An ultrasensitive microfluidic approach reveals correlations between the physico-chemical and biological activity of experimental peptide antibiotics.

This is the final version. Available from Nature Research via the DOI in this record.Data availability: All the data necessary for understanding the paper is available in the main text or supplementary information. Codes for the analysis of the GUV data are available at https://github.com/mrcsfltchr/TrapAnalysis.Antimicrobial resistance challenges the ability of modern medicine to contain infections. Given the dire need for new antimicrobials, polypeptide antibiotics hold particular promise. These agents hit multiple targets in bacteria starting with their most exposed regions-their membranes. However, suitable approaches to quantify the efficacy of polypeptide antibiotics at the membrane and cellular level have been lacking. Here, we employ two complementary microfluidic platforms to probe the structure-activity relationships of two experimental series of polypeptide antibiotics. We reveal strong correlations between each peptide's physicochemical activity at the membrane level and biological activity at the cellular level. We achieve this knowledge by assaying the membranolytic activities of the compounds on hundreds of individual giant lipid vesicles, and by quantifying phenotypic responses within clonal bacterial populations with single-cell resolution. Our strategy proved capable of detecting differential responses for peptides with single amino acid substitutions between them, and can accelerate the rational design and development of peptide antimicrobials.Wellcome TrustEngineering and Physical Sciences Research CouncilEuropean Research Councils Department for Business, Energy and Industrial Strategy and Innovate UKMedical Research CouncilBiotechnology and Biological Sciences Research CouncilRoyal SocietyGordon and Betty Moore Foundation Marine Microbiology InitiativeMarie Skłodowska-Curie grantCambridge-National Physical LaboratoryWinton Programme for the Physics of SustainabilityTrinity-Henry Barlow Scholarshi