Fibronectin adsorption on osteoconductive hydroxyapatite and non-osteoconductiveα-alumina

Abstract

The osteoconductivity mechanism of hydroxyapatite (HAp) has not been elucidated. It is hypothesized that specific proteins adsorb on HAp, promoting its osteoconductivity. To verify this hypothesis, we compared the adsorption behavior of fibronectin (Fn) on HAp powder and on α-alumina (α-Al2O3) powder, a material with no osteoconductivity. More Fn adsorbed on α-Al2O3 than on HAp, irrespective of the Fn concentration, and there was no significant difference in the secondary structure of Fn adsorbed on HAp and α-Al2O3. Further, it is possible that Fn did not adsorb on HAp and α-Al2O3 through the Arg-Gry-Asp motif of Fn. The amount of Fn adsorbed on HAp oriented to the a(b)-axis with very little decrease in carbonate and the adsorbed Fn had a smaller α-helix structure content. The results suggest that the secondary and/or higher-order structure rather than the amount of adsorbed Fn might affect the osteoconductivity of HAp, which might be electrostatically controlled by the crystal face orientation and/or carbonate content of HAp, although this should be confirmed by a cell culture test in the future.

Proteomic identification of serum proteins to induce osteoconductivity of hydroxyapatite

“…HAp powder (HAP-200, Taihei Chemical Industrial, Osaka, Japan) and α-Al 2O3 powder (ALO14PB, Kojundo Chemical, Saitama, Japan) were used as materials for protein adsorption. We confirmed the composition and purity of HAP-200 and ALO14PB by X-ray diffraction analysis, which established that they contained only HAp and α-Al 2O3, respectively 14) . Based on the measured surface area, 867 mg of HAp powders and 386 mg of α-Al 2O3 powders, which gave the same surface area of 3.2 m 2 , were used for adsorption of serum proteins.…”

“…However, adsorption of bovine serum albumin led to inhibition of the attachment of RAW264.7 macrophages on α-Al 2O3 but not on the HAp surface 13) . Further, we revealed that fibronectin or laminin adsorbed on HAp enhanced the attachment and spreading of MC3T3-E1 cells; however, on α-Al 2O3, they showed no such effect [14][15][16] . These studies suggest that serum proteins display remarkably different functions depending on whether they are adsorbed on a bioceramic material.…”

“…Then, aided by these proteins, some cells attach to the surface of the materials 10,11) . We have been investigating the adsorption behavior of certain proteins on osteoconductive HAp and nonosteoconductive alpha-alumina (α-Al 2O3) and their effects on cellular responses [12][13][14][15][16] . These investigations revealed that bovine serum albumin adsorbed onto HAp and α-Al 2O3 to inhibit the attachment and spreading of osteoblast-like MC3T3-E1 cells but did not affect their proliferation.…”

Enhancement of cell differentiation on a surface potential-controlled nitrogen-doped TiO₂ surface

“…Soaking in serum-containing medium resulted in a similar amount of Fn adsorbed on all three surfaces. The zeta potential of Fn is ¹7 mV 26) but Fn adsorption was not dependent on the surface potential of the samples. We reduced the effect of ions in each medium by assessing Fn adsorption on the samples after soaking in Fn-containing Tris-HCl solution.…”

The biocompatibility of silver and nanohydroxyapatite coatings on titanium dental implants with human primary osteoblast cells

“…One approach to resolving this dilemma is to make a composite material where the different components promote antimicrobial activity and biocompatible properties respectively. For the latter, synthetic HA is well-known to simulate the mineral properties of natural bone, and is regarded as a biocompatible and osteoconductive material [12,13]. Traditional micron scale HA has been used for some years to enhance the biocompatibility of bone implants [14].…”