A comprehensive review of techniques for biofunctionalization of titanium

A number of surface modification techniques using immobilization of biofunctional molecules of Titanium (Ti) for dental implants as well as surface properties of Ti and Ti alloys have been developed. The method using passive surface oxide film on titanium takes advantage of the fact that the surface film on Ti consists mainly of amorphous or low-crystalline and non-stoichiometric TiO2. In another method, the reconstruction of passive films, calcium phosphate naturally forms on Ti and its alloys, which is characteristic of Ti. A third method uses the surface active hydroxyl group. The oxide surface immediately reacts with water molecules and hydroxyl groups are formed. The hydroxyl groups dissociate in aqueous solutions and show acidic and basic properties. Several additional methods are also possible, including surface modification techniques, immobilization of poly(ethylene glycol), and immobilization of biomolecules such as bone morphogenetic protein, peptide, collagen, hydrogel, and gelatin

Gellan Gum-based luminal fillers for peripheral nerve regeneration: an in vivo study in the rat sciatic nerve repair model

Peripheral nerve injuries (PNI) resulting in a gap to be bridged between the transected nerve ends are commonly reconstructed with autologous nerve tissue, but there is a need for valuable alternatives. This experimental work considers the innovative use of the biomaterial Gellan Gum (GG) as a luminal filler for nerve guidance channels made from chitosan with a 5% degree of acetylation. The engineered constructs should remodel the structural support given to regenerating axons by the so-called bands of Büngner. Four different GG formulations were produced by combining varying amounts of High-Acyl GG (HA-GG) and Methacrylated GG (MA-GG). The effective porosity of the freeze-dried networks was analysed by SEM and micro-CT 3D reconstructions, while the degradation and swelling abilities were characterized in vitro for up to 30 days. The metabolic activity and viability of immortalized Schwann cells seeded onto the freeze-dried networks were also evaluated. Finally, the developed hydrogel formulations were freezedried within the chitosan nerve guides and implanted in a 10 mm rat sciatic nerve defect. Functional and histomorphological analyses after 3, 6, and 12 weeks in vivo revealed that although it did not result in improved nerve regeneration, the NGC25:75 formulations could provide a basis for further development of GG scaffolds as luminal fillers for hollow nerve guidance channels.This study was supported by the European Community’s Seventh Framework Programme (FP7-HEALTH-2011) under grant agreement no. 278612 (BIOHYBRID). Medical grade chitosan for manufacturing the chitosan films and nerve guides was supplied by Altakitin SA (Lisbon, Portugal). The chitosan materials were supplied by Medovent GmbH (Mainz, Germany). This study was also funded by the European Union’s FP7 Programme under grant agreement no. REGPOT-CT2012-316331-POLARIS. The authors thank Silke Fischer, Natascha Heidrich, Jennifer Metzen, Maike Wesemann (all from the Institute of Neuroanatomy and Cell Biology, Hannover Medical School) for their excellent technical support. The authors also acknowledge the Portuguese Foundation for Science and Technology (FCT) for the financial support provided to Joana Silva-Correia (IF/00115/2015) and Joaquim M. Oliveira (IF/00423/2012 and IF/01285/2015) under the programme “Investigador FCT”.info:eu-repo/semantics/publishedVersio