P. Moraille, Z. Ferron, C. DeWolf, A. Badia
Universite de Montreal,
Canada
Keywords: photothermal AFM-IR, SPM, phase separation, ultrathin organic films, nanoIR
Summary:
Organized organic ultrathin films are used to tailor surfaces with specific (bio) physical chemical properties. Solid-supported lipid monolayers and bilayers are simple model systems that are instrumental in studying various biological phenomena and molecular mechanisms for more complex biological systems [1]. Microscopy, surface spectroscopy and analytical techniques have provided critical information regarding the chemical composition and surface activity of in vivo surfactant structures [2]. Recently AFM-IR, a technique coupling an atomic force microscope with a pulsed tunable IR laser source, has become one of the most influential tools for nanoscale correlation of chemical and mechanical properties with the morphology of laterally segregated structures [3]. We use resonance-enhanced atomic force microscopy-infrared spectroscopy (AFM-IR) as a tool for the compositional and structural investigation of biologically relevant phase-separated lipid-supported monolayers. Furthermore, orthogonal polarization of light excitation is used to demonstrate the orientation sensitivity of AFM-IR to molecules adsorbed on a surface. The results show spectroscopic signal enhancement for bands oriented along the direction of polarization. This correlation between the polarization state of the incident radiation and the relative absorption of specific functional groups can be used as a promising tool to gain deeper insight into phase morphology, molecular distribution and orientation within the monolayers. [1] N.Nisticò, Appl. Mater. Today 35, 101998 (2023). [2] J. Pérez-Gil, Biochimica et Biophysica Acta Volume 1778, 1676–1695 (2008). [3] A. Dazzi & C.B. Prater, Chem. Rev. 117, 7, 5146–5173 (2017). [4] ACS Meas. Sci. Au. 3, 301−314 (2023).