Studying biophysical barriers to DNA delivery by advanced light microscopy

Advanced light microscopy (ALM) has been intensively employed by biophysicists to reveal cellular mechanisms. As described in this review, ALM clearly has potential to enhance our understanding of the mechanisms that affect macromolecular therapeutics or nanoscopic drug vectors in biological environments. However, while in recent years confocal microscopy and related techniques became rather routinely used in drug delivery it remains challenging to extract reliable information on the biophysical behaviour of drug delivery systems from ALM measurements. This review discusses studies in which confocal imaging, fluorescence recovery after photobleaching (FRAP), fluorescence correlation spectroscopy (FCS) and fluorescence energy transfer were employed to reveal biophysical properties of DNA and DNA containing nanoparticles in extra- and intracellular media.