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 how strongly the PMB binds the OM at physiological temperature compared to the lower temperatures already measured. This titration experiment using increasing PMB concentrations at 37C will provide critical final data and allow us to publish in a high impact journal.