title: Controllable preparation of a nano-hydroxyapatite coating on carbon fibers by electrochemical deposition and chemical treatment.
abstract: A nano-hydroxyapatite (HA) coating with appropriate thickness and morphology similar to that of human bone tissue was directly prepared onto the surfaces of carbon fibers (CFs). A mixed solution of nitric acid, hydrochloric acid, sulfuric acid, and hydrogen peroxide (NHSH) was used in the preparation process. The coating was fabricated by combining NHSH treatment and electrochemical deposition (ECD). NHSH treatment is easy to operate, produces rapid reaction, and highly effective. This method was first used to induce the nucleation and growth of HA crystals on the CF surfaces. Numerous O-containing functional groups, such as hydroxyl (-OH) and carboxyl (-COOH) groups, were grafted onto the CF surfaces by NHSH treatment (NHSH-CFs); as such, the amounts of these groups on the functionalized CFs increased by nearly 8- and 12-fold, respectively, compared with those on untreated CFs. After treatment, the NHSH-CFs not only acquired larger specific surface areas but retained surfaces free from serious corrosion or breakage. Hence, NHSH-CFs are ideal depositional substrates of HA coating during ECD. ECD was successfully used to prepare a nano-rod-like HA coating on the NHSH-CF surfaces. The elemental composition, structure, and morphology of the HA coating were effectively controlled by adjusting various technological parameters, such as the current density, deposition time, and temperature. The average central diameter of HA crystals and the coating density increased with increasing deposition time. The average central diameter of most HA crystals on the NHSH-CFs varied from approximately 60 nm to 210 nm as the deposition time increased from 60 min to 180 min. Further studies on a possible deposition mechanism revealed that numerous O-containing functional groups on the NHSH-CF surfaces could associate with electrolyte ions (Ca(2+)) to form special chemical bonds. These bonds can induce HA coating deposition and improve the interfacial bonding strength between the HA coating and NHCH-CFs. The results of this study and the proposed preparation of uniform and dense nano-HA coating provide theoretical and practical guidance for future investigations of active HA coatings on fiber materials for medical products and implants. This work also lays the foundation for the wider use of HA-coated CFs/HA composite implants in clinical application.
authors.affiliation: College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China.
authors.forename: Xudong
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China. Electronic address: zhaoxueni@sust.edu.cn.
authors.forename: Xueni
authors.initials: X
authors.lastname: Zhao
authors.affiliation: College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China.
authors.forename: Wanying
authors.initials: W
authors.lastname: Wang
authors.affiliation: College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.affiliation: College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China.
authors.forename: Fuzhen
authors.initials: F
authors.lastname: He
authors.affiliation: College of Mechanical & Electrical Engineering, Shaanxi University of Science & Technology, Xi'an, Shaanxi 710021, China.
authors.forename: Jianjun
authors.initials: J
authors.lastname: Yang
mesh_terms: D000143:Acids / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D000077482:Carbon Fiber; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D056951:Photoelectron Spectroscopy; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D000143:Acids; D000077482:Carbon Fiber; D020099:Coated Materials, Biocompatible; D002244:Carbon; D017886:Durapatite
keywords: Carbon fibers; Chemical treatment; Electrochemical deposition; Nano-HA coating