Introduction
Titanium and titanium compounds have raised a great interest for hard tissues regeneration for the interfacial properties that can be achieved. They include corrosion resistance, lack of inflammatory response and ability for osseointegration. The sol-gel technique can be used to obtained organic-inorganic hybrid materials at low temperatures and with a good distribution of components. The properties of sol-gel hybrids can be tailored by modifying the composition and synthesis conditions. In this study, degradable poly (ester urethane)s /titania hybrids has been prepared and a preliminary evaluation of their potential to be used for calcified tissue regeneration was performed.
Materials and Methods
Polyester based on poly (ethylene glycol succinate) of 1729 Da and polylactic acids of 5055 Da were synthesized, to use them as precursors. Then polyester urethanes (PURS) were synthesized by a two step method using a 2:3:1 mol ratio of polyesters:1,6-hexamethylenediisocyanate:1-4 butanediol. Finally, 80%organic-:20%inorganic hybrids were obtained by the sol-gel reaction with titanium isopropoxide as inorganic precursor. All the materials were characterized by FTIR, XRD, TGA DSC, GPC, Raman spectroscopy. Furthermore bioactivity and cytoxicity MTT assay, with a MG63 cells were determined only for hybrid materials.
Results and discussion
Polyester urethanes were identified by the IR bands located near 3429 and 1545 cm-1 that can be related to the (NH-) group and at 1725 and 1625cm-1 bands that can be related to the carboxylic groups. Also NMR spectroscopy confirms the formation of the Polyester urethanes by resonances at 7.8 ppm that can be attributed to amina groups. Contact angle shows that both polyurethanes obtained were hydrophilic with 40° for polyurethane synthesised with PEG and ~30° for polyurethane with PLA. The DSC/TGA results suggest that degradation and thermal behaviour of polyurethanes can be modulated with the nature of soft segment used showing a faster degradation for polyester glycol succinate than polylactic acid.
For the hybrids synthesis Raman results shows changes in bands before 700 cm-1 which suggest the chemical interaction between organic and inorganic component and SEM/EDS denotes a solid with no phase separation with suggest a homogeneous distribution of the inorganic component. The Hybrid materials were slowly degradable in PBS with loss weight about 20% after 28 days submerged in PBS and it could be attributed to the polymer chains rupture and dissolution. On the other hand apatite layer can be observed by SEM and characterized by the appearance of bands related to phosphate at IR after 21 days submerged in SBF suggesting the potential bioactivity of the studied system. A cell viability over 80% could be appreciated for the hybrids materials.
Conclusions.
The sol-gel synthesis allowed the obtained of monophonic hybrid materials, consisting in Titania / polyurethanes. The synthesis of Polyurethanes using a Polyester glycol succinate and Polylactic acid as soft segment were confirmed by IR and RMN, no matter the polyester used polyurethanes results hydrophilic materials. The synthesized hybrids were shown to have good biological properties with the formation of hydroxyapatite layer on the material surface after 28 days of soaking, both hybrid materials shows a non toxic effects in MTT test using MG63 cell line.
This work was supported by grants MAT2014-51918-C2-1-R from CSIC, Spain and CONACYT scholar ship
References:
[1] R. Zhou et al. J Mater Scie/Mater Med 2014;25:1307
[2] Marcin Sobzcak .Polymer plastic technology and engineering 54 (2015) 155-172
[3] M. Catauro. Material Science Engineering,.C47(2015)135-141