# Surface Functionalization of Polyethylene by Silicon Nitride Laser Cladding  
[PERSON]  
1 Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan; [EMAIL_ADDRESS] (M.Z.); [EMAIL_ADDRESS] (E.M.); [EMAIL_ADDRESS] (F.B.); [EMAIL_ADDRESS] (W.Z.)  
2 Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, 465 Kajii-cho, Kawaramachi dori, Kyoto 602-0841, Japan; [EMAIL_ADDRESS] (T.A.); [EMAIL_ADDRESS] (T.Y.); [EMAIL_ADDRESS] (N.K.)  
3 Shirei, Co., Shijohei Kawanishi Riokobo, Kyoto 610-0101, Japan; [EMAIL_ADDRESS] (P.)  
4  
[PERSON]  
1 Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan; [EMAIL_ADDRESS] (M.Z.); [EMAIL_ADDRESS] (E.M.); [EMAIL_ADDRESS] (F.B.); [EMAIL_ADDRESS] (W.Z.)  
5  
[PERSON]  
1 Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan; [EMAIL_ADDRESS] (M.Z.); [EMAIL_ADDRESS] (E.M.); [EMAIL_ADDRESS] (F.B.); [EMAIL_ADDRESS] (W.Z.)  
6  
[PERSON]  
3 Department of Dental Medicine, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, 465 Kajii-cho, Kawaramachi dori, Kyoto 602-0841, Japan; [EMAIL_ADDRESS] (T.A.); [EMAIL_ADDRESS] (T.Y.); [EMAIL_ADDRESS] (N.K.)  
7  
[PERSON]  
5 [PERSON]  
2 Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, 465 Kajii-cho, Kawaramachi dori, Kyoto 602-0841, Japan; [EMAIL_ADDRESS] (T.A.); [EMAIL_ADDRESS] (T.Y.); [EMAIL_ADDRESS] (N.K.)  
26  
[PERSON]  
1 Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, Kyoto 606-8585, Japan; [EMAIL_ADDRESS] (M.Z.); [EMAIL_ADDRESS] (E.M.); [EMAIL_ADDRESS] (F.B.); [EMAIL_ADDRESS] (W.Z.)  
2 Department of Immunology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kamigyo-ku, 465 Kajii-cho, Kawaramachi dori, Kyoto 602-0841, Japan; [EMAIL_ADDRESS] (T.A.); [EMAIL_ADDRESS] (T.Y.); [EMAIL_ADDRESS] (N.K.)  
4  
Shirei, Co., Shijohei Kawanishi Riokobo, Kyoto 610-0101, Japan; [EMAIL_ADDRESS] (P.)  
6  
Footnote 6: email: {15.5  
polymers, such as PE, PVC, PP, and polystyrene, while the remaining plastics comprise only a minor fraction of the medical market.  
Technical polymers are selected and modified depending on their specific applications. For example, packaging materials are often coated with a barrier layer to protect them against damage by humidity and oxygen. Energetic photon [2,3], ion [4], and electron beam [5,6] processes are used to modify polymeric surfaces in different ways. Polymers can also be coated or combined with a second phase during synthesis to form polymer-matrix composites. In orthopaedics, PE [7] has been prepared as a composite using different dispersoids such as carbon black [8,9], ceramics (TiO\({}_{2}\)[10], Al\({}_{2}\)O\({}_{3}\)[11], CaCO\({}_{3}\)[12], hydroxyapatite [13]), and metallic fibres [14].  
Silicon nitride (Si\({}_{3}\)N\({}_{4}\)) is a structural non-oxide ceramic and a candidate for a number of orthopedic applications because of its high strength and toughness [15]. However, unlike polymers, it is not bioinert, but bioactive. Its unique surface chemistry provides it with antibacterial [16] and osteeconductive [17] characteristics. Silicon nitride is currently cleared for use as an intervertebral spacer in spinal fusion surgery [18].  
In this paper, we attempted to functionalize the surface of bulk PE by coating it with activated Si\({}_{3}\)N\({}_{4}\) powder. It was hypothesized that the Si\({}_{3}\)N\({}_{4}\) coating would protect the polymer from oxidation while conferring both antibacterial and osteogenic properties. If true, this approach might be useful in improving the lifetime of PE while concurrently reducing the risk of infection and promoting osteointegration.