We report the synthesis of fine (∼ 5 nm) citric acid capped CoFe₂O₄ (CA-CoFe₂O₄) nanoparticles by coprecipitation method at different pH conditions that changes gradually from 6 to 11. Structural and magnetic characterization performed by TEM, XRD and SQUID confirm that synthesis under lower pH (6 and 9) leads to the formation of citric acid shell covering the individual nanoparticles. Capping layer increases inter-particle distance what results in the decrease of the interaction strength. On the other hand, higher pH (10 and 11) apparently hampers the proper formation of the layer that, in consequence, builds thinner organic coating. Therefore, individual nanoparticles are in closer contact and acting of strong mutual interactions results in the formation of larger agglomerates with pomegranate-like structure. For biomedical applications of studied systems the viability study on A549 lung cancer cells was performed. The high power confocal analyses confirmed the presence of nanoparticles both in the nucleus as well as in the perikaryon of the cells and no changes in morphology indicating the adverse effect of nanoparticles were observed.

我们报道了精细 (∼ 5  nm) 柠檬酸封端的 CoFe ₂ O ₄ (CA-CoFe ₂ O ₄) 纳米粒子在不同 pH 条件下从 6 逐渐变化到 11。通过 TEM、XRD 和 SQUID 进行的结构和磁性表征证实，在较低 pH（6 和 9）下的合成导致形成覆盖个体的柠檬酸壳纳米粒子。覆盖层增加了颗粒间距离，导致相互作用强度降低。另一方面，较高的 pH 值（10 和 11）显然会阻碍层的正确形成，从而形成更薄的有机涂层。因此，单个纳米颗粒更紧密地接触，并且强烈的相互作用导致形成具有石榴状结构的更大团聚体。为了研究系统的生物医学应用，对 A549 肺癌细胞进行了生存力研究。