Cyanine 5.5 monosuccinimidyl ester [equivalent to Cy5.5® NHS ester]
Example protocol
PREPARATION OF STOCK SOLUTIONS
Unless otherwise noted, all unused stock solutions should be divided into single-use aliquots and stored at -20 °C after preparation. Avoid repeated freeze-thaw cycles
Mix 100 µL of a reaction buffer (e.g., 1 M sodium carbonate solution or 1 M phosphate buffer with pH ~9.0) with 900 µL of the target protein solution (e.g. antibody, protein concentration >2 mg/mL if possible) to give 1 mL protein labeling stock solution.
Note: The pH of the protein solution (Solution A) should be 8.5 ± 0.5. If the pH of the protein solution is lower than 8.0, adjust the pH to the range of 8.0-9.0 using 1 M sodium bicarbonate solution or 1 M pH 9.0 phosphate buffer.
Note: The protein should be dissolved in 1X phosphate buffered saline (PBS), pH 7.2-7.4. If the protein is dissolved in Tris or glycine buffer, it must be dialyzed against 1X PBS, pH 7.2-7.4, to remove free amines or ammonium salts (such as ammonium sulfate and ammonium acetate) that are widely used for protein precipitation.
Note: Impure antibodies or antibodies stabilized with bovine serum albumin (BSA) or gelatin will not be labeled well. The presence of sodium azide or thimerosal might also interfere with the conjugation reaction. Sodium azide or thimerosal can be removed by dialysis or spin column for optimal labeling results.
Note: The conjugation efficiency is significantly reduced if the protein concentration is less than 2 mg/mL. For optimal labeling efficiency the final protein concentration range of 2-10 mg/mL is recommended.
Add anhydrous DMSO into the vial of Cyanine 5.5 monosuccinimidyl ester to make a 10 mM stock solution. Mix well by pipetting or vortex.
Note: Prepare the dye stock solution (Solution B) before starting the conjugation. Use promptly. Extended storage of the dye stock solution may reduce the dye activity. Solution B can be stored in freezer for two weeks when kept from light and moisture. Avoid freeze-thaw cycles.
SAMPLE EXPERIMENTAL PROTOCOL
This labeling protocol was developed for the conjugate of Goat anti-mouse IgG with Cyanine 5.5 monosuccinimidyl ester. You might need further optimization for your particular proteins.
Note: Each protein requires distinct dye/protein ratio, which also depends on the properties of dyes. Over labeling of a protein could detrimentally affects its binding affinity while the protein conjugates of low dye/protein ratio gives reduced sensitivity.
Use 10:1 molar ratio of Solution B (dye)/Solution A (protein) as the starting point: Add 5 µL of the dye stock solution (Solution B, assuming the dye stock solution is 10 mM) into the vial of the protein solution (95 µL of Solution A) with effective shaking. The concentration of the protein is ~0.05 mM assuming the protein concentration is 10 mg/mL and the molecular weight of the protein is ~200KD.
Note: We recommend to use 10:1 molar ratio of Solution B (dye)/Solution A (protein). If it is too less or too high, determine the optimal dye/protein ratio at 5:1, 15:1 and 20:1 respectively.
- Continue to rotate or shake the reaction mixture at room temperature for 30-60 minutes.
The following protocol is an example of dye-protein conjugate purification by using a Sephadex G-25 column.
- Prepare Sephadex G-25 column according to the manufacture instruction.
- Load the reaction mixture (From "Run conjugation reaction") to the top of the Sephadex G-25 column.
- Add PBS (pH 7.2-7.4) as soon as the sample runs just below the top resin surface.
Add more PBS (pH 7.2-7.4) to the desired sample to complete the column purification. Combine the fractions that contain the desired dye-protein conjugate.
Note: For immediate use, the dye-protein conjugate need be diluted with staining buffer, and aliquoted for multiple uses.
Note: For longer term storage, dye-protein conjugate solution need be concentrated or freeze dried.
Calculators
Common stock solution preparation
0.1 mg | 0.5 mg | 1 mg | 5 mg | 10 mg | |
1 mM | 75.89 µL | 379.449 µL | 758.898 µL | 3.794 mL | 7.589 mL |
5 mM | 15.178 µL | 75.89 µL | 151.78 µL | 758.898 µL | 1.518 mL |
10 mM | 7.589 µL | 37.945 µL | 75.89 µL | 379.449 µL | 758.898 µL |
Molarity calculator
Mass (Calculate) | Molecular weight | Volume (Calculate) | Concentration (Calculate) | Moles | ||||
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Spectrum
Product family
Name | Excitation (nm) | Emission (nm) | Extinction coefficient (cm -1 M -1) | Quantum yield | Correction Factor (260 nm) | Correction Factor (280 nm) |
Cyanine 3.5 monosuccinimidyl ester [equivalent to Cy3.5® NHS ester] | 579 | 591 | 150000 | 0.15 | 0.08 | 0.178 |
Cyanine 5.5 bissuccinimidyl ester [equivalent to Cy5.5® bisNHS ester] | 683 | 703 | 250000 | 0.27 | 0.05 | 0.101 |
Cyanine 7.5 monosuccinimidyl ester [equivalent to Cy7.5® NHS ester] | 785 | 801 | 250000 | - | - | - |
Citations
Authors: Pu, Zhichen and Li, Lingling and Zhang, Yan and Shui, Yinping and Liu, Jun and Wang, Xiaohu and Jiang, Xiaogan and Zhang, Liqin and Yang, Hui
Journal: Phytomedicine (2025): 156563
Authors: Lee, Seonju and Lee, Seon Ah and Shinn, Jongyoon and Lee, Yonghyun
Journal: International Journal of Nanomedicine (2024): 4893--4906
Authors: Wang, Peifeng and Du, Yang and Zhao, Xingyang and Hu, Yueyang and Zhou, Tianjun and Liang, Xiaolong and Fang, Chihua and Tian, Jie
Journal: Materials \& Design (2023): 112137
Authors: Ghoneim, Mohamed and Musselman, Catherine A
Journal: STAR protocols (2023): 102229
Authors: Xu, Jiaqi and Chu, Tianjiao and Yu, Tingting and Li, Naishi and Wang, Chunling and Li, Chen and Zhang, Yinlong and Meng, Huan and Nie, Guangjun
Journal: ACS nano (2022): 13037--13048
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