CELL ADHESION ON HYDROPHOBIC POLYMER SURFACES

ADHEZIJA CELIC NA HIDROFOBNIH POLIMERNIH POVRŠINAH

Morana Jaganjac1, Lidija Milković1, Ana Cipak1, Miran Mozetič2, Nina Recek2, Neven Žarković1, Alenka Vesel2

1Rudjer Boskovic Institute, Div. Molecular Medicine, Bijenicka 54, 10000 Zagreb, Croatia
2Jozef Stefan Institute, Plasma laboratory, Jamova 39, 1000 Ljubljana, Slovenia

morana.jaganjac@irb.hr

Prejem rokopisa – received: 2011-06-02; sprejem za objavo – accepted for publication: 2011-07-22

Adhesion of human osteosarcoma (HOS) cells on hydrophobic polymer surface was studied. Surface of polymer polystyrene (PS) was made hydrophobic by treatment in plasma created in tetrafluoromethane gas (CF4). The PS samples were exposed for 30 s to CF4 plasma created by RF generator powered at 200 W. This treatment time allowed for optimal polymer surface functionalization with fluorine functional groups. This caused an increase of surface hydrophobicity from initial 85° to about 110° as measured by water contact angle. The HOS cells were deposited on untreated and plasma treated samples and incubated for 1, 2 and 6 days. Both untreated and plasma treated samples were tested for biocompatibility by two different methods: optical micrographs were used to study the cell morphology and MTT test was used to study the cell viability. The results showed better adhesion of cells on plasma treated samples with more hydrophobic surface in comparison to the untreated sample. MTT test revealed about 1.6-times higher activity of cell enzymes after 6-day incubation for plasma treated sample. Optical micrographs have shown that both untreated and fluorine-plasma treated polymer surfaces are not optimal for cell proliferation, since cells need about 2 days to adapt to the surface. After this adaptation time cells start to proliferate on the polymer surface, especially, on that one treated in plasma.

Keywords: plasma surface modification, human osteosarcoma cells (HOS), biopolymers, hydrophobic surface, CF4 plasma

Preučevali smo adhezijo rakastih (HOS) celic na hidrofobnih polimernih površinah. Hidrofobizacija površine polimera polistirena (PS) je potekala v CF4 plazmi generirani z RF generatorjem moči 200 W. Vzorce polimera PS smo izpostavili plazmi za 30 s, kar je zadoščalo za optimalno funkcionalizacijo polimerne površine z nepolarnimi fluorovimi skupinami. To je povzročilo porast kontaktnega kota vodne kapljice iz 85° za neobdelan vzorec na 110° za plazemsko obdelan vzorec, kar je jasen dokaz, da se je hidrofobnost površine povečala. Biokompatibilnost neobdelanih in plazemsko obdelanih vzorcev smo spremljali z optičnim mikroskopom in MTT testom. Z optičnim mikroskopom smo preučevali morfologijo celic, medtem ko smo z MTT testom preučevali viabilnost celic. HOS celice smo deponirali na vzorce in jih inkubirali 1 dan, 2 dni in 6 dni. Iz rezultatov je razvidna boljša adhezija celic na plazemsko obdelanih bolj hidrofobnih površinah v primerjavi z neobdelano zmerno hidrofobno površino. Z MTT testom smo na plazemsko obdelani površini ugotovili 1,6-krat večjo aktivnost celičnih encimov po 6-dnevni inkubaciji v primerjavi z neobdelano. Posnetki z optičnim mikroskopom nakazujejo, da neobdelana in plazemsko obdelana površina nista najbolj optimalni za vezavo celic, saj celice potrebujejo precej časa (še posebej v primeru neobdelane površine), da se privadijo na okolje. Šele po tem času privajanja je opaziti proliferacijo celic po površini, ki je še posebej opazna na plazemsko obdelanem vzorcu.

Ključne besede: plazemska modifikacija površin, rakaste celice, biopolimeri, hidrofobna površina, CF4 plazma