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Polymer carriers modified by plasma and functionalized with Au nanoparticles as substrates for mouse 3T3 fibroblasts

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Bacakova M. , Makajova Z. , Slepickova-Kasalkova N. , Svorcik V. , Bacakova L.

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tom Vol. 14, no. 109-111 spec. iss.

5

EN

Polymers have been o f ten applied in biology and medicine for construction of tissue replacements. However, the inert surface o f the most polymers is not able to support and control cell adhesion, migration, proliferation, differentiation and other cell functions. Hence, the modification of polymer surface led to achieve appropriate properties. The polymer surface can be modified by plasma discharge by which the polymer surface chemistry and morphology is changed. Plasma treatment leads to creation of radicals, unsaturated bonds and new chemical groups, mainly oxygen containing groups. Oxidized groups increase the wettability of polymers, which supports adsorption of cell adhesion-mediating extracellular matrix (ECM) molecules in appropriate spatial conformation increasing accessibility of specific sites in these molecules by cell adhesion receptors. In addition, other surface properties of polymers are altered by plasma etching which strongly influence cell-material interaction. Radicals and unsaturated chemical bonds which are created by plasma can be utilized for grafting new chemical groups, biomolecules and nanoparticles. The biomolecules grafted on the polymer surface, such as amino acids, RGD-containing oligopeptides (i.e., ligands for integrin receptors), ECM molecules, enazymes, hormones, and also carbon and gold nanoparticles, not only have specific biological effects on cells but also change physical and chemical properties of the polymer surface, and by this way they support its bioactivity. This study is focused on physiochemical properties and biocompatibility of modified polymers. The studied materials were poly(L-lactide) (PLLA) foils, nanofibrous PLLA meshes and polyethylene terephtalate (PTFE) foils. PLLA and PTFE foils were modified in plasma with Ar + ions for time intervals of 50, 10 0 and 300 s with power 8 W, and then grafted with Au nanoparticles. Changes in the surface wettability were determined by reflection goniometry . The presence an d concentration o f Au nanoparticles were examine d by X-ray Photoelectron Spectroscopy (XPS). For the biocompatibility testing, the polymers were seeded by mouse embryonic fibroblasts of the line 3T3, i.e., t he cells of ten utilized as a feeder for keratinocytes. The cell adhesion and growth was evaluated by the number of cells, their morphology and the size of cell adhesion area in the 1st, 3rd and 6th day after seeding. The results indicate that the water drop contact angle increases with the time of exposure to plasma, which means that the vettability decreases. However, the following exposure of plasma-irradiated polymers to a sodium citrate solution (i.e., a storage solution for Au nanoparticles) and grafting with Au nanoparticles decrease the contact angle, i.e., increase the material surface wettability. Our tests of biocompatibility indicate that the modification of the polymer surface in fluences positively the cell behavior. The cells adhered at higher numbers and by a larger cell adhesion area on modified polymers; it was mainly manifested on PTFE.

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Vascular smooth muscle cells in cultures on low density polyethylene modified with plasma discharge and biofunctionalization

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Parizek M. , Kasalkova N. , Bacakova L. , Kolarova K. , Lisa V. , Svorcik V.

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2009

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tom Vol. 12, no. 89-91

25--28

EN

Low density polyethylene (LDPE) was modified by an Ar plasma discharge and then grafted with glycine (Gly), bovine serum albumin (BSA) or polyethylene glykol (PEG). Some plasma-treated samples and samples grafted with BSA were exposed to a suspension of colloidal carbon particles (C, BSA+C). Pristine LDPE and tissue culture polystyrene dishes (PSC) were used as control samples. The materials were seeded with rat aortic smooth muscle cells and incubated in a medium DMEM with 10% of fetal bovine serum. On day 1 after seeding, the cells on LDPE modified with plasma only, Gly, BSA and BSA+C adhered in similar numbers as on PSC, while the values on non-modified and PEG-modified samples were significantly lower. On day 5, the highest cell numbers were found again on LDPE with Gly, BSA and BSA+C. On day 7, the highest number of cells was found on LDPE modified only with plasma. The latter cells also dis-played the largest cell spreading area. The increased cell colonization was probably due to the formation of oxygen-containing chemical functional groups after plasma irradiation, and also due to positive effects of grafted Gly, BSA and BSA in combination with colloidal C particles.

3

Vascular smooth muscle cells in cultures on synthetic polymers with adhesive microdomains

86%

Parizek M. , Bacakova L. , Lisa V. , Kubova O. , Svorcik V. , Heitz J.

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tom R. 9, nr 58-60

7-10

EN

Polyethylene terephtalate was modified by UV light irradiation produced by a Xe2-excimer lamp for 10, 20 or 30 min in an acetylene atmosphere. For creation of microdomains for selective cell adhesion, a contact nickel mask (apertures of the diameter of 500 m, centre-to-centre distance 2 mm) was used. The material was then seeded with rat aortic smooth muscle cells (passage 3, 17 000 cells/cm square). After 1, 3 and 7 days of cultivation, the cells were homogeneously distributed on the samples without any preference of the irradiated microdomains. Moreover, on day 1, the number of initially adhered cells was similar on all tested samples. However, on day 3, the number of cells on the irradiated samples was significantly higher than that on control unmodified PET and increased proportionally to the time of exposure to UV light. On day 7 after seeding, however, the cell number on the unmodified PET exceeded the value on all irradiated samples. In the second set of experiments, polyethylene (PE) was irradiated by Ar+ ions in order to create the adhesive microdomains (dose 10\12-10\14 ions/cm square, energy 150 and 15 keV, contact mask with holes of 100 m diameter and distance 200 m). The highest selectivity of the adhesion and growth of rat aortic smooth muscle cells (89% of all cells) was found on the microdomains created at the energy of 150 keV and the dose of 3x10\12 ions Ar+. The lowest selectivity (30%) occurred on samples irradiated with 150 keV Ar+ ions of the dose of 3x10\14 ions/cm square. Therefore, both methods seem to be suitable for modification of materials with highly hydrophobic surfaces in purpose to increase the cell colonization, for example when constructing bioartificial vascular replacements. The second method can be also used for the creation of domains for a regionally selective adhesion and growth of cells on biomaterials.