Cy2 (CY2 Non-Sulfonated) is a cyanine dye with long wavelength, tunable absorption and emission, high extinction coefficient and good water solubility. Cy2 can be used to label amino groups in oligonucleotides, peptides, and proteins.

Instructions
1. Dissolution and preparation: Cy2 has good water solubility and can be dissolved in deionized water or appropriate buffer. Generally speaking, the working concentration range of Cy2 is 0.1–1 μM, and the specific concentration depends on the experimental requirements.
Note: When preparing, it is recommended to use low temperature storage to avoid dye degradation.
2. Labeling steps:
1) Labeling oligonucleotides, peptides or proteins (2-10mg/ml; pH protein solution should be 8.5±0.5.):
2) Dissolve the target molecule in an appropriate buffer (such as PBS or Tris-HCl, pH 7.4).
3) Add Cy2 to the solution in a certain proportion, usually the concentration of Cy2 is 0.1-1 mM, adjusted according to the amino content of the target molecule and the labeling efficiency.
3. Incubation:
After mixing the dye with the molecule, incubate for 30–60 minutes, and the incubation conditions are usually carried out at room temperature. During the incubation process, the reaction can be carried out with slight shaking to promote uniform labeling.
4. Cleaning and purification:
1) After the labeling reaction, it is usually necessary to remove unbound dyes by gel electrophoresis, dialysis or other purification methods.
2) The purified samples can be subjected to fluorescence detection.
5. Fluorescence detection:
1) Detection is performed using a fluorescence spectrophotometer or fluorescence microscope.
2) The excitation wavelength of Cy2 is about 490 nm, and the emission wavelength is in the range of 510–520 nm.
3) During the detection process, the excitation and emission wavelengths can be adjusted according to actual needs to obtain the best signal.