Copyright WILEY-VCH Verlag GmbH & Co. KGaA, 69469 Weinheim, Germany, 2007. Supporting Information for Macromol. Rapid Commun., DOI: 10.1002/marc.200700548.
Macromolecular Recognition: Interaction of Cyclodextrins with an Alternating Copolymer of Sodium Maleate and Dodecyl Vinyl Ether
Daisuke Taura, Akihito Hashidzume, and Akira Harada*
Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan Phone/Fax: +81-6-6850-5445 E-mail:
[email protected].
S1
Experimental Details for Additional Measurements
VPO measurements were performed by a Gonotec OSMOMAT070 vapor pressure osmometer equipped two thermistor probes using toluene as a solvent at 60 °C.
GPC
analyses were carried out at 40 °C on a TOSOH CCP & 8010 system equipped with two TOSOH TSKgel MultiporeHXL-M columns connected in series, using THF as eluent at a flow rate of 0.8 mL/min.
TOSOH UV-8010 and TOSOH RI-8012 detectors were used.
The
molecular weights were calibrated by polystyrene standards (TOSOH TSK POLYSTYRENE standard).
Steady-state fluorescence spectra were measured on a Hitachi F-2500
fluorescence spectrophotometer using a 1 cm path length quartz cuvette. Emission spectra were measured with excitation at 333 nm.
The slit widths for both excitation and emission
sides were kept at 2.5 nm during measurement.
For fluorescence measurements, a saturated
solution of pyrene in water containing 11 mM NaHCO3 and 11mM Na2CO3 was used to prepare sample solutions.
Sedimentation equilibrium experiments for micelle-like
aggregates formed from pC12MA were performed using an Optima XL-I type ultracentrifuge (Beckman-Coulter) equipped with a Rayleigh interference optical system and a diode laser operating at 675 nm at 30.0 °C, and analyzed according to the standard procedure. Specific density increments ∂ρ/∂c were measured by an oscillation U-tube densitometer (Anton-Paar, DMS5000).
For sedimentation equilibrium and specific density increment measurements,
an aqueous solution containing 11 mM NaHCO3 and 11mM Na2CO3 was used to prepare sample solutions.
The details of sedimentation equilibrium instrumentation and theory are
described in the literature.[1]
S2
Analysis of the Binding Isotherm by the Zimm-Bragg Model
In the absence of α-CD, pC12MA chains adopt a folded conformation because of self-association of dodecyl (C12) groups to form micelle-like aggregates.[2] On the other hand, when α-CD is added to an aqueous solution of pC12MA to form inclusion complexes with C12 groups in pC12MA, it is likely that the polymer chains become unfolded[3] and that the chain unfolding allows further complexation of α-CD in a cooperative manner.
Thus,
the cooperativity shown in Figure 3 may originate dominantly from an increase in the availability of C12 groups for the complexation of α-CD.
There have been several models
describing cooperative binding.[4,5] Among them, the model proposed by Zimm-Bragg[6] is one of the simplest models.
The Zimm-Bragg model is based on the one-dimensional Ising
model, where the cooperativity originates from attractive interaction between neighboring bound species.
Although the driving force for the cooperativity in the Zimm-Bragg model is
different from that in the present α-CD/pC12MA system, we attempted to fit the Zimm-Bragg model to the data in Figure 3. Using the model proposed by Zimm-Bragg,[6] the concentrations of complexed α-CD, CCD,c, is provided as
1 CCD,c = CCD,sat + 2 2
KuCCD,f −1
(KuCCD,f −1)
2
+ 4KCCD,f
(1)
where K and u are the binding constant and the cooperative parameter, respectively, and CCD,sat and CCD,f are the concentrations of complexed α-CD at saturation and free α-CD, respectively. Figure 3 also includes the best-fitted curve using the Zimm-Bragg model. The fitted curve fairly agrees with the experimental data, suggesting that the complexation of S3
α-CD with pC12MA is phenomenologically similar to other cooperative binding systems with different origins of the cooperativity.[7] From the fitting, the parameters, K and u, were estimated to be 3.8 ± 0.5 M−1 and 21 ± 3, respectively.
The smaller K value may result from
the competition with self-association of C12 groups.
The u value much larger than unity
indicates positive cooperativity in the complexation of α-CD with pC12MA.
References
[1] H. Fujita, "Foundations of Ultracentrifugal Analysis", Chemical Analysis, Wiley-Interscience, New York, 1975, Vol. 42. [2] T. Kawata, A. Hashidzume, T. Sato, Macromolecules 2007, 40, 1174. [3] B. J. Ravoo, J.-C. Jacquier, Macromolecules 2002, 35, 6412. [4] K. Shirahama, "The Nature of Polymer-Surfactant Interactions", in: Polymer-Surfactant Systems, J. C. T. Kwak, Ed., Surfactant Science Series, Marcel Dekker, New York, 1998; Vol. 77, pp 143. [5] P. Linse, L. Piculell, P. Hansson, "Models of Polymer-Surfactant Complexation", in: Polymer-Surfactant Systems, J. C. T. Kwak, Ed., Surfactant Science Series, Marcel Dekker, New York, 1998; Vol. 77, pp 193. [6] B. H. Zimm, J. K. Bragg, J. Chem. Phys. 1959, 31, 526. [7] For example: [7a] I. Satake, J. T. Yang, Biopolymers 1976, 15, 2263; [7b] K. Hayakawa, J. C. T. Kwak, J. Phys. Chem. 1982, 86, 386; [7c] S. Kosmella, J. Koetz, K. Shirahama, J. Liu, J. Phys. Chem. B 1998, 102, 645.
S4
Figure S1. Fluorescence spectrum (a) for pyrene solubilized in 0.41 g/L pC12MA aqueous solution (1.1 mM C12 groups) containing 11 mM NaHCO3 and 11 mM Na2CO3 and apparent molecular weight as a function of concentration (b) for pC12MA aqueous solution containing 11 mM NaHCO3 and 11 mM Na2CO3.
S5
Figure S2. 2D NOESY spectra for pC12MA (1.1 mM in C12 unit) in the presence of 40 mM α-CD (a), 15 mM β-CD (b), and 40 mM γ-CD (c) measured in D2O containing 11 mM NaHCO3 and 11 mM Na2CO3 at 30 °C.
S6
Figure S3. PGSE NMR data of pC12MA in the absence (a) and presence (b) of 40 mM α-CD measured in D2O containing 11 mM NaHCO3 and 11 mM Na2CO3 at 30 °C.
S7
