Cancellous-Bone-like Porous Iron Scaffold Coated with Strontium Incorporated Octacalcium Phosphate Nanowhiskers for Bone Regeneration

Abstract

The repair of large bone defects poses a grand challenge in tissue engineering. Thus, developing biocompatible scaffolds with mechanical and structural similarity to human cancellous bone is in great demand. Herein, we fabricated a three-dimensional (3D) porous iron (Fe) scaffold with interconnected pores via a template-assisted electrodeposition method. The porous Fe scaffold with a skeleton diameter of 143 μm had the porosity >90%, an average pore size of 345 μm, and a yield strength of 3.5 MPa. Such structure and mechanical strength were close to those of cancellous bone. In order to enhance the biocompatibility of the scaffold, strontium incorporated octacalcium phosphate (Sr-OCP) was coated on the skeletons of the porous Fe scaffold. The coated Sr-OCP was in the form of nanowhiskers with a mean diameter of 300 nm and length of 30 μm. Such Sr-OCP coating could effectively reduce the release rate of the Fe ions to a level which was safe for the human body. Both in vitro cytotoxicity tests by extraction method and direct contact assay confirmed that the Sr-OCP coating could promote the cell adhesion and substantially enhance the biocompatibility of the porous Fe scaffolds. Thus, the cancellous-bone-like porous structure with compatible mechanical properties and excellent biocompatibility enables the present Sr-OCP coated porous Fe scaffold to be a promising candidate for bone repair and regeneration.

Conductive Scaffolds for Bone Tissue Engineering: Current State and Future Outlook

“…For example, while metal-based scaffolds show greater overall structural stability when compared to polymer-based scaffolds, they tend to lack the required biological traits of natural bone. By incorporating biologically relevant coatings onto metal-based scaffolds, improved biocompatibility and osteogenic differentiation of cells can be achieved while maintaining their given physical properties [ 56 , 57 ].…”

Insight into the bioabsorption of Fe‐based materials and their current developments in bone applications

“…Being the simplest coating technique, dip coating has been used to coat Fe surface with various materials such as poly(lactic-co-glycolic acid) (PLGA), [35] curcumin, [33] poly(lactic acid) (PLA), [144] PLA/HA, [144] and silver (Ag) containing calcium phosphate (CaP). [157] In other studies, strontiumoctacalcium phosphate (Sr-OCP) [158] and iron-tungsten (Fe-W) [123] alloys have been coated on porous Fe via electrodeposition techniques. Despite having several advantages of low cost and simple experimental arrangement, it is quite challenging to control operating parameters such as applied voltage and electrolyte concentration to attain a desired coating morphology, thickness, and particle size.…”

“…Despite having several advantages of low cost and simple experimental arrangement, it is quite challenging to control operating parameters such as applied voltage and electrolyte concentration to attain a desired coating morphology, thickness, and particle size. [159] Overall, the polyester coatings of PLA and PLGA expedited Fe corrosion but could deteriorate the viability at a longer corrosion period [144] while bioceramic-based coatings (i.e., HA, Ag-CaP, and Sr-OCP) [122,157,158] and organic curcumin coating [33] have decelerated Fe corrosion despite enhancing the cell viability.…”

“…Sr-OCP coated Fe [158] Fe = 38.57 μg mL −1 per day (Fe 2+ release) Sr-OCP coated Fe = 3.71 μg mL −1 per day MC3T3-E1 Sr-OCP coated Fe scaffolds showed 72% cell viabilities after a 48-h incubation while uncoated Fe exhibited only 5% viability due to the lower Fe ion concentrations released by the former.…”

Advances in Use of Nanomaterials for Musculoskeletal Regeneration

“…The coating was in the form of nanowhiskers with the mean diameter of 300 nm and the length of 30 µm and decreased the release rate of Fe ions to a level safe for the human body. The cell adhesion and biocompatibility were enhanced [210]. Polymer/phosphate glass/Fe 3 O 4 MNP (CG/PG/MNP) composite scaffolds were developed using a freeze drying technique.…”