Synlett 2010(3): 449-452  
DOI: 10.1055/s-0029-1219178
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Alkyne-Terminated PCDA Linker for Applying Click Chemistry on PDA Layers

Ja-Young Namgunga#, Bong-Hyun Junb#, Yoon-Sik Lee*a
a School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea
b School of Electrical Engineering and Computer Science, Seoul National University, Seoul 151-747, Korea
Fax: +82(2)8769625; e-Mail: yslee@snu.ac.kr;
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Publikationsverlauf

Received 28 August 2009
Publikationsdatum:
08. Januar 2010 (online)

Abstract

An alkyne-terminated PCDA (10,12-pentacosadiynoic acid) linker, which can undergo a simple click reaction with azide compounds, was synthesized for the purpose of immobilizing various kinds of biomolecular surface ligands on PDA (polydiacetylene) layers. In order to confirm the ability of the linker compound to anchor azide-modified surface ligands, we carried out a model ­reaction with benzyl azide under typical click-reaction conditions. We were able to confirm that the model reaction proceeded smoothly by observing the color change of PDA, including its thermochromic reversibility.

    References and Notes

  • 1 Cheng Q. Stevens RC. Adv. Mater.  1997,  9:  481 
  • 2 Cheng Q. Stevens RC. Langmuir  1998,  14:  1974 
  • 3 Jelinek R. Drug Dev. Res.  2000,  50:  497 
  • 4 Reichert A. Nagy JO. Spevak W. Charych D. J. Am. Chem. Soc.  1995,  117:  829 
  • 5 Pan JJ. Charych D. Langmuir  1997,  13:  1365 
  • 6 Ma Z. Li J. Liu M. Cao J. Zou Z. Tu J. Jiang L.
    J. Am. Chem. Soc.  1998,  120:  12678 
  • 7 Wang C. Ma Z. Anal. Bioanal. Chem.  2005,  382:  1708 
  • 8 Gill I. Ballesteros A. Angew. Chem. Int. Ed.  2003,  42:  3264 
  • 9 Kolusheva S. Kafri R. Katz M. Jelinek R. J. Am. Chem. Soc.  2001,  123:  417 
  • 10 Lee SW. Kang CD. Yang DH. Lee JS. Kim JM. Ahn DJ. Sim S. J. Adv. Funct. Mater.  2007,  17:  2038 
  • 11 Schlossbauer A. Schaffert D. Kecht J. Wagner E. Bein T. J. Am. Chem. Soc.  2008,  130:  12558 
  • 12 Kaiser E. Colescott RL. Bossinger CD. Cook PI. Anal. Biochem.  1970,  34:  595 
  • 13a Shim HY. Lee SH. Ahn DJ. Kim JM. Mater. Sci. Eng. C  2004,  24:  157 
  • 13b Kim JM. Ji EK. Woo SM. Lee H. Ahn DJ. Adv. Mater.  2003,  15:  1118 
  • 13c Jonas U. Shah K. Norvez S. Charych DH. J. Am. Chem. Soc.  1999,  121:  4580 
  • 14 Kim J.-M. Lee J.-S. Choi H. Sohn D. Ahn DJ. Macromolecules  2005,  38:  9366 
  • Preparation of an Alkyne-Terminated PCDA Linker
  • 15a

    To 1 g of pretreated 2-CTC resins (1.3 mmol/g of Cl, 100-200 mesh) with 10 mL of CH2Cl2, A (1.9 mL, 10 equiv based on the amount of Cl) and Et3N (3.6 mL, 20 equiv based on the amount of Cl) were added. The reaction mixture was shaken for 3 h at r.t. After that, the resins were filtered and washed with CH2Cl2 and MeOH (5 times each), and dried in a vacuum for 12 h. The loading level of amino groups was determined to be 0.76 mmol/g by Fmoc titration.

  • 15b

    Then, 300 mg of B (0.76 mmol/g of amino groups) in DMF (2 mL, for HBTU) and CH2Cl2 (2 mL, for PCDA), HBTU (260 mg, 3 equiv), DIEA (93 µL, 3 equiv), and PCDA (256 mg, 3 equiv) were added one by one; the equivalent ratios were based on the amount of amino groups on B. The reaction mixture was shaken for 4 h at r.t. and washed with CH2Cl2 and MeOH (5 times each). The resulting products were cleaved from the beads with 2% of TFA in CH2Cl2 (2 min, r.t.) several times. The combined CH2Cl2 solution was washed with deionized H2O, and the solvent was removed, affording the product C in 50% yield (94% LC purity). The product was characterized by ¹H NMR.

  • 15c

    To 20 mL of an CH2Cl2-CHCl3 (4:1) solution of C (210 mg, 0.42 mmol), pentynoic acid (150 mg, 0.84 mmol) and EDCI˙HCl (160 mg, 0.46 mmol) were added, and the reaction mixture was stirred for 3 h at r.t. After adding 20 mL of deionized H2O to the reaction solution, the product was extracted with an excess of EtOAc. The organic layer was dried with MgSO4, and the solvent was removed to give the final product D in quantitative yield. It was identified by ¹H NMR and IR spectroscopy (characteristic IR peak of alkyne C-H stretching at 3291 cm).

16

Preparation of PDA Liposomes in PBS Solution
An alkyne-terminated PCDA linker solution and PCDA solution were prepared by dissolving D (5.8 mg, 0.01 mmol) in 10 mL of CHCl3 and PCDA (3.7 mg, 0.01 mmol) in 10 mL of CHCl3, respectively. The linker solution (1 mL) and 9 mL of PCDA solution were taken and mixed. After removing the solvent by a rotary evaporator, 10 mL of PBS solution (pH 7.4) was added to give a total PCDA lipid concentration of 1.0 mM. Then, the sample was homogenized for 10 min, and the resulting solution was filtered by a polytetrafluoro-ethylene (PTFE) valve (Libra tube). The filtrate was cooled to 4 ˚C and kept at this temperature for 12 h to stabilize the PDA vesicles formed in the PBS solution.

17

Reaction of PDA Liposomes Having Terminal Alkynes with Benzyl Azide
Benzyl azide (5.32 mg, 40 µmol) was dissolved in 1.5 mL
of t-BuOH-H2O (1:2) and 150 µL of the solution (4 equiv based on the amount of terminal triple bonds) was taken
and added to 10 mL of the previously prepared liposome solution. Ascorbic acid (2 mg) was added to a 1 mM aqueous solution of CuSO4˙5H2O (10 mL), and the resulting mixture was stirred for 10 min at r.t. Subsequently, 2 mL of copper-containing solution was added to the reaction mixture. The resulting mixture was shaken for 3 h at r.t.