Assay kit

This assay kit uses activated Europium (Eu) complexes to label antibodies or proteins for immunostaining or cellular protein tracing. The activated Eu complexes can directly form covalent bonds with target antibody proteins or other macromolecules containing primary amine groups. The kit includes dialysis tubes to remove unreacted complexes and other small amine compounds, such as tris and glycine, which can interfere with the detection or labeling reaction. The labeling process is very easy: add activated Eu complexes (Reagent A) to the protein solution which remain above the dialysis membrane and incubate at 37 °C for 2 hours. Excess unreacted Eu complexes can be removed through the centrifugation. The maximum excitation and emission wavelengths of the labeled protein are 335 nm and 620 nm, respectively. The large stokes shift of 285 nm, with no overlap between the absorption and emission spectra, resulting in good phosphorescent stability. Under continuous exitation at 335 nm for one hour, the emission intensity remains almost constant. Furthermore, the Eu complexes lifetime of phosphorescent photon is 1.0 ms, allowing for effective differentiation of endogenous fluorescent signals from the sample by using time-resolution spectroscopic equipment. This kit contains all the necessary reagents for labeling, including a storage buffer for storing the labeled protein.