J Surfact Deterg (2015) 18:1081–1088
1087
Compared with the homologue surfactants investigated
above, 2-ODTAB showed stronger ability to form vesicles
similar carbon atom number. The delicate molecular
structure of 2-ODTAB endows the surfactant with pro-
nounced self-assembly properties and reveals the impor-
tance of the linkage region that connects the polar head
groups with the hydrophobic segments in a surfactant.
These design principles can be applied rationally to syn-
thesize surfactants with novel aggregation properties.
(
Fig. 4a). Vesicles with diameters of 100–200 nm were
observed by cryogenic TEM at 3 mM (Fig. 6d), which is
just above its cac. Although the 10–10 has a cac close to
that of 2-ODTAB, vesicles were observed at 6 mM, a much
higher concentration than its corresponding cac. Consid-
ering that the number of carbon atoms in the hydrophobic
chain of 10–10 is larger than that of 2-ODTAB, it is
obvious that 2-ODTAB has a stronger ability to form
vesicles. This fact demonstrates the superiority of the
Acknowledgments Support from the National Natural Science
Foundation of China (31300486) and the Fundamental Research
Funds for the Central Universities (JUSRP1017) are gratefully
acknowledged. We would like to thank the Center for Biological
imaging (CBI), Institute of Biophysics, Chinese Academy of Science
for our cryogenic TEM images.
2
-ODTAB molecular structure in vesicle formation.
Because the two alkyl tails in 2-ODTAB are connected by
only one carbon atom to the ionic head group, there is more
freedom for the head groups. Both the alkyl tails and head
groups in 2-ODTAB can adopt configurations by suit-
able rotation or extension in vesicle bilayers, which
accounts for the stability of vesicular aggregates.
References
1
. Dreiss CA (2007) Wormlike micelles: where do we stand? Recent
developments, linear rheology and scattering techniques. Soft
Matter 3:956–970
The 2-ODTAB solutions were further investigated with
cryogenic TEM. Although DLS gave rather narrow size
distribution signals of aggregates, rich vesicular morpholo-
gies were observed. In a 2-ODTAB solution of 3 mM
2
. Peresypkin AV, Menger FM (1999) Zwitterionic geminis.
Coacervate formation from a single organic compound. Org Lett
1
:1347–1350
(
Fig. 6d), vesicles with various diameters between 10 nm
3
4
. Gradzielski M (2008) Recent developments in the characterisation
of microemulsions. Curr Opin Colloid Interface Sci 13:263–269
. Jouyban A, Panahi-Azar V, Fakhree MA et al (2014) Solubi-
lization of clonazepam, diazepam and lamotrigine using ethanol
and sodium dodecyl sulfate. J Solut Chem 43:1997–2009
. Al-Hadabi BA, Aoudia M (2014) Surfactant–surfactant and sur-
factant–solute interactions in SLES–Brij35 mixed micelles: effect
of the degree of ethoxylation on pyrene solubilization enhance-
ment in water. Colloids Surf A 459:82–89
. Tian S, Long J, He S (2015) Reversible solubilization of typical
polycyclic aromatic hydrocarbons (PAH) by a gas switchable
surfactant. J Surfactants Deterg 18:1–7
. Garcia-Perez A, da Silva MA, Eriksson J et al (2014) Remarkable
viscoelasticity in mixtures of cyclodextrins and nonionic surfac-
tants. Langmuir 30:11552–11562
and nearly 300 nm all coexisted. Vesicle fusion phe-
nomenon [32] was observed by chance (indicated by the
arrow in Fig. 6e), where a small vesicle is swallowed by a
large vesicle nearby to form a larger one. This is perhaps one
of the pathways for the vesicle growth. With increasing
surfactant concentration, DLS shows an increase in aggre-
gate size. Larger vesicles with diameters of even 600 nm
were present in 10 mM solution (Fig. 6f). Another phe-
nomenon called vesicle fission [33] was also observed
5
6
7
8
9
(
indicated by the arrow in Fig. 6f). These data illustrate that
although with only 18 carbon atoms in the hydrophobic
chain, the double-tailed surfactant 2-ODTAB has the ability
to form stable vesicles of different sizes at low concentra-
tions as in other traditional vesicular solutions.
. Bhattacharya S, Haldar S (1995) Synthesis, thermotropic behavior,
and permeability properties of vesicular membranes composed of
cationic mixed-chain surfactants. Langmuir 11:4748–4757
. Bhattacharya S, Haldar S (1996) The effects of cholesterol
inclusion on the vesicular membranes of cationic lipids. Biochim
Biophys Acta Biomembr 1283:21–30
Conclusions
10. Bhattacharya S, De S (1999) Synthesis and vesicle formation
from dimeric pseudoglyceryl lipids with (CH spacers: pro-
2 m
)
nounced m-value dependence of thermal properties, vesicle
fusion, and cholesterol complexation. Chem Eur J 5:2335–2347
1. Israelachvili JN, Mitchell DJ, Ninham BW (1976) Theory of self-
assembly of hydrocarbon amphiphiles into micelles and bilayers.
J Chem Soc Faraday Trans 2(72):1525–1568
2. Patra T, Ghosh S, Dey J (2014) Cationic vesicles of a carnitine-
derived single-tailed surfactant: physicochemical characterization
and evaluation of in vitro gene transfection efficiency. J Colloid
Interface Sci 436:138–145
3. Guo X, Yu F, Ran X et al (2014) Vesicle formation between single-
chained cationic surfactant and plasmid DNA and its application in
cell transfection. Colloid Polym Sci 292:3103–3111
4. Jang J, Ha H (2002) Fabrication of hollow polystyrene nano-
spheres in microemulsion polymerization using triblock copoly-
mers. Langmuir 18:5613–5618
The solution properties of a newly synthesized double-
tailed surfactant 2-ODTAB with a protrudent head group
were investigated. The properties of the traditional double-
tailed homologue surfactants in which two tails are directly
connected to the ionic head group were also explored for
comparison. All surfactants investigated formed vesicles
above certain concentrations expect 8–8, which forms
loosely packed large aggregates which then transform into
small micelles with increasing concentration. Because of
the head group peculiarity, 2-ODTAB forms more
stable aggregates at low concentration compared with the
traditional double-tailed surfactant 10–10 containing
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