Article in Polymer Chemistry · June 2011 DOI: 10.1039/C0PY00422G CITATIONS 8 READS 48 5 authors, including:
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1
SUPPLEMENTARY INFORMATION FOR
Arginine-specific protein modification using
α-oxo-aldehyde functional polymers prepared by
atom transfer radical polymerization
Marc A. Gauthier,1,2 Maxime Ayer,2 Justyna Kowal,1 Frederik R. Wurm1 and Harm-Anton
Klok1,*
1 École Polytechnique Fédérale de Lausanne (EPFL), Institut des Matériaux and Institut des
Sciences et Ingénierie Chimiques, Laboratoire des Polymères, Bâtiment MXD, Station 12, CH-1015 Lausanne, Switzerland.
2 Swiss Federal Institute of Technology Zürich (ETHZ), Department of Chemistry and
Applied Biosciences, Institute of Pharmaceutical Sciences, Drug Formulation & Delivery, Wolfgang-Pauli Str. 10, HCl J 396.4, 8093 Zürich, Switzerland.
* Author to whom correspondence should be addressed. Email: harm-anton.klok@epfl.ch
(H.-A.K.)
E-mail addresses of other authors: marc.gauthier@pharma.ethz.ch, ayerm@student.ethz.ch, justyna.kowal@unibas.ch, frederik.wurm@epfl.ch
2
Synthesis of 3-bromo-1,1-dimethoxypropan-2-one (15). 15 was prepared following a
modified procedure from De Kimpe et al.1 by bromination of 2 (3.14 g, 15.7 mmol) in a 100
mL round-bottom flask containing 2.62 g N-bromosuccinimide (2.62 g, 14.7 mmol) in 50 mL
CCl4. The solution was deoxygenated by bubbling with nitrogen for 15 minutes then stirred
under inert atmosphere for 24 h at room temperature. Solids were removed by filtration through a sand plug and 5 g strong-acid ion-exchange resin (Amberlyte IR-120) added to the filtrate, which was then agitated for 30 minutes. The resin was removed by filtration and solvent removed in vacuo. 15 was recovered as a single fraction by distillation (100–130 ºC / 10 mbar) to yield 2.20 g (71 %) of a colorless liquid, which was stored at –30 ºC until used.
Scheme S1. Synthesis of functional ATRP initiators from methylglyoxal 1,1-dimethylacetal.
Reaction conditions: (i) cyclohexylamine, CaCl2, 45 ºC; (ii) N-bromosuccinimide, CCl4; (iii)
3 e h g c D2O (5) (15) (3) a i, j, k m l p o u, v, w y z x ac ab t q s 5 4 3 2 1 ad ah ae ag (2) Chemical Shift (ppm) (1) Compound f e g c a b h d m j i k p l o n (5) (15) (3) (2) (1) Compound y z v u w ac x ab aa q t s r 200 180 160 140 120 100 80 60 40 20 0 ad ae ah ag af Chemical Shift (ppm)
Figure S1. Assigned 1H and 13C NMR spectra of compounds 1-5, and 15. All spectra
recorded in CDCl3 except for 1 in D2O. Note that letter-based assignments in Figure S1 are
4 0 2 4 6 8 10 12 14 16 18 20 22 24 0 1 2 3 0 2 4 6 8 10 12 14 16 18 20 22 24 0 1 2 3 HMTETA 0 2 4 6 8 10 12 14 16 18 20 22 24 0 1 2 3 4 4,4'-dimethyl 2,2'-bipyridine ln(M 0 /M t ) ln(M 0 /M t ) Time (hours) 2,2'-bipyridine 0 2 4 6 8 10 12 14 16 18 20 22 24 0 1 2 3 PMDETA Time (hours)
Figure S2. Semi-logarithmic kinetic plots for the polymerization of MMA using 15 as
initiator in toluene at 90 ºC ([M]:[I]:[Cu]:[L] = 100:1:1:2) using HMTETA, PMDETA, 2,2’-bipyridine or 4,4’-dimethyl 2,2’-2,2’-bipyridine as ligands. Same procedure used as for polymerization of MMA using 5 (see main manuscript). Each colored line represents a different attempt at polymerization under exactly the same conditions. This Figure demonstrates substantial irreproducibility. Increasing initiator concentration by a factor of 2 or 5 did not significantly improve results.
5 20 40 60 80 100 0 10 20 30 M n (k Da ) Conversion (%) 0 50 100 150 200 0 1 2 3 4 ln(M 0 /M t ) Time (min) 1.0 1.1 1.2 1.3 M w /M n
Figure S3. Polymerization of PEGMA with [M0]:[I] ratios of 50 (circles), and 30 (triangles)
in anisole at 60 ºC. (Top) Evolution of experimental Mn,SEC (filled symbols) and Mw/Mn
versus conversion in comparison to theoretical values (open symbols). (Bottom)
Semi-logarithmic kinetic plots of monomer conversion. Kinetic plot determined by 1H NMR
6 0 20 40 60 80 5 10 15 20 25 M n (k Da ) Conversion (%) 0 50 100 150 200 250 0.0 0.5 1.0 ln(M 0 /M t ) Time (min) 1.0 1.1 1.2 M w /M n
Figure S4. Polymerization of DMAEMA with [M0]:[I] ratios of 300 (squares), 250 (circles)
and 200 (triangles) in anisole at 30 ºC. (Top) Evolution of experimental Mn,SEC (filled
symbols) and Mw/Mn versus conversion in comparison to theoretical values (open symbols).
(Bottom) Semi-logarithmic kinetic plots of monomer conversion. Kinetic plot determined by
1H NMR spectroscopy in CDCl
7 40 60 80 100 0 5 10 15 20 M n (k g. mo l -1 ) Conversion (%) 0 50 100 150 0 1 2 3 4 ln(M 0 /M t ) Time (min) 1.00 1.25 1.50 M w /M n
Figure S5. Polymerization of tBuMA with [M0]:[I] ratios of 100 (squares), 50 (circles) and 33
(triangles) in toluene at 75 ºC. (Top) Evolution of experimental Mn,SEC (filled symbols) and
Mw/Mn versus conversion in comparison to theoretical values (open symbols). (Bottom)
Semi-logarithmic kinetic plots of monomer conversion. Kinetic plot determined by 1H NMR
8 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 d c b Chemical Shift (ppm) a HMTETA
Figure S6. 1H NMR spectrum of polymerization medium (toluene, CuBr, HMTETA and 5) without monomer left to react at 75 ºC for 3 h to evaluate possible routes of initiator deactivation. The principal route of deactivation of 5 appears to be proton abstraction from solvent or monomer following activation of 5 to a radical species by Cu(I). This process results in the formation of 1,1-dimetoxybutan-2-one. Assignment based on chemical shift, integration, and multiplicity considerations. Peak assignments in Scheme S2.
Scheme S2. 1,1-dimethoxybutan-2-one. Note that letter-based assignments in Figure S6
correspond uniquely to those found in Scheme S2 and are not consistent with those of the rest of the document.
9 20 40 60 80 100 5 10 15 20 25 30 M n (k Da ) Conversion (%) 0 50 100 150 200 0 1 2 ln(M 0 /M t ) Time (min) 1.0 1.5 2.0 2.5 PDI
Figure S7. Polymerization of DMEAMA with [M0]:[I] ratios of 50 (squares), 100 (circles)
and 150 (triangles) under conditions given in the main manuscript for the preparation of 7.
(Top) Evolution of experimental Mn and Mw/Mn (filled symbols) versus conversion in
comparison to theoretical values (open symbols). (Bottom) Semi-logarithmic kinetic plots of
monomer conversion. Polymers with [M0]:[I] ratios of 100 and below had relatively broad
10 d,f e a h b * H2O acetone d6 * g c 10 9 8 7 6 5 Polymer 10 n * H2O CDCl3 o c d,f e h g * Polymer 6 4 3 2 1 0 Chemical Shift (ppm)
Figure S8. 1H NMR spectrum of 6 (top, Mn,NMR 32,8 kDa) and its corresponding deprotected
polymer 10 (bottom) produced by I2-mediated transacetalization. Peaks assigned using
11 acetone-d6 f e k j H2O,c a i b 5 4 3 2 1 Polymer 7 + I2 (2 h at 90 ºC) k j c a r i,q b,p Chemical Shift (ppm) Polymer 7 + I2 (at time zero)
acetone-d6
f e
Figure S9. 1H NMR spectra of 7 (top, Mn,NMR 14.6 kDa) in acetone containing 3 molar eq. I2
(relative to polymer end-group) and the reaction mixture obtained following incubation at 90 ºC for 2 h (bottom). The bottom spectrum shows that the acetal remains intact and peaks caused by the halogenation of the amines appear. These peaks are assigned based on chemical shift and integration considerations (i.e., peak r integrates for 18H because 3 molar eq. of amines are halogenated). Peak assignments in Scheme S3.
Scheme S3. Deprotection of PDMAEMA (7) via I2-mediated transacetalization leading to the
halogenated polymer, for which a simplified structure is given. The actual structure of the modified polymer involves coordination of two dimethylamino groups to one iodide anion (to
give a net positive charge), with I3– as negative counterion.2 Note that letter-based
assignments in Figure S9 correspond uniquely to those found in Scheme S3 and are not consistent with those of the rest of the document.
12 c f l e a acetone-d6 acetone-d6 b v w u 10 9 8 7 6 5 4 3 2 1 0 Polymer 8 + I2 (after 24 h) a * Purified partially deprotected polymer
Chemical Shift (ppm) * D2O e,s l f,t Polymer 8 + I2 (at time zero)
Figure S10. 1H NMR spectra of 8 (top, Mn,NMR 8,8 kDa) in acetone containing 3 molar eq. I2
(relative to polymer end-group) and the reaction mixture obtained following incubation at room temperature for 24 h (middle). The latter spectra shows the formation of tert-butanol and 2-methyl 1,2-propene in the supernatant above the polymer. After the 24 h incubation period, precipitation was observed. The water-soluble fraction of precipitated polymer was
dissolved in H2O, purified by size-exclusion chromatography, isolated by freeze-drying and a
1H NMR spectrum taken in D
2O (bottom). This spectrum shows residual tert-butyl ester
groups (peak g, 1.48 ppm) as well as an intact acetal end-group (a, 3.49 ppm). The star
denotes Et2O contaminant. Peak assignments are given in Scheme S4.
Scheme S4. Deprotection of PtBuMA (8) via I2-mediated transacetalization. Note that
letter-based assignments in Figure S10 correspond uniquely to those found in Scheme S4 and are not consistent with those of the rest of the document.
13
16 18 20 22 24
6
10 (via TFA deprotection) 10 (via I2 deprotection) A B C D 12 14 16 18 7
11 (via TFA deprotection)
12 14 16 18
8
12 (via TFA deprotection)
*
10 12 14 16 18
Retention volume (mL)
9
13 (via I2 deprotection)
Figure S11. SEC chromatograms of polymers 6-13 showing no significant perturbation of
molecular weight distribution following deprotection. (A) SEC chromatograms of 6 (Mn
18,400 ; Mw/Mn 1.20), 10 (via TFA deprotection, Mn 16,900 ; Mw/Mn 1.27), and 10 (via I2
deprotection, Mn 18,900 ; Mw/Mn 1.22) recorded in DMF ; (B) SEC chromatograms of 7 (Mn
15,800 ; Mw/Mn 1.16) and 11 (via TFA deprotection, Mn 14,200 ; Mw/Mn 1.23) recorded in
THF + 5 % Et3N ; (C) SEC chromatogram of 8 (Mn 15,300 ; Mw/Mn 1.28) recorded in THF
and 12 (via TFA deprotection, Mn 17,600, Mw/Mn 1.24) recorded in 10 mM NaHPO4 (pH
7.4). The red star marks the solvent elution peak ; (D) SEC chromatograms of 9 (Mn 6,400 ;
Mw/Mn 1.27) and 13 (via I2 deprotection, Mn 6,300 ; Mw/Mn 1.19) recorded in THF.
Molecular weights for 6-11 and 13 are given relative to PMMA. Molecular weight of 12 is given relative to PEG.
14 B 3156.6 (B) 3074.5 (A) 3000 3100 3200 3300 3400 3500 m/Z 3414.0 (C) 3400.4 (D) A
Figure S12. MALDI-TOF mass spectra of (A) 9 and (B) 13. The quasi-single distribution
seen in the top Figure demonstrates that 5 is the sole initiating species during ATRP and that all polymers therefore bear a protected α-oxo-aldehyde group. Deprotection of 9 to yield 13
was accomplished by I2-mediated transacetalization in acetone (90 ºC, 15 min). The
conditions used were milder than those typically used to achieve deprotection in order to visualize the hemiacetal (peak C), which is an intermediate of the deprotection reaction and confirms the deprotection mechanism. The fully deprotected polymer (peak D) corresponds to the di-hydrate of 13.
Scheme S5. Summary of compounds observed in the MALDI-TOF mass spectra seen in
15 HEWL-11 pH7.4 HEWL-10 pH9 HEWL-11 pH9 11 11 HEWL-12 pH7.4 15 20 25 HEWL-12 pH9 Time (min) 15 20 25 30 Residual HEWL HEWL-10 pH7.4 2 h 6 h 21 h 41 h 4 d 7 d Residual HEWL
Figure S13. Raw HPLC chromatograms for the modification of HEWL with 10-12 at pH 9
16
Figure S14. (a) SDS-PAGE of reaction mixtures containing HEWL and 10-12 performed at
pH 9. Reactions were quenched with NH2OH to cleave any polymer conjugated to HEWL at
lysine residues. This image shows quasi-total transformation of HEWL to a conjugate. (b) Control SDS-PAGE containing 10, 11, 12, and HEWL. This image illustrates that the polymers themselves are revealed by the silver staining used to reveal the gel.
References for Supplementary Information
1. N. G. De Kimpe and M. T. Rocchetti, J. Agric. Food Chem. 1998, 46, 2278-2281.
2. G . Bowmaker and S. Hannan, Aust. J. Chem. 1971, 24, 2237-2248.
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