the DHP emission intensity drastically decreased. These
results indicate that most DHP molecules were incorporated
from the solution into the coagulated SWNT/Cur-pNIPAM
complex. The fluorescence intensity of the collected solid was
extremely weak, wherein energy transfer from DHP to SWNT
could occur.
KAKWNHI (20111011). This work was supported by
Kyushu-area Nanotechnology Network Project of the MEXT.
Notes and references
1 (a) Y.-L. Zhao and J. F. Stoddart, Acc. Chem. Res., 2009, 42, 1161;
(b) B. K. Gorityala, J. Ma, X. Wang, P. Chen and X.-W. Liu,
Chem. Soc. Rev., 2010, 39, 2925; (c) J. M. Schnorr and
T. M. Swager, Chem. Mater., 2011, 23, 646.
The incorporation phenomenon was further examined
by using pNIPAM itself. As shown in Fig. S4 and S5,w the
UV/Vis/NIR absorption and the fluorescence spectra changed
reversibly and DHP was totally separated from the solution
through centrifugation at 40 1C because of incorporation into
the coagulated pNIPAM. However, the fluorescence intensity
of DHP became quite strong at 40 1C owing to the hydro-
phobic environment of the coagulated pNIPAM.16 This fact
supports a view that energy transfer from DHP to SWNT
occurs in the coagulated mixture of DHP and SWNT/
Cur-pNIPAM complex, where DHP exists in the energy
transfer range from the central SWNT.
2 (a) E. Miyako, H. Nagata, K. Hirano and T. Hirotsu, Angew. Chem.,
Int. Ed., 2008, 47, 3610; (b) P. W. Barone, S. Baik, D. A. Heller and
M. S. Strano, Nat. Mater., 2005, 4, 86; (c) S. Banerjee,
T. Hemraj-Benny and S. S. Wong, Adv. Mater., 2005, 17, 17.
3 M. Numata and S. Shinkai, Chem. Commun., 2011, 47, 1961.
4 M. Numata, M. Asai, K. Kaneko, A.-H. Bae, T. Hasegawa,
K. Sakurai and S. Shinkai, J. Am. Chem. Soc., 2005, 127, 5875.
5 (a) M. Ikeda, T. Hasegawa, M. Numata, K. Sugikawa, K. Sakurai,
M. Fujiki and S. Shinkai, J. Am. Chem. Soc., 2007, 129, 3979;
(b) M. Numata, K. Sugikawa, K. Kaneko and S. Shinkai,
Chem.–Eur. J., 2008, 14, 2398; (c) K. Sugikawa, M. Numata,
K. Kaneko, K. Sada and S. Shinkai, Langmuir, 2008, 24, 13270;
(d) K. Sugikawa, M. Numata, D. Kinoshita, K. Kaneko, K. Sada,
A. Asano, S. Seki and S. Shinkai, Org. Biomol. Chem., 2011, 9, 146.
6 T. Shiraki, A. Dawn, Y. Tsuchiya and S. Shinkai, J. Am. Chem.
Soc., 2010, 132, 13928.
As DHP itself has no absorption band at the NIR region,
NIR laser irradiation induced similar coagulation in the
DHP and SWNT/Cur-pNIPAM mixture (Fig. S6w). At the
irradiated spot, the fluorescence of DHP was quenched
according to the same mechanism occurring in the thermo-
induced coagulation phase of the SWNT/Cur-pNIPAM
complex and DHP mixture. Toshima et al. reported that
porphyrins bearing hydroxyphenyl groups (including DHP)
decompose proteins upon UV or visible light irradiation,
where reactive oxygen species (ROS) are generated by
photo-excitation of porphyrin and O2.17 In addition, porphyrins
including Foscan (meta-tetra(hydroxyphenyl) chlorine) and
Photofrin (hematoporphyrin derivatives) are practically
employed for PDT.14 In our system, the photo-excited DHP
can emit the fluorescence light but it can be quenched by
temperature control or by NIR laser irradiation in the
presence of SWNT/Cur-pNIPAM complex. This method,
therefore, is expected to develop a novel site selective PDT
technique18 by dual light irradiation using visible and NIR
light sources; for example, a non-disease site close to a disease
site can be protected by irradiating with NIR laser through
SWNT quenching and only the disease site was selectively
decomposed by visible light irradiation.
7 (a) C. H. Alarcon, S. Pennadam and C. Alxander, Chem. Soc. Rev.,
´
2005, 34, 276; (b) M. M. Caruso, D. A. Davis, Q. Shen,
S. A. Odom, N. R. Sottos, S. R. White and J. S. Moore, Chem.
Rev., 2009, 109, 5755; (c) M. A. C. Stuart, W. T. S. Huck,
J. Genzer, M. Muller, C. Ober, M. Stamm, G. B. Sukhorukov,
¨
I. Szleifer, V. V. Tsukruk, M. Urban, F. Winnik, S. Zauscher,
I. Luzinov and S. Minko, Nat. Mater., 2010, 9, 101.
8 J. Xu, J. Ye and S. Liu, Macromolecules, 2007, 40, 9103.
9 (a) T. Tanaka, H. Jin, Y. Miyata, S. Fujii, H. Suga, Y. Naitoh,
T. Minari, T. Miyadera, K. Tsukagoshi and H. Kataura, Nano
Lett., 2009, 9, 1497; (b) H. Cathcart, V. Nicolosi, J. M. Hughes,
W. J. Blau, J. M. Kelly, S. J. Quinn and J. N. Coleman, J. Am.
Chem. Soc., 2008, 130, 12734; (c) S. Niyogi, M. A. Hamon, H. Hu,
B. Zhao, P. Bhowmik, R. Sen, M. E. Itkis and R. C. Haddon, Acc.
Chem. Res., 2002, 35, 1105.
10 (a) D. Wang and L. Chen, Nano Lett., 2007, 7, 1480; (b) K. C. Etika,
F. D. Jochum, M. A. Cox, P. Schattling, P. Theato and
J. C. Grunlan, Macromol. Rapid Commun., 2010, 31, 1368.
11 This Cur-pNIPAM is able to solubilize SWNT even into organic
solvents. When the solutions (including the aqueous solution) are
cast, the fine films are obtained. These characteristic properties will
be discussed more in detail elsewhere.
12 For recent reviews: (a) A. K. Andriola Silva Brun-Graeppi,
C. Richard, M. Bessodes, D. Scherman and O.-W. Merten, Prog.
Polym. Sci., 2010, 35, 1311; (b) S. Rimmer, I. Soutar and
L. Swanson, Polym. Int., 2009, 58, 273.
13 (a) N. W. S. Kam, M. O’Connell, J. A. Wisdom and H. Dai, Proc.
Natl. Acad. Sci. U. S. A., 2005, 102, 11600; (b) T. Fujigaya,
T. Morimoto, Y. Niidome and N. Nakashima, Adv. Mater., 2008,
20, 3610; (c) Y. Shen, A. G. Skirtach, T. Seki, S. Yagai, H. Li,
In conclusion, we have succeeded in fabricating a thermo-
responsive SWNT wrapped with Cur-pNIPAM that showed
the reversible heat-induced coagulation in water by temperature
or by NIR laser irradiation. The references reporting the
combination of SWNT and pNIPAM are still limited because
of their weak interaction.10 On the other hand, SWNT/
Cur-pNIPAM complex was stable and could be applied to a
catch-and-release system of a porphyrin, which is expected to
be applicable to novel PDT control techniques. Therefore,
we believe that modified Curs that possess broad wrapping
abilities and designable side chains would become universal
compounds to develop novel smart materials such as sensors,
opto-electronic devices and drug delivery systems.
H. Mohwald and T. Nakanishi, J. Am. Chem. Soc., 2010, 132, 8566.
¨
14 (a) J. F. Lovell, T. W. B. Liu, J. Chen and G. Zheng, Chem. Rev.,
2010, 110, 2839; (b) R. R. Allison, G. H. Downie, R. Cuenca,
X.-H. Hu, C. J. H. Childs and C. H. Sibata, Photodiagn. Photodyn.
Ther., 2004, 1, 27.
15 (a) G. De Luca, A. Romeo and L. M. Scolaro, J. Phys. Chem. B,
2006, 110, 14135; (b) G. De Luca, G. Pollicino, A. Romeo,
S. Patane and L. M. Scolaro, Chem. Mater., 2006, 18, 5429.
16 (a) Y. Shiraishi, R. Miyamoto and T. Hirai, Langmuir, 2008, 24,
4273; (b) S. Uchiyama, Y. Matsumura, A. P. de Silva and K. Iwai,
Anal. Chem., 2003, 75, 5926; (c) H. G. Schild, Prog. Polym. Sci.,
1992, 17, 163.
17 S. Tanimoto, S. Matsumura and K. Toshima, Chem. Commun.,
2008, 3678.
18 (a) S. Ozlem and E. U. Akkaya, J. Am. Chem. Soc., 2009, 131, 48;
(b) Y. Koide, Y. Urano, A. Yatsushige, K. Hanaoka, T. Terai and
T. Nagano, J. Am. Chem. Soc., 2009, 131, 6058.
We thank Prof. S. Yamada (Kyushu University) and Prof.
H. Yonemura (Kyushu University) for the use of Surelite-I.
This work was financially supported by the MEXT, Japan;
c
This journal is The Royal Society of Chemistry 2011
Chem. Commun., 2011, 47, 7065–7067 7067