Optical Antenna-Based Fluorescence Correlation Spectroscopy to Probe the Nanoscale Dynamics of Biological Membranes

Abstract

The plasma membrane of living cells is compartmentalized at multiple spatial scales ranging from the nano- to the mesoscale. This nonrandom organization is crucial for a large number of cellular functions. At the nanoscale, cell membranes organize into dynamic nanoassemblies enriched by cholesterol, sphingolipids, and certain types of proteins. Investigating these nanoassemblies known as lipid rafts is of paramount interest in fundamental cell biology. However, this goal requires simultaneous nanometer spatial precision and microsecond temporal resolution, which is beyond the reach of common microscopes. Optical antennas based on metallic nanostructures efficiently enhance and confine light into nanometer dimensions, breaching the diffraction limit of light. In this Perspective, we discuss recent progress combining optical antennas with fluorescence correlation spectroscopy (FCS) to monitor microsecond dynamics at nanoscale spatial dimensions. These new developments offer numerous opportunities to investigate lipid and protein dynamics in both mimetic and native biological membranes.

Normal vibrations of ternary DOPC/DPPC/cholesterol lipid bilayers by low-frequency Raman spectroscopy

“…[1][2][3][4] This inhomogeneity gives rise to the concept of lipid ras which are assumed to be nanoscale domains of lipids and proteins in the membrane. [1][2][3][4][5][6] Lipid ra formation is thought to be important for various cellular processes. 5,6 To explore membrane properties, bilayers made from synthetic lipids are oen used.…”

Lipid rafts as signaling hubs in cancer cell survival/death and invasion: implications in tumor progression and therapy

“…On these grounds, sorting of proteins in rafts may restrict or potentiate signaling cross-talk. Membrane rafts are assumed to be transient and dynamic structures (90,91), and advanced imaging techniques have revealed that several signaling molecules are transiently recruited to membrane domains with the aid of protein-protein, protein-lipid, and/or lipid-lipid interactions (23, [92][93][94][95]. This transient and dynamic spatial compartmentalization of signaling pathways in lipid rafts provides a high flexibility and plasticity in signal transduction.…”

Vibrational eigenmodes of phospholipid layers in low‐wavenumber Raman spectrum of multilamellar vesicles

“…Mesoscopic vibrational and relaxational dynamics of phospholipid bilayers are described by Brillouin light, inelastic X‐ray, and neutron scattering spectroscopies. Also, molecular dynamics are studied by experimental methods using probes, like fluorescence spectroscopy or electron spin resonance …”

“…Phospholipid bilayers, being models of plasma membrane of living cells and perspective materials for drug delivery systems, are popular subjects of research studies. [1][2][3][4][5][6][7][8][9] Phospholipid bilayer structure is studied by Xray and neutron scattering techniques, [10,11] and by cryogenic electron microscopy, [12] lipid-order parameters can be described also by nuclear magnetic resonance method. [13,14] Differential scanning calorimetry allows to extract the entropies and temperatures of phase transitions in phospholipid bilayers, the most important being the transition from ordered low-temperature gel state to disordered fluid (liquid crystalline) state.…”

“…[19][20][21] Mesoscopic vibrational and relaxational dynamics of phospholipid bilayers are described by Brillouin light, [20] inelastic X-ray, [22] and neutron [8,23] scattering spectroscopies. Also, molecular dynamics are studied by experimental methods using probes, like fluorescence spectroscopy [7,24] or electron spin resonance. [25,26] Recently, it was suggested to use the low-wavenumber Raman spectroscopy for characterization of lipid bilayer dynamics on the scale of bilayer thickness.…”