Supporting Information for,
Modulation of Anionic Reverse Micellar Interface with
Non-ionic Surfactants can Regulate Enzyme Activity
within the Micellar Waterpool
Arindam Das, Animesh Parta and Rajib Kumar Mitra*
Department of Chemical Biological and Macromolecular Sciences
S.N. Bose National Centre for Basic Sciences
Block JD, Sector III, Salt Lake, Kolkata 700098, INDIA
* e-mail: rajib@bose.res.in
Calculation of aggregation number: The aggregation number (Nagg), i.e., the
number of surfactant molecules per reverse micelle is defined as (Langmuir 2010,
26(13), 10524-10531)
rDLS  3

3N agg  VH2O,total
 Vsurf ,hphile   lhphobe


4  nsurf ,micelle

Where rDLS is hydrodynamic radius of the reverse micelle, 
(S1)
d hydrodynamic
2
; d hydrodynamic
is measured from DLS experiment.
VH 2O ,total is total volume of water in the system as for W0=10 RM, volume of water
added in the 2ml solution is 0.072 ml.
nsurf ,micelle is no. of surfactant molecules in all reverse micelle i.e. total no. of
surfactant molecules in 2ml solution of 0.2M concentration is
N av * 2*0.2
, N av is
1000
Avogadro number.
Vsurf ,hphile
is volume of the hydrophilic part of the surfactant which is calculated
from [J. Phys. Chem. 1984, 88, 1243-1248]. For XBrij = 0.1system, Vsurf ,hphile is
calculated from this equation
Vsurf ,hphile  x1VAOT  x2VBrij
(S2)
Where x1 is 0.9 and x2 is 0.1. VAOT is head group volume of AOT (0.65 nm3,
obtained from [Proc. Indian National Sci. Acad. 62, 1996, 215-232].
VBrij , hphile
is calculated from [Phys. Chem. Chem. Phys., 1999, 1, 3321-3329],
where molar volume of single PEO group i.e. CH2CH2O is given and we multiply
it by no. of PEO group of different Brij molecules and then molar volume of OH
is added.
lhphobe
is length of hydrophobic tail of the surfactant. As here AOT concentration
is higher at XBrij = 0.1, so, we use only the hydrophobic tail length of AOT which
is 1.257 nm [obtained from Proc. Indian National Sci. Acad. 62, 1996, 215-232].
Figure S1. Normalised scattering profiles at a fixed w0=10 of RM systems AOT (red), XB-30 =
0.1(green), XB-35 = 0.1 (dark cyan), XB-52 = 0.1 (dark green), XB-58 = 0.1 (blue), XB-92 = 0.1
(wine) and XB-97 = 0.1 (purple).
Figure S2 Aggregation number of RMs at different water content (w0). The inset shows the
aggregation number of the mixed RMs as a function of the HLB of the added Brij. The dotted
line is the aggregation number of the AOT/IPM RM system.
Table S 1. Maximum solubilization capacity (w0,max) and solvation dynamics parameters for
ANS probe in AOT and different mixed RM systems at different w0.
w0
λemmax (nm)
τ1 (a1)
(ns)
τ2 (a2)
(ns)
< τs>
(ns)
AOT (w0,max ~ 24)
5
10
15
470
472
474
0.17 (0.48)
0.19 (0.63)
0.20 (0.71)
XBj30 = 0.1 (w0,max ~ 29)
1.59 (0.52)
1.16 (0.37)
1.33 (0.29)
0.90
0.55
0.52
5
10
15
473
477
479
0.19 (0.48)
0.17 (0.57)
0.17 (0.68)
XBj35 = 0.1 (w0,max ~ 23)
1.59 (0.52)
1.20 (0.43)
1.11 (0.37)
0.92
0.61
0.52
5
10
15
478
485
487
0.21 (0.47)
0.19 (0.53)
0.16 (0.58)
XBj52 = 0.1 (w0,max ~ 29)
1.70 (0.53)
1.38 (0.47)
1.10 (0.42)
1.0
0.75
0.55
5
10
15
477
480
483
0.21 (0.59)
0.21 (0.69)
0.24 (0.77)
XBj58 = 0.1 (w0,max ~ 23)
1.95 (0.41)
1.37 (0.31)
1.24 (0.23)
0.92
0.57
0.47
5
10
15
478
484
486
0.21 (0.49)
0.19 (0.54)
0.18 (0.58)
XBj92 = 0.1 (w0,max ~ 30)
1.71 (0.51)
1.32 (0.46)
1.10 (0.42)
0.98
0.71
0.57
5
10
15
477
479
483
0.18 (0.48)
0.16 (0.53)
0.14 (0.58)
XBj97 = 0.1 (w0,max ~ 28)
1.53 (0.52)
1.02 (0.47)
0.90 (0.42)
0.88
0.56
0.46
5
10
15
478
481
486
0.18 (0.40)
0.18 (0.56)
0.16 (0.58)
1.58 (0.60)
1.26 (0.44)
1.05 (0.42)
0.98
0.66
0.53