The mechanical characteristics and in vitro biocompatibility of poly(glycerol sebacate)-bioglass elastomeric composites.
ABSTRACT Biodegradable elastomeric materials have gained much recent attention in the field of soft tissue engineering. Poly(glycerol sebacate) (PGS) is one of a new family of elastomers which are promising candidates used for soft tissue engineering. However, PGS has a limited range of mechanical properties and has drawbacks, such as cytotoxicity caused by the acidic degradation products of very soft PGS and degradation kinetics that are too fast in vivo to provide sufficient mechanical support to the tissue. However, the development of PGS/based elastomeric composites containing alkaline bioactive fillers could be a method for addressing these drawbacks and thus may pave the way towards wide clinical applications. In this study, we synthesized a new PGS composite system consisting of a micron-sized Bioglass filler. In addition to much improved cytocompatibility, the PGS/Bioglass composites demonstrated three remarkable mechanical properties. First, contrary to previous reports, the addition of microsized Bioglass increases the elongation at break from 160 to 550%, while enhancing the Young's modulus of the composites by up to a factor of four. Second, the modulus of the PGS/Bioglass composites drops abruptly in a physiological environment (culture medium), and the level of drop can be tuned such that the addition of Bioglass does not harden the composite in vivo and thus the desired compliance required for soft tissue engineering are maintained. Third, after the abrupt drop in modulus, the composites exhibited mechanical stability over an extended period. This latter observation is an important feature of the new composites, because they can provide reliable mechanical support to damaged tissues during the lag phase of the healing process. These mechanical properties, together with improved biocompatibility, make this family of composites better candidates than plastic and related composite biomaterials for the applications of tissue engineering.
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ABSTRACT: The great supply of glycerol as a byproduct of the production of biodiesel has motivated interest in its use in new applications. In this study, we report the synthesis and properties of organic–inorganic hybrid materials based on glycerol. Glycerol (Gly) was reacted with 3-isocyanatopropyltriethoxysilane (IPTES) in the presence of dibutyltin dilaurate (DBTDL) as a catalyst, using a molar ratio (r = IPTES/Gly) between 0.75 and 3. The sol–gel polycondensation of the resulting precursors in the presence of a formic acid solution led to transparent solid materials with a biphasic structure consisting of glycerol-rich domains dispersed in the organic–inorganic hybrid matrix. An increase in the r value changed the hybrid materials from hydrophilic to hydrophobic. The contact angle of water droplets varied from 43.6° for r = 0.75 to 95.1° for r = 3. Each of the materials exhibited a broad glass-to-rubber transition, with the maximum of the damping peak located in the 54–70 °C range. The relatively intense tan δ peaks of the hybrid materials suggest their possible use in devices requiring vibrational damping. The maximum damping capacity corresponded to the hybrid with r = 1.5, which exhibited a loss area LA (area under the loss modulus peak) of 13.5 GPa·K. High values of the rubbery modulus were observed, varying from 130 MPa for r = 0.75 to 720 MPa for r = 3. Values of the glassy modulus were also high, and the maximum value was observed for the hybrid with r = 1.5. The hybrid materials could also be colored through the incorporation of a very small amount of functionalized gold nanoparticles.Industrial & Engineering Chemistry Research 05/2012; 51(22):7793–7799. · 2.24 Impact Factor
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ABSTRACT: Cardiovascular diseases (CVD's), especially myocardial infarction (MI), are the leading cause of morbidity and mortality in the world also resulting in huge economic burden on national economies. A cardiac patch strategy aims at regenerating an infarcted heart by providing healthy functional cells to the injured region via a carrier substrate, and providing mechanical support, thereby preventing deleterious ventricular remodeling. In this work, polyaniline (PANI) was doped with camphorsulfonic acid and blended with poly (glycerol-sebacate) at ratios of 10, 20, and 30 vol.% PANI content to produce electrically conductive composite cardiac patches via the solvent casting method. The composites were characterized in terms of their electrical, mechanical, and physicochemical properties. The in vitro biodegradability of the composites was also evaluated. Electrical conductivity increased from 0 S/cm for pure PGS to 0.018 S/cm for 30 vol.% PANI-PGS samples. Moreover, the conductivities were preserved for at least 100 hours post fabrication. Tensile tests revealed an improvement in the elastic modulus, tensile strength, and elasticity with increasing polyaniline content. The degradation products caused a local drop in pH, which was higher in all composite samples compared to pure PGS, hinting at a buffering effect due to the presence of PANI. Finally, the cytocompatibility of the composites was confirmed when C2C12 cells attached and proliferated on samples with varying polyaniline content. Furthermore, leaching of acid dopants from the developed composites did not have any deleterious effect on the viability of C2C12 cells. Taken together, these results confirm the potential of PANI-PGS composites for use as substrates to modulate cellular behavior via electrical stimulation, and as biocompatible scaffolds for cardiac tissue engineering applications.Acta Biomaterialia 02/2014; · 5.68 Impact Factor
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ABSTRACT: Fabrication of nonlinear elastic materials that resemble biological tissues remains a challenge in biomaterials research. Here, a new fabrication protocol to produce elastomeric fibrous scaffolds was established, using the core/shell electrospinning technique. A prepolymer of poly(xylitol sebacate) with a 2:5 mol ratio of xylitol:sebacic acid (PXS2:5) was first formulated, then co-electrospun with polyvinyl alcohol (PVA - 95,000 Mw). After cross-linking of core polymer PXS2:5, the PVA shells were rinsed off in water, leaving a porous elastomeric network of PXS2:5 fibres. Under aqueous conditions, the PXS2:5 fibrous scaffolds exhibited stable, nonlinear J-shaped stress-strain curves, with large average rupture elongation (76%) and Young's modulus (~1.0 MPa), which were in the range of muscle tissue. Rupture elongation of PXS2:5 was also much higher when electrospun, compared to 2D solid sheets (45%). In direct contact with cell monolayers under physiological conditions, PXS2:5 scaffolds were as biocompatible as those made of poly-L-lactic acid (PLLA), with improvements over culture medium alone. In conclusion, the newly developed porous PXS2:5 scaffolds show tissue-like mechanical properties and excellent biocompatibility, making them very promising for bioengineering of soft tissues and organs.Journal of the Mechanical Behavior of Biomedical Materials 09/2014; · 3.05 Impact Factor