Integrated optical molecular imaging system for four-dimensional real-time detection in living single cells

A novel, multifunctional optical imaging system was developed by integrating four-dimensional (4D) real-time confocal microscopy (RT-CM), multicolor total internal reflection microscopy (TIRFM), and Nomarski differential interference contrast (DIC) microscopy based on an epifluorescence microscope platform. A microcell incubator was combined with the imaging system for extended, real-time monitoring of living cells. The 4D images were generated by a combination of 3D images and multiple spatial or time images of a specimen, obtained at 10 nm intervals. Optical sectioning was accomplished with a z-motor, which obtained 4D information with sequential layered sections. The integrated imaging system showed excellent detection sensitivity at the single-molecule level and 3D-spatial resolution (20 nm x-y and 10 nm z-axis) without moving the cell sample. This could be a tool for obtaining crucial information needed to develop approaches for characterizing and understanding the dynamics of biomolecules and nanoparticles in individual living cells and molecular interactions at the single-molecule level.