Monitoring of NBD-probes and their location in lipid membranes via their triplet state parameters
(English)Manuscript (preprint) (Other academic)
By a combination of fluorescence correlation spectroscopy (FCS) and transient state (TRAST)imaging, the triplet state kinetics of the membrane fluorophore 7-nitrobenz-2-oxa-1,3-diazole-4-yl(NBD) was studied in small unilamellar vesicles (SUVs). It was shown that spin-labels, included inSUV membranes together with the NBD-labeled lipids, induce prominent effects on the triplet statekinetics of NBD. The relative effects on the triplet state kinetics are considerably larger than thoseobserved in traditional fluorescence quenching studies, and can provide information about thelocalization and the interactions between the lipids in the SUVs, using considerably lowerconcentrations of spin-labeled lipids in the membranes. From the effects of the spin labels on thetriplet state kinetics of NBD, we revisited the folding behavior of NBD-labeled phospholipid chains inthe membranes. Our results indicate that the NBD probe on the acyl chain of the phospholipids do notunambiguously loop back towards the membrane surface, as previously reported, but may alternatebetween a straight and a folded acyl chain, with the NBD label at the surface, or deep into themembrane bilayer. Our study suggests that the triplet state parameters of NBD can provide anadditional set of orthogonal parameters, which can increase accuracy and precision of fluorescencebasedmolecular dynamics and interaction studies with NDB as a probe molecule.
FCS, TRAST, lipid membrane, NBD
IdentifiersURN: urn:nbn:se:kth:diva-187739OAI: oai:DiVA.org:kth-187739DiVA: diva2:931464
QC 201605272016-05-272016-05-272016-05-27Bibliographically approved