Supporting Information

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1 Electronic Supplementary Material (ESI) for Journal of Materials Chemistry B. This journal is The Royal Society of Chemistry 2015 Supporting Information Macromolecular crowding and hydrophobic effects on Fmocdiphenylalanine hydrogel formation in PEG:water mixtures Md. Musfizur Hassan, a Adam D. Martin, a and Pall Thordarson* a a School of Chemistry, The Australian Centre for Nanomedicine and the ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of New South Wales, Sydney, NSW 2052, Australia. *To whom correspondence should be addressed. p.thordarson@unsw.edu.au Table of Content 1. Experimental Methods S2 2. Rheology of 1% (w/v) of 1 in various PEG:water (50:50%, v/v) mixtures S4 3. Photographs of gels formed from 1% w/v 1 in various PEG:water S7 (50:50%, v/v) mixtures 4. Rheology of various PEG:water (50:50%, v/v) mixtures (without gelator 1) S8 5. Rheological properties of gels formed from 1% w/v 1 in various PEG:water S11 (50:50%, v/v) as a function of viscosity 6. Photographs of gels formed from 1% w/v 1 at various concentration of S12 PEG 400 in water 7. Rheological properties of gels formed from 1% w/v 1 at various concentrations S13 of PEG 400 in water as a function of viscosity PEG 400 in water 8. Thermal stability studies S14 9. Strain sweep of gels from 1 formed in PEG 400:water (50:50%, v/v) S15 vs in pure water with ph switch. 10. Rheology of gels formed from gelator 1 in water added to PEG 400. S Photographs of gels formed from gelator 1 in water added to PEG 400. S High tension (HT) data from circular dichroism (CD) measurements on S18 gels from References S19 S1

2 Synthesis of Fmoc-diphenylalanine 1 1. Experimental Methods Scheme S1. Synthesis of Fmoc-diphenylalanine 1 The synthesis of 1 was adapted from the methods previously reported by König and Rödel 1 and Gagnon et al. 2 A mixture of fluorenylmethyloxycarbonyl-l-phenylalanine-oh (0.732 g, 1.89 mmol) pentafluorophenol (0.352 g, 1.91 mmol) and N,N-dicyclohexylcarbodiimide (0.405 g, 1.96 mmol) were dissolved in ethyl acetate (80 ml) and the mixure was stirred for 24 hours at room temperature under inert conditions. The precipitated dicychlohexyl urea was filtered off, the solvent removed under reduced pressure and the crude white product collected. A clear solution of L-phenylalanine (0.293 g, 1.77 mmol) in water (20 ml) and N,Ndiisopropylethylamine (0.30 ml, 1.7 mmol) was prepared. The solution was added dropwise to the crude product dissolved in acetonitrile (100 ml) and the resulting mixture allowed to stir for 22 hours at room temperature. The acetonitrile was then removed in vacuo until the crude product precipitated out of solution as a white solid. To this suspension, water (100 ml) was S2

3 added to dissolve the impurities and the remaining precipitate filtered. This precipitate was redissolved in acetonitrile (100 ml), followed by the addition of aqueous hydrochloride acid (10 M, 30 ml). The organic solvent was removed slowly in vacuo, giving a white precipitate. This precipitate was washed with aqueous hydrochloric acid (1 M, 2 x 100 ml) followed by water (2 x 100 ml). This product was then lyophilised to give of Fmoc-L-phenylanaline-L-phenylalanine 1 as a white powder (0.760 g, 82%). The characterisation data is in good agreement with assignments based on previously reported synthesis by Adams et al. 3 S3

4 2. Rheology of 1% (w/v) of 1 in various PEG:water (50:50%, v/v) mixtures Figure S1. Storage and loss modulus of 1% (w/v) gels of 1 in ethylene glycol:water (50:50%, v/v) recorded at a strain of 1%. Error bars indicate two times standard deviation of the logaveraged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. Figure S2. Storage and loss modulus of 1% (w/v) gels of 1 in PEG 200:water (50:50%, v/v) recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. S4

5 Figure S3. Storage and loss modulus of 1% (w/v) gels of 1 in PEG 400:water (50:50%, v/v) recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. Figure S4. Storage and loss modulus of 1% (w/v) gels of 1 in PEG 8,000:water (50:50%, v/v) recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. S5

6 Figure S5. Storage and loss modulus of 1% (w/v) gels of 1 in PEG 10,000:water (50:50%, v/v) recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. Figure S6. Storage and loss modulus of 1% (w/v) gels of 1 in PEG 20,000:water (50:50%, v/v) recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. S6

7 3. Photographs of gels formed from 1% w/v 1 in various PEG:water (50:50%, v/v) mixtures Figure S7. Photographs of the inversion test (top to bottom) of gels formed from 1% w/v 1 in various PEG:water (50:50%, v/v) mixtures. From left to right the PEG used is: ethylene glycol, PEG 200, PEG 400, PEG 8,000, PEG 10,000 and PEG 20,000. S7

8 4. Rheology of various PEG:water (50:50%, v/v) mixtures (without gelator 1) Figure S8. Storage and loss modulus of ethylene glycol:water (50:50%, v/v) with no gelator added, recorded at a strain of 1%. Error bars indicate two times standard deviation of the logaveraged mean from repeat experiments (n = 3). Figure S9. Storage and loss modulus of PEG 200:water (50:50%, v/v) with no gelator added, recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3). S8

9 Figure S10. Storage and loss modulus of PEG 400:water (50:50%, v/v) with no gelator added, recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3). Figure S11. Storage and loss modulus of PEG 8,000:water (50:50%, v/v) with no gelator added, recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. S9

10 Figure S12. Storage and loss modulus of PEG 10,000:water (50:50%, v/v) with no gelator added, recorded at a strain of 1%. Error bars indicate two times standard deviation of the logaveraged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. Figure S13. Storage and loss modulus of PEG 20,000:water (50:50%, v/v) with no gelator added, recorded at a strain of 1%. Error bars indicate two times standard deviation of the logaveraged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. S10

11 5. Rheological properties of gels formed from 1% w/v 1 in various PEG:water (50:50%, v/v) as a function of viscosity Figure S14. The rheological data from Fig. 1 in the paper of gels formed from 1 various PEG:water (50:50%, v/v) mixtures plotted as a function of complex viscosity of the various PEG:water (50:50%, v/v) mixtures without the gelator. 4 Blue = G or storage modulus and red = G or loss modulus of the different gels from 1 in various PEG:water (50:50%, v/v) mixtures. Green = G or storage modulus for gels formed in pure water by the ph switch method (Gdl) 5 vs. complex viscosity of pure water with Gdl but no gelator 1. S11

12 6. Photographs of gels formed from 1% w/v 1 at various concentrations of PEG 400 in water Figure S15. Photographs of the inversion test (top to bottom) of gels formed from 1% w/v 1 in various concentrations of PEG 400: water mixtures (v/v). From left to right: 5%, 10%, 20%, 30%, 40%, 50%, 60%, 65%, 70%, 85%, 100% PEG 400 to water (v/v) and gel formed from 1% w/v 1 in pure water by the ph switch method (Gdl). 5 S12

13 7. Rheological properties of gels formed from 1% w/v 1 at various concentrations of PEG 400 in water as a function of viscosity Figure S16. The rheological data from Fig. 2a in the paper of gels formed from 1 at various concentrations of PEG 400 in water (%, v/v) plotted as a function of complex viscosity of solutions from PEG 400 at various concentrations in water (v/v) without the gelator. 4 Blue = G or storage modulus and red = G or loss modulus of the different gels from 1 at various PEG 400 water (v/v) concentrations. Green = G or storage modulus for gels formed in pure water by the ph switch method (Gdl) 5 vs. complex viscosity of pure water with Gdl but no gelator 1. S13

14 8. Thermal stability studies Figure S17. Storage (G ) and loss modulus (G ) of 1% (w/v) 1 in PEG 400:water (50:50%, v/v) recorded at a frequency of 1 Hz and strain of 0.5% as a function of temperature. Error bars indicate two times the log standard deviation from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. S14

15 9. Strain sweep of gels from 1 formed in PEG 400:water (50:50%, v/v) vs in pure water with ph switch. Figure S18. Strain sweep showing storage and loss modulus of 1% (w/v) gels of 1 in PEG 400:water (50:50%, v/v) recorded at a frequency of 1 Hz. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. Figure S19. Strain sweep showing storage and loss modulus of 1% (w/v) gels of 1 formed in pure water with a ph switch (Gdl) 5 recorded at a frequency of 1 Hz. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. S15

16 10. Rheology of gels formed from gelator 1 in water added to PEG 400. Figure S20. Storage and loss modulus of 1% (w/v) gels of 1 formed by dissolving 1 first in basic water, followed by addition of PEG 400 to a final 50:50% (v/v) ratio, recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. Figure S21. Storage and loss modulus of 1% (w/v) gels of 1 formed by dissolving 1 first in basic water, followed by addition of PEG 400 to a final 50:50% (v/v) ratio and then one equivalent of glucono-δ-lactone (ph switch method), 5 recorded at a strain of 1%. Error bars indicate two times standard deviation of the log-averaged mean from repeat experiments (n = 3) but in most cases they are smaller than the symbol markers and not visible. S16

17 11. Photographs of gels formed from gelator 1 in water added to PEG 400. Figure S22. Photographs of the inversion test (top to bottom) of gels formed by dissolving 1 first in basic water, followed by addition of PEG 400 to a final 50:50% (v/v) ratio and then: Left: addition of one equivalent of glucono-δ-lactone (ph switch method) 5 or Right: no glucono-δlactone added. S17

18 12. High tension (HT) data from circular dichroism (CD) measurements on gels from 1. Figure S23. High tension (HT) data corresponding to the circular dichroism (CD) data in Fig. 3b in the paper of 1% (w/v) hydrogel of 1 dispersed in water to achieve a final concentration of 0.13% (w/v). S18

19 13. References 1 B. König and M. Rödela, Synthetic Comm., 1999, 29, P. Gagnon, X. Huang, E. Therrien and J. W. Keillor, Tetrahedron Lett., 2002, 43, D. J. Adams, L. M. Mullen, M. Berta, L. Chen and W. J. Frith, Soft Matter, 2010, 6, G. Pont, L. Chen, D. G. Spiller and D. J. Adams, Soft Matter, 2012, 8, D. J. Adams, M. F. Butler, W. J. Frith, M. Kirkland, L. Mullen and P. Sanderson, Soft Matter, 2009, 5, S19