Molecular Imaging

Optical microscopes such as confocal microscopes can be used to analyze molecular interactions in living samples in real-time. Due to the limitations given by the resolution of light molecular imaging techniques mostly rely on indirect measurements. For example, fluorescent molecules can transmit energy if they are brought into close proximity (fluorescence resonance energy transfer or FRET) and the efficiency of this process is correlated to the distance between molecules. The fluorescence emission pattern in small excited volumes can be  used to measure the concentration of fluorescent molecules or their interaction with other molecules (fluorescence correlation spectroscopy or FCS).