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Nanostrukturalne powłoki na bazie tytanu do kontaktu z krwią; diagnostyka strukturalna, adhezja komórek w warunkach hydrodynamicznych

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Odpowiedź komórek na obciążenia mechaniczne w warunkach ich oddziaływania z implantowanym materiałem jest ważnym elementem determinującym powodzenie implantu [1]. Zjawiska te występują szczególnie w systemach naczyniowych oraz mięśniowych. Komórki budujące naczynia krwionośne poddawane są ciśnieniu pulsacyjnemu przepływającej krwi. W celu określenia sił mechanicznych oddziałujących na komórki naczyniowe wprowadzonych zostało kilka dynamicznych testów in vitro. Większość z nich wykorzystuje relację pomiędzy adhezją komórek a naprężeniem ścinającym, występującym pomiędzy komórką a powierzchnią biomateriału. Z fizykochemicznego punktu widzenia, bio-adhezja dotyczy trzech składowych: komórek, stałego podłoża i ciekłego medium [2]. W ostatnim dwudziestoleciu liczne eksperymentalne [...]

Platelets activation and adhesion on TiN+Ti2N+αTi(N) layer produced in plasma space on Ti6Al4V alloy

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The original extracorporeal pulsatile heart support device, called POLVAD, has been developed in Poland. It was used in over 200 patients with the longest duration of 1 year. The innovative tilting disc valve for this device is developing. The valve consists of original valve ring, free of pivot element crossing the blood stream (Fig. 1). The valve ring is made of titanium alloy Ti6Al4V type. Titanium and its’ alloys demonstrate numbers of beneficial properties in medical applications. They are a subject to study metallosis, they demonstrate very good biotolerance to tissue habitat, high resistance to corrosion, and thermodynamical stability in physiological conditions. The thromobogenicity is one among t he problems, regarding titanium and its’ alloys applications as the biomaterials. For that reasons appropriate surface modifying layers of titanium are developed - to improve material properties for blood contact. Nowadays, surface engineering techniques are used as base point for creation a proper chemical composition, structure and physicochemical status of biomaterial surfaces - to obtain its required biological properties and functions. The surface modifications of titanium and its’ alloys influence surface layer structure and morphology, adhesion and inside layer residual stress. They influence a total implant stability in live organism habitat as well as improve biocompatibility. The microstructure, roughness and thrombogenicity of diffusive titanium nitride layers on titanium Ti6A14Al alloy are examined in the work - together with thrombogenicity testing, performing as the material induced platelets activation and its adhesion to the biomaterial surface. MATERIAL AND METHODS The titanium nitride layers were formed at the Surface Engineering Department of Warsaw University of Technology. Three diffusive layers: TiN+Ti2N+αTi(N), TiO2+Ti2N+αTi(N), and Ti(OCN[...]

Blood permeability testing of chitosan sealed polyester vascular prosthesis

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The aim of the investigation was to determine blood permeability through the vascular grafts sealed with chitosan. The measurement method of water permeability of vascular grafts is specified in appropriate standard [1]. However the standard’s procedure does not reflect real prosthesis’ work conditions, particularly when it is applied as an element of heart assist system [2]. In respect of this it was intended to perform testing according to distinct procedure giving more complete representation of vascular prosthesis’ properties and taking into consideration mechanical extensibility of woven fabric during work with pulsatile pressure load. MATERIALS AND METHODS Vascular grafts The material of the investigation were BARD 004187 style 6010 vascular prosthesis of 16mm internal diameter [3]. Graft samples marked as 10 and 20 were sealed with layers based on chitosan. “10" and “20" runs was sealed with material of relative molecular mass respectively about 130 kD and 100 kD. Reference samples, marked as 0REF were not modified in any way. For testing purposes sample sets together with mounting elements and soft ring seals were prepared (Fig. 1). In such a set active graft’s length (intended for contact with blood) was 70 mm and active graft’s wall area was 35 cm2. Operating medium As an operating medium the blood collected from animals with CPDA-1 [4] anticoagulant was used. Transport of biological material to the laboratory was performed in temperature of 10°C. Time elapsed from blood collecting to beginning of the investigation was about 1.5 h. Biological material’s stability was determined by biochemical tests (hematocrit level, degree of hemolysis) [5] on the spot of drawing, directly before and during investigation. Testing methodology Vascular prosthesis’ samples were divided in three groups: a, b and c. In "a" group the grafts were subjected to the test without prelimin[...]

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