Understanding peptide�lipid interactions at high resolution is a key issue in current biophysical and pharmaceutical research. In this project, we used Surface-Enhanced Raman Spectroscopy (SERS) and atomic force microscopy (AFM) imaging to characterize and visualize the interaction of the cationic antimicrobial peptide (RW)4-NH2 with lipid domains in model membranes. Dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylethanolamine (DPPE), and Dipalmitoylglycerophosphoglycerol (DPPG) were used as model membranes. Gold was used as SERS-active substrate. Various supported lipid bilayers were prepared by fusion of unilamellar vesicles on gold and imaged in the dried state. A significant SERS enhancement was gained for the antimicrobial peptide and lipids. The SERS spectra of the antimicrobial peptides and lipids are highly resolved. SERS spectra of the antimicrobial peptides show appearance of new peaks as compared to the Raman spectra of the bulk. Changes in the order parameter upon membrane binding and insertion provided insights into the orientation of the peptide in the model membranes. AFM images showed some heterogeneity in the bilayer as microdomains due to the presence of the antimicrobial peptide. Disappearance of large vesicle aggregates was observed. The present study gives a critical view of the two techniques, which can be useful for other studies concerning peptide�membrane interactions

Investigating peptide-lipid interactions in model membranes by SERS and AFM

248th National Meeting (2014)

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