Using Fluorescence Quenching as an Indicator for Successful Reaction in Copper (I) Catalyzed [3+2] Cycloaddition

Overview

Objectives/Goals -Find reaction conditions for using fluorescence quenching as an indicator for successful reaction in copper(I) catalyzed [3+2] cycloaddition. -Find copper binding ligands that can accelerate the [3+2] cycloaddition. Methods/Materials Materials: Dansyl azide, dabsyl alkyne, tris-HCl buffer pH 7.0, 7.5, 8.0 8.5, copper sulfate, DMSO, H(2)O, sodium ascorbate, 96-well plate, phenanthroline. Procedures: 1) Place 100uL of 50uM dansyl azide/dabsyl alkyne mixture into columns 1-6. 2) Place 100uL of 50uM unreactive quencher/dansyl azide mixture into row D and H in columns 7-12. 3) Place 75uL of 50uM unreactive quencher/dansyl azide mixture and 25uL of 50uM adduct solution into row C and G in columns 7-12. 4) Place 50uL of 50uM unreactive quencher/dansyl azide mixture and 50uL of 50uM adduct solution into row B and F in columns 7-12. 5) Place 100uL of 50uM adduct solution into row A and E in columns 7-12. 6) Place 50uL of 1mM CuSO(4) solution in water into rows A-D. 7) Place 50uL of 500uM CuSO(4) solution in water into rows E-H. 8) Place 50uL of Tris-HCl buffer pH=8.5 into columns 1-12. 9) Place 25uL of 10mM ligand into columns 1 and 7. 10) Place 25uL of 5mM ligand into columns 2 and 8. 11) Place 25uL of 2mM ligand into columns 3 and 9. 12) Place 25uL of 1mM ligand into columns 4 and 10. 13) Place 25uL of 500uM ligand into columns 5 and 11. 14) Place 25uL of 250uM ligand into columns 6 and 12. 15) Place 50uL of 100mM sodium ascorbate into columns 1-12. 16) Place 96-well plate in UV plate reader for 1 hour, set to collect fluorescence values every 2 minutes. Results Reaction conditions were found at 50uM fluorophore concentration. Ligands found that accelerate reaction to 100% completion are commercially available. Kinetics were done on best ligands and graphs with equations have been determined to calculate the concentration of the substrates at a certain time period. Conclusions/Discussion These conditions are very useful for efficiently labeling and functionalizing viruses with compounds in [3+2] cycloaddition to make them target for example certain cells in the human body, like cancer. Also, these conditions for reaction in [3+2] cycloaddition may have many other applications.

Competition history

• CSEF 2004 Chemistry · Entry S0519

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