POSA for fast, amplified and multiplexed protein imaging.

Fluorescent π-conjugated polymers (FCPs) are known for their superior brightness but are still unavailable for highly multiplexed molecular imaging in single cells as they are hydrophobic and lack targeting capability toward biomolecules. Herein, we develop a π-conjugated polymer-based amplification (POSA) method to achieve highly multiplexed signal amplification. Optical amplification by virtue of the high brightness of FCPs makes POSA a simple and quick signal amplification technique that can spatially resolve the distribution of multiplexed proteins in single cells, with a 28- to 126-fold signal amplification effect. By this POSA method, we demonstrate that the high brightness of FCPs can be used to strengthen the images of subcellular biomolecules and showcase the phenomenon of optical amplification of FCPs at the cellular level. Additionally, with its sensitivity, ease of use, and quick imaging features, the POSA technique proves to be a valuable tool for advanced biological research.