Polymyxin B nonapeptide is primarily used in research and development within the field of antimicrobial studies. Its application is significant in understanding bacterial resistance mechanisms, particularly against Gram-negative bacteria. The compound is often utilized as a tool to study the interactions between antimicrobial agents and bacterial membranes, helping to develop new strategies to combat resistant strains. Additionally, it has potential in the formulation of novel antibiotic therapies, where it can be modified or combined with other agents to enhance efficacy and reduce toxicity. Its role in advancing the understanding of membrane permeability and drug delivery systems is also noteworthy, making it a valuable component in the ongoing fight against bacterial infections.