AVS 53rd International Symposium
    Plasma Science and Technology Thursday Sessions
       Session PS1+BI-ThM

Paper PS1+BI-ThM1
Study of Plasma Modified PTFE for Biological Applications : Relationship between Non Fouling Properties - Plasma Treatment - Surface Composition and Surface Roughness

Thursday, November 16, 2006, 8:00 am, Room 2009

Session: Plasmas in Bioscience
Presenter: N. Vandencasteele, Université Libre de Bruxelles, Belgium
Authors: N. Vandencasteele, Université Libre de Bruxelles, Belgium
B. Nisol, Unviersité Libre de Bruxelles, Belgium
P. Viville, Université de Mons-Hainaut, Belgium
R. Lazzaroni, Université de Mons-Hainaut, Belgium
D.G. Castner, University of Washington
F. Reniers, Unviersité Libre de Bruxelles, Belgium
Correspondent: Click to Email
Polytetrafluoroethylene was treated by oxygen or nitrogen RF low pressure plasmas. The modified samples were characterized by XPS for surface composition, contact angle for surface energy and atomic force microscopy for surface roughness. The adsorption of bovine serum albumine (BSA) was used as a probe for the (non)fouling properties and potential biological applications. Evidence for BSA adsorption was determined by the appearance or the increase of the N 1s XPS peak. PTFE modified by Nitrogen plasma shows a strong decrease of the contact angle that has previously been correlated to an increase of the nitrogen surface concentration due to grafting and to a decrease of the fluorine concentration.@footnote 1@ Further exposure to BSA leads to an increase of the N 1s signal, and to a concomitant decrease of the F 1s peak, indicating that some protein was adsorbed onto the plasma modified surface. The exposure of PTFE to an oxygen plasma leads to virtually no grafting. XPS results show that there is less than 1% of oxygen on the surface after the treatment. A strong increase in the chamber pressure was observed during the treatment, and optical emission spectrometry reveals the presence of CO, CO@sub 2@ and F in the gas phase, indicating a strong etching of the surface. Depending on the plasma power, water contact angles as high as 170 deg. could be obtained, indicating a super-hydrophobic behaviour, and new surface structures were observed by AFM. At high power, a strong increase in roughness is evidenced, together with the formation of a regular structure. According to the Cassie Baxter model, this increase of roughness is responsible for the super hydrophobic behaviour. Lower amounts of BSA adsorption were detected on high power oxygen plasma-modified PTFE samples compared to nitrogen plasma-modified PTFE samples. @FootnoteText@ @footnote 1@ N. Vandencasteele, D.H. Fairbrother, F. Reniers. Plasma processes and polymers 2, 493-500, (2005).