Nanoparticle interaction with biological membranes: Does nanotechnology present a janus face?

Polycationic organic nanoparticles are shown to disrupt model biological membranes and living cell membranes at nanomolar concentrations. The degree of disruption is shown to be related to nanoparticle size and charge, as well as to the phase-fluid, liquid crystalline, or gel-of the biological membrane. Disruption events on model membranes have been directly imaged using scanning probe microsopy, whereas disruption events on living cells have been analyzed using cytosolic enzyme leakage assays, dye diffusion assays, and fluorescence microscopy.