Hydroxyapatite (HA) nanorods were synthesized using a citrate-assisted hydrothermal method. NaH 2 PO 4 , Na 2 HPO 4 , and Na 3 PO 4 were used as the phosphate sources and the influences of pH value were investigated. The XRD results show that pure hexagonal HA can be synthesized using Na 3 PO 4 ·12H 2 O as the phosphate source with the citrate solution pH ranging from 5.0 to 7.6. The zeta potential evaluation demonstrates that as-synthesized HA nanorods are colloidally stable and the aqueous dispersion can be maintained homogenous without any sediment or creaming for more than at least a month. The Ca/P molar ratio of the HA nanorods is about 1.60, indicating that the HA nanorods are calcium-deficient hydroxyapatite. Besides, owing to the excellent colloidal stability and rod-like morphology with a high aspect ratio (>6), the HA aqueous dispersion undergoes a phase transition from an isotropic state to a liquid crystalline state upon increasing the particle concentration to 17wt%. The completely liquid crystalline phase forms when the particle concentration reaches above 30wt%.
Lin Duan,Haoyang Deng,Qianqing Zhang,Peijie Gao,Lang Wu
Bisphenol A (BPA) and fluoroquinolone antibiotics (FQs) have been detected frequently in aquatic environments. Studies have shown that high levels of BPA and FQs exposure have adverse effects on chondrogenesis in young terrestrial vertebrates. However, little is known about their combined toxicity to bone metabolism. Here, we evaluated the single and combined effects of BPA and norfloxacin (NOR, a typical species of FQs) at an environmentally relevant level (1 μg/L) on early skeletal development in zebrafish. We found that both individual and combined BPA and NOR exposure resulted in poor embryo quality and decreased calcium-phosphorus ratio. The malformation increased after exposure to BPA and NOR, and craniofacial cartilage ossification was delayed. At the molecular level, the transcriptions of genes related to ossification were down-regulated significantly, and the lysine oxidase activity decreased. Hence, we infer that an environmentally relevant concentration of BPA and NOR have adverse effects on early skeletal development in fish. In addition, combined exposure to BPA and NOR seems to have an antagonistic effect on early skeletal development.
危险品化学品经营许可证（带存储）