title: Surface nitridation improves bone cell response to melt-derived bioactive silicate/borosilicate glass composite scaffolds.
abstract: Novel bioactive amorphous glass-glass composite scaffolds (ICIE16/BSG) with interconnected porosity have been developed. Hierarchically interconnected porous glass scaffolds were prepared from a mixture of two melt-derived glasses: a ICIE16 bioactive glass that was previously developed by Wu et al. (2011) to prevent crystallization, and a borosilicate glass of composition 73.48 SiO2-11.35 B2O3-15.15 Na2O (wt%). The resulting melt derived glass-glass composite scaffolds (ICIE16/BSG) were subject to surface functionalization to further improve its interaction with biological systems. Surface functionalization was performed by a nitridation process with hot gas N2/ammonia at 550°C for 2h, obtaining the ICIE16/BSG-NITRI. Evaluation of the degradation rate and the conversion to hydroxyapatite after immersion in simulated body fluid predicted a good biological activity of all the scaffolds, but particularly of the nitrided ones. In vitro evaluation of osteoblastic cells cultured onto the nitrided and non-nitrided scaffolds showed cell attachment, proliferation and differentiation on all scaffolds, but both proliferation and differentiation were improved in the nitrided ICIE16/BSG-NITRI.
  
  
  CONCLUSIONS
  Biomaterials are often required in the clinic to stimulate bone repair. We have developed a novel bioglass (ICIE16/SBG-NITRI) that can be sintered into highly porous 3D scaffolds, and we have further improved its bioactivity by nitridation. ICIE16/SBG-NITRI was synthesized from a mixture of two melt-derived glasses through combined gel casting and foam replication techniques, followed by nitridation. To mimic bone, it presents high-interconnected porosity while being mechanically stable. Nitridation improved its reactivity and bioactivity facilitating its resorption and the deposition of apatite (bone-like mineral) on its surface and increasing its degradation rate. The nitrided surface also improved the bioglass' interaction with bone cells, which were found to attach better to ICIE16/SBG-NITRI and to differentiate earlier on its surface.
authors.affiliation: Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), c/ Kelsen n° 5, 28049 Madrid, Spain.
authors.forename: Felipe
authors.initials: F
authors.lastname: Orgaz
authors.affiliation: Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), c/ Kelsen n° 5, 28049 Madrid, Spain.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Dzika
authors.affiliation: Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), c/ Kelsen n° 5, 28049 Madrid, Spain.
authors.forename: Olga
authors.initials: O
authors.lastname: Szycht
authors.affiliation: Universidad de Málaga, Departamento de Anatomía y Medicina Legal, Facultad de Medicina, Campus de Teatinos, 29071 Málaga, Spain; Centro de Investigación Biomédica en Red. Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, c/ Monforte de Lemos 3-5, Pabellón 11, Planta 0, 28029 Madrid, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Amat
authors.affiliation: Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas (ICV-CSIC), c/ Kelsen n° 5, 28049 Madrid, Spain.
authors.forename: Flora
authors.initials: F
authors.lastname: Barba
authors.affiliation: Universidad de Málaga & IBIMA, Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Campus de Teatinos, 29071 Málaga, Spain; Centro de Investigación Biomédica en Red. Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, c/ Monforte de Lemos 3-5, Pabellón 11, Planta 0, 28029 Madrid, Spain; BIONAND-Universidad de Málaga, c/ Severo Ochoa 35, Campanillas, 29590 Málaga, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Becerra
authors.affiliation: Centro de Investigación Biomédica en Red. Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Instituto de Salud Carlos III, c/ Monforte de Lemos 3-5, Pabellón 11, Planta 0, 28029 Madrid, Spain; BIONAND-Universidad de Málaga, c/ Severo Ochoa 35, Campanillas, 29590 Málaga, Spain; Universidad de Málaga & IBIMA, Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Campus de Teatinos, 29071 Málaga, Spain. Electronic address: lsantos@uma.es.
authors.forename: Leonor
authors.initials: L
authors.lastname: Santos-Ruiz
mesh_terms: D000641:Ammonia / Q000737:chemistry; D000818:Animals; D002460:Cell Line; D002516:Ceramics / Q000737:chemistry / Q000494:pharmacology; D051379:Mice; D009584:Nitrogen / Q000737:chemistry; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D017640:Silicates / Q000737:chemistry / Q000494:pharmacology; D013499:Surface Properties; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: C022107:Bioglass; D017640:Silicates; D000641:Ammonia; D009584:Nitrogen
keywords: Ammonia nitridation; Bioglasses; Bone regeneration; Bone repair; Bone substitutes; Cell adhesion; Glass–glass composite scaffolds; Osteoblastic cell; Osteogenic differentiation; Surface functionalization; Tissue engineering