AVS 50th International Symposium
    Biomaterial Interfaces Friday Sessions
       Session BI+PS-FrM

Paper BI+PS-FrM5
Chemical Modifications of PVC Endotracheal Tubes by RF-Oxygen Glow Discharge Pre-functionalization and NaOH/AgNO@sub 3@ Wet Treatments to Reduce Bacterial Adhesion

Friday, November 7, 2003, 9:40 am, Room 318/319

Session: Plasma Methods for Bio-interfaces
Presenter: D.J. Balazs, Swiss Federal Inst. of Tech., Switzerland
Authors: D.J. Balazs, Swiss Federal Inst. of Tech., Switzerland
K. Triandafillu, Swiss Federal Inst. of Tech., Switzerland
P. Wood, Univ. Hospital of Geneva, Switzerland
Y. Chevolot, Goemar Laboratories, France
C. van Delden, Univ. Hospital of Geneva, Switzerland
H. Harms, Swiss Federal Inst. of Tech., Switzerland
C. Hollenstein, Swiss Federal Inst. of Tech., Switzerland
H.J. Mathieu, Swiss Federal Inst. of Tech., Switzerland
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The use of silver as an antibacterial agent can be traced back to ancient times, and is currently used in several medical applications.@footnote 1@ Bacterial colonization of intubation tubes is responsible for 90% of all nosocomial pneumonia cases, 40 % of which lead to death, despite aggressive antibiotic therapy.@footnote 2@ We have developed an approach based on the surface modification of medical grade poly(vinyl chloride) (PVC) to create an anti-colonization surface, rich in silver ions. The modification consists of an oxygen plasma treatment, followed by a two step wet treatment in sodium hydroxide (NaOH) and silver nitrate (AgNO@sub 3@) solutions. XPS analysis and contact angle measurements were used to investigate the chemical nature and surface wettability of the films following each step of the modification. Saponification with NaOH of esters, like those of PVC plasticizers was determined to be a simple, irreversible method of hydrolysis, producing sodium carboxylate and phthalate salts. Following a subsequent in incubation in the AgNO@sub 3@ solution, XPS showed evidence of a replacement reaction that produced a surface rich in silver ions. The potential of wet treatments that incorporate silver as a germicidal agent was demonstrated in bacterial and biofilm studies, using various P. aeruginosa strains. The native and O@sub 2@ pre-functionalized PVC surfaces submitted to the wet treatments exhibited a 100% reduction in initial bacterial adhesion. The efficacy of the wet treatment to reduce colonization over a longer period was demonstrated as 7-logarithmic drop in biofilm population at 24h and an 8-logarithmic reduction at 72 h, as compared to native PVC substrates. @FootnoteText@@footnote 1@ R.O. Darouiche, (1999) Clin. Infect. Dis. 29, 1371-1377. @footnote 2@ J.L. Vincent, D.J. Bihari, et al., (1995) JAMA 274: 639-644. .