Scheme 6 (a) If a polycation binds to a cluster of DNA binding sites in a non-cooperative manner,
a gradual increase in polycation concentration generates a gradual increase in the average
occupancy of the cluster. (b) Conversely, if the polycation binding to adjacent sites is cooperative,
a gradual increase in polycation concentration generates a “digital” on/off response as the
concentration sweeps a threshold value (dashed line). The higher the binding cooperativity, the
steeper the transition between the “off” and the “on” states. Adapted and reprinted with permission
from [67]. Copyright 2010 Elsevier
Scheme 7 Tapping mode AFM height topographs of (A) uncomplexed pBR322, (C) linear DNA,
and (B, D) the respective complexes of these formed when mixed with chitosan. C DNA ¼ 4
μg mL
À1
. Reprinted with permission from [68]. Copyright 2004 American Chemical Society
116
A. Bertin
a gradual increase in polycation concentration generates a gradual increase in the average
occupancy of the cluster. (b) Conversely, if the polycation binding to adjacent sites is cooperative,
a gradual increase in polycation concentration generates a “digital” on/off response as the
concentration sweeps a threshold value (dashed line). The higher the binding cooperativity, the
steeper the transition between the “off” and the “on” states. Adapted and reprinted with permission
from [67]. Copyright 2010 Elsevier
Scheme 7 Tapping mode AFM height topographs of (A) uncomplexed pBR322, (C) linear DNA,
and (B, D) the respective complexes of these formed when mixed with chitosan. C DNA ¼ 4
μg mL
À1
. Reprinted with permission from [68]. Copyright 2004 American Chemical Society
116
A. Bertin