Near-field scanning optical microscopy: a tool for nanometric exploration of biological membranes

Abstract

Near-field scanning optical microscopy (NSOM) is an emerging optical technique that enables simultaneous high-resolution fluorescence and topography measurements. Here we discuss selected applications of NSOM to biological systems that help illustrate the utility of its high spatial resolution and simultaneous collection of both fluorescence and topography. For the biological sciences, these attributes seem particularly well suited for addressing ongoing issues in membrane organization, such as those regarding lipid rafts, and protein-protein interactions. Here we highlight a few NSOM measurements on model membranes, isolated biological membranes, and cultured cells that help illustrate some of these capabilities. We finish by highlighting nontraditional applications of NSOM that take advantage of the small probe to create nanometric sensors or new modes of imaging.

Recent progress on lipid lateral heterogeneity in plasma membranes: From rafts to submicrometric domains

“…AFM has become extremely advanced by a multiparametric analysis of samples by combining super-resolution imaging, topography, molecular interactions and mechanical measurement [154]. A related method is Near-Field Scanning Optical Microscopy (NSOM) with a resolution that can reach ~20nm [155]. NSOM has revealed clustering of GM1 and GM3 in domains of ~40-360nm at the apical PM of epithelial cells [156].…”

Electrons, Photons, and Force: Quantitative Single-Molecule Measurements from Physics to Biology

“…(218) The scanning probe illumination is both a limitation and an advantage since it limits photon throughput and confines analysis to surfaces but also enables simultaneous topographic measurements. (219)…”

Identifying the development in phase and amplitude of dipole and multipole radiation

“…Furthermore, R is the intermolecular donor-acceptor separation vector, ck is the magnitude of the energy transferred and e ikR is the phase factor (time does not feature explicitly; we introduce it later). Note that the wave-vector magnitude is not denoted by p here, because k is a specific value determined by the energetics of the emissive and absorptive transitions, as opposed to the summation variable in the mode expansion (4).…”

“…The levels of intensity required to produce a meaningful signal are much lower than for conventionally propagating light, and there is a supplementary advantage that significantly subwavelength resolution can be achieved. In the visible wavelength range, for example, where it was long anticipated that such features might be exploited in achieving enhanced resolution imaging [1], the vision has come to fruition in the techniques of near-field microscopy [2] that are now extensively used in biological applications [3,4]. In the same context many recent developments are associated with the local influence of surface plasmons [5], related to the special features of near-field light generated in the vicinity of nanostructured metal surfaces.…”