rate was proportional to the specific surface area and inversely proportional to crystallization. The in vitro experiment evaluated by MG63 cells showed that SrHA nanorods with a length greater than 100 nm had the best biological performance both in cell proliferation and differentiation (* p < 0.05 compared with HA-1 and SrHA-1; * p < 0.01 compared with HA-2). In addition, HA nanoparticles with a lower aspect ratio had better bioactivity than higher ones (* p < 0.05). This study demonstrated that nanosized HA and SrHA with subtle differences (including dimensions, crystallization, specific surface area, and degradation rate) could affect the cellular growth and thus might have an impact on bone growth in vivo. This work provides a view of the role of nano-HAs as ideal biocompatible materials in future clinical applications.

89Sr‐doped hydroxyapatite nanoparticles as a potential therapeutic agent for bone tumors

“…48,59 Thus, these results demonstrate the possibility to use HA-Sr samples in the treatment of bone tumors since the bone regeneration at the affected site may not be compromised even in the presence of the materials that will be treating the region by the beta emission of radionuclides 32 P and 89 Sr. 48,59 Thus, these results demonstrate the possibility to use HA-Sr samples in the treatment of bone tumors since the bone regeneration at the affected site may not be compromised even in the presence of the materials that will be treating the region by the beta emission of radionuclides 32 P and 89 Sr.…”

“…These suspensions were incubated under constant shaking (50 rpm) and temperature (37°C) for varying time intervals (2,5,8,24,48, and 72 hours). This assay was performed by the preparation of suspensions of samples in Milli-Q ® water at a concentration of 2.2 mg/ mL.…”

“…The principle of CCK-8 is based on the photometric detection of the reduction of tetrazolium salt to a water-soluble formazan product. 2,9 According to Geng and collaborators, 48 the cell proliferation assay conducted on MG-63 osteosarcoma cells demonstrated that both HA and HA-Sr nanorods can lead an increase in cell division after the period of a few days when the material is in contact with the cells, probably due to the presence of Ca 2+ and Sr 2+ ions. 47 The results are shown in Figures 14 and 15.…”

“…This assay was performed by the preparation of suspensions of samples in Milli-Q ® water at a concentration of 2.2 mg/ mL. These suspensions were incubated under constant shaking (50 rpm) and temperature (37°C) for varying time intervals (2,5,8,24,48, and 72 hours). After each time, the suspensions were filtered and the pass-through liquids were analyzed by the ICP-AES-Spectroflame, Spectro Analytical Instruments, Germany, technique to obtain Sr contents.…”

“…The high cellular viability for all materials was already expected, since HA and Sr are already known to be biocompatible materials. 2,9 According to Geng and collaborators, 48 the cell proliferation assay conducted on MG-63 osteosarcoma cells demonstrated that both HA and HA-Sr nanorods can lead an increase in cell division after the period of a few days when the material is in contact with the cells, probably due to the presence of Ca 2+ and Sr 2+ ions. Taking this into consideration and that the result of the present study was obtained after 48 hours, there may have been an increase in cell proliferation, caused by the release of Sr ions from the HA-Sr complex, as already discussed in the stability test of the doped samples.…”