Structure and properties of thermoplastic polyurethanes based on poly(dimethylsiloxane): Assessment of biocompatibility

Abstract

Properties and biocompatibility of a series of thermoplastic poly(urethane-siloxane)s (TPUSs) based on α,ω-dihydroxy ethoxy propyl poly(dimethylsiloxane) (PDMS) for potential biomedical application were studied. Thin films of TPUSs with a different PDMS soft segment content were characterized by (1) H NMR, quantitative (13) C NMR, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), contact angle, and water absorption measurements. Different techniques (FTIR, AFM, and DMA) showed that decrease of PDMS content promotes microphase separation in TPUSs. Samples with a higher PDMS content have more hydrophobic surface and better waterproof performances, but lower degree of crystallinity. Biocompatibility of TPUSs was examined after attachment of endothelial cells to the untreated copolymer surface or surface pretreated with multicomponent protein mixture, and by using competitive protein adsorption assay. TPUSs did not exhibit any cytotoxicity toward endothelial cells, as measured by lactate dehydrogenase and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assays. The untreated and proteins preadsorbed TPUS samples favored endothelial cells adhesion and growth, indicating good biocompatibility. All TPUSs adsorbed more albumin than fibrinogen in competitive protein adsorption experiment, which is feature regarded as beneficial for biocompatibility. The results indicate that TPUSs have good surface, thermo-mechanical, and biocompatible properties, which can be tailored for biomedical application requirements by adequate selection of the soft/hard segments ratio of the copolymers.

Synthesis and structure-property relationships of biodegradable polyurethanes

“…% hard segment have been synthesized and characterized [91,93]. FTIR, AFM and dynamic mechanic analysis (DMA) confirmed the phaseseparated structure in these copolymers.…”

“…The synthesis of PU copolymers using siloxane-containing prepolymers with PCL and ethylene oxide terminal units has been described [90][91][92][93][94][95][96][97][98]; these terminal units of siloxane-containing prepolymers were used in order to increase the miscibility of polar and non-polar reactants. Thermoplastic PU elastomers based on PDMS were synthesized by a two-step polyaddition procedure in solution, from MDI, 1,4-BD and α,ω-dihydroxy-PCL-b-PDMS-b-PCL [94].…”

“…Thermoplastic PU elastomers based on PDMS were synthesized by a two-step polyaddition procedure in solution, from MDI, 1,4-BD and α,ω-dihydroxy-PCL-b-PDMS-b-PCL [94]. The combination of the properties of PCL and PDMS makes these block copolymers good candidates for surface modifying additives, drug encapsulation and biomaterial applications.…”

“…In particular, copolymers with symmetrical hard segments showed significantly higher moduli and a wider, temperatureinsensitive rubbery plateau. In addition, compared to thermoplastic PUs, the presence of bidentate hydrogen bonds in polyurea results in substantially more cohesive hard phase formation, which further results in an increase of the moduli and in the expansion of the rubbery plateau in these materials [113].…”

“…Elastomeric BioPUs have been proposed for use in orthopaedic applications (bone tissue substitutes, cartilage repair) [128,129], for abdominal wall repair, as a temporary support for transplanted human retinal pigment epithelium cells, as a tracheal prosthesis and in soft tissue engineering [130]. Keeping in mind the broad spectrum of PU biomedical applications, this section will focus only on the issues related to biocompatibility, degradation behaviour and overall properties of BioPU-based porous tissue scaffolds and drug delivery systems, as well as nanocomposites, but not on other numerous biostable PUs, the detailed discussion of which is given elsewhere [113].…”