Surface-induced thrombosis and lack of endothelialization are major drawbacks that hamper the widespread application of polyurethanes for the fabrication of implantable cardiovascular devices. Endothelialization of the blood-contacting surfaces of these devices may avoid thrombus formation and may be implemented by strategies that introduce micro and submicron patterns that favor adhesion and growth of endothelial cells. In this study, we used laser radiation to directly introduce topographical patterns in the low micrometer range on castor oil-based polyurethane, which is currently employed to fabricate cardiovascular devices. We have investigated cell adhesion, proliferation, morphology and alignment in response to these topographies. Reported results show that line-like and pillar-like patterns improved adhesion and proliferation rate of cultured endothelial cells. The line-like pattern with 1 μm groove periodicity was the most efficient to enhance cell adhesion and induced marked polarization and alignment. Our study suggests the viability of using laser radiation to functionalize PU-based implants by the introduction of specific microtopography to facilitate the development of a functional endothelium on target surfaces.

No abstract

Pyrethroids are insecticides widely used in agriculture to control ectoparasites and biological vectors. They can reach the water bodies by leaching and or runoff. Fishes are highly sensitive to pyrethroids and the nervous system sensibility and the deficient drug metabolism are the clues but the toxicity mechanisms are yet unclear. The acute toxicity assays allow evaluating the potential, environmental risks of specific pesticides. Type II pyrethroids are becoming widely used and there is no law concerning the limits of use to this kind of pesticide in Brazil. The LC 50 ;96h was evaluated for three pyrethroid basedinsecticides (PBI): cypermethrin, deltamethrin and λ-cyhalothrin in fish Brycon amazonicus. The LC 50 ;96h for the cypermethrin based-insecticide (CBI) was 36 µg L -1 ; for deltamethrin based-insecticide (DBI) was 2.6 µg L -1 ; and for λ-cyhalothrin (LBI) was 6.5 µg L -1 . During the tests some behavioral alterations were registered just after the exposure; they were more evident at the highest xenobiotics concentrations. These alterations were indicative of asphyxia and nervous system damages. The three insecticides are highly toxics to B. amazonicus and the degree of toxicity is: deltamethrin> λ-cyhalothrin> cypermethrin. The behavioral alterations observed are worrying since long-term exposure to sublethal concentrations can affect survival and reproductive ratios.

Surface functionalization of polymers aims to introduce novel properties that favor bioactive responses. We have investigated the possibility of surface functionalization of polyethylene terephthalate (PET) sheets by the combination of laser ablation with hot embossing and the application of such techniques in the field of stem cell research. We investigated the response of human induced pluripotent stem cellderived cardiomyocytes (hiPSC-CMs) to topography in the low micrometer range.HiPSC-CMs are expected to offer new therapeutic tools for myocardial replacement or regeneration after an infarct or other causes of cardiac tissue loss. However, hiPSC-CMs are phenotypically immature compared to myocytes in the adult myocardium, hampering their clinical application. We aimed to develop and test a high-throughput technique for surface structuring that would improve hiPSC-CMs structural maturation.

No abstract