Photoactivated chemical bleaching of dyes

A method of probing multiple targets in a biological sample comprising:

• (a) binding multiple probes to multiple targets present in the biological sample including multiple targets, wherein the multiple probes includes a first set of probes and a second set of probes;
• (b) detecting a first set of signals from the first set of probes bound in step (a);
• (c) contacting the sample comprising the bound probe of step (a) with an electron transfer reagent and an additive which prevents target modification in step (d) below;
• (d) irradiating the sample of step (c);
• (e) generating a second set of signals from the second set of probes bound in step (a);
• (f) detecting the second set of signals.

A series of at least two images depicting optically labeled biological targets wherein:

• the images are obtained in the process of probing multiple targets in a biological sample, wherein the process comprises:
• (a) binding at least one optical probe to one or more targets present in the biological sample including multiple targets;
• (b) detecting a signal from the optical probe bound in step (a);
• (c) contacting the sample comprising the bound optical probe of step (a) with an electron transfer reagent and an additive which prevents target modification in step (d) below;
• (d) irradiating the sample of step (c);
• (e) binding at least one optical probe to one or more targets present in the sample of step (d);
• and
• (f) detecting a signal from the optical probe bound in step (e).

An automated process for photoactivated chemical bleaching of a biological sample loaded/captured in a flow cell device, comprising the following automated steps of

• a) binding at least one probe to one or more targets present in the biological sample;
• b) detecting a signal from the at least one probe bound in step (a);
• c) filling the flow cell with an electron transfer reagent and optionally an additive which prevents target modification during subsequent sample irradiation;
• d) irradiating the sample by exposure to light to inactivate signals from the probe;
• e) optionally washing out the electron transfer reagent and the additive;
• and
• f) repeating steps a) and b) with at least one other probe, for another round of imaging.