The atomic force microscope (AFM) was used to directly measure the forces o
f interaction between E. coli D21 bacteria and hydrophilic glass or hydroph
obic N-octadecyltrichlorosilane (OTS)-treated glass substrates coated with
the block copolymers, poly(ethylene glycol) (PEG)-lysine dendron or Pluroni
c F127 surfactant, respectively. Short-range repulsive interactions between
bacterial cells and substrates coated with the block copolymers were detec
ted by the AFM over distances of separation comparable to the extended leng
th of the PEG polymer chains. In contrast, glass and OTS-treated glass devo
id of PEG-lysine dendron or Pluronic F127 exerted long-range attractive for
ces on E. coli D21 bacteria. Thus, polymeric brush layers appear to not onl
y block the long-range attractive forces of interaction between bacteria an
d substrates but also introduce repulsive steric effects.