Reduced bacterial adhesion to fibrinogen-coated substrates via nitric oxide release

Abstract

The ability of nitric oxide (NO)-releasing xerogels to reduce fibrinogen-mediated adhesion of Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli is described. A negative correlation was observed between NO surface flux and bacterial adhesion for each species tested. For S. aureus and E. coli, reduced adhesion correlated directly with NO flux from 0 to 30 pmol cm(-2)s(-1). A similar dependence for S. epidermidis was evident from 18 to 30 pmol cm(-2)s(-1). At a NO flux of 30 pmol cm(-2)s(-1), surface coverage of S. aureus, S. epidermidis, and E. coli was reduced by 96, 48, and 88%, respectively, compared to non-NO-releasing controls. Polymeric NO release was thus demonstrated to be an effective approach for significantly reducing fibrinogen-mediated adhesion of both gram-positive and gram-negative bacteria in vitro, thereby illustrating the advantage of active NO release as a strategy for inhibiting bacterial adhesion in the presence of pre-adsorbed protein.

Figures

Figure 1

Nitric oxide release profiles for 10 (A), 20 (B), 30 (C), and 40% (D) AHAP3 xerogels (v/v, balance BTMOS) from t = 0 to t = 8 h. Inset: NO release from t = 3 to t = 4.5 h, corresponding to the period during which xerogels were incubated in bacterial suspensions.

Figure 2

Effect of pre-adsorbed fibrinogen and BSA on S. aureus, S. epidermidis, and E. coli adhesion to PVC-coated control 40% AHAP3 xerogels (v/v, balance BTMOS) at 37 °C. For each bacterial species, the difference in adhesion between substrates with no pre-adsorbed protein and both fibrinogen and BSA-coated substrates was significant (p < 0.05).

Figure 3

Influence of NO surface flux on S. aureus (A), E. coli (B), and S. epidermidis (C) adhesion to PVC-coated NO-releasing xerogels.

Figure 4

Representative phase contrast images of E. coli (A, D); S. aureus (B, E); and S. epidermidis (C, F) adhesion to fibrinogen-coated control (A, B, C) and NO-releasing (D, E, F) 40% AHAP3 xerogels (v/v, balance BTMOS) at 37 °C. Cells are white. Images are 215 × 270 µm2.