Multimodal microscope enables structural and functional cellular imaging (Vol. 50, No. 2)

Answering cell physiology and pharmacology research questions often requires structural and functional information to be obtained from a network of cells. The authors have developed a multi-modal imaging system based on surface plasmon resonance (SPR) that combines several additional imaging modalities including bright-field, epifluorescence, total internal reflection microscopy and SPR fluorescence microscopy. The microscope features a wide field of view that can study ~40 cells simultaneously with subcellular resolution.

SPR is the collective oscillation of free electrons in a metal excited by polarized light. The resonance condition is highly dependent upon the refractive index of the media. Exploiting this allows the detection of both spatial and temporal variations in refractive index (RI) label-free.

In this work the authors describe a detailed design of the microscopy platform including standard tests for characterization of spatial resolution and sensitivity. Using SPR for imaging requires that the cell of interest is closely adhered to the surface. The spatial variation of refractive index was shown to be reasonably homogenous from a cultured neuron. Finally, a prototypical functional imaging experiment is reported where spatiotemporal cellular functions of stem cell-derived cardiomyocytes have been realised by detecting localized contractions.

C. L. Howe, K. F. Webb, S.A. Abayzeed, D. J. Anderson, C. Denning and N. A. Russell, Surface plasmon resonance imaging of excitable cells, J. Phys. D: Appl. Phys. 52, 104001 (2019)
[Abstract]