Abstract

Franz Proust66322*

Although the experimental attempts to measure a single molecule/particle, i.e., an individual molecule/ particle, in dilute liquids or live cells without immobilization on a surface or hydrodynamic flow at room temperature or under physiological conditions have failed so far, this failure spurred the theory on Brownian molecular motion based on the stochastic nature of diffusion. This new physical theory for the quantifying the thermodynamic jitter of molecules/particles is inspiring for many and forms the theoretical basis of single-molecule biophysics and biochemistry, which underlies the stochastic nature of diffusion. Theoretical considerations for analyzing mobility data are summarized. Measuring the individual molecule or the individual particle is considered among the most challenging trends of research in spectroscopy, microscopy and nanoscopy.