CY7  (Synonyms: Sulfo-Cyanine7)

CY7 is a CY dye. CY, short for Cyanine, is a compound consisting of two nitrogen atoms connected by an odd number of methyl units. Cyanine compounds have the characteristics of long wavelength, adjustable absorption and emission, high extinction coefficient, good water solubility and relatively simple synthesis^[1]. CY dyes are of en used for the labeling of proteins, antibodies and small molecular compounds. For the labeling of protein antibodies, the combination can be completed through a simple mixing reaction. Below, we introduce the labeling method of protein antibody labeling, which has certain reference significance^[2].

Stock solution preparation
1. Protein preparation
For optimal labeling, prepare the protein (antibody) concentration to 2 mg/mL.
1) The pH of the protein solution should be 8.5±0.5. If the pH is lower than 8.0, adjust with 1 M sodium bicarbonate.
2) If the protein concentration is lower than 2 mg/mL, the labeling efficiency will be greatly reduced. For optimal labeling efficiency, the recommended final protein concentration range is 2-10 mg/mL.
3) The protein must be in a buffer free of primary amines (such as Tris or glycine) and ammonium ions, otherwise the labeling efficiency will be affected.
2. Dye preparation
Dilute CY dye in anhydrous DMSO to make a 10 mM stock solution. Mix thoroughly by glass tube or vortex.
Note: It is recommended that the CY stock solution be stored at -20 °C or -80 °C in the dark after aliquoting.
Before use, the condensation solution (500 μg/mL) (HY-D0178) must be used for activation before subsequent labeling experiments can be performed.
3. Calculation of the amount of dye working solution
The amount of CY dye required for the labeling reaction depends on the amount of protein to be labeled. The optimal molar ratio of CY dye to protein is about 10.
For example: If the required labeled protein is 500 μL of 2 mg/mL IgG (MW=150,000), and 100 μL DMSO is used to dissolve a tube of 1 mg CY dye, the required CY volume is 3.95 μL. The detailed calculation process is as follows (taking CY3-NHS ester as an example):
1) mmol (IgG) = mg/mL (IgG) ×mL (IgG) / MW (IgG) =2 mg/mL×0.5 mL / 150,000 mg/mmol= 6.7×10^-6 mmol
2) mmol (CY3-NHS ester) = mmol (IgG) ×10 =6.7×10^-6 mmol×10 = 6.7×10^-5 mmol
3) μL (CY3-NHS ester) = mmol (CY3-NHS ester) ×MW (CY3-NHS ester) / mg/μL (CY3-NHS ester) = 6.7×10^-5 mmol× 590.15 mg/mmol / 0.01 mg/μL =3.95 μL (CY3-NHS ester)

Instructions
1. Labeling reaction
1) Take a calculated volume of freshly prepared 10 mg/mL CY dye and slowly add it to 0.5 mL of protein sample solution, gently shake to mix, and then briefly centrifuge to collect the sample at the bottom of the reaction tube. Avoid violent mixing to prevent protein sample denaturation and inactivation.
2) Place the reaction tube in a dark place, gently shake and incubate at room temperature for 60 minutes. Every 10–15 minutes, gently invert the reaction tube several times to fully mix the two reactants and improve labeling efficiency.
2. Protein purification and desalting
The following scheme uses SepHadex G-25 column to purify dye-protein conjugates as an example.
1) Prepare SepHadex G-25 column according to the manufacturer's instructions.
2) Load the reaction mixture onto the top of the SepHadex G-25 column.
3) As soon as the sample runs below the top resin surface, add PBS (pH 7.2-7.4).
4) Add more PBS (pH 7.2-7.4) to the desired sample to complete the column purification. Combine the fractions containing the desired dye-protein conjugate.

682.85

C₃₅H₄₂N₂O₈S₂

943298-08-6

Solid

Light yellow to green yellow

770

740

CC(/C(N1CCCCCC(O)=O)=C\C=C\C=C\C=C\C2=[N+](CC)C(C=CC(S(=O)([O-])=O)=C3)=C3C2(C)C)(C)C4=C1C=CC(S(=O)(O)=O)=C4

Room temperature in continental US; may vary elsewhere.

4°C, protect from light

*In solvent : -80°C, 6 months; -20°C, 1 month (protect from light)

* Please refer to the solubility information to select the appropriate solvent. Once prepared, please aliquot and store the solution to prevent product inactivation from repeated freeze-thaw cycles.
Storage method and period of stock solution: -80°C, 6 months; -20°C, 1 month (protect from light). When stored at -80°C, please use it within 6 months. When stored at -20°C, please use it within 1 month.

• [1]. Ptaszek M. Rational design of fluorophores for in vivo applications. Prog Mol Biol Transl Sci. 2013;113:59-108.  [Content Brief]

  [2]. Lim B, et al. A Unique Recombinant Fluoroprobe Targeting Activated Platelets Allows In Vivo Detection of Arterial Thrombosis and Pulmonary Embolism Using a Novel Three-Dimensional Fluorescence Emission Computed Tomography (FLECT) Technology. Theranostics. 2017 Feb 26;7(5):1047-1061.  [Content Brief]

  [3]. Shindy, H. A. (2017). Fundamentals in the chemistry of cyanine dyes: A review. Dyes and Pigments, 145, 505–513. doi:10.1016/j.dyepig.2017.06.029