Smooth and rough Proteus mirabilis lipopolysaccharides studied by total internal reflection ellipsometry

• Proteus mirabilis lipopolysaccharides were adsorbed on the gold surface.
• Thickness of adsorbed layers was determined by total internal reflection ellipsometry.
• Atomic force microscopy was used to visualize lipopolysaccharide build-up on gold surface.
• Time is important in the evolution of biomolecular film thickness created on gold surface.

Total internal reflection ellipsometry (TIRE), a label-free optical detection technique for studying interactions between biomolecules, was used to examine the adsorption of various forms of lipopolysaccharides (LPSs) isolated from Proteus mirabilis S1959, R110, and R45 strains on a gold surface. The thickness of the adsorbed layers was determined by TIRE, with the average values for S1959, R110, and R45 LPS layers being 78 ± 5, 39 ± 3, and 12 ± 2 nm, respectively. The thickness of LPS layers corresponds to the presence and length of O-specific parts in P. mirabilis LPS molecules.Atomic force microscopy was used as a complementary technique for visualizing lipopolysaccharides on the surface. Force measurements seem to confirm the data obtained from TIRE experiments.