Photoresponsive self-healing supramolecular hydrogels for light-induced release of DNA and doxorubicin

Article abstract of DOI:10.1039/c5cc09633b

An azobenzene-containing cyclic dipeptide PAP-DKP-Lys is a photoresponsive low-MW hydrogelator. The gelation process can be triggered with temperature, pH, light, and ionic strength. The resulting self-healing gels can encapsulate dsDNA or an anticancer d

Full text of DOI:10.1039/c5cc09633b

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: Z. Pianowski, J.
Karcher and K. Schneider, Chem. Commun., 2016, DOI: 10.1039/C5CC09633B.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
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
Information for Authors.
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 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.
www.rsc.org/chemcomm

Please do not adjust margins
Page 1 of 4
ChemComm
View Article Online
DOI: 10.1039/C5CC09633B
Journal Name
COMMUNICATION
Photoresponsive self-healing supramolecular hydrogels for light-
induced release of DNA and doxorubicin
Zbigniew L. Pianowski,*a,b Johannes Karchera and Knut Schneidera
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
www.rsc.org/
An azobenzene-containing cyclic dipeptide PAP-DKP-Lys is
a
Controlled delivery of therapeutic oligonucleotides, and their
photoresponsive low-MW hydrogelator. The gelation process can protection from premature degradation, are crucial issues for
be triggered with temperature, pH, light, and ionic strength. The successful gene therapy methods. Encapsulation of DNA for
resulting self-healing gels can encapsulate dsDNA or an anticancer gene delivery has been studied using polymeric hydrogels, like
drug doxorubicin, and release them in a light-dependent manner.
collagen, alginate, PEG/PLA systems or engineered silk elastin.
To slow down rapid DNA diffusion typical for such systems,
DNA can be also organized into nanoparticles (by condensing
with cationic peptides, lipids or polymers) encapsulated inside
fibrin or PEG hydrogels.18
In this communication we describe the first, to our knowledge,
supramolecular hydrogel based on LMWG that preferentially
encapsulates oligonucleotides inside its fibrous network and
can efficiently release them upon irradiation. We designed and
Hydrogels are materials used for tissue engineering,1 drug
delivery systems,2 construction of self-healing materials3 and
environmental sensors.4 They contain over 90% of water
absorbed into covalent or supramolecular fibril networks, and
possess the degree of flexibility similar to natural tissues. Low-
molecular weight gelators (LMWGs) are small molecules that
form supramolecular hydrogels stabilised by π-π stacking,
hydrogen bonding, ionic and/or van der Waals interactions.
Particularly privileged scaffolds for LMWG are peptides, ureas
and nucleobases, due to their extensive hydrogen-bonding
networks that promote self-assembly.5 Such gels can react on
triggers like changes of pH, temperature, ion concentrations,5,6
redox potential7 or light.8 Numerous light-responsive hydrogel
systems were designed based on photocaged compounds,9
photoswitches8 and light-activated molecular motors.10
Particularly, the perspective of using light to release bioactive
or therapeutically relevant compounds (e.g. drugs or
oligonucleotides) from hydrogels is very attractive and could
find numerous therapeutic applications.11
synthesized a LMWG
1 containing a molecular photoswitch
and a basic residue that can specifically interact with nucleic
acids. We investigated its gelating properties under variety of
conditions, including the presence of DNA (Fig. 1).
Azobenzenes, diarylethylenes or spiropyrans are common
examples of molecular photoswitches which can reversibly
transform light into molecular motion or polarity changes.
They were used to photomodulate activities and structures of
bioactive compounds,12 biopolymers13,14 and artificial
nanoscale systems.15 They can be added as dopants to hy-
drogels,16 covalently attached to, or partially replacing the
structure of known gelators.8, 17
Figure 1 The supramolecular hydrogel formed from PAP-
DKP-Lys
1 in water (left) becomes liquid upon UV light
a.Institut für Organische Chemie, Karlsruher Institut für Technologie,
Fritz-Haber-Weg 6, D-76131 Karlsruhe, Germany.
irradiation (right). The gel is reconstituted after irradiation
with blue light. Polyacids (e.g. DNA) may additionally stabilize
the fibres.
b.Institut für Toxikologie und Genetik, Karlsruher Institut für Technologie,
Herman-von-Helmholtz Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany.
E-mail: pianowski@kit.edu.
Electronic Supplementary Information (ESI) available: Synthetic procedures, NMR,
LCMS, SEM and rheology characterization of the described compounds and
mixtures. See DOI: 10.1039/x0xx00000x
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
View Article Online
DOI: 10.1039/C5CC09633B
Figure 2 Synthesis and photoisomerization of the supramo-
lecular hydrogelator (PAP-DKP-Lys)
1
The compound
1 can form supramolecular hydrogels alone or
with a variety of dopants like NaCl, acids, or DNA. Some of the
gels exhibit excellent self-healing parameters (thixotropy).
DNA oligomers and an anticancer drug doxorubicin can be
released from hydrogels based on
manner.
1 in the light-dependent
Our goal was to create a light-responsive hydrogel with
specific affinity towards DNA. We hypothesised that the
significant change in molecular geometry and polarity, which is
characteristic for azobenzene photoisomerization, will be
sufficient to strongly destabilise and eventually destroy the gel
structure and cause its transition into sol. The design was
based on known 2,5-diketopiperazine-based gelators19
stabilised by hydrogen bonding provided by the heterocycle
and the π-π stacking of non-polar phenyl rings. Replacing the
phenyl with non-polar and planar trans-azobenzenes retains
this pattern of stabilization. But photoswitching them to polar
and non-planar cis-azobenzenes (Fig. 2, right) would disturb
tight packing of the molecules in fibres and possibly destroy
the long-distant self-assembly.
Figure 3 Scanning electron microscopy (SEM). A-D: SEM
images of xerogels. Gels A-C: 20 g/L of
- in diH2O; gels - in 50 mM aq. NaCl; gels
additionally 2 g/L htDNA; : environmental SEM of the
hydrogel in darkness ( ) and upon UV light irradiation (
1
, gel
D
: 15 g/L of
1
; gels
A
,
C
B,
D
C
and
D:
E-F
D
E
F)
DNA oligomers (htDNA, c.a. 1300 bp long). Hydrogels formed
with htDNA (2 g/L) and 2% (20 g/L) of the gelator in water
1
did not exhibit significantly improved mechanical properties,
however their melting temperatures increased by more than
10 °C (see Table S2) in comparison to the undopped 2% gel
We synthesized the desired molecule
unnatural photochromic aminoacid
Boc-PAP-OH.14 It was
coupled with protected L-lysine and cyclised to the
corresponding 2,5-diketopiperazine Fig. 2, left). The
compound is insoluble in acetonitrile or toluene, and soluble
1 starting from an
2
(20 g/L of
by in 50 mM aqueous NaCl resulted in both elevated melting
temperatures and improved mechanical stability comparing to
hydrogels formed by in water without additives.
1 in diH2O). Addition of htDNA to hydrogels formed
1
(
1
1
in methanol, DMF and DMSO. It is also soluble (upon short
boiling) in hot water to the maximal concentration of 3%. After
After examining various proportions of the components, we
continued detailed characterization with the gel composed of
cooling down, such aqueous solutions (above 1.5% of 1) form
2 g/L htDNA and 15 g/L (1.5%) of
(gel ) due to the most appealing mechanical properties.
The morphology of the gel samples described above was
determined using scanning electron microscopy (SEM) (Fig. 3
also Fig. S6-S9, Supp. Info). We examined xerogels formed by
lyophilization of the hydrogel samples containing only (gel
or and htDNA (gel ) in water, or gels containing the same
ingredients in 50 mM aq. NaCl (gels and , respectively).
Additionally, a diluted sample of was characterized using
1 in 50 mM aqueous NaCl
hydrogels which are however fragile and become liquid after
shaking. Replacing water with 50 mM aqueous NaCl solution
results in striking improvement of mechanical properties and
increased melting temperatures of gels. Similar behaviour is
observed after lowering the pH with trifluoroacetic acid (TFA).
D
,
1
A)
In that case, the minimal concentration of
1 necessary for gel
1
C
formation is 1.0%. Generally, both the presence of salt or acids
improves rigidity of the gels.
B
D
1
In comparison to monoprotic acids, polyacids like DNA should
transmission electron microscopy (TEM) to visualize in details
stabilise structures of gels formed by
1 to even higher extent
its fibrous structure (Fig. S13).
by cooperative effect of multiple salt bridges. To verify that
hypothesis, we used commercially available double-stranded
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
Repeated stress did not lead to the significant material fatigue
View Article Online
DOI: 10.1039/C5CC09633B
destruction + healing
(
Fig. 4 and Fig. S2-S5 of the Supp. Info).
The compound
light for at least 24 hours (see Supp. Info Fig. S14) and can
1
is resistant on photodegradation with UV
20 g/L PAP-DKP-Lys 50 mM NaCl diH O
2
1.00E+06
Storage modulus G'
undergo over 100 full cycles of photoisomerization. (Fig. S15
)
1.00E+05
1.00E+04
1.00E+03
1.00E+02
1.00E+01
1.00E+00
1.00E-01
1.00E-02
without degradation.
Finally, to investigate the potential of hydrogels formed by
for oligonucleotide storage and their light-controlled release
we measured diffusion of htDNA from the gel [2 g/L htDNA
and 15 g/L (1.5%) in 50 mM NaCl] in darkness and upon UV
1
D
1
light irradiation. To have a comparison with guest molecules of
small MW, we also prepared a hydrogel composed of 2 mg/L
doxorubicin (DOX, a common anticancer drug) and 15 mg/L
(1.5%) of
1 in 50 mM NaCl. Both gel samples (1 mL each) were
irradiated with UV light for 30 min. and incubated with 1 mL of
50 mM aq. NaCl changed every 5 minutes. Concentration of
the guest molecule in every fraction was measured afterwards.
The results were compared with guest concentrations in
fractions collected over gel samples without UV irradiation.
As demonstrated on the Fig. 5, diffusion of DOX from the gel in
darkness is at least 3-fold slower than its release under UV
light irradiation. Much more striking difference was observed
in the case of htDNA: in absence of UV light the DNA was
retained inside the gel within the detection limit of our
experimental setup, whereas UV light released most of the
oligonucleotides within 30 minutes (See also Fig. S16).
0
500
1000 1500 2000 2500 3000 3500 4000
Time [s]
Figure 4 Self-healing properties of the gel
50 mM NaCl). The storage modulus is rapidly (< 1 min.)
recovered after 100% deformation.
B (20 g/L of 1 in
The samples of gel
D irradiated with UV light for 30 min.
(365 nm, 20 W) became mechanically very fragile and turned
into liquid upon inversion of the vial or slight shaking. That
observation is in agreement with our hypothesis that the
trans–to-cis photoisomerization should break the long-distant
aromatic stacking between the molecules, then cause the
fibres to dissipate, and ultimately lead to gel dissolution. The
liquid could be stored in darkness at room temperature for
several days without significant changes, which is in
agreement with the reported thermal half-life of the
unsubstituted cis-azobenzene (on the scale of days at room
temperature20). If the same liquid, however, is irradiated for
30 min. with blue light (460 nm, 10 W), the samples gelate
fully in the timescale of a few hours in darkness yielding clear,
homogenous and mechanically stable hydrogels. This time is
apparently needed to initiate fibre formation that ultimately
Photomodulation of cargo release
% release
90
80
70
60
50
40
30
20
10
0
5 min
10 min
15 min
20 min
25 min
30 min
reconstitutes the original gel structure. The sample
D was also
DNA dark
DNA UV
DOX dark
DOX UV
imaged (Fig. 3 E-F, also Fig. S10-S12, Supp. Info) under low-
vacuum (“environmental”) SEM conditions (eSEM). The
observed structures (Fig. 3E, S10) almost entirely disappeared
Figure 5 Photomodulation of the cargo release from hydrogels.
Gel composition: “DNA” 2 g/L htDNA + 15 g/L in 50 mM NaCl,
“DOX” 2 g/L doxorubicin (DOX) + 15 g/L in 50 mM NaCl;
1
(
Fig. 3F, S11) after 30 min. of irradiation with UV light, along
1
with the gel-to-sol transition of the sample. Similar structures
were observed again (Fig. S12) in the samples where the
photoisomerization cycle was completed with blue light and
resulted in regeneration of the rigid gel.
release of the guest molecules upon UV irradiation (DNA UV,
DOX UV) or in darkness (DNA dark, DOX dark), data points in
5 min. intervals.
Mechanical properties of the gels were characterized by
rheological strain sweep and frequency sweep experiments
(Supp. Info, Fig. S2-S5). The storage modulus (G’) and the loss
modulus (G”) differed by one row of magnitude, indicating the
viscoelastic behaviour. The mechanical properties improve
with increasing NaCl concentration (Page S17, Supp. Info).
All the investigated samples revealed self-healing properties
To conclude, prior research on supramolecular hydrogels
formed by LMWG molecules demonstrated that such mate-
rials can quickly respond to numerous physical and chemical
stimuli. In contrary to polymeric materials, light-stimulated
oligonucleotide release from LMWG-based hydrogels was,
however, not reported. By the rational design of cationic
LMWG
1 we were able to prepare photoresponsive gels that
(thixotropy). Samples
mechanical properties (plotted as regeneration of the G’ value)
B and D recovered their initial
tightly bind long dsDNA oligomers inside their fibrous
structures and efficiently release them upon light irradiation.
in the time range below one minute from deformation.
Doxorubicin can be also encapsulated in gels formed by
1 and
Samples
A and C regenerated with slightly slower rates.
released in a light-dependent manner. These results indicate
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
11 Y. Qiu, K. Park, Adv. Drug Delivery Reviews, 2001, 53, 321-
that light can be an effective and selective trigger for releasing
oligonucleotides and other types of bioactive molecules from
LMWG-based hydrogels. Mechanical and physical properties of
View Article Online
339.
12 V. A. Velema, J. P. van der Berg, M. J. Hansen, W. Szymanski,
A. J. M. Driessen, B. L. Feringa, Nature Chem., 2013, , 924-
DOI: 10.1039/C5CC09633B
5
hydrogels formed by
1 can be extensively modified by
928; V. A. Velema, W. Szymanski, B. L. Feringa, J. Am. Chem.
Soc., 2014, 136, 2178−2191; A. Rullo, A. Reiner, A. Reiter, D.
Trauner, E. Y. Isacoff, G. A. Woolley, Chem. Commun., 2014,
50, 14613-14615; M. Stein, S. J. Middendorp, V. Carta,
E. Pejo, D. E. Raines, S. A. Forman, E. Sigel, D. Trauner,
Angew. Chem., Int. Ed., 2012, 51, 10500-10504; I. Tochitsky,
M. R. Banghart, A. Mourot, J. Z. Yao, B. Gaub, R. H. Kramer,
D. Trauner, Nature Chem., 2012, 4, 105-111.
changing concentration of the gelator, as well as the pH and
concentrations of inorganic ions. The latter features indicate
prospective applicability of the material in the area of
environmental sensing. Together with the observed self-
healing behaviour it indicates considerable potential of
compositions based on
1 as smart materials for therapeutic
13 M. Schutt, S. S. Krupka, A. G. Milbradt, S. Deindl, E. K. Sinner,
purposes, particularly for photodynamic therapy based on
release of cytotoxic drugs or therapeutic oligonucleotides. To
consider applications in living organism, further studies will be
performed with the focus on issues like general toxicity of the
gelator, photoswitching with visible light for better tissue
penetration, or tuning the aminoacid residue to the particular
cargo types.
We gratefully acknowledge Prof. Dr. Stefan Bräse and the KIT
Karlsruhe, furthermore Mr. Volker Zibat, Mr. M. Ardakani and
PD Dr. Reinhard Schneider (LEM KIT Karlsruhe) for electron
microscopy imaging, as well as Mr. Lukas Arendt and Prof.
Manfred Wilhelm for their support in rheological
measurements. We also acknowledge the support of Deutsche
Forschungsgemeinschaft (“Graduiertenkolleg” GRK 2039).
D. Oesterhelt, C. Renner, L. Moroder, Chem. Biol., 2003, 10
487–490; O. Babii, S. Afonin, M. Berditsch,S. Reiβer, P. K.
,
Mykhailiuk, V. S. Kubyshkin, T. Steinbrecher, A. S. Ulrich, I. V.
Komarov, Angew. Chem., Int. Ed., 2014, 53(13), 3392-3395; J.
Bredenbeck, J. Helbing, J. R. Kumita, G. A. Woolley, P. A.
Hamm, Proc. Natl. Acad. Sci. U. S. A., 2005, 102, 2379–2384;
F. Zhang, K. A. Timm, K. M. Arndt, G. A. Woolley, Angew.
Chem., Int. Ed., 2010, 49, 3943-3946; H. Cahova, A. Jaeschke,
Angew. Chem., Int. Ed., 2013, 52, 3186-3190; D. Matsunaga,
H. Asanuma, M. Komiyama, J. Am. Chem. Soc., 2004, 126
11452–11453; T. Goldau, K. Murayama, C. Brieke, S.
,
Steinwand, P. Mondal, M. Biswas, I. Burghardt, J. Wachtveitl,
H. Asanuma, A. Heckel, Chem. Eur. J., 2015, 21, 2845-2854;
A. Aemissegger, V. Kräutler, W. F. van Gunsteren, D. Hilvert,
J. Am. Chem. Soc., 2005, 127, 2929–2936; T. Stafforst, D.
Hilvert, Angew. Chem., Int. Ed., 2010, 49, 9998-10001.
14 M. Bose, D. Groff, J. Xie, E. Brustad, P. G. Schultz, J. Am.
Chem. Soc., 2006, 128, 388–389.
15 W. Browne, B. L. Feringa, Nat. Nanotechnol., 2006, 1, 25-35;
Notes and references
R. Klajn, J. F. Stoddart, B. Grzybowski, Chem. Soc. Rev., 2010,
39, 2203–2237; D. Manna, T. Udayabhaskararao, H. Zhao, R.
Klajn, Angew. Chem., Int. Ed., 2015, 54, 12394 –12397; P. K.
Kundu, D. Samanta, R. Leizrowice, B. Margulis, H. Zhao, M.
Börner, T. Udayabhaskararao, D. Manna, R. Klajn, Nature
1
2
3
A. Mellati, S. Dai, J. Bi, B. Jin and H. Zhang, RSC Adv., 2014, 4,
63951-63961; D. E. Discher, P. Janmey and Y. L. Wang,
Science, 2005, 310 (5751), 1139-1143; V. Jayawarna, M. Ali,
T. A. Jowitt, A. E. Miller, A. Saiani, J. E. Gough, R. V. Ulijn, Adv.
Mater., 2006, 18, 611-614.
Chem., 2015,
Dommaschk, S. Grosjean, R. Herges, S. Bräse, C. Wöll, ACS
Nano, 2014, , 1463–1467; Z. Wang, L. Heinke, J. Jelic, M.
7, 646-652; L. Heinke, M. Cakici, M.
R. Ischakov, L. Adler-Abramovich, L. Buzhansky, T. Shekhter
and E. Gazit, Bioorg. Med. Chem., 2013, 21, 3517-3522; A.
Vintiloiu, J. C. Leroux, J. Controlled Release, 2008, 125, 179-
192; D. A. Salick, D. J. Pochan, J. P. Schneider, Adv. Mater.,
2009, 21, 4120-4123.
8
Cakici, M. Dommaschk, R. J. Maurer, H. Oberhofer, S.
Grosjean, R. Herges, S. Bräse, K. Reuter, C. Wöll, Phys. Chem.
Chem. Phys., 2015, 17, 14582-14587.
M. Nakahata, Y. Takashima, H. Yamaguchi, A. Harada, Nat.
16 G.-F. Liu, W. Ji, W.-L. Wang, C. L. Feng, ACS Applied Materials
Commun., 2011, 2, 511-516.
and Interfaces, 2015, 7, 301-307; C. Maity, W. E. Hendriksen,
4
5
G. O. Lloyd, J. W. Steed, Nature Chem., 2009, 1, 437-442.
J. H. van Esch, R. Eelkema, Angew. Chem., Int. Ed., 2015, 54
998-1001.
,
A. J. Kleinsmann, N. M. Weckenmann, B. J. Nachtsheim,
Chem. Eur. J., 2014, 20, 9753-9761.
17 W. A. Velema, M. C. A. Stuart, W. Szymanski, B. L. Feringa,
Chem. Commun., 2013, 49, 5001-5003; X. Li, Y. Gao, Y.
Kuang, B. Xu, Chem. Commun., 2010, 46, 5364–5366; J. T.
6
P. W. J. M. Frederix, G. G. Scott, Y. M. Abul-Haija, D.
Kalafatovic, C. G. Pappas, N. Javid, N. T. Hunt, R. V. Ulijn, T.
Tuttle, Nature Chem., 2014, 7, 30-37; H. Qian, I. Aprahamian,
Chem. Commun., 2015, 51, 11158-11161; S. Fleming, R. V.
Ulijn, Chem. Soc. Rev., 2014, 43, 8150-8177.
van Herpt, M. C. A. Stuart, W. R. Browne, B. L. Feringa, Chem.
Eur. J., 2014, 20, 3077 – 3083.
18 S. Gojgini, T. Tokatlian, T. Segura, Mol. Pharmaceutics, 2011,
7
8
R. Afrasiabi, H.-B. Kraatz, Chem. Eur. J., 2015, 21, 7695-7700.
J. ten Schiphorst, S. Coleman, J. E. Stumpel, A. Ben Azouz, D.
Diamond, A. P. H. J. Schenning, Chem. Mater., 2015, 27
5925-5931; L. Peng, M. You, Q. Yuan, C. Wu, D. Han, Y. Chen,
Z. Zhong, J. Xue, W. Tan, J. Am. Chem. Soc., 2012, 134
8
, 1582-1591; K. W. Chun, J. B. Lee, S. H. Kim, T. G. Park,
Biomaterials, 2005, 26, 3319–3326; D. Trentin, J. Hubbell, H.
Hall, J. Controlled Release, 2005, 102, 263–275.
19 A. J. Kleinsmann, B. J. Nachtsheim, Chem. Commun., 2013,
49, 7818-782.
,
,
12302−12307; J. K. Sahoo, S. K. M. Nalluri, N. Javid, H. Webb,
R. V. Ulijn, Chem. Commun., 2014, 50, 5462-5464.
T. Yoshii, M. Ikeda, I. Hamachi, Angew. Chem., Int. Ed., 2014,
126, 7392-7395; T. Muraoka, C.-Y. Koh, H. Cui, S. I. Stupp,
Angew. Chem., Int. Ed., 2009, 48, 5946–5949; I. Tomatsu, K.
Peng, A. Kros, Advanced Drug Delivery Reviews, 2011, 63
1257-1266.
20 N. Nishimura, T. Sueyoshi, H. Yamanaka, E. Imai, S.
Yamamoto and S. Hasegawa, Bull. Chem. Soc. Jpn., 1976, 49
1381–1387; E. R. Talaty and J. C. Fargo, J. Chem. Soc., 1967,
65–66.
,
9
,
10 Q. Li, G. Fuks, E. Moulin, M. Maaloum, M. Rawiso, I. Kulic, J.
T. Foy and N. Giuseppone, Nature Nanotech., 2015, 10, 161-
165.
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins