Thin-sections of protein-mineral nanoparticles seeded by fetuin-A or albumin show distinct morphologies.

<p>Protein-mineral nanoparticles were prepared as described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008058#pone-0008058-g006" target="_blank">Fig. 6</a>, by diluting either BSF at 2.1 µg/ml (A–C), HSA at 120 µg/ml (D–F), or both proteins at these same concentrations (G–I) into DMEM and then adding 0.3 mM each of CaCl₂ and NaH₂PO₄, followed by incubation in cell culture conditions for 1 month. Thin-sections were prepared without fixation or staining, as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008058#s3" target="_blank"><i>Materials and Methods</i></a>. BSF-NLP (A–C) resembled multi-layered laminations with alternate electron densities. HSA-NLP (D–F) appeared mostly as incompletely sealed, single-layered formations. The BSF-HSA-NLP particles had rough surfaces covered with elongated crystal projections (G), with some structures appearing either as multi-layered (H) or single-layered (I). Control, commercial grades of CaCO₃ (J), Ca₃(PO₄)₂ (K), and HAP (L) were incubated in DMEM as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0008058#pone-0008058-g010" target="_blank">Fig. 10</a>. These controls showed mainly monolithic platelets or aggregates of crystalline formations that contrasted with the round nanoparticles shown above. Scale bars: 100 nm (H, I, L); 200 nm (C, K); 250 nm (F); 500 nm (B, D, E, G, J); 1 µm (A).