Thermoplastic PCL-b-PEG-b-PCL and HDI Polyurethanes for Extrusion-Based 3D-Printing of Tough Hydrogels.

Novel tough hydrogel materials are required for 3D-printing applications. Here, a series of thermoplastic polyurethanes (TPUs) based on poly(ɛ-caprolactone)-b-poly(ethylene glycol)-b-poly(ɛ-caprolactone) (PCL-b-PEG-b-PCL) triblock copolymers and hexamethylene diisocyanate (HDI) were developed with PEG contents varying between 30 and 70 mol%. These showed excellent mechanical properties not only when dry, but also when hydrated: TPUs prepared from PCL-b-PEG-b-PCL with PEG of Mn 6 kg/mol (PCL7-PEG6-PCL7) took up 122 wt.% upon hydration and had an E-modulus of 52 ± 10 MPa, a tensile strength of 17 ± 2 MPa, and a strain at break of 1553 ± 155% in the hydrated state. They had a fracture energy of 17976 ± 3011 N/mm² and a high tearing energy of 72 kJ/m². TPUs prepared using PEG with Mn of 10 kg/mol (PCL5-PEG10-PCL5) took up 534% water and were more flexible. When wet, they had an E-modulus of 7 ± 2 MPa, a tensile strength of 4 ± 1 MPa, and a strain at break of 147 ± 41%. These hydrogels had a fracture energy of 513 ± 267 N/mm² and a tearing energy of 16 kJ/m². The latter TPU was first extruded into filaments and then processed into designed porous hydrogel structures by 3D-printing. These hydrogels can be used in 3D printing of tissue engineering scaffolds with high fracture toughness.

Triblock copolymers based on ε-caprolactone and trimethylene carbonate for the 3D printing of tissue engineering scaffolds.

BACKGROUND: Biodegradable PCL-b-PTMC-b-PCL triblock copolymers based on trimethylene carbonate (TMC) and ε-caprolactone (CL) were prepared and used in the 3D printing of tissue engineering scaffolds. Triblock copolymers of various molecular weights containing equal amounts of TMC and CL were prepared. These block copolymers combine the low glass transition temperature of amorphous PTMC (approximately -20°C) and the semi-crystallinity of PCL (glass transition approximately -60°C and melting temperature approximately 60°C). METHODS: PCL-b-PTMC-b-PCL triblock copolymers were synthesized by sequential ring opening polymerization (ROP) of TMC and ε-CL. From these materials, films were prepared by solvent casting and porous structures were prepared by extrusion-based 3D printing. RESULTS: Films prepared from a polymer with a relatively high molecular weight of 62 kg/mol had a melting temperature of 58°C and showed tough and resilient behavior, with values of the elastic modulus, tensile strength and elongation at break of approximately 120 MPa, 16 MPa and 620%, respectively. Porous structures were prepared by 3D printing. Ethylene carbonate was used as a crystalizable and water-extractable solvent to prepare structures with microporous strands. Solutions, containing 25 wt% of the triblock copolymer, were extruded at 50°C then cooled at different temperatures. Slow cooling at room temperature resulted in pores with widths of 18 ± 6 µm and lengths of 221 ± 77 µm, rapid cooling with dry ice resulted in pores with widths of 13 ± 3 µm and lengths of 58 ± 12 µm. These PCL-b-PTMC-b-PCL triblock copolymers processed into porous structures at relatively low temperatures may find wide application as designed degradable tissue engineering scaffolds. CONCLUSIONS: In this preliminary study we prepared biodegradable triblock copolymers based on 1,3-trimethylene carbonate and ε-caprolactone and assessed their physical characteristics. Furthermore, we evaluated their potential as melt-processable thermoplastic elastomeric biomaterials in 3D printing of tissue engineering scaffolds.

In vitro fertilization in normoresponder patients with endometriomas: comparison with basal simple ovarian cysts.

OBJECTIVE: To investigate whether the space-occupying effect of an endometrioma, rather than endometriosis itself, affects results in in vitro fertilization (IVF) using women with simple ovarian cysts as the control group. METHODS: 85 normoresponder patients with endometriomas of 10-50 mm who underwent IVF treatment directly without initial removal were compared with 83 normoresponder patients with simple ovarian cysts of 10-35 mm detected at the beginning of stimulation and initiated treatment without aspiration. RESULTS: Gonadotropin consumption was higher in the endometrioma group (3,013 vs. 2,451 IU; p = 0.001), although significantly fewer numbers of oocytes were retrieved (13.9 vs. 16.4; p = 0.03). However, oocyte maturation rates were similar. The transferred grade I embryos ratio was evaluated and found to be better in the cyst group (79.7 vs. 70.7%; p = 0.03). Consequently, the implantation rate was found to be significantly higher in the cyst group (28 vs. 19%; p = 0.02), although pregnancy and ongoing pregnancy rates were similar. CONCLUSION: The presence of an endometriotic cyst during the IVF cycle was demonstrated to be associated with a lower embryo quality and implantation rate, although pregnancy success was unaffected. This adverse effect is suggested to be the result of the disease itself, not the presence of a cystic mass.