Bioinspired Mineralization of Type I Collagen Fibrils with Apatite in Presence of Citrate and Europium Ions
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AuthorGómez Morales, Jaime; Fernández Penas, Raquel; Verdugo-Escamilla, Cristóbal; Degli Esposti, Lorenzo; Oltolina, Francesca; Prat, María; Iafisco, Michele; Fernández Sánchez, Jorge Fernando
Collagen mineralizationApatiteAmorphous calcium phosphateCitrateEuropiumLuminescenceCytocompatibility
Gómez Morales, J. [et al.]. Bioinspired Mineralization of Type I Collagen Fibrils with Apatite in Presence of Citrate and Europium Ions. Crystals 2019, 9, 13; doi:10.3390/cryst9010013.
SponsorshipThis research was funded by Spanish MINEICO and co–funded by FEDER (grant number MAT2014–60533–R). C. V.–E. acknowledges the Spanish MINEICO for his contract PTA2015–11103–I. M.I. acknowledges support by the Italian National Research Program–National Research Council (PNRCNR) Aging Program 2012–2014. The Excellence Network of Crystallography and Crystallization “Factoría de Cristalización” FIS2015–71928–REDC funded by Spanish MINEICO is also acknowledged.
Synthetic nanostructured hybrid composites based on collagen and nanocrystalline apatites are interesting materials for the generation of scaffolds for bone tissue engineering. In this work, mineralized collagen fibrils were prepared in the presence of citrate and Eu3+. Citrate is an indispensable and essential structural/functional component of bone. Eu3+ endows the mineralized fibrils of the necessary luminescent features to be potentially employed as a diagnostic tool in biomedical applications. The assembly and mineralization of collagen were performed by the neutralization method, which consists in adding dropwise a Ca(OH)2 solution to a H3PO4 solution containing the dispersed type I collagen until neutralization. In the absence of citrate, the resultant collagen fibrils were mineralized with nanocrystalline apatites. When citrate was added in the titrant solution in a Citrate/Ca molar ratio of 2 or 1, it acted as an inhibitor of the transformation of amorphous calcium phosphate (ACP) to nanocrystalline apatite. The addition of Eu3+ and citrate in the same titrant solution lead to the formation of Eu3+–doped citrate–coated ACP/collagen fibrils. Interestingly, the relative luminescent intensity and luminescence lifetime of this latter composite were superior to those of Eu3+–doped apatite/collagen prepared in absence of citrate. The cytocompatibility tests, evaluated by the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) colorimetric assay in a dose–dependent manner on GTL–16 human gastric carcinoma cells, on MG–63 human osteosarcoma cells and on the m17.ASC, a spontaneously immortalized mouse mesenchymal stem cell clone from subcutaneous adipose tissue, show that, in general, all samples are highly cytocompatible.