Imaging live cell membranes via surface plasmon-enhanced fluorescence and phase microscopy.

This paper demonstrates the first combination for wide-field surface plasmon (SP) phase microscopy and SP-enhanced fluorescence microscopy to image living cells' contacts on the surface of a bio-substrate simultaneously. The phase microscopy with a phase-shift interferometry and common-path optical setup can provide high-sensitivity phase information in long-term stability. Simultaneously, the fluorescence microscopy with the enhancement of a local electromagnetic field can supply bright fluorescent images. The combined microscope imposes a high numerical aperture objective upon the excitation of surface plasmon through a silver film with a thickness of 30 nm. The developed SP microscope is successfully applied to the real-time bright observation of the transfected fluorescence of living cells localized near the cell membrane on the bio-substrate and the high-sensitivity phase image of the cell-substrate contacts at the same time.