Preparation, Characterization and In Vitro Biological Evaluation of a Novel Pearl Powder/Poly-Amino Acid Composite as a Potential Substitute for Bone Repair and Reconstruction

Abstract

Many studies about fabricating organic-inorganic composite materials have been carried out in order to mimic the natural structure of bone. Pearl, which has a special block-and-mortar hierarchical structure, is a superior bone repair material with high osteogenic activity, but it shows few applications in the clinical bone repair and reconstruction because of its brittle and uneasily shaped properties. In this work, pearl powder (P)/poly (amino acid) (PAA) composites were successfully prepared by a method of in situ melting polycondensation to combine the high osteogenic activity of the pearl and the pliability of the PAA. The mechanical properties, in vitro bioactivity and biocompatibility as well as osteogenic activity of the composites were investigated. The results showed that P/PAA composites have both good mechanical properties and bioactivity. The compressive strength, bending strength and tensile strength of the composites reached a maximum of 161 MPa, 50 MPa and 42 MPa, respectively; in addition, apatite particles successfully deposited on the composites surface after immersion in simulated body fluid (SBF) for 7 days indicated that P/PAA composites showed an enhanced mineralization capacity and bioactivity due to incorporation of pearl powder and PAA. The cell culture results revealed that higher cell proliferation and better adhesion morphology of mouse bone marrow mesenchymal stem cells (MSCs) appeared on the composite surface. Moreover, cells growing on the surface of the composites exhibited higher alkaline phosphatase (ALP) activity, more calcium nodule-formation, and higher expression levels of osteogenic differentiation-related genes (COL 1, RunX2, OCN, and OPN) than cells grown on PAA surface. The P/PAA composites exhibited both superior mechanical properties to the pearl powder, higher bioactivity and osteogenic capability compared with those of PAA.

Effects of particle size of hydroxyapatite on mechanical property and cytocompatibility of hydroxyapatite/poly(amino acid) composites

“…As can be seen in Figure 5C, the peak 1 of O 1s may be attributed to the oxygen of amide bond in PAA, and its binding energy had slightly raised in the composites. [43] The peak 2 and peak 3 of O 1s could be attributed to OH groups and PO 4 3À of HA. [44] And their binding energy were obviously higher in composites than that in pure HA.…”

“…It could be considered that possible interactions existed between the HA and the surrounding PAA. [28,43] What's more, the increase of binding energy for OH in PAA/HA1 and PAA/HA2 was especially remarkable, indicating the existence of a stronger chemical interaction. When the particle size decreased to nanoscale, the specific surface area of particle increased rapidly, meaning that multiple uncoordinated atoms of material situated at its surface, which increased the surface energy.…”

Pearl Powder—An Emerging Material for Biomedical Applications: A Review

“…Mineralization on these composite nanofibres improved with an increasing proportion of pearl powder. Polyaminoacid (PAA) scaffolds impregnated with pearl powder have also been investigated as composites for bone healing [ 77 ]. These composites were prepared using an in situ melting polycondensation process to incorporate the high osteogenic influence of pearl with the flexibility and biocompatibility of PAA.…”

Biological evaluation of the modified nano-amorphous phosphate calcium doped with citrate/poly-amino acid composite as a potential candidate for bone repair and reconstruction

“…Moreover, as to cetylpyridinium chloride can dissolve the stained red calcium nodules and changed into a purple transparent solution after dissolution. The OD values were tested at its maximum absorption wavelength (620 nm) to quantitatively reflect the deposition of calcium nodules [ 18 ].…”