Bioactive composite gradient coatings of nano-hydroxyapatite/polyamide66 fabricated on polyamide66 substrates

Abstract

Tightly bonding of bioactive coating is the first crucial need for orthopaedic implants. This study describes a novel and convenient technique to prepare bioactive coating with high adhesion on orthopaedic substitutes made of polymeric matrix. Here, a chemical corrosion method has been adopted to fabricate a coating on the surface of injection-moulded polyamide66 (PA66) substrates by corrosive nano-hydroxyapatite/polyamide66 (n-HA/PA66) composite slurry. Scanning electron microscopy observation shows that a porous chemical corrosion region presents between the coating and dense PA66 substrate. Energy-dispersive X-ray spectroscopy analysis indicates that the chemical corrosion region is mainly composed of PA66 matrix, and the coating layer is an n-HA-rich layer. Both the pore size and n-HA composition increase gradually from the polymeric substrate towards the coating surface. Mechanical testing shows the bonding strength can reach 13.7 + 0.2 MPa, which is much higher than that fabricated on polymeric matrix by other coating methods. The gradual transition in coating structure and composition benefits for the interface bonding and for the surface bone-bonding bioactivity. Subsequent cell experiments corroborate n-HA-rich coating and a porous structure is benefitting for cell attachment and proliferation. The convenient coating method could be popularized and applied on similar polymer implants to produce a tightly and porous bioactive coating for bone tissue regeneration.

In vitro and in vivo biocompatibility and osteogenesis of graphene-reinforced nanohydroxyapatite polyamide66 ternary biocomposite as orthopedic implant material

“…[3][4][5] nHA ceramics are clinically used to coat the surface of orthopedic implants and for biomedical Polymers, such as high-density polyethylene, polyetheretherketone, and polyamides, have apparent advantages such as good mechanical properties and processability. 9,10 As a result, nHA has been incorporated into polymers to fabricate organic/inorganic composites, which have improved mechanical properties compared to nHA alone, for bone tissue engineering applications. Polylactic acid (PLA) is widely used in bone tissue engineering because of its biodegradability and thermal plasticity.…”

“…Numerous studies have thoroughly demonstrated the biocompatibility of nHA/PA66 composites in vivo and in vitro. 9,16,19 However, the biological safety, especially in vivo safety, of graphenepolymer composites is controversial. There have been very few related studies on the in vivo safety of such composite materials; moreover, the results from these studies have not been consistent and are even contradictory.…”

Interfacial and biological properties of the gradient coating on polyamide substrate for bone substitute

“…Therefore, the bonding of coating to substrate is a kind of chemical bonding. Furthermore, higher shear strength can be obtained by adjusting the reaction conditions [8]. After interfacial bonding test, the pores of the fracture surface deform along the direction of the external load.…”

“…Therefore, surface engineering of polymers is an interesting way to modify the material and biological responses [12]. There have been several ways to improve the bioactivity of PA for bone repair, such as compounding with bioactive inorganic particles [8,13], grafting with bioactive groups [14] and forming bioactive coatings [5,15]. Compared with the first two methods, bioactive coating is a relatively facile and low-cost technique.…”

Integrating mechanical and biological control of cell proliferation through bioinspired multieffector materials

“…Since ideally, mechanical stimulation should act synergistically with biological signals, 3D scaffolds might be appropriate as combined with sets of soluble factors embedded in the matrices, as discussed in deep below. This is exemplified by the emerging biomimetic materials used in implants for bone regeneration such as nano-hydroxyapatite/polyamide66 and derivatives (37) that show excellent biocompatibility, stability and osteoconductivity.…”