Bacterial adhesion to poly(HEMA)-based hydrogels.

The effects of water content and comonomer chemistry upon the adhesion of Pseudomonas aeruginosa to poly(hydroxyethyl methacrylate)-based hydrogels were studied. Hydrogels which varied in swollen water content from 33-69 wt% were polymerized onto glass microscope slides pretreated with a vinyl silane. The hydrogel water content was varied by adding methacrylic acid (1-5 wt%) or N-vinyl pyrrolidone (NVP, 10-25 wt%) or combinations of the two comonomers. The resulting hydrogel surfaces, which were 0.1 mm thick, transparent, and adherent to the glass slide, formed the test surfaces of laminar flow cells (Re = 1.3, wall shear rate = 1.6/s). The bacteria were grown for 8 h in tryptic soy broth (TSB), washed by filtration, and collected on 0.45-microns filters, resuspended in phosphate buffered saline (PBS) at pH = 7.2, and recirculated through the flow cell and across the test surface at 0.85 mL/min for 2 h. Results show that P. aeruginosa adhered less to hydrogels with higher water contents. In the presence of TSB and possible poly(NVP) contamination, the concentration of adherent bacteria was reduced to low and uniform levels independent of the hydrogel chemistry.