title: Multiscale characterization of acrylic bone cement modified with functionalized mesoporous silica nanoparticles.
abstract: Acrylic bone cement is widely used to anchor orthopedic implants to bone and mechanical failure of the cement mantle surrounding an implant can contribute to aseptic loosening. In an effort to enhance the mechanical properties of bone cement, a variety of nanoparticles and fibers can be incorporated into the cement matrix. Mesoporous silica nanoparticles (MSNs) are a class of particles that display high potential for use as reinforcement within bone cement. Therefore, the purpose of this study was to quantify the impact of modifying an acrylic cement with various low-loadings of mesoporous silica. Three types of MSNs (one plain variety and two modified with functional groups) at two loading ratios (0.1 and 0.2wt/wt) were incorporated into a commercially available bone cement. The mechanical properties were characterized using four-point bending, microindentation and nanoindentation (static, stress relaxation, and creep) while material properties were assessed through dynamic mechanical analysis, differential scanning calorimetry, thermogravimetric analysis, FTIR spectroscopy, and scanning electron microscopy. Four-point flexural testing and nanoindentation revealed minimal impact on the properties of the cements, except for several changes in the nano-level static mechanical properties. Conversely, microindentation testing demonstrated that the addition of MSNs significantly increased the microhardness. The stress relaxation and creep properties of the cements measured with nanoindentation displayed no effect resulting from the addition of MSNs. The measured material properties were consistent among all cements. Analysis of scanning electron micrographs images revealed that surface functionalization enhanced particle dispersion within the cement matrix and resulted in fewer particle agglomerates. These results suggest that the loading ratios of mesoporous silica used in this study were not an effective reinforcement material. Future work should be conducted to determine the impact of higher MSN loading ratios and alternative functional groups.
authors.affiliation: Materials Science Program, University of Wisconsin-Madison, Madison, WI, USA; Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI, USA. Electronic address: jaslane@wisc.edu.
authors.forename: Josh
authors.initials: J
authors.lastname: Slane
authors.affiliation: Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA; Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibañez, Viña del Mar, Chile.
authors.forename: Juan
authors.initials: J
authors.lastname: Vivanco
authors.affiliation: Department of Biomedical Engineering, Bucknell University, Lewisburg, PA, USA.
authors.forename: Donna
authors.initials: D
authors.lastname: Ebenstein
authors.affiliation: Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Squire
authors.affiliation: Materials Science Program, University of Wisconsin-Madison, Madison, WI, USA; Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: Heidi-Lynn
authors.initials: HL
authors.lastname: Ploeg
mesh_terms: D008422:Materials Testing; D055595:Mechanical Phenomena; D055616:Microtechnology; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
chemical_list: D012822:Silicon Dioxide; D019904:Polymethyl Methacrylate
keywords: Bone cement; Mechanical properties; Nanoindentation; Orthopedics; Reinforced polymer