Understanding the Collapse Mechanism in Langmuir Monolayers through Polarization Modulation-Infrared Reflection Absorption Spectroscopy

Author(s)

Goto, Thiago Eichi ^[1] ; Caseli, Luciano ^[1]

Affiliation

^[1] Univ Fed Sao Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Diadema, SP - Brazil

• Document type: Journal article
• Source: Langmuir; v. 29, n. 29, p. 9063-9071, JUL 23 2013.
• Web of Science Citations: 27

Abstract

The collapse of films at the air-water interface is related to a type of 2D-to-3D transition that occurs when a Langmuir monolayer is compressed beyond its stability limit. Studies on this issue are extremely important because defects in ultrathin solid films can be better understood if the molecular mechanisms related to collapse processes are elucidated. This paper explores how the changes of vibration of specific groups of lipid molecules, as revealed by polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), are affected by the monolayer collapse. Different mechanisms of collapse were studied, for those lipids that undergo constant-area collapse (such as stearic acid) and for those that undergo constant-pressure collapse (such as DPPC, DPPG, and DODAB). Lipid charges also affect the mechanism of collapse, as demonstrated for two oppositely charged lipids. (AU)

• FAPESP's process: 08/10851-0 - Ultrathin films to fabrication of biosensors and biomembrane mimicking: applications in environmental and health areas
• Grantee: Luciano Caseli
• Support Opportunities: Research Grants - Young Investigators Grants