纳米羟基磷灰石表面修饰及其DNA结合性能的实验研究

Surface modification and DNA-binding assessment of nano-hydroxyapatite

目的探讨纳米羟基磷灰石(nano-hydroxyapatite,nHA)的表面修饰对DNA结合能力的影响。方法采用化学共沉淀-水热合成法制备nHA;应用聚乙烯亚胺(polyethylenimine,PEI)对其进行表面修饰,对修饰及未修饰纳米粒进行透射电镜观察及Zeta电位检测;凝胶电泳检测纳米粒修饰前后在不同pH值、不同浓度下与DNA结合及保护DNA抗核酸酶消化的能力。结果经PEI表面修饰的nHA透射电镜下呈短棒状,粒径较均匀,分散程度良好;而未修饰的纳米粒较易团聚及分散性差。纳米粒经表面修饰后其Zeta电位为正,在不同pH值、不同浓度下与DNA具有较强的结合及抗核酸酶消化的能力;而未修饰的nHA表面带负电荷,与DNA结合及抗核酸酶消化的能力较差。在pH为7.0环境条件下经表面修饰的nHA浓度为250μg/ml时能更有效结合和保护DNA。结论 nHA经PEI表面修饰后可成为一种有效的DNA结合及转运载体。

Objective To evaluate the impact of surface modification on the DNA-binding ability of nano-hydroxyapatite（nHA）.Methods Chemical co-precipitation-hydrothermal synthesis was utilized to prepare the nHA particles,and polyethylenimine（PEI） was used forsurface modification of the nHA.Transmission electron microscopic（TEM） observation and zeta potential detection of the nHA were carried out before and after surface modification.The abilities of the nanoparticles,at different pH values and different concentrations,for DNA-binding and DNA protection against nuclease digestion were assessed before and after surface modification by electrophoresis.Results TEM observation showed a short rod-like morphology of PEI-modified nHA with uniform particle size and good dispersion;the nHA without the modification tended to aggregate with poordispersion.With a positive zeta potential,the PEI-modified nHA showed an obviously enhanced ability of DNA binding at different pH values and concentrations,with strong capacity to protect the DNA against Dnase I digestion.At the concentration of 250 ？？/ml and a pH value of 7.0,the nHA-PEI showed an optimal efficiency of DNA-binding and DNA protection.Conclusion nHA with surface modification by PEI can serve as an effective vector for DNA binding and transfer.