Immunofluorescence (IF/ICC) Troubleshooting: Positive Control is negative or very weak

1. Improper fixation method resulting in antibody can't be combined with the corresponding target point.
2. The concentration of the antibody is too low. It is necessary to do the preliminary experiment to get the optimal working concentration.
3. The labeled second antibody is unstable and easy to quench. It is recommended that avoid light when you do the experiment with labeled second antibody. If necessary, the more stable fluorescent group should be chose.