The outer membrane of Gram negative bacterial is an effective barrier for many harmful agents. We have been developing and testing advanced models of the Gram negative bacterial outer surface to understand the biochemistry of this important biological surface with molecular precision. So how do cationic antimicrobial agents bind to the anionic phosphate groups of the Lipopolysaccharides (LPS) during their membrane disruption activity? Here, using neutron reflectometry we intend to induce holes in the core region of a model asymmetric gram negative bacterial outer membrane and, using a new titration technique we have developed, examine the Debye screening lengths of the electrostatic bonds formed between a cationic antimicrobial protein (colicin N) and the anionic phosphate groups of the core oligosaccharides of LPS. We hypothesise that the holes allow for short range electrostatic bonds.