Method for photobleaching stained cells

A method for detecting a target moiety in a sample of biological specimens comprising:

• a) providing at least one conjugate with the general formula (I) Xn—P—Ym, with X is a fluorescent moiety, Y an antigen recognizing moiety, n, m are integers between 1 and 100 and P is a spacer comprising polyethyleneglycol according to general formula I
• (R7CH2CHR5O)—(CR1R2CR3R4O)o—(CH2CHR6R8) (I)
• Wherein R1 to R8 are independently H or a branched or a linear oligomer of ethylene glycol with at least 1 and a maximum of 20000 repeating units or a covalent bond to Y or X, with the provisio that at least two of R1 to R8 are covalent bonds to Y or X
• and o is an integer of 1-500;
• b) contacting the sample of biological specimens with at least one conjugate, thereby labeling the target moiety recognized by the antigen recognizing moiety Y with the conjugate;
• c) exiting the labelled target moieties with light having a wavelength within the absorbance spectrum of fluorescent moiety X;
• d) detecting the labelled target moieties by detecting the fluorescence radiation emitted by the fluorescent moiety;
• and
• e) degrading the fluorescent moiety X of the labelled target moieties by irradiating the conjugate with light having a wavelength within the absorbance spectrum of fluorescent moiety X for a time sufficient to deliver enough energy to reduce the fluorescence radiation emitted by the fluorescent moiety at least by 75% of the initial fluorescence radiation.