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Correlating Membrane Morphological Responses with Micellar Aggregation Behavior of Capric Acid and Monocaprin
journal contribution
posted on 2017-03-06, 00:00 authored by Bo Kyeong Yoon, Joshua A. Jackman, Min Chul Kim, Tun Naw Sut, Nam-Joon ChoThe
interaction of single-chain lipid amphiphiles with phospholipid
membranes is relevant to many scientific fields, including molecular
evolution, medicine, and biofuels. Two widely studied compounds within
this class are the medium-chain saturated fatty acid, capric acid,
and its monoglyceride derivative, monocaprin. To date, most studies
about these compounds have involved in vitro evaluation of their biological
activities, while mechanistic details of how capric acid and monocaprin
interact with phospholipid bilayers remain elusive. Herein, we investigated
the effect of these two compounds on the morphological and fluidic
properties of prefabricated, supported lipid bilayers (SLBs). The
critical micelle concentration (CMC) of each compound was determined
by fluorescence spectroscopy measurements. At or above its CMC, capric
acid induced the formation of elongated tubules protruding from the
SLB, as determined by quartz crystal microbalance-dissipation and
fluorescence microscopy experiments. By contrast, monocaprin induced
the formation of elongated tubules or membrane buds
below and above its CMC, respectively. Fluorescence recovery after
photobleaching (FRAP) experiments indicated that capric acid increased
bilayer fluidity only above its CMC, whereas monocaprin increased
bilayer fluidity both above and below its CMC. We discuss these findings
in the context of the two compounds’ structural properties,
including net charge, molecular length and hydrogen-bonding capacity.
Collectively, the findings demonstrate that capric acid and monocaprin
differentially affect the morphological and fluidic properties of
SLBs, and that the aggregation state of the compounds plays a critical
role in modulating their interactions with phospholipid membranes.
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fluorescence spectroscopy measurementsFRAPsingle-chain lipid amphiphilesMicellar Aggregation Behaviorphospholipid membranescompoundCMCquartz crystal microbalance-dissipationfluidic propertiesfluorescence microscopy experimentsbilayer fluiditycapric acidmonocaprinCorrelating Membrane Morphological ResponsesSLB
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