Details

Autor(en) / Beteiligte

• Singh, Moirangthem Kiran
• Khan, Mohammad Firoz
• Shweta, Him
• Sen, Sobhan

Titel

Probe-location dependent resonance energy transfer at lipid/water interfaces: comparison between the gel- and fluid-phase of lipid bilayerElectronic supplementary information (ESI) available. See DOI: 10.1039/c7cp03108d

Erscheinungsjahr

2017-10

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Despite significant interest in understanding the role of the local dielectric environment and lipid-bilayer fluidity/rigidity in resonance energy transfer between chromophores at lipid/water interfaces, a comprehensive approach to quantify such environmental dependence on energy transfer is missing - primarily because of the scarcity of suitable probes. Here we present the results on multi-chromophoric Förster resonance energy transfer (FRET) from a series of 4-aminophthalimide-based molecules (4AP-C n ; n = 2-10, 12) of different lipophilicity (donors), which reside at different depths across the lipid/water interfaces, to rhodamine-6G (Rh6G; acceptor) molecules that stay in a water-rich region near the lipid headgroups. We apply steady-state and time-resolved fluorescence spectroscopy, and find that multi-chromophoric FRET from the series of 4AP-C n donors to the Rh6G acceptor occurs in a peculiar stepwise fashion at the lipid/water interface of a gel-phase (L β′ ) DPPC (1,2-dipalmitoyl- sn-glycero -3-phosphocholine) bilayer at room temperature. However, the same donor-acceptor pairs show only subtle but continuous donor-depth-dependent FRET at the lipid/water interface of a fluid-phase (L α ) DOPC (1,2-dioleoyl- sn-glycero -3-phosphocholine) bilayer. These features were found to correlate with the lipid-phase dependent local environmental polarity sensed by 4AP-C n donors at the interfaces. Molecular dynamics (MD) simulations, combined with experimental results, show that relative depth (and angle) variation of the 4AP-C n donors and Rh6G acceptor directly controls the FRET efficiencies through fine tuning of the emission and absorption spectra of the donors and acceptor, respectively. The results indicate that the 4AP-C n probes are well-suited as donors for FRET studies, which allow the FRET parameters at lipid/water interfaces of gel- and fluid-phases of lipid-bilayers to be quantified and compared simultaneously. Effect of dielectric environment and lipid fluidity/rigidity in multi-chromophoric FRET from a series of donors to acceptors at lipid/water interfaces are monitored by tailored donor-acceptor pairs.