The co-precipitation method followed by ultrasound and heat treatment is a common way to prepare below 100 nm sized hydroxyapathe nanoparticles for biomedical studies and applications. The size and pH value of the ob...The co-precipitation method followed by ultrasound and heat treatment is a common way to prepare below 100 nm sized hydroxyapathe nanoparticles for biomedical studies and applications. The size and pH value of the obtained calcium phosphate nanoparticles in aqueous sol have a strong impact on the interactions with cells and tissue. The physical and chemical properties of material samples for in vitro and in vivo studies are often assumed to remain constant from the time after fabrication to the actual use. Only little attention is paid to eventual changes of the material over time or due to the different in vitro conditions. In this study, the physical and chemical transformation of calcium phosphate nanoparticles after preparation and in vitro was investigated. As the result showed, dispersed nano sized amorphons calcium phosphate precipitation as well as crystallized hydroxyapathe nanoparticles continue to crystallize even when kept at 4℃ leading to declining pH values and particle sizes. Due to the pH buffer in the medium the pH value of the cell culture remained stable after adding 20% nanoparticle sol in vitro. However, hydroxyapathe nanoparticles immediately became unstable in the presents of cell culture medium. The resulting loose agglomerations showed a size of above 500 nm.展开更多
The panicle size has a strong impact on the interactions between nanoparticles and cells. However, the synthesis process of nanoparticles limits the range of achievable average panicle sizes. When biocompatible hydrox...The panicle size has a strong impact on the interactions between nanoparticles and cells. However, the synthesis process of nanoparticles limits the range of achievable average panicle sizes. When biocompatible hydroxyapatite nanoparticles （HAP） are doped with the luminescent rare earth elemeat Europium （Eu）, the panicle size becomes larger compared to pure HAP. Hence, a panicle size reduction is necessary to achieve similar experimental conditions when stbstituting pure HAP with luminescent HAP ： Eu nanoparticles to investigate particlecell-interactions in cell culture experiments. While the sedimentation process of particles in liquids and gels has been well described in literature, the separation of particles in dispersed colloids has not been studied, yet. In this study, the size depending separation and particle size redaction of a homogeneous dispersed nanoparticle sol by gravity and centrifugation were investigated. As the results showed, shorter time of centrifugation at higher speed can reduce the average particle size compared to the decline of the panicle concentation in the upper sol layer most efficiently. This ceatrifugation method has some similarity to the overspeeding technique which is commonly used to lower the transient time to reach the equilibrium of sedimentation.展开更多
文摘The co-precipitation method followed by ultrasound and heat treatment is a common way to prepare below 100 nm sized hydroxyapathe nanoparticles for biomedical studies and applications. The size and pH value of the obtained calcium phosphate nanoparticles in aqueous sol have a strong impact on the interactions with cells and tissue. The physical and chemical properties of material samples for in vitro and in vivo studies are often assumed to remain constant from the time after fabrication to the actual use. Only little attention is paid to eventual changes of the material over time or due to the different in vitro conditions. In this study, the physical and chemical transformation of calcium phosphate nanoparticles after preparation and in vitro was investigated. As the result showed, dispersed nano sized amorphons calcium phosphate precipitation as well as crystallized hydroxyapathe nanoparticles continue to crystallize even when kept at 4℃ leading to declining pH values and particle sizes. Due to the pH buffer in the medium the pH value of the cell culture remained stable after adding 20% nanoparticle sol in vitro. However, hydroxyapathe nanoparticles immediately became unstable in the presents of cell culture medium. The resulting loose agglomerations showed a size of above 500 nm.
文摘The panicle size has a strong impact on the interactions between nanoparticles and cells. However, the synthesis process of nanoparticles limits the range of achievable average panicle sizes. When biocompatible hydroxyapatite nanoparticles （HAP） are doped with the luminescent rare earth elemeat Europium （Eu）, the panicle size becomes larger compared to pure HAP. Hence, a panicle size reduction is necessary to achieve similar experimental conditions when stbstituting pure HAP with luminescent HAP ： Eu nanoparticles to investigate particlecell-interactions in cell culture experiments. While the sedimentation process of particles in liquids and gels has been well described in literature, the separation of particles in dispersed colloids has not been studied, yet. In this study, the size depending separation and particle size redaction of a homogeneous dispersed nanoparticle sol by gravity and centrifugation were investigated. As the results showed, shorter time of centrifugation at higher speed can reduce the average particle size compared to the decline of the panicle concentation in the upper sol layer most efficiently. This ceatrifugation method has some similarity to the overspeeding technique which is commonly used to lower the transient time to reach the equilibrium of sedimentation.
