Development of a Highly Proliferated Bilayer Coating on 316L Stainless Steel Implants

Abstract

In this research, a bilayer coating has been applied on the surface of 316 L stainless steel (316LSS) to provide highly proliferated metallic implants for bone regeneration. The first layer was prepared using electrophoretic deposition of graphene oxide (GO), while the top layer was coated utilizing electrospinning of poly (ε-caprolactone) (PCL)/gelatin (Ge)/forsterite solutions. The morphology, porosity, wettability, biodegradability, bioactivity, cell attachment and cell viability of the prepared coatings were evaluated. The Field Emission Scanning Electron Microscopy (FESEM) results revealed the formation of uniform, continuous, and bead-free nanofibers. The Energy Dispersive X-ray (EDS) results confirmed well-distributed forsterite nanoparticles in the structure of the top coating. The porosity of the electrospun nanofibers was found to be above 70%. The water contact angle measurements indicated an improvement in the wettability of the coating by increasing the amount of nanoparticles. Furthermore, the electrospun nanofibers containing 1 and 3 wt.% of forsterite nanoparticles showed significant bioactivity after soaking in the simulated body fluid (SBF) solution for 21 days. In addition, to investigate the in vitro analysis, the MG-63 cells were cultured on the PCL/Ge/forsterite and GO-PCL/Ge/forsterite coatings. The results confirmed an excellent cell adhesion along with considerable cell growth and proliferation. It should be also noted that the existence of the forsterite nanoparticles and the GO layer substantially enhanced the cell proliferation of the coatings.

Keywords: biocomposites; cell culture; electrospinning; graphene oxide; nanofibers.

Figure 1

FESEM micrographs of the prepared PCL/Ge nanofibers containing (A) 0%, (B) 1%, and (C) 3 wt.% forsterite nanoparticles.

Figure 2

FESEM micrographs (A) and (B), and the distribution map of Mg element (C) and (D) of the electrospun PCL/Ge nanofibers with 1% and 3% forsterite nanoparticles.

Figure 3

The water contact angles of GO layer and PCL/Ge nanofibers containing 0, 1 and 3 wt.% forsterite.

Figure 4

The pH values of the PBS solutions containing PCL/Ge with 0, 1 and 3 wt.% forsterite during 21 days immersion.

Figure 5

FESEM micrographs of the PCL/Ge/forsterite with 1 and 3 wt.% after 3, 7, 14, and 21 days immersion in the SBF solution.

Figure 6

XRD patterns of PCL/Ge nanofibers containing (A) 1 and (B) 3% of forsterite after 21 days of immersion in SBF.

Figure 7

Morphology of the MG-63 cells on PCL/Ge/forsterite nanofibers with 1 and 3 wt.% and GO-PCL/Ge/forsterite with 1 and 3 wt.% after one and seven days of cell culture.

Figure 7

Morphology of the MG-63 cells on PCL/Ge/forsterite nanofibers with 1 and 3 wt.% and GO-PCL/Ge/forsterite with 1 and 3 wt.% after one and seven days of cell culture.

Figure 8

The MTS results of PCL/Ge structures containing 0, 1 and 3 wt.% forsterite nanoparticles, (A) without the GO layer and (B) with the GO layer (*significant difference at p_value < 0.05).