Abstract:The application of renewable raw materials encourages research in the biopolymers area. The Poly(Lacticco-Glycolic Acid)/Poly(Isoprene) (PLGA/IR) blend combines biocompatibility for application in the health field with excellent mechanical properties. The blend was obtained by solubilization of polymers in organic solvents. To investigate the polymer thermochemical properties, FTIR and DSC were applied. To investigate the composition's influence over polymer mechanical properties, tensile and hardness test were applied. To analyze the blends response in the cell environment, a stent was produced by injection molding process, and Cell Viability Test and Previous Implantability were used. The Infrared spectra show that chemical composition is related only with polymers proportion in the blend. The calorimetry shows a partial miscibility in the blend. The tensile test shows that adding Poly(Isoprene) to Poly(Lactic-co-Glycolic Acid) induced a relevant reduction in the Young modulus, tensile stress and tenacity of the material, which was altered from the fragile raw PLGA to a ductile material. The composition did not affect the blend hardness. The cell viability test shows that the blend has potential application as biomaterial, while the first results of implantability indicate that the polymeric stent kept its original position and caused low fibrosis.

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Current treatments of craniosynostosis rely on the application of metal springs for cranial bone deviation. However, those metal springs demand a second surgical procedure for their removal. An attractive alternative would be the substitution of metal for bioresorbable polymers in the composition of the springs. The addition of poly(isoprene), PI, to poly(lactic-co-glycolic acid), PLGA, produces a polymeric blend with partial miscibility and distinct mechanical behavior that may benefit the patient recover. It is necessary to compare the histotoxicity of PLGA/PI to that presented by PLGA. In order to verify the histological behavior of the blend, 46 male Wistar rats (Rattus norvegicus, albino strain) underwent implantation of PLGA or PLGA/PI in the skull and were allocated into subgroups by timing of euthanasia (15, 30, 60, or 90 days). After euthanasia, the skull was removed and the histotoxicity was assessed histopathologically. The PLGA/PI blend showed greater histotoxicity in animals euthanized at 60 days, although in this period the histotoxicity of the PLGA/PI blend was similar to that of the PLGA copolymer at 15 days. Despite the instability of histological response, presented in different periods of observation, the results obtained in long-term show that the material has high potential for studies in craniosynostosis treatment.

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Abstract:The polymeric blend of Poly (Lactic-co-Glycolic Acid) (PLGA) and Polyisoprene

Natural bone is formed by a complex composite, essentially constituted of biological apatite and fibers of collagen. The combination of materials such as biopolymers and bioceramics may result in an interesting material for application in bone tissue regeneration. This work aims to obtain polymeric fibers containing Poly (Lactic-co-Glycolic Acid) and Poly (Isoprene), supplemented with hydroxyapatite (HA) and α-tricalcium phosphate (TCP). The thermal, mechanical and morphological properties of the fibers were evaluated . Even presenting a larger diameter, fibers with α-TCP presented lower elastic modulus than fibers with HA. Both fibers presented similar thermal behavior, with glass transition temperature in the same range that the one presented by raw PLGA and similar degradation temperatures. Is safe to say that the presence of ceramics in the fibers have a potential for further investigations aiming bone tissue regeneration.

Herein, fullerenol (Ful), a highly water‐soluble derivative of C60 fullerene with demonstrated antioxidant activity, is incorporated into calcium phosphate cements (CPCs) to enhance their osteogenic ability. CPCs with added carboxymethyl cellulose/gelatin (CMC/Gel) are doped with biocompatible Ful particles at concentrations of 0.02, 0.04, and 0.1 wt v%−1 and evaluated for Ful‐mediated mechanical performance, antioxidant activity, and in vitro cellular osteogenesis. CMC/gel cements with the highest Ful concentration decrease setting times due to increased hydrogen bonding from Ful's hydroxyl groups. In vitro studies of reactive oxygen species (ROS) scavenging with CMC/gel cements demonstrate potent antioxidant activity with Ful incorporation and cement scavenging capacity is highest for 0.02 and 0.04 wt v%−1 Ful. In vitro cytotoxicity studies reveal that 0.02 and 0.04 wt v%−1 Ful cements also protect cellular viability. Finally, increase of alkaline phosphatase (ALP) activity and expression of runt‐related transcription factor 2 (Runx2) in MC3T3‐E1 preosteoblast cells treated with low‐dose Ful cements demonstrate Ful‐mediated osteogenic differentiation. These results strongly indicate that the osteogenic abilities of Ful‐loaded cements are correlated with their antioxidant activity levels. Overall, this study demonstrates exciting potential of Fullerenol as an antioxidant and proosteogenic additive for improving the performance of calcium phosphate cements in bone reconstruction procedures.

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