Infrared Surface Plasmon Resonance: A Novel Tool for Real Time Sensing of Variations in Living Cells

Abstract

We developed a novel surface plasmon resonance (SPR) method, based on Fourier transform infrared (FTIR) spectroscopy, as a label-free technique for studying dynamic processes occurring within living cells in real time. With this method, the long (micrometer) infrared wavelength produced by the FTIR generates an evanescent wave that penetrates deep into the sample. In this way, it enables increased depth of sensing changes, covering significant portions of the cell-height volumes. HeLa cells cultivated on a gold-coated prism were subjected to acute cholesterol enrichment or depletion using cyclodextrins. Cholesterol insertion into the cell plasma membrane resulted in an exponential shift of the SPR signal toward longer wavelengths over time, whereas cholesterol depletion caused a shift in the opposite direction. Upon application of the inactive analog alpha-cyclodextrin (alpha-CD), the effects were minimal. A similar trend in the SPR signal shifts was observed on a model membrane system. Our data suggest that FTIR-SPR can be implemented as a sensitive technique for monitoring in real time dynamic changes taking place in living cells.

Infrared Surface Plasmon Spectroscopy of Living Cells

“…So far we used this technique to study alterations in membrane cholesterol levels in HeLa cells [12], de novo formation of early endocytic transport vesicles in response to transferrin internalization by human melanoma cells [13], and detection of glucose uptake by erythrocytes [11].…”

Surface plasmon-based infrared spectroscopy for cell biosensing

“…[1][2][3] Successful implementation of the label-free biosensing techniques in biochemical assays, especially in the context of high-throughput screening, encourages the development of similar techniques at cellular level. In contrast to target-based labeling approaches that reveal specific oneto-one binding interactions, the label-free methods provide information on macroscopic cell properties, such as refractive index, [4][5][6][7][8] electrical conductivity, 9,10 viscosity, and mass. 11,12 The challenge here is to extract useful bio-functional information (e.g., cell morphology, cell adhesion, cytotoxicity, etc.)…”

“…from somewhat ambiguous label-free measurements of the physical parameters of the cells. In this respect, the optical label-free platforms, like surface plasmon 4,5,[13][14][15] or waveguide [6][7][8] biosensors, have an advantage over the nonoptical platforms (e.g., impedance 9,10 and quartz crystal microbalance 11,12 ) since they can be backed by direct optical imaging. Although the majority of optical label-free biosensors operate in the visible wavelength range, and are typically used for bio-molecule affinity characterization, 16,17 several groups recently applied these sensors to probe living cells.…”

“…Although the majority of optical label-free biosensors operate in the visible wavelength range, and are typically used for bio-molecule affinity characterization, 16,17 several groups recently applied these sensors to probe living cells. [4][5][6][7][8][13][14][15] We present a label-free method for cell sensing based on the infrared reflection spectroscopy. 18 We use the confined infrared waves such as surface plasmon (SP) and guided (TM) modes to study in real-time and label-free manner the structure and functioning of living cells on substrate.…”

Rapid and label‐free classification of human glioma cells by infrared spectroscopic imaging

“…However, all these techniques are based on an irreversible treatment of the cells and do not allow sensitive label-free characterization under in situ conditions. Label-free methods were first introduced in biochemical sensor technology (17) and generate increasing interest in cell biology (18). Vibrational spectroscopy, one of the most versatile analytical technique is a new and promising tool for the analysis of cells.…”