Bioactivity and biocompatibility of porous gradient bioceramic coating prepared via laser cladding process

In this work, porous gradient bioceramic coating was fabricated via laser cladding process, and its bioactivity and biocompatibility were evaluated by various tests such as simulated body fluid (SBF) soaking, cell proliferation, cell fixation, osteoblast staining, osteoblast alkaline phosphatase (ALP) activity, and hydroxyproline (HYP) activity. Various porous bioceramic coatings were prepared with 0, 2.5, 5, 7.5, and 1 Owt% forming agents, and they were denoted as 0 wt% PFA, 2.5 wt% PFA, 5 wt% PFA, 7.5 wt% PFA, and 10 wt% PFA coating, respectively. Among these coatings, 2.5 wt% PFA and 5 wt% PFA coatings after immersing in SBF showed good ability towards mineralization and deposition of bioactive phase components, i.e., HA and p-TCP. In contrast to other coatings prepared in this work, the presence of pore structure on the surfaces of 2.5 wt% PFA and 5 wt% PFA coatings favored the deposition of bone-like apatite. The results obtained from the cell proliferation experiment revealed that 2.5-5 wt% PFA porous coatings possessed superior cell proliferation ability when compared to the other coatings. After investigating the cell fixation morphology, the pore structures of 2.5-5 wt% PFA coatings were shown to be more beneficial for the attachment and growth of MG63 cells on the surface or within the pore structure. Furthermore, the osteoblast staining test proved an extensive wide-ranged MG63 cell growth on the surfaces of 2.5-5 wt% PFA porous coatings. The ALP activity result revealed the increase in ALP contents for 2.5-10 wt% PFA porous coatings. This was especially noticeable for 2.5 wt% PFA coating as it presented the highest ALP content after 6 days. The HYP activity result indicated a continuous HYP content increment for 0-10 wt% PFA porous coatings, with only a slight difference observed between 2 days and 6 days. Therefore, a porous gradient coating with a certain pore structure, i.e., large pore size, even pore distribution, and high pore number, could significantly influence its bioactivity and biocompatibility. Based on the collective results, 2.5 wt% PFA coating with a uniform pore distribution and numerous large-sized pores exhibited the best comprehensive bioactivity and biocompatibility.

Automated summary

The porous gradient bioceramic coating fabricated via laser cladding process was evaluated for bioactivity and biocompatibility through various tests. Results showed that the 2.5 wt% PFA and 5 wt% PFA coatings exhibited good ability towards mineralization and deposition of bioactive phase components.