Mechanisms of membrane potential sensing with second-harmonic generation microscopy.
We characterize the transmembrane voltage response of a novel second-harmonic generation (SHG) marker using a screening protocol with giant unilamellar vesicles. Two mechanisms are found to contribute to the voltage response: (1) an electro-optic-induced alteration of the molecular hyperpolarizability and (2) an electric-field-induced alteration of the degree of molecular alignment. We quantify the relative weights and of these contributions and provide an upper limit to their response time, which is found to be submillisecond. The identification of two voltage response mechanisms leads to new strategies for the molecular design of membrane potential markers.
Pons
Thomas
T
ESPCI, INSERM EPI 0002, CNRS FRE 2500, Neurophysiologie et Nouvelles Microscopies, Paris, France.
Moreaux
Laurent
L
Mongin
Oliver
O
Blanchard-Desce
Mireille
M
Mertz
Jerome
J
D002462:Cell Membrane / Q000502:physiology / Q000528:radiation effects; D004558:Electric Stimulation; D005240:Feasibility Studies; D005456:Fluorescent Dyes / Q000737:chemistry* / Q000528:radiation effects*; D008051:Lipid Bilayers / Q000737:chemistry* / Q000528:radiation effects; D008081:Liposomes / Q000737:chemistry* / Q000528:radiation effects; D008564:Membrane Potentials; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D010713:Phosphatidylcholines / Q000737:chemistry*
D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; C017251:1,2-oleoylphosphatidylcholine