Self-assembly of photochromic diarylethene-peptide conjugates stabilized by β-sheet formation at the liquid/graphite interface

Article abstract of DOI:10.1039/c9cc02093d

Two-dimensional (2-D) self-assembly of diarylethene (DAE)-peptide conjugates at the octanoic acid/graphite interface was investigated by scanning tunnelling microscopy (STM). The open-ring isomer of a DAE-peptide conjugate formed a stable 2-D molecular assembly with an antiparallel β-sheet structure. Quantitative analysis of surface coverage depending on concentration revealed a stronger stabilization effect of the oligopeptide than that of the alkyl group with a similar side chain length.

Full text of DOI:10.1039/c9cc02093d

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: N. Nishitani, T.
Hirose and K. Matsuda, Chem. Commun., 2019, DOI: 10.1039/C9CC02093D.
This is an Accepted Manuscript, which has been through the
Volume 52 Number
1 4 January 2016 Pages 1–216
Royal Society of Chemistry peer review process and has been
accepted for publication.
ChemComm
Accepted Manuscripts are published online shortly after
Chemical Communications
www.rsc.org/chemcomm
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
author guidelines.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the ethical guidelines, outlined
in our author and reviewer resource centre, still apply. In no
event shall the Royal Society of Chemistry be held responsible
for any errors or omissions in this Accepted Manuscript or any
consequences arising from the use of any information it contains.
ISSN 1359-7345
COMMUNICATION
Marilyn M. Olmstead, Alan L. Balch, Josep M. Poblet, Luis Echegoyenet al.
Reactivity differences of Sc3N@C2n (2n 68 and 80). Synthesis of the
first methanofullerene derivatives of Sc N@D5h-C80
=
3
rsc.li/chemcomm

Please do not adjust margins
ChemComm
Page 1 of 4
View Article Online
DOI: 10.1039/C9CC02093D
Journal Name
COMMUNICATION
Self‐Assembly of Photochromic Diarylethene–Peptide Conjugates
Stabilized by ‐Sheet Formation at the Liquid/Graphite Interface†
Nobuhiko Nishitani,a Takashi Hiroseb and Kenji Matsuda*a
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
Two‐dimensional (2‐D) self‐assembly of diarylethene (DAE)
–
Photochromic compounds are key molecular components of
peptide conjugates at the octanoic acid/graphite interface was photoresponsive 2‐D self‐assemblies that can be utilized as
investigated by scanning tunneling microscopy (STM). The open‐ optoelectronic nanodevices working at the molecular level.23,24
ring isomer of a DAE–peptide conjugate formed a stable 2‐D We have previously reported photochromic diarylethenes
molecular assembly with an antiparallel ‐sheet structure. (DAEs) showing a phototriggered multi‐state ordering trans‐
Quantitative analysis of surface coverage depending on formation at the liquid/graphite interface, where 2‐D ordering
concentrations revealed
a stronger stabilization effect of domains composed of one isomer of DAE were replaced by
oligopeptide than that of alkyl group with similar side chain length. different domains of the other isomer upon light irradiation.25–
29 On the other hand, photoswitching of individual molecules at
Three‐dimensional structure of proteins is closely related to
the sophisticated functions of biomolecules, which originates
from composition and sequence of amino acids.1–3 The motif of
self‐assembly seen in biomolecules has been used to create
the single‐molecule level with keeping the original ordering
domains has not been achieved, likely due to fast exchange of
molecular components; the photoisomerized isomer in a 2‐D
ordering is likely exchanged with the original isomer via
adsorption/desorption dynamics at the liquid/solid interface.
According to the literature, STM observation of the single‐
molecule‐level photoswitching is limited to only self‐assembled
monolayer (SAM) on Au(111) surfaces30,31 and vapor‐deposited
monolayer under ultra‐high vacuum (UHV) conditions,32–34
where exchange of molecular components is restricted. We
envision that slow adsorption/desorption dynamics is a
necessary condition to observe single‐molecule switching at
liquid/solid interfaces with keeping the original 2‐D ordering
domains.
artificial supramolecular systems such as those consisting of
peptide conjugated molecules.4–11
–
Self‐assembly on surface is a powerful approach to
construct functionalized two‐dimensional (2‐D) nano‐
architectures.12–14 Oligopeptides should be a promising building
blocks not only for 3‐D systems but also for 2‐D self‐assemblies.
De Feyter, Meijer, Schenning, and co‐workers reported a
pioneering work on 2‐D self‐assembly of
molecules bearing oligopeptide in 2008, in which the formation
of an antiparallel ‐sheet was clearly visualized by scanning
‐conjugated

tunnelling microscopy (STM) with the single‐molecule
resolution.15 Recently, Wang et al. have reported systematic
studies on conformational dynamics and site‐specific analysis of
Herein, we report the synthesis of DAE–peptide conjugates
and their 2‐D self‐assembly at the liquid/graphite interface
(Figure 1). We found that the DAE–peptide conjugate, having
both oligopeptide and hexadecyl chains, formed a stable 2‐D
amyloid

peptides using STM since 2012.16–22 Direct
visualization of the bioinspired 2‐D self‐assemblies has been
widely investigated using STM, however, the stabilization
energy of 2‐D assemblies by the formation of hydrogen bonding
structures of oligopeptide has not been discussed quantitatively.
molecular assembly, which was stabilized by the antiparallel
sheet structure of oligopeptide moieties. A strong stabilization
effect of the formation of antiparallel ‐sheet on 2‐D self‐
assembly was successfully quantified by the analysis of surface
coverage depending on concentration changes.
‐

open-ring isomer
closed-ring isomer
F
F
F
F
F F
Department of Synthetic Chemistry and Biological Chemistry, Graduate School of
Engineering, Kyoto University, Katsura, Nishikyo‐ku, Kyoto 615‐8510, Japan. E‐
mail: kmatsuda@sbchem.kyoto‐u.ac.jp
Institute for Chemical Research, Kyoto University, Uji, Kyoto 611‐0011, Japan.
† Electronic Supplementary Informaꢀon (ESI) available: Experimental procedures,
additional STM images, and 1H and 13C NMR spectra. See DOI: 10.1039/x0xx00000x
F
F
F
F
F
F
UV
S
S
O
O
O
S
S
O
O
O
H
N
H
N
H
N
H
N
H
N
H
N
R
R
N
H
N
H
NH2
N
H
N
H
NH2
vis.
O
O
O
O
O
O
1o: R = H
2o
1c: R = H
2c
: R = C16H33
: R = C16H33
Figure 1. (a) Chemical Structures and photochromic reaction of DAEs
1
and
2.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1‐3 | 1
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 2 of 4
COMMUNICATION
Journal Name
Diarylethenes 1o and 2o were synthesized using a solid‐
phase peptide synthesis (see the ESI). Glycyl‐alanyl sequence
(Gly‐Ala‐Gly‐Ala‐Gly, GAGAG) is the key repeating motif for the
View Article Online
DOI: 10.1039/C9CC02093D

‐sheet structure in silk fibers,35,36 which was commonly
introduced to 1o and 2o. In addition, a hexadecyl chain was
introduced into 2o to enhance the affinity to the graphite
surface. The GAGAG peptide bearing N‐terminated amine was
prepared by Fmoc solid‐phase synthesis. Solid‐phase coupling
of GAGAG peptide with carboxylic acid derivatives of DAEs, and
subsequent cleavage from the resin provided 1o and 2o in 68%
and 47% yield, respectively. The synthetic details and
characterization using NMR spectroscopy and mass
spectrometry are shown in Supporting Information (ESI).
Figure 2. (a) UV‐vis. spectral change of 2 in octanoic acid upon photoisomerization (c =
40 μM, cell length: 10 mm). (b) CD spectra of 2o in octanoic acid (cell length: 2 mm).
absorption spectra. Considering that CD signal was observed at
320–340 nm where oligopeptide has no absorption,
diarylethene core moiety of 1o and 2o took a chiral
conformation in aggregates induced by the chiral peptide chain.
The manner of 2‐D ordering of 1o and 2o was investigated
by STM at the octanoic acid/highly oriented pyrolytic graphite
(HOPG) interface. Octanoic acid solution of 1o or 2o was
deposited on a freshly cleaved HOPG substrate, and then STM
image was recorded at the liquid/solid interface. No ordering
was observed for 1o at concentrations of 200 μM or less (Figure
S5a). Although 2‐D orderings was detected using saturated
solution of 1o, the detailed structure was unfortunately not
clear (Figure S5b).
Photoisomerization reaction of
1 and 2 was investigated in
octanoic acid by UV‐vis absorption spectroscopy (Figures 2a and
S1). The open‐ring isomers 1o and 2o showed absorption bands
at 336 and 343 nm, respectively. The molar extinction
coefficient (
) was 1.2 × 104 M−1cm−1 at the maximum
absorption wavelength both for 1o and 2o. The magnitude of
absorption spectra was linearly increased with increasing
concentration at concentrations of 40
a negative deviation from linearity at 100
1o and 2o did not form any aggregate at concentrations of 40

M or less, and showed

M, suggesting that

M or less in octanoic acid (Figures S2 and S3).
In contrast, a clear stripe‐patterned ordering of 2o was
recorded at 200 μM (Figure 3a), suggesting that hexadecyl chain
has an important role to stabilize 2‐D ordering at the
liquid/HOPG interface. According to high‐resolution STM
images of 2o, the lattice parameters were determined as a = 5.8
Upon irradiation with UV light (313 nm) to an octanoic acid
solution of 2o, new absorption band appeared at 435 nm,
suggesting the photoisomerization from the open‐ring isomer
2o to the closed‐ring isomer 2c. The original spectrum of 2o was
fully restored by successive irradiation with visible light (> 460
nm), indicating a reversible photoisomerization reaction. The
closed‐ring isomer 2c could not be isolated by HPLC. Instead,
assuming the molar extinction coefficient of 2c is identical to a
± 0.1 nm, b = 0.96 ± 0.02 nm,
 = 87 ± 1°, from which the unit
area occupied by one molecule of 2o on surface was
determined as S = 2.80 ± 0.14 nm2 (Figure 3b). The stripe‐
patterned ordering was well reproduced by the molecular
mechanics/molecular dynamics (MM/MD) calculations,
suggesting that oligopeptide chain of 2o took an antiparallel β‐
sheet structure in the 2‐D ordering, where methyl group of
alanine extended to the liquid phase to avoid collision with the
substrate (Figure 3c). It is noted that DAE core of 2o took a
reference
thienyl)perfluorocyclopentene (
in hexane),37 the conversion ratio of 2c to 2o at the
photostationary state (PSS) was estimated to be around 85% in
octanoic acid.
compound,
i.e.,

1,2‐bis(3,5‐dimethyl‐3‐
= 5.8 × 103 M−1cm−1 at 425 nm
Self‐assembly of 1o and 2o in solution phase was detected
by circular dichromism (CD) spectroscopy (Figures 2b and S4).
photoactive
antiparallel
conformation,
therefore,
photoisomerization reaction from the open‐ to the closed‐ring
isomer is possible in 2‐D self‐assembly. The formation of
1o and 2o showed a negative Cotton effect at 320
100 μM or higher in octanoic acid, whereas no CD signal was
observed for 2o under dilute conditions, i.e., 40 M or less,
which was consistent with concentration dependence of
–340 nm at
antiparallel
‐sheet conformation is consistent with the

previous report by De Feyter et al., in which a similar pattern of
Figure 3. (a) STM images of 2o at the octanoic acid/HOPG interface (ct = 200 μM, Iset = 10 pA, Vbias = −800 mV). (b) High‐resolution STM image of molecular ordering of
2o at the octanoic acid/graphite interface (ct = 200 M, Iset = 40 pA, Vbias = −800 mV) and the molecular model of 2o simulated by MM/MD calculations. (c) Enlarged

image of the molecular model showing the formation of antiparallel
six‐fold hydrogen bond network.

‐sheet conformation composed of GAGAG oligopeptide sequence. Yellow dotted line denotes the
2 | J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 4
ChemComm
Please do not adjust margins
Journal Name
COMMUNICATION
2‐D ordering was observed for a oligo(p‐phenylenevinylene) where Kn and Ke are the nucleation and elongation equilibrium
View Article Online
derivative with GAGAG oligopeptide at the liquid/HOPG constants, respectively, and

is the deDgOrIe: 1e0.1o0f39c/oCo9pCeCr0a2t0iv9i3tDy
interface.15
The stabilization effect of the formation of antiparallel
defined as the ratio of two equilibrium constants (Kn/Ke). By

‐
non‐linear regression analysis using eq 1, optimized adsorption
sheet structure was quantitatively analyzed for the first time in parameters Kn and Ke of 2o were determined as Kn = 60
this study. The surface coverage of 2o depending on the change and Ke = (1.7 0.1) value of 2o
104 M−1, respectively. The
of concentration was observed by STM (Figure 4). The mean was calculated as = (4 4)
10−3 from the two equilibrium

60 M−1






value of surface coverage at a concentration was determined by constants. The Gibbs free energy for adsorption in elongation
15 STM images recorded at different places on HOPG substrate processes (ΔGe) was calculated according to the equation ΔGe =
(Table S1). Note that the surface coverage observed by STM was −RT ln Ke, in which R is the gas constant and T is the temperature.
stable at least during several hours after the sample deposition. The ΔGe value for 2o (−24.1 kJ mol−1) was negatively larger by
As shown in Figure 4b, 2o showed a steep increase of surface 8.6 kJ mol−1 than that of 3o (−15.5 kJ mol−1), suggesting that
coverage with increasing concentration. We noticed that oligopeptide moieties of 2o has a significant stabilization effect
concentration for the 2‐D ordering formation of 2o was similar on the formation of 2‐D self‐assembly compared with that of
to that for the aggregation in solution phase, i.e., ca. 50
octanoic acid according to concentration dependence of CD energy of lateral intermolecular interaction (Emol–mol), which is
spectra (Figure 2b). the sum of van der Waals and hydrogen bond interactions, for
2‐thienyl‐type DAE 3o bearing two of N‐ 2o was negatively larger than that of 3o by 60.6 kJ∙mol−1 (Figure
M in alkyl chain moieties of 3o. According to MM calculations, the
A
tetradecylcarbamoylethyl groups composed of totally 36 non‐ S13 and Tables S2–S5), suggesting that the negatively larger ΔGe
hydrogen atoms (C34N2) in the main chain, was used as a value of 2o than that of 3o is attributed to the large
reference compound.40 The length of side chains of 3o is similar intermolecular interaction of oligopeptide chains in the 2‐D
to that of 2o composed of totally 35 non‐hydrogen atoms molecular ordering.
(C29N6) for the two chains. The critical concentration (ccrit),
defined as the concentration at which surface coverage domains, the domain size tended to be small for compounds
saturates, of 2o (ccrit = 70 M) was significantly smaller than that showing an isodesmic‐type self‐assembly process (i.e., the
of 3o (ccrit = 2000
M), suggesting that the ordering 2o was value is close to 1),38,41 whereas the large domain size was
strongly stabilized by the formation of antiparallel ‐sheet. commonly observed for compounds showing highly
cooperative self‐assembly processes (i.e., << 1) whose domain
sizes were typically larger than the maximum scan size of STM
providing molecular resolution (
500 × 500 nm2).27,38,40,41,43 It is
noted that the domain size of 2o, showing the small value of
10−3, was remarkably small ( 100 × 100 nm2) even when the
surface coverage was not saturated (ct = 50 M, Figure S8). The
According to our previous reports on the size of 2‐D ordering





∼

4

∼

size of 2‐D ordering domains is likely related to the nucleation
process at the liquid/solid interface. The small domain size of 2o
may be attributed to the fast nucleation rate and/or slow
adsorption/desorption dynamics at the liquid/solid interface.
Next, the mixing of the closed‐ring isomer 2c in the 2‐D
domain composed of 2o was examined by STM. UV light (313
nm) was irradiated before the deposition on HOPG substrate to
prepare a mixed solution of 2o/2c (= 60/40) (ct = 200 M). As
shown in Figure 5, the resolution of STM image significantly
decreased compared to that of pure 2o (Figure 3a), and some
Figure 4. (a) Chemical Structure of diarylethene 3o. (b) Concentration dependence
of surface coverages of 2o and 3o at the octanoic acid/graphite interface. The red
and black solid lines denote the best‐fit curves simulated by the
nucleaꢀon−elongaꢀon model. Data points for 3o were taken from ref 40.
The experimental plots of surface coverage were
successfully reproduced by the nucleation–elongation model
for 2‐D self‐assembly at the liquid/solid interface that was
developed by our group.27,28,38–43 According to our model, the
surface coverage () can be described as follows:
ꢁ
ꢃ
ꢃꢋꢌ
ꢄꢅꢆ ꢇꢈ ꢂ ꢉꢀ
ꢎꢏꢐꢑ
ꢁ
ꢃ
ꢀ ꢍ 1 ꢂ ꢀ ∙
, ꢉ ꢍ
ꢁ1ꢃ
ꢊ
ꢁ
1 ꢂ ꢅꢆ ꢇꢈ ꢂ ꢉꢀ
ꢒ ∙ ꢓꢔ ∙ ꢕ
Figure 5. The STM image of a mixture of 2o/2c (60/40) at the octanoic acid/HOPG
interface (ct = 200 μM, Iset = 10 pA, Vbias = −800 mV).
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1‐3 | 3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 4 of 4
COMMUNICATION
Journal Name
14 K. S. Mali, N. Pearce, S. De Feyter, N. R. Champness, Chem. Soc.
parts of DAE core moiety in the 2‐D ordering were found to have
a brighter contrast than the others after UV light irradiation.
However, it is difficult to conclude the generated brighter parts
to be mixed adsorption of 2c or multi‐layer adsorption of 2o
from this experimental result using STM. The further study for
photoisomerization reaction in 2‐D ordering is currently under
investigation in our group.
In conclusion, we reported the solid‐phase peptide synthesis
and self‐assembly behavior of DAE–peptide conjugates at the
liquid/graphite interface. The DAE–peptide conjugate having a
hexadecyl chain formed a stable 2‐D molecular assembly at the
octanoic acid/graphite interface. Oligopeptide moieties formed
View Article Online
Rev. 2017, 46, 2520–2542.
DOI: 10.1039/C9CC02093D
15 R. Matmour, I. De Cat, S. J. George, W. Adriaens, P. Leclère, P.
H. H. Bomans, N. A. J. M. Sommerdijk, J. C. Gielen, P. C. M.
Christianen, J. T. Heldens, J. C. M. van Hest, D. W. P. M. Löwik,
S. De Feyter, E. W. Meijer. A. P. H. J. Schenning, J. Am. Chem.
Soc. 2008, 130, 14576–14583.
16 N. Kalashnyk, J. T. Nielsen, E. H. Nielsen, T. Skrydstrup, D. E.
Otzen, E. Lægsgaard, C. Wang, F. Besenbacher, N. C. Nielsen,
T. R. Linderoth, ACS Nano 2012, 6, 6882−6889.
17 S. A. Claridge, J. C. Thomas, M. A. Silverman, J. J. Schwartz, Y.
Yang, C. Wang, P. S. Weiss, J. Am. Chem. Soc. 2013, 135,
18528−18535.
18 X. Mao, Y. Guo, Y. Luo, L. Niu, L. Liu, X. Ma, H. Wang, Y. Yang,
G. Wei, C. Wang, J. Am. Chem. Soc. 2013, 135, 2181−2187.
an antiparallel ‐sheet structure and DAE core moieties took
19 Y. Yang, C. Wang, Philos. Trans. A Math. Phys. Eng. Sci. 2013
,
photoactive antiparallel conformation at the 2‐D interface.
Quantitative analysis of surface coverage depending on
concentrations revealed that oligopeptides are useful
molecular motifs to construct stable 2‐D molecular orderings,
i.e., the critical concentration for the formation of 2‐D ordering
can be decreased by more than one order of magnitude by
replacing alkyl side chain with GAGAG oligopeptide having a
comparable chain length. The molecular design strategy in this
work will provide a key concept for fabrication of photo‐
functional 2‐D molecular assembly which works at the single‐
molecule level.
This work was supported by JSPS KAKENHI Grant Numbers
JP26107008, JP18K05077, and JP17J10353 from the MEXT,
Japan. N. N. acknowledges the LIMS program from the MEXT,
Japan. We thank Dr. Tomonori Tamura and Prof. Itaru Hamachi
(Graduate School of Engineering, Kyoto University) for
assistance with the solid‐phase peptide synthesis, and Prof.
Michinori Suginome (Graduate School of Engineering, Kyoto
University) for providing a microwave peptide synthesizer.
371: 20120311.
20 L. Liu, L. Niu, M. Xu, Q. Han, H. Duan, M. Dong, F. Besenbacher,
C. Wang, Y. Yang, ACS Nano 2014, 8, 9503−9510.
21 Y. Yu, Y. Yang, C. Wang, Chin. J. Chem. 2015, 33, 24–34.
22 F. Qu, L. Yu, H. Xie, Y. Zheng, J. Xu, Y. Zou, Y. Yang, C. Wang, J.
Phys. Chem. C 2017, 121, 10364−10369.
23 J. L. Zhang, J. Q. Zhong, J. D. Lin, W. P. Hu, K. Wu, G. Q. Xu, A.
T. S. Wee, W. Chen, Chem. Soc. Rev. 2015, 44, 2998–3022.
24 D. Frath, S. Yokoyama, T. Hirose, K. Matsuda, J. Photochem.
Photobiol. C 2017, 34, 29−40.
25 R. Arai, S. Uemura, M. Irie, K. Matsuda, J. Am. Chem. Soc. 2008
,
130, 9371–9379.
26 T. Sakano, Y. Imaizumi, T. Hirose, K. Matsuda, Chem. Lett.
2013, 42, 1537–1539.
27 S. Yokoyama, T. Hirose, K. Matsuda, Chem. Commun. 2014, 50
5964–5966.
28 N. Maeda, T. Hirose, S. Yokoyama, K. Matsuda, J. Phys. Chem.
C
2016, 120, 9317–9325.
29 S. Yokoyama, T. Hirose, K. Matsuda, Langmuir 2015, 31, 6404–
6414.
30 N. Katsonis, T. Kudernac, M. Walko, S. J. van der Molen, B. J.
van Wees, B. L. Feringa, Adv. Mater. 2006, 18, 1397–1400.
31 Arramel, T. C. Pijper, T. Kudernac, N. Katsonis, M. van der
Maas, B. L. Feringa, B. J. van Wees, Nanoscale 2013, 5, 9277–
9282.
32 M. J. Comstock, N. Levy, A. Kirakosian, J. Cho, F. Lauterwasser,
J. H. Harvey, D. A. Strubbe, J. M. J. Fréchet, D. Trauner, S. G.
Louie, M. F. Crommie, Phys. Rev. Lett. 2007, 99, 038301.
33 I. V. Pechenezhskiy, J. Cho, G. D. Nguyen, L. Berbil‐Bautista, B.
L. Giles, D. A. Poulsen, J. M. J. Fréchet, M. F. Crommie, J. Phys.
Chem. C 2012, 116, 1052–1055.
34 H. Böckmann, S. Liu, J. Mielke, S. Gawinkowski, J. Waluk, L.
Grill, M. Wolf, T. Kumagai, Nano Lett. 2016, 16, 1034–1041.
35 K. Okuyama, R. Somashekar, K. Noguchi, S. Ichimura,
Biopolymers 2001, 59, 310–319.
36 O. A. Gus’kova, P. G. Khalatur, P. Bäuerle, A. R. Khokhlov,
Chem. Phys. Lett. 2008, 461, 64–70.
37 K. Uchida, M. Irie, Chem. Lett. 1995, 24, 969–970.
38 N. Nishitani, T. Hirose, K. Matsuda, Chem. Asian J. 2015, 10,
1926–1931.
39 D. Frath, T. Sakano, Y. Imaizumi, S. Yokoyama, T. Hirose, K.
Matsuda, Chem. Eur. J. 2015, 21, 11350–11358.
40 S. Yokoyama, T. Hirose, K. Matsuda, Chem. Eur. J. 2015, 21,
13569–13576.
Conflicts of interest
There are no conflicts to declare.
Notes and references
1
2
3
P. Y. Chou, G. D. Fasman, Biochemistry 1974, 13, 222–245.
C. K. Smith, L. Regan, Science 1995, 270, 980–982.
L. Regan, D. Caballero, M. R. Hinrichsen, A. Virrueta, D. M.
Williams, C. S. O’Hern, Pept. Sci. 2015, 104, 334–350.
Y. Matsuzawa, K. Ueki, M. Yoshida, N. Tamaoki, T. Nakamura,
H. Sakai, M. Abe, Adv. Funct. Mater. 2007, 17, 1507–1514.
A. Jatsch, E.‐K. Schillinger, S. Schmid, P. Bäuerle, J. Mater.
Chem. 2010, 20, 3563–3578.
4
5
6
7
8
S. H. Kim, J. R. Parquette, Nanoscale 2012, 4, 6940–6947.
J. D. Tovar, Acc. Chem. Res. 2013, 46, 1527–1537.
H. A. M. Ardoña, J. D. Tovar, Bioconjugate Chem. 2015, 26,
2290−2302.
N. Kameta, M. Masuda, T. Shimizu, Chem. Eur. J. 2015, 21,
8832–8839.
9
41 N. Nishitani, T. Hirose, K. Matsuda, Langmuir 2017, 33, 9151–
9159.
10 H. Shigemitsu, I. Hamachi, Chem. Asian J. 2015, 10, 2026–2038.
11 M. Rad‐Malekshahi, L. Lempsink, M. Amidi, W. E. Hennink, E.
Mastrobattista, Bioconjugate Chem. 2016, 27, 3−18.
12 J.ꢁ A.ꢁ A. W. Elemans, S. Lei, S. De Feyter, Angew. Chem. Int. Ed.
2009, 48, 7298–7332.
42 N. Maeda, T. Hirose, K. Matsuda, Angew. Chem. Int. Ed. 2017
56, 2371–2375.
,
43 N. Nishitani, T. Hirose, K. Matsuda, Chem. Lett. 2019, 48, 253–
256.
13 D. Bonifazi, S. Mohnani, A. Llanes‐Pallas, Chem. Eur. J. 2009
,
15, 7004–7025.
4 | J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins