Supporting Information

Non-leaching antimicrobial surfaces through polydopamine

bio-inspired coating of quaternary ammonium salts or an

ultrashort antimicrobial lipopeptide

Tal Shalev,a Anna Gopin,a Michael Bauer,b Robert W. Starkb,c,d and Shai

Rahimipour*a

a Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel. E-mail:

rahimis@biu.ac.il b Center for Nanoscience CeNS, Ludwig-Maximilians-Universität Mu !nchen, Mu !nchen 80799,

Germany; c Department of Materials and Geosciences, Technische Universität Darmstadt,

Darmstadt 64287, Germany; d Center of Smart Interfaces, Technische Universität Darmstadt,

Darmstadt 64287, Germany

Electronic Supplementary Material (ESI) for Journal of Materials ChemistryThis journal is © The Royal Society of Chemistry 2012

Peptides Synthesis

Coupling was carried out in N-methyl-2-pyrrolidone (NMP), and 2-(1H-benzotriazol-1-

yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HBTU) was used as the coupling

agent. Peptides were labeled with 4-nitrobenzo-1,2,5-oxadiazole (NBD) as a fluorescent

probe, by reacting the N-terminal of the anchored peptides with NBD-Cl. The peptides

were cleaved from the resin and deprotected by a mixture of trifluoroacetic acid (TFA) :

triisopropylsilane (TIS) : H2O (95 : 2.5 : 2.5), while peptides containing a cysteine

residue were de-protected and cleaved from the resin by a TFA : TIS : H2O :

ethanedithiol (94 : 2.5 : 1 : 2.5) solution and purified to homogeneity by RP-HPLC. The

pure peptides were analyzed by mass spectrometry using a MALDI-TOF/TOF or ESI

mass spectrometer.

Synthesis of fluorescent probes (1, 2). The probes were synthesized on Rink amide

resin. For the synthesis of the probe 1, Fmoc-Cys(Trt)-OH and Fmoc-11-amino-

undecanoic acid were sequentially coupled to the resin by the HBTU/DIPEA method.

Following the deprotection of the last Fmoc group, 4-chloro-7-nitrobenzofurazan (NBD-

Cl, 2 eq. in 2 ml DMF) and DIPEA (4 eq.) were added to the resin and the mixture was

shaked for 24 h at 37ºC. The crude peptide was cleaved from the resin and purified by

HPLC. MS(ESI): m/z calcd for: C20H30N6O5S [MH]+: 466; found 466, 489 [M+Na]+.

For the preparation of probe 2, Fmoc-Lys(Boc)-OH was coupled to the Rink amide resin

by the HBTU/DIPEA method. Fmoc-14-amino-5-oxo-3,9,12-trioxa-6-azatetradecan-1-

oic acid was then coupled twice to the resin followed by introduction of a NBD group to

the terminal amine. The crude peptide was then analyzed and purified to homogeneity by

preparative HPLC. MS: m/z calcd for: C32H53N10O14 [M+ H]+: 801.4; found: 801, 823

[M+Na]+.

Synthesis of quaternary ammonium salts (3, 4). Fmoc-Cys(Trt)-OH (in case of 3) or Fmoc-Lys(Boc)-OH (in case of 4) were attached to the Rink amine resin followed by

the coupling of Fmoc-11-aminoundecanoic acid, using the HBTU/DIPEA method. Next,

4-(Dimethylamino) butyric Acid (1eq. in 2 mL DMF) was coupled to the terminal amine,

using the mixture of HOBT\DIC\DMAP (1.1:1.1:0.1) and DIPEA (4 eq.) at 37°C for 3

Electronic Supplementary Material (ESI) for Journal of Materials ChemistryThis journal is © The Royal Society of Chemistry 2012

hours. One-bromodecane (4 eq. in DMF) and DIPEA (4 eq.) were then added to the resin

and mixed for 96 hours. The crude peptides were cleaved and purified as detailed above. 1H-NMR 3: (300 MHz, CDCl3) δ(ppm) 0.87 (t, 3H, J=6.5, H-C1), 1.39-1.22 (bs, 28H, H-

C2, H-C3, H-C4, H-C5, H-C6, H-C7, H-C8, H-C20, H-C21, H-C22, H-C23, H-C24, H-

C25), 1.42 (bs, 2H, H-C26), 1.66 (bs, 2H, H-C9), 2.29-2.1 (m, 4H, H-C14, H-C27), 2.43

(t, 2H, J=7.45 Hz, H-C15), 3.05 (s, 6H, H-C11, H-C12), 3.4-3.17 (m, 8H, H-C10, H-C13,

H-C18, H-C33), 4.78 (dd, 1H, J=12.22Hz, J=5.88Hz, H-C30), 7.15 (bs, 2H, H-N32), 7.94

(bs, 2H, H-N17, H-N27) 13C-NMR 3: (500 MHz, DMSO-d6) δ(ppm) 13.93 (C1), 22.08 (C2), 26.45 (C33), 31.27

(C3), 51.68 (C11, C12), 55.74 (C30), 170.33 (C28), 172.04 (C16), 172.38 (C31).

HR-MS (MALDI-TOF-TOF) 3: m/z calcd for: C30H61N4O3S, [M+ H]+: 557.446; found:

557.4459;

1H-NMR 4: (300MHz,CDCl3), δ(ppm) 0.87 (t, 3H, J=6.5, H-C1), 1.39-1.22 (bs, 28H, H-

C2, H-C3, H-C4, H-C5, H-C6, H-C7, H-C8, H-C20, H-C21, H-C22, H-C23, H-C24, H-

25), 1.42 (m, 4H, H-C26, H-C35), 1.66 (bs, 4H, H-C9, H-C33), 2.08 (p, 2H, H-C14,

J=7.82Hz), 2.43 (t, 2H, H-C15, J=7.45), 2.68 (m, 2H, H-C36), 3.04 (s, 6H, H-C11,H-

C12), 3.4-3.17 (m, 6H, H-C10, H-C13, H-C18), 4.47 (dd, 1H, H-C30, J=11.97 Hz,

J=4.93 Hz), 5.28 (d, 2H, H-C37, J=0.33 Hz), 7.15 (bs, 2H, H-N32), 7.94 (bs, 2H, H-N17,

H-N27).

HR-MS (MALDI-TOF-TOF) 4: m/z calcd for: C33H68N5O3, [M+ H]+: 582.531; found:

582.5317.

 

Electronic Supplementary Material (ESI) for Journal of Materials ChemistryThis journal is © The Royal Society of Chemistry 2012

 

Fig. S1 A possible mechanism of dopamine oxidation to reactive polydopamine

 

 

 

 

 

Fig. S2 Surface analysis of PDA fabricated glass surface by AFM. (A) Glass slides were

partially dip-coated in dopamine solution for overnight and then studied by AFM. 3D

analysis of the surface is represented in (B).

Electronic Supplementary Material (ESI) for Journal of Materials ChemistryThis journal is © The Royal Society of Chemistry 2012

Fig. S3 Representative photographs of the S. aureus colonies grown on PDA-coated

polyolefin and polystyrene slides (control slides) or those grown on PDA surfaces

fabricated with AMP 6. PDA-coated polyolefin or polystyrene slides were fabricated with

6 and then sprayed with an aqueous suspension of S. aureus cells (≈106 cells per ml of

distilled water). The slides were dried and incubated under 1.5% agar in a bacterial

growth medium at 37°C for overnight.

Fig. S4 The lack of bacterial growth around the PDA-coated surfaces fabricated with

AMP 6 indicates that the AMP does not leach to the close environment.

Electronic Supplementary Material (ESI) for Journal of Materials ChemistryThis journal is © The Royal Society of Chemistry 2012