title: Biocompatibility and bioactivity of porous polymer-derived Ca-Mg silicate ceramics.
abstract: Magnesium is a trace element in the human body, known to have important effects on cell differentiation and the mineralisation of calcified tissues. This study aimed to synthesise highly porous Ca-Mg silicate foamed scaffolds from preceramic polymers, with analysis of their biological response. Akermanite (Ak) and wollastonite-diopside (WD) ceramic foams were obtained from the pyrolysis of a liquid silicone mixed with reactive fillers. The porous structure was obtained by controlled water release from selected fillers (magnesium hydroxide and borax) at 350°C. The homogeneous distribution of open pores, with interconnects of modal diameters of 160-180μm was obtained and maintained after firing at 1100°C. Foams, with porosity exceeding 80%, exhibited compressive strength values of 1-2MPa. In vitro studies were conducted by immersion in SBF for 21days, showing suitable dissolution rates, pH and ionic concentrations. Cytotoxicity analysis performed in accordance with ISO10993-5 and ISO10993-12 standards confirmed excellent biocompatibility of both Ak and WD foams. In addition, MC3T3-E1 cells cultured on the Mg-containing scaffolds demonstrated enhanced osteogenic differentiation and the expression of osteogenic markers including Collagen Type I, Osteopontin and Osteocalcin, in comparison to Mg-free counterparts. The results suggest that the addition of magnesium can further enhance the bioactivity and the potential for bone regeneration applications of Ca-silicate materials.
  
  
  
  Here, we show that the incorporation of Mg in Ca-silicates plays a significant role in the enhancement of the osteogenic differentiation and matrix formation of MC3T3-E1 cells, cultured on polymer-derived highly porous scaffolds. Reduced degradation rates and improved mechanical properties are also observed, compared to Mg-free counterparts, suggesting the great potential of Ca-Mg silicates as bone tissue engineering materials. Excellent biocompatibility of the new materials, in accordance to the ISO10993-5 and ISO10993-12 standard guidelines, confirms the preceramic polymer route as an efficient synthesis methodology for bone scaffolds. The use of hydrated fillers as porogens is an additional novelty feature presented in the manuscript.
authors.affiliation: Dipartimento di Ingegneria Industriale, University of Padova, Via Marzolo, 9, 35131 Padova, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Fiocco
authors.affiliation: Department of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: S
authors.initials: S
authors.lastname: Li
authors.affiliation: Department of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, UK; Institute of Biomedical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ London, UK; Department of Bioengineering, Imperial College London, South Kensington Campus, SW7 2AZ London, UK.
authors.forename: M M
authors.initials: MM
authors.lastname: Stevens
authors.affiliation: Dipartimento di Ingegneria Industriale, University of Padova, Via Marzolo, 9, 35131 Padova, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Bernardo
authors.affiliation: Department of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. Electronic address: julian.r.jones@imperial.ac.uk.
authors.forename: J R
authors.initials: JR
authors.lastname: Jones
mesh_terms: D000818:Animals; D000943:Antigens, Differentiation / Q000096:biosynthesis; D017610:Calcium Compounds / Q000737:chemistry / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002516:Ceramics / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D019245:Compressive Strength; D017633:Magnesium Silicates / Q000737:chemistry / Q000494:pharmacology; D008422:Materials Testing; D051379:Mice; D016062:Porosity; D017640:Silicates / Q000737:chemistry / Q000494:pharmacology; D012824:Silicic Acid / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000943:Antigens, Differentiation; D017610:Calcium Compounds; D017633:Magnesium Silicates; D017640:Silicates; C005013:Florisil; D012824:Silicic Acid; C074224:diopside; C023506:Glass ceramics; C031293:calcium silicate
keywords: Bioactive; Ca-Mg silicates; Ceramic foams; Porous; Preceramic polymers