Nanoparticles based on conjugated polymers are emerging as a new class of luminescent nanoparticles. These nanoparticles have many potential applications including imaging agents, biosensors, and photonics owing to their high quantum yields, high molar absorptivity, photo stability and easy synthesis. The recent cell assay studies have also showed that these nanoparticles were not cytotoxic.4Moreover, conjugated polymer nanoparticles can be modified easily to deliver therapeutic agents such as cancer drugs, genetic materials (e.g. RNA, siRNA) and biomolecules to the desired targets. Here, we present the resent studies in our lab involving the synthesis and applications of nanoparticles using various conjugated polymers which emit blue, green, yellow and red. In order to obtain shape-persistent and stable nanoparticles, a novel method was developed in which the nanoparticles were prepared either via Cu-catalyzed or cucurbit[6]uril (CB6)-catalyzed click reactions between azide groups containing hydrophobic fluorene-based conjugated polymers and a hydrophilic diaminodialkyne containing cross-linker. Through the click reaction, not only does the cross-linking confer stability, but it also introduces functional groups, such as triazoles and amines, to the nanoparticles. TEM images of the nanoparticles also showed that they display very interesting morphologies. Incorporation of hydrophilic functional groups to the hydrophobic conjugated polymers resulted in a distinct phase separation, producing Janus-like or patchy particles.