TY - JOUR
T1 - Probe-location dependent resonance energy transfer at lipid/water interfaces
T2 - Comparison between the gel- and fluid-phase of lipid bilayer
AU - Singh, Moirangthem Kiran
AU - Khan, Mohammad Firoz
AU - Shweta, Him
AU - Sen, Sobhan
N1 - Funding Information:
This work was supported by the Department of Science and Technology (DST-PURSE) and JNU-UPE-II (project id 75). TCSPC data were collected at AIRF, JNU. We thank Dr Pritam Mukhopadhyay, SPS, JNU for helpful discussion on the synthesis of the fluorescent probes and use of the fluorometer. M. K. S. and M. F. K. thank CSIR and DBT-BUILDER (no. BT/PR5006/INF/153/2012), and H. S. thanks UGC for fellowships. We thank NVIDIA (India) for freely providing a GPU-card (Tesla-K20) to conduct academic research.
Publisher Copyright:
© the Owner Societies 2017.
PY - 2017
Y1 - 2017
N2 - 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-Cn; 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-Cn donors to the Rh6G acceptor occurs in a peculiar stepwise fashion at the lipid/water interface of a gel-phase (Lβ′) 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 (Lα) 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-Cn donors at the interfaces. Molecular dynamics (MD) simulations, combined with experimental results, show that relative depth (and angle) variation of the 4AP-Cn 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-Cn 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.
AB - 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-Cn; 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-Cn donors to the Rh6G acceptor occurs in a peculiar stepwise fashion at the lipid/water interface of a gel-phase (Lβ′) 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 (Lα) 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-Cn donors at the interfaces. Molecular dynamics (MD) simulations, combined with experimental results, show that relative depth (and angle) variation of the 4AP-Cn 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-Cn 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.
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U2 - 10.1039/c7cp03108d
DO - 10.1039/c7cp03108d
M3 - Article
C2 - 28726898
AN - SCOPUS:85030695560
SN - 1463-9076
VL - 19
SP - 25870
EP - 25885
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 38
ER -