Polyurethanes with separately tunable biodegradation behavior and mechanical properties for tissue engineering

Abstract

Two series (random and block) poly(glycolide-co-ε-caprolactone) macrodiols with various glycolide to ε-caprolactone ratios (50/50 and 30/70, R-PG50C, R-PG30C, B-PG50C, and B-PG30C) were synthesized. Next, segmented polyurethanes (PUs) were synthesized based on the synthesized macrodiols, 1,6-hexamethylene diisocyanate and 1,4-butanediol (PU-R30, PU-R50, PU-B30, and PU-B50). Effect of glycolide (G) and ε-caprolactone (C) monomers arrangement (random or block) on the PUs properties were investigated via FTIR, 1 H NMR, DSC, TGA, DMA, SEM, and mechanical tests. All PUs illustrated T g (−33°C to −48°C) and T m (102°C to 139°C) corresponding to the soft and the hard segments, respectively. Polymers based on block macrodiols also showed T m related to the soft segments. While PUs underwent a two-step thermal degradation, the PUs based on block macrodiols indicated higher degradation temperature.Dynamic mechanical analysis results evidenced development of a well-defined microphase separated structure in PU-R30. Contact angle (about 70°-80°) and water uptake (around 20% after 24 hours) of the PU films are close to those suitable for tissue engineering materials. The PU based on R-PG30C (PU-R30) exhibited the highest tensile strength (2.87 MPa) followed by PU-B50 and PU-R50. Over a 63-day in vitro degradation study in phosphate buffered saline, the PUs showed variable weight loss (up to 40%) depending on their soft segments composition and arrangement. Also, the PUs showed no cytotoxicity. Thus, these PUs with tunable biodegra- To the best of our knowledge, there are not much reports on systematic synthesis of polyurethanes based on (glycolide-cocaprolactone) macrodiols of different glycolide to caprolactone ratios (as the soft segment), and HDI and butanediol (BD) (as components of the hard segment). Therefore, in this work, PGC macrodiols with different monomer ratios and different comonomers were synthesized and characterized. Then 2 series of SPUs based on these macrodiols and HDI and BD were produced. The effect of macrodiol structure on physicochemical, mechanical properties, and biodegradation rate of the synthesized polymers was investigated. | MATERIALS AND METHODS | MaterialsGlycolide, 1,4-butanediol and tin (II) 2-ethylhexanoate (Sn(Oct)2) were purchased from Sigma_ Aldrich Co, Germany. ε-Caprolactone (>99%), ethylene glycol, 1,6-hexamethylene diisocyanate, 1,2-dichroethane, and n-hexane were obtained from Merck Chemicals, Germany.1,2-Dichroethane and ε-caprolactone were dried prior to use. | Synthesis of PGC macrodiolsRandom and block PGC (R-PGC and B-PGC) macrodiols were synthesized via ring opening polymerization of glycolide and ε-caprolactone initiated by ethylene glycol. In random series, glycolide, ε-caprolactone, ethylene glycol, and the catalyst (stannous octoate)were heated at 130°C under a flow of dry N 2 . After certain time, the reaction mixture was cooled down to room temperature. To remove the catalyst and any residual monomers, the mixture was dissolved in 1.2-dichloroethane, and the copolymer w...

Synthesis of Zwitterionic and Trehalose Polymers with Variable Degradation Rates and Stabilization of Insulin

“…The polymers were then conjugated to bovine serum albumin (BSA), and the hydrolytic stability of the resulting conjugates was studied at neutral, acidic, and basic pH . Shokrolahi and co-workers investigated the degradation of polyurethanes consisting of glycolide or caprolactone macroblocks, which exhibited variable degradation rates depending on the macroblock composition . Chilkoti and co-workers described the preparation of water-soluble poly­(carbonate)-based polymers for protein conjugation and observed 50% polymer molecular weight loss in 12 h .…”

“…20 Shokrolahi and co-workers investigated the degradation of polyurethanes consisting of glycolide or caprolactone macroblocks, which exhibited variable degradation rates depending on the macroblock composition. 21 Chilkoti and co-workers described the preparation of water-soluble poly(carbonate)based polymers for protein conjugation and observed 50% polymer molecular weight loss in 12 h. 22 Additionally, the degradable monomers cyclic ketene acetals (CKAs) can be incorporated into vinyl polymers at controlled ratios to target specific hydrolytic stabilities. 23−25 We recently showed that the hydrolytic stability of fluorous 5,6-benzo-2-methylene-1,3dioxepane copolymers could be tuned by adjusting the fluorine content of the polymers.…”

An overview of advanced biocompatible and biomimetic materials for creation of replacement structures in the musculoskeletal systems: focusing on cartilage tissue engineering

“…Also, PU due to its soft tissue-like properties and electroactivity can be employed as a scaffold in muscle tissue engineering [153]. Previous studies demonstrated electroactive polymers could support cell proliferation and differentiation [154].…”

Vitamin C Loaded Poly(urethane-urea)/ZnAl-LDH Aligned Scaffolds Increase Proliferation of Corneal Keratocytes and Up-Regulate Vimentin Secretion

“…However, mechanical properties of the polymer did not match those required for soft tissues. So, in this present submission synthesis of a poly­(urethane-urea) (PUU) based on the same macro-diol of our previous publication, is reported, for which physiochemical and mechanical properties, as well as in vitro and in vivo biodegradation behavior are reported in comparison with its PU counterpart. To mimic a native corneal ECM, the PUU was electrospun into a scaffold to which zinc and vitamin C were added in a specially designed structure.…”