Prolonged incubation and stacked film exposure improve sensitivity in western blotting.

INTRODUCTION: Western blotting is a basic technique for protein detection. For proteins of less abundance or antibodies of poorer quality, an increased sensitivity is often desired. Although it is commonly known that higher concentrations of antibodies and prolonged film exposure times will help improve sensitivity in western blots, both measures come with their own risks, and it is often unclear to which extent these measures should be applied.
METHODS: We conducted time-course studies to investigate protein-antibody interactions and primary antibody-secondary antibody interactions in western blotting. We also propose a protocol of stacked film exposure and have tested it in standard curves and cancer cell samples.
RESULTS: Our study found that protein-primary antibody interactions and primary antibody-secondary antibody interactions could take a longer time than commonly used "one hour" or "overnight", and in some cases longer than 48h, to reach its maximum binding. We also show that the modified protocol of stacked film exposure works well for both standard curves and biological samples, reaching a maximum sensitivity in western blots without blurring target signals or increasing backgrounds. DISCUSSION: In addition to regular optimization of antibody concentrations and film exposure time, a prolonged incubation with antibodies and stacked film exposure will also help improve sensitivity and reduce background in western blotting.