Concise Article
MedChemComm
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tapping mode with 15 mm z-scale size. All images were obtained
with a scan speed of 0.5 Hz and a resolution of 1024 ꢄ 1024
pixels. The height, width, and 3D-toplogical information was
acquired and processed with JPKSPM data-processing
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Amphiphile–membrane interactions
Membrane vesicles with the desired lipid ratios were prepared
as described previously.26 Changes in the surface hydration of
vesicles were studied aer incubation of the vesicles with 10
weight percent of facial amphiphiles at 25 ꢃC for 4 h. We
recorded the generalized polarization of Laurdan in a 96-well
plate in a Molecular Devices M5 instrument. Fluorescence of
Laurdan was recorded using an excitation wavelength of 350
nm and emission wavelengths of 440 nm and 490 nm. The
generalized polarization (GP) was calculated using the equa-
tion GP ¼ (I440 ꢂ I490)/(I440 + I490). Similarly, we measured
changes in steady-state anisotropy of DPH in a 96-well plate
using lex at 350 nm and lem of 45ꢃ2 nm aer incubation of these
vesicles with amphiphiles at 25 C in a Molecular Devices M5
instrument.
Acknowledgements
AB conceived the idea. AB and RS designed the experiments.
MS, PB, AS synthesized the amphiphile molecules. SB per-
formed all the experiments with E. coli and S. aureus. SB, SK, RS
performed experiments with mycobacteria. MS performed the
Laurdan and DPH-based experiments with model membranes.
VS performed AFM experiments. SB, MS, VS, RS, and AB
analyzed the data. AB and RS wrote the manuscript. AB and RS
supervised the overall research. The authors thank RCB,
THSTI, DST and DBT for funding. SB thanks DBT for a
Research Fellowship. VS thanks RCB for a Research Fellowship.
RS and AB thank DBT and DST for their Ramalingaswamy and
Ramanujan Fellowships, respectively. The authors are grateful
to Prof. Anil K. Tyagi, Delhi University, for access to BSL3
facility.
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