One-Pot Synthesis of Conjugated Polymer Dots with Ultrasmall Size below 10 nm through Schiff-base Chemistry and Their Bioapplications in Monitoring Lysosomal pH

Abstract Developing new strategies for facile synthesis of conjugated polymer dots (CPdots) derived from novel monomer species is highly desirable to improve their application. This paper describes a super-simple method, based on Schiff base condensation, for facilely fabricating ultrasmall CPdots under room temperature. This novel CPdots, prepared by reacting the o-benzoquinone with o-phenylenediamine catalyzed by hydrochloric acid, defined as OOPdots, show a variety of superior properties, such as uniform small size, red emission and high quantum yield. With abundant imine and amino groups on the surface, the OOPdots exhibit an excellent pH responsiveness via modulation of the self-assemble or dissociation. Further experiments indicate that the resulting OOPdots are high-performance probes for labeling lysosomes in living cells and zebrafish. This work not only expands the application scope of OOPdots in the field of biological imaging, but also provides guidance for their rapid and large-scale preparation.