Brewster Angle Microscopy

Abstract

Brewster angle microscopy (BAM) is the technique of choice for imaging monolayers of supramolecular systems at the water–air interface. BAM is based on the optical principle of the Brewster angle, in which p ‐polarized light incident on the water surface at the Brewster angle is nearly completely extinguished. The presence of a monolayer violates this condition and provides the basis for imaging. BAM is a general method for imaging either spread or adsorbed monolayers. BAM can be applied to study phase transitions, characterize domain microstructure, study phase separation in mixed monolayers, follow changes due to complex formation, and observe collapse or multilayer formation. The method is also sensitive to the presence of optical anisotropy in monolayer films due to variations in molecular orientation. BAM has been applied to monolayers of a range of macrocyclic compounds, especially calixarene and cyclodextrin derivatives. BAM has been applied to study chiral phase separation in monolayers of chiral amphiphiles. It is possible to apply BAM in a quantitative manner to estimate variations in monolayer thickness.

Sequence-Specific DNA Interactions with Calixarene-Based Langmuir Monolayers

“…In order to confirm the interaction with DNA at the air–water interface, the morphologies of 1 -based monolayers were analyzed using BAM; the most relevant images recorded at a surface pressure of 0.5 mN m –1 are given in Figure .…”

Two‐Dimensional Calix[4]arene‐based Metal–Organic Coordination Networks of Tunable Crystallinity

“…Thea nisotropy of the crystalline structures observed on both pure water and 10 mm CuCl 2 subphases is unambiguously evidenced by reflectivity variations observed in BAM( Figure S2). [12] Theo rientationdependent contrast provides evidence for monocrystallinity of the single domains in the dendritic networks.T he optical contrast in the BAMm icrographs can be ascribed to the anisotropy of the arrangement of the molecules in their 2D lattice as well as to the anisotropy of 1,which may assume apinched-cone conformation at the interface,asobserved in the solid state. [13] By further compression of the layer, smaller, differently oriented crystalline domains reorient and append to larger domains such that ac rystalline layer is propagated with acharacteristic domain size before the collapse pressure is reached.…”

Tensile Loads on Tethered Actin Filaments Induce Accumulation of Cell Adhesion-Associated Proteins in Vitro

“…Time-dependent changes in the size of the molecular accumulation were examined using Brewster angle microscopy after detaching the bead; Brewster angle microscopy visualizes protein clusters at the glass−water interface without fixation or staining. 38 Brewster angle illumination of the bead showed a strong scattered pattern around a glass bead, which disturbed the measurement of the weak light scattering from the molecular accumulation (Figure 6A). Time lapse images of the linkage were taken after detaching the bead from the substrate, where the strong scattered pattern from the bead was no more overlapped (Figure 6A).…”

“…The bead displaced and held for 2 min was then detached from the linkage by forcedly pushing it with the glass microneedle, which would decrease the tensile stress in the link. Time-dependent changes in the size of the molecular accumulation were examined using Brewster angle microscopy after detaching the bead; Brewster angle microscopy visualizes protein clusters at the glass–water interface without fixation or staining . Brewster angle illumination of the bead showed a strong scattered pattern around a glass bead, which disturbed the measurement of the weak light scattering from the molecular accumulation (Figure A).…”