The Gram negative bacterial outer membrane protects the bacterium from toxins such as antibiotics and is partially responsible for the rapid rise in antibiotic resistance in these bacteria. Its outer surface is formed by a lipid, lipopolysaccharide (LPS) which is unique to Gram negative bacteria. We are developing models of these bacterial outer membranes and have successfully recreated their interaction with the antibiotic Polymyxin B which acts directly upon LPS . We can now observe the effects of natural LPS modifications which occur in resistant bacteria and here we wish to study the effect of reduction in LPS negative charge. We will observe how it reduces antibiotic binding and also its cost to the viability of the bacterium, in terms of membrane stability. This will enable the design of better antibiotics effective against antibiotic resistant bacteria.