Fabrication of Submicro-Nano Structures on Polyetheretherketone Surface by Femtosecond Laser for Exciting Cellular Responses of MC3T3-E1 Cells/Gingival Epithelial Cells

Abstract

Purpose: Polyetheretherketone (PEEK) exhibits high mechanical strengths and outstanding biocompatibility but biological inertness that does not excite the cell responses and stimulate bone formation. The objective of this study was to construct submicro-nano structures on PEEK by femtosecond laser (FSL) for exciting the responses of MC3T3-E1 cells and gingival epithelial (GE) cells, which induce regeneration of bone/gingival tissues for long-term stability of dental implants.

Materials and methods: In this study, submicro-nano structures were created on PEEK surface by FSL with power of 80 mW (80FPK) and 160 mW (160FPK).

Results: Compared with PEEK, both 80FPK and 160FPK with submicro-nano structures exhibited elevated surface performances (hydrophilicity, surface energy, roughness and protein absorption). Furthermore, in comparison with 80FPK, 160FPK further enhanced the surface performances. In addition, compared with PEEK, both 80FPK and 160FPK significantly excited not only the responses (adhesion, proliferation, alkaline phosphatase [ALP] activity and osteogenic gene expression) of MC3T3-E1 cells but also responses (adhesion as well as proliferation) of GE cells of human in vitro. Moreover, in comparison with 80FPK, 160FPK further enhanced the responses of MC3T3-E1 cells/GE cells.

Conclusion: FSL created submicro-nano structures on PEEK with elevated surface performances, which played crucial roles in exciting the responses of MC3T3-E1 cells/GE cells. Consequently, 160FPK with elevated surface performances and outstanding cytocompatibility would have enormous potential as an implant for dental replacement.

Keywords: cell responses; functional group; polyetheretherketone; PEEK; submicro-nano structures; surface modification.

Figure 1

SEM images of surface morphologies of PEEK (A, D and G), 80FPK (B, E and H) and 160FPK (C, F and I) under different magnification.

Figure 2

AFM images (A–C) and roughness (D) of PEEK (A), 80FPK (B) and 160FPK (C); FTIR (E) and XRD (F) of specimens (*p < 0.05, vs. PEEK).

Figure 3

Wide-scan XPS spectrum (A and C) and C1s core-level XPS spectrum (B and D) of PEEK (A and B) and 160FPK (C and D).

Figure 4

Water contact angles (A) and surface energies (B) of specimens, and adsorption of BSA (C) and Fn (D) on specimens (*p < 0.05, vs. PEEK).

Figure 5

CLSM images of morphologies of MC3T3-E1 cells on PEEK (A), 80FPK (B) and 160FPK (C) at 24 hours after culturing.

Figure 6

SEM micrographs of morphologies of MC3T3-E1 cells on PEEK (A and D), 80FPK (B and E) and 160FPK (C and F) at 1 (A–C) and 3 days (D–F) after culturing.

Figure 7

Attachment ratios (A), OD values (B) and ALP activities (C) of MC3T3-E1 cells on PEEK, 80FPK and 160FPK at different times after culturing (*p < 0.05, vs. PEEK).

Figure 8

Expressions of osteogenic genes of ALP (A), Runx2 (B), OPN (C) and OCN (D) of MC3T3-E1 cells on the specimens at different time after culturing (*p < 0.05, **p < 0.01, vs. PEEK; #p < 0.05, 160FPK vs. 80FPK).

Figure 9

CLSM images of morphologies of GE cells on PEEK (A and D), 80FPK (B and E) and 160FPK (C and F) at 12 (A–C) and 24 (D–F) hours after culturing.

Figure 10

SEM micrographs of morphologies of GE cells on PEEK (A and D), 80FPK (B and E) and 160FPK (C and F) at 3 days (different magnification) after culturing.

Figure 11

Attachment ratios (A) and OD values (B) of GE cells on PEEK, 80FPK and 160FPK at different time after culturing (*p < 0.05, vs. PEEK).