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 aim of this study was to evaluate the effect of TiO2 nanoparticles on the mechanical and anti-aging properties of a medical silicone elastomer, and to assess the biocompatibility of this novel combination. TiO2 (P25, Degussa, Germany) nanoparticles were mixed with the silicone elastomer (MDX4-4210, Dow Corning, USA) at 2%, 4%, 6% (w/w) using silicone fluid as diluent (Q7-9180, Dow Corning, USA). Blank silicone elastomer served as the control material. The physical properties and biocompatibility of the composites were examined. The tensile strength was tested for 0% and 6% (w/w) before and after artificial aging. SEM analysis was performed. TiO2 nanoparticles improved the tensile strength and Shore A hardness of the silicone elastomer (P<0.05). However, a decrease in the elongation at break and tear strength were found for the 6% (w/w) composite (P<0.05). All the aging methods had no effect on the tensile strength of the 6% (w/w) composite (P>0.05), but thermal aging significantly decreased the tensile strength of the control group (P<0.05). Cellular viability assays indicated that the composite exhibited biocompatibility. We obtained a promising restorative material, which yields favorable physical and anti-aging properties, and is biocompatible in our in vitro cellular studies.Journal of dentistry 01/2014; · 3.20 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; · 5.09 Impact Factor
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ABSTRACT: Hydrogels are hydrophilic polymer-based materials with high water content and physical characteristics that resemble the native extracellular matrix. Because of their remarkable properties, hydrogel systems are used for a wide range of biomedical applications, such as three-dimensional (3D) matrices for tissue engineering, drug-delivery vehicles, composite biomaterials, and as injectable fillers in minimally invasive surgeries. In addition, the rational design of hydrogels with controlled physical and biological properties can be used to modulate cellular functionality and tissue morphogenesis. Here, the development of advanced hydrogels with tunable physiochemical properties is highlighted, with particular emphasis on elastomeric, light-sensitive, composite, and shape-memory hydrogels. Emerging technologies developed over the past decade to control hydrogel architecture are also discussed and a number of potential applications and challenges in the utilization of hydrogels in regenerative medicine are reviewed. It is anticipated that the continued development of sophisticated hydrogels will result in clinical applications that will improve patient care and quality of life.Advanced Materials 01/2014; 26(1):85-124. · 14.83 Impact Factor