In situ sensitive fluorescence imaging of neurons cultured on a plasmonic dish using fluorescence microscopy.

A plasmonic dish was fabricated as a novel cell-culture dish for in situ sensitive imaging applications, in which the cover glass of a glass-bottomed dish was replaced by a grating substrate coated with a film of silver. Neuronal cells were successfully cultured over a period of more than 2 weeks in the plasmonic dish. The fluorescence images of their cells including dendrites were simply observed in situ using a conventional fluorescence microscope. The fluorescence from neuronal cells growing along the dish surface was enhanced using the surface plasmon resonance field. Under an epi-fluorescence microscope and employing a donut-type pinhole, the fluorescence intensity of the neuron dendrites was found to be enhanced efficiently by an order of magnitude compared with that using a conventional glass-bottomed dish. In a transmitted-light fluorescence microscope, the surface-selective fluorescence image of a fine dendrite growing along the dish surface was observed; therefore, the spatial resolution was improved compared with the epi-fluorescence image of the identical dendrite.