= exp
(−훾2훿2퐺2퐷(Δ − 훿)
(1)
10.1002/chem.201704924
Chemistry - A European Journal
FULL PAPER
laser Doppler micro-electrophoresis, respectively. The liposome
dispersion concentration was kept constant at 0.15 mM and IL
concentrations were chosen to vary below and above their EC50
values. All measurements were conducted at constant
temperature of 20 ˚C using disposable cuvettes and disposable
folded capillary cells for size and zeta potential measurements,
respectively. All samples were measured three times – one run
consisting of a minimum of ten individual measurements and the
error bars were calculated as standard deviations. The ILs were
mixed with liposomes 10–15 minutes before each measurement.
contact angle meter (CAM 200 Optical Contact Angle Meter,
Biolin Scientific, KSV Instruments, Finland) measuring the surface
tension of a drop upon an increasing concentration of the IL
(optical pendant drop method). The method is described in more
detailed in our previous articles.[7b,35]
Acknowledgements
Financial support from the Academy of Finland (project number
266342 SKW) and Magnus Ehrnrooth foundation (project number
4703943) are greatly acknowledged. Harry Ahlgren, Ganesh
Poudel, Jesper Långbacka, and Jean-Paul Heeb are
acknowledged for their assistance with the DSC, DLS, and NMR
measurements.
Differential scanning calorimetry
Microcalorimetry (DSC) measurements were conducted with a
VP-DSC MicroCalorimeter (MicroCal LLC, MA, USA) to
determine the effect of ILs on the main phase transition
temperature (Tm) of DPPC liposomes. A heating rate of 60 ˚C∙h-1
was used within a temperature range from 10 to 60 ˚C.
Multilamellar DPPC liposome dispersions (0.4 mM) with and
without ILs were degassed under vacuum for ca. 5 min prior to
the DSC measurements. The concentrations of the ILs varied
below and above their EC50 values and all samples were diluted
in Milli-Q water. Three heating and three cooling scans were
recorded and the samples were kept at 10 ˚C for 30 min prior to
the heating scans.
Keywords: analytical methods • cytotoxicity • ionic liquids •
liposomes • toxicology
[1]
[2]
[3]
[4]
K. S. Egorova, E. G. Gordeev, V. P. Ananikov, Chem. Rev. 2017, 117,
7132-7189.
M. Amde, J.-F. Liu, L. Pang, Environ. Sci. Technol. 2015, 49, 12611-
12627.
A. A. Toledo Hijo, G. J. Maximo, M. C. Costa, E. A. Batista, A. J. Meirelles,
ACS Sustain. Chem. Eng. 2016, 4, 5347-5369.
Nuclear magnetic resonance spectroscopy
Z. S. Qureshi, K. M. Deshmukh, B. M. Bhanage, Clean Technol. Environ.
Policy 2014, 16, 1487-1513.
1H and PFG NMR measurements were performed on a 500 MHz
Bruker Avance III spectrometer equipped with a 5 mm BBFO
probe with Z-axis gradient. All PFG NMR measurements were
conducted on 1H nuclei with diffusion ordered spectroscopy
(DOSY) using a stimulated echo pulse sequence (longitudinal
eddy delay and bipolar gradient pulses). The gradient strength (G)
of the pulses varied from 2 to 95% of the maximum gradient
strength (0.47 T∙m-1) in 32 steps. The durations of the gradient
pulses (δ, 2 ms), the delay time (Δ, 150 ms), and the temperature
(T, 21 ˚C) were kept constant. The signal attenuation (S) of probe
molecules with gradient strength variation were recorded and
analyzed using Top Spin software to extract the translational
diffusion coefficients (D). When probe molecules are in
unhindered motion, the signal is attenuated with respect to the
signal in the absence of a gradient (S0) as
[5]
[6]
P. Sun, D. W. Armstrong, Anal. Chim. Acta 2010, 661, 1-16.
a) K. S. Egorova, V. P. Ananikov, ChemSusChem 2014, 7, 336-360; b)
T. P. Thuy Pham, C.-W. Cho, Y.-S. Yun, Water Res. 2010, 44, 352-372;
c) D. Zhao, Y. Liao, Z. Zhang, CLEAN–Soil, Air, Water 2007, 35, 42-48;
d) M. Cvjetko Bubalo, K. Radošević, I. Radojčić Redovniković, J.
Halambek, V. Gaurina Srček, Ecotox. Environ. Safe. 2014, 99, 1-12; e)
S. P. Costa, A. M. Azevedo, P. C. Pinto, M. Saraiva, ChemSusChem
2017, 10, 2321-2347.
[7]
[8]
[9]
a) P. Galletti, D. Malferrari, C. Samori, G. Sartor, E. Tagliavini, Colloid
Surf. B-Biointerfaces 2015, 125, 142-150; b) S.-K. Mikkola, A. Robciuc,
J. Lokajová, A. J. Holding, M. Lämmerhofer, I. Kilpeläinen, J. M.
Holopainen, A. W. T. King, S. K. Wiedmer, Environ. Sci. Technol. 2015,
49, 1870-1878; c) A. H. Rantamäki, S.-K. Ruokonen, E. Sklavounos, L.
Kyllönen, A. W. King, S. K. Wiedmer, Sci. Rep. 2017, 7, 1-12; d) K. O.
Evans, Colloid Surf. A-Physicochem. Eng. Asp. 2006, 274, 11-17.
a) N. Gal, D. Malferarri, S. Kolusheva, P. Galletti, E. Tagliavini, R. Jelinek,
Biochim. Biophys. Acta-Biomembr. 2012, 1818, 2967–2974; b) J. Ranke,
A. Muller, U. Bottin-Weber, F. Stock, S. Stolte, J. Arning, R. Stormann,
B. Jastorff, Ecotox. Environ. Safe. 2007, 67, 430-438; c) B. Jing, N. Lan,
J. Qiu, Y. Zhu, J. Phys. Chem. B 2016, 120, 2781-2789; d) M. Galluzzi,
S. W. Zhang, S. Mohamadi, A. Vakurov, A. Podesta, A. Nelson, Langmuir
2013, 29, 6573-6581.
퐼
퐼
0
3
1
where the gyromagnetic ratio (γ) is 42.6 MHz∙T-1 for H nuclei.
Furthermore, the hydrodynamic radius (Rh) of the diffusing
aggregates were estimated from the Stokes-Einstein equation
M. Matzke, J. Arning, J. Ranke, B. Jastorff, S. Stolte, in Handbook of
Green Chemistry, Bremen, Germany, 2010, pp. 233–298.
[10] B. Yoo, J. K. Shah, Y. Zhu, E. J. Maginn, Soft Matter 2014, 8641-8651.
[11] O. Lopez, A. de la Maza, L. Coderch, C. Lopez-Iglesias, E. Wehrli, J. L.
Parra, FEBS Lett. 1998, 426, 314-318.
푘
푇
퐵
퐷 =
(2)
6휋휂푅
ℎ
[12] E. H. Hayakawa, E. Mochizuki, T. Tsuda, K. Akiyoshi, H. Matsuoka, S.
Kuwabata, Plos One 2013, 8, e85467.
where kB is the Boltzmann constant, T is the temperature, and η
[13] S.-K. Ruokonen, C. Sanwald, M. Sundvik, S. Polnick, K. Vyavaharkar, F.
Duša, A. J. Holding, A. W. T. King, I. A. Kilpeläinen, M. Lämmerhofer, P.
Panula, S. K. Wiedmer, Environ. Sci. Technol. 2016, 50, 7116-7125.
is the viscosity.
Critical micelle concentration determinations
The critical micelle concentration (CMC) determinations of
[Ch][Hex] and [N4441][OAc] in water were performed using a
This article is protected by copyright. All rights reserved.