Observation of the in-vivo Reporter of Green Fluorescent Protein in a Plant Root by Scanning Near-Field Optical Microscopy

An in vivo reporter of green-fluorescent protein (GFP) in a living plant root has been imaged by scanning near-field optical microscope (SNOM) in the transmission mode. The exciting light is 488 nm wavelength of the argon ion laser and the bandpass filters (514±10) nm is put into the detecting optical pathway. The results indicate that in the living plant cells, the GFPs gather together and form an area of 2-4μm, rather than being individually distributed. The transmission coefficient of the eigenfunction is incorporated into Bethe's theoretical model modified by Grober, and the near-field excited light intensity along the fibre probe axis (z-axis) in the air medium and biological medium is calculated. Based on that, along the z-axis direction of the GFP detected in the sample, numerous GFPs locate near the epidermal cells wall (in the range of 0-38 nm) in the living root. The experiments show that SNOM has an advantage of optical nanometer-scale resolution along the z-axis.