Gram-negative bacteria, which cause a variety of diseases including meningitis, plague, sepsis and food poisoning, are becoming increasingly antibiotic resistant. One reason is their robust outer membrane (OM) which can resist antibiotic penetration. We have been combining our recently developed OM model with neutron science to measure the penetration of an important antibiotic, polymyxin (PMB), into the OM. These have shown the importance of the critical melting of the OM at body temperature in allowing PMB to work. These have been supported by in vivo data on live bacteria. We need to measure where the antibiotic resides in the OM model and this proposal seeks to set up a fully deuterated OM model using d-LPS produced in our own laboratory. This will help with our short term objectives with PMB but also provide a new sample environment for future antibiotic penetration studies.