Exploring the application of poly(1,2-ethanediol citrate)/polylactide nonwovens in cell culturing

Biomaterials containing citric acid as a building unit show potential for use as blood vessel and skin tissue substitutes. The success in commercializing implants containing a polymer matrix of poly(1,8-octanediol citrate) provides a rationale for exploring polycitrates based on other diols. Changing the aliphatic chain length of the diol allows functional design strategies to control the implant's mechanical properties, degradation profile and surface energy. In the present work, poly(1,2-ethanediol citrate) was synthesized and used as an additive to polylactide in the electrospinning process. It was established that the content of polycitrate greatly influences the nonwovens' properties: an equal mass ratio of polymers resulted in the best morphology. The obtained nonwovens were characterized by surface hydrophilicity, tensile strength, and thermal properties. L929 cell cultures were carried out on their surface. The materials were found to be non-cytotoxic and the degree of porosity was suitable for cell colonization. On the basis of the most important parameters for assessing the condition of cultured cells (cell density and viability, cell metabolic activity and lactate dehydrogenase activity), the potential of PLLA + PECit nonwovens for application in tissue engineering was established.

Correlations between Microscale Indentation Creep and Macroscale Tensile Creep of Polymers

We compared the results of various microscale indentation creep (microcreep) measurements with macroscale tensile creep (macrocreep) measurements of three common polymers: high-density polyethylene (PE), polypropylene (PP), and polystyrene (PS). The main objective was to verify if the short-term microcreep experiments could predict long-term macrocreep behavior of the selected polymers, whose properties ranged from very soft and ductile (PE) to very hard and brittle (PS). The second objective was to compare several creep predictive schemes: the empirical power law model (PL) and several types of phenomenological elasto-visco-plastic models (EVP). In order to facilitate this task, we developed a universal program package named MCREEP, which fits PL and EVP models to both tensile and indentation creep data. All experimental results and theoretical predictions documented that: (i) regardless of the creep experiment type, both micro- and macrocreep resistance increased in the following order: PE < PP < PS, (ii) the short-term microcreep experiments could be used to predict qualitatively the long-term macrocreep behavior, and (iii) the simple empirical power law model yielded better predictions of long-term creep behavior than the more sophisticated elasto-visco-plastic models.

Hydrogel Tissue Expanders for Stomatology. Part II. Poly(styrene-maleic anhydride) Hydrogels

Self-inflating soft tissue expanders represent a valuable modality in reconstructive surgery. For this purpose, particularly synthetic hydrogels that increase their volume by swelling in aqueous environment are used. The current challenge in the field is to deliver a material with a suitable protracted swelling response, ideally with an induction period (for sutured wound healing) followed by a linear increase in volume lasting several days for required tissue reconstruction. Here, we report on synthesis, swelling, thermal, mechanical and biological properties of novel hydrogel tissue expanders based on poly(styrene-alt-maleic anhydride) copolymers covalently crosslinked with p-divinylbenzene. The hydrogels exerted hydrolysis-driven swelling response with induction period over the first two days with minimal volume change and gradual volume growth within 30 days in buffered saline solution. Their final swollen volume reached more than 14 times the dry volume with little dependence on the crosslinker content. The mechanical coherence of samples during swelling and in their fully swollen state was excellent, the compression modulus of elasticity being between 750 and 850 kPa. In vitro cell culture experiments and in vivo evaluation in mice models showed excellent biocompatibility and suitable swelling responses meeting thus the application requirements as soft tissue expanders.

Porous Heat-Treated Polyacrylonitrile Scaffolds for Bone Tissue Engineering

Heat-treated polyacrylonitrile (HT-PAN), also referred to as black orlon (BO), is a promising carbon-based material used for applications in tissue engineering and regenerative medicine. To the best of our knowledge, no such complex bone morphology-mimicking three-dimensional (3D) BO structure has been reported to date. We report that BO can be easily made into 3D cryogel scaffolds with porous structures, using succinonitrile as a porogen. The cryogels possess a porous morphology, similar to bone tissue. The prepared scaffolds showed strong osteoconductive activity, providing excellent support for the adhesion, proliferation, and mitochondrial activity of human bone-derived cells. This effect was more apparent in scaffolds prepared from a matrix with a higher content of PAN (i.e., 10% rather than 5%). The scaffolds with 10% of PAN also showed enhanced mechanical properties, as revealed by higher compressive modulus and higher compressive strength. Therefore, these scaffolds have a robust potential for use in bone tissue engineering.

Synergistic effects in mechanical properties of PLA/PCL blends with optimized composition, processing, and morphology

Blending of poly(lactic acid) with poly(ε-caprolactone) can increase the impact strength above the values of the individual components.

Maltotriose transport and utilization in baker's and brewer's yeast

Maltotriose is metabolized by baker's and brewer's yeast only oxidatively, with a respiratory quotient of 1.0, the QCO2Ar being, depending on the strain used, 0-11, as compared with QCO2air of 6-42 microL CO2 per h per mg dry substance. The transport appeared to proceed by facilitated diffusion (no effects of NaF, iodoacetamide and 3-chlorophenylhydrazonomalononitrile) with a KT of more than 50 mM and was inhibited by maltose greater than maltotriose greater than methyl-alpha-D-glucoside greater than maltotetraose greater than D-fructose greater than D-glucose. The transport was present constitutively in both Saccharomyces cerevisiae (baker's yeast) and in S. uvarum (brewer's yeast) and it was not significantly stimulated by preincubation with glucose or maltose. The pH optimum was 4.5-5.5, the temperature dependence yielded an activation energy of 26 kJ/mol.