Preparation and bioactive properties of nano bioactive glass and segmented polyurethane composites

Abstract

Composites of glutamine-based segmented polyurethanes with 5 to 25 wt.% bioactive glass nanoparticles were prepared, characterized, and their mineralization potential was evaluated in simulated body fluid. Biocompatibility with dental pulp stem cells was assessed by MTS to an extended range of compositions (1 to 25 wt.% of bioactive glass nanoparticles). Physicochemical characterization showed that composites retained many of the matrix properties, i.e. those corresponding to semicrystalline elastomeric polymers as they exhibited a glass transition temperature (Tg) between -41 and -36℃ and a melting temperature (Tm) between 46 and 49℃ in agreement with X-ray reflections at 23.6° and 21.3°. However, with bioactive glass nanoparticles addition, tensile strength and strain were reduced from 22.2 to 12.2 MPa and 667.2 to 457.8%, respectively with 25 wt.% of bioactive glass nanoparticles. Although Fourier transform infrared spectroscopy did not show evidence of mineralization after conditioning of these composites in simulated body fluid, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray microanalysis showed the formation of an apatite layer on the surface which increased with higher bioactive glass concentrations and longer conditioning time. Dental pulp stem cells proliferation at day 5 was improved in bioactive glass nanoparticles composites containing lower amounts of the filler (1-2.5 wt.%) but it was compromised at day 9 in composites containing high contents of nBG (5, 15, 25 wt.%). However, Runx2 gene expression was particularly upregulated for the dental pulp stem cells cultured with composites loaded with 15 and 25 wt.% of bioactive glass nanoparticles. In conclusion, low content bioactive glass nanoparticles and segmented polyurethanes composites deserve further investigation for applications such as guided bone regeneration membranes, where osteoconductivity is desirable but not a demanding mechanical performance.

Preparation and characterization of titanium—segmented polyurethane composites for bone tissue engineering

“…In general, the mechanical properties of composites of PU/Ti were lower than PU/bioactive glass composites in spite of their higher rigidity, except for the Young's modulus that was significantly higher at low strain rates. 4 However, the mechanical properties of these composites are far from those exhibited by trabecular bone from human femur (17.5 AE 1.12 GPa) or cortical bone (22.1 GPa) measured by ultrasonic technique. 29…”

“…23,24 At 1636 cm À1 , urea absorptions were detected in agreement with previous works. 4,10,25 In composites, infrared absorptions from the PU remain and bands from Ti were not observed since metal-metal bonds cannot be detected by conventional FTIR spectrometers using ATR technique or because they were masked due to their low concentration. For pristine titanium only adsorbed water (3432 cm À1 ), carbon-containing species (2921 and 2852 cm À1 ), and oxidized titanium (705 cm À1 ) were observed.…”

“…DSC thermograms showed that the PU and their composites are semicrystalline as the exhibited a melting temperature (T m ) of 52 C, while DMA thermograms (data not shown) showed a significant drop in the storage modulus of the composite between À40 C and À20 C, suggesting their alpha transition (T a ) at this temperature range. 3,4 As the T g of PCL is located at À60 C, their shift to higher temperatures is suggesting polymer movement restrictions when incorporated into the PU. However, as this transition was not affected by Ti particles, it is suggested that Ti particles are probably located either in the interface between soft and rigid segment or in the rigid segment bulk.…”

“…1,2 In previous studies, our group prepared SPU with polycaprolactone diol (PCL) as soft segment and 4,4-methylene-bis cyclohexyl diisocyanate (HMDI) and l -glutamine (GLU) as the rigid segment and improved their biocompatibility by the addition of either hydroxyapatite or silica-based bioactive glasses. 3,4 In the first case, alveolar odontoblast were able to adhere to these composites while in the second, dental pulp stem cells expressed high levels of RunX2 osteogenic markers. In an effort to improve the mechanical and biological properties of glutamine-based PUs, titanium particles (Ti) are used in this study.…”

Recent Developments in Polyurethane-Based Materials for Bone Tissue Engineering

“…In the other paper by the same research group, PU glutamine-based segmented polyurethanes with 5–25 wt.% bioactive glass nanoparticles were prepared and it has been found that compositions with low content of bioactive glass nanoparticles are promising material for applications such as guided bone regeneration membranes [ 111 ].…”