Synthesis of PEGylated Salicylaldehyde Azine via Metal-free Click Chemistry for Cellular Imaging Application

Ill tliis work, two kinds of PEGylated salicylaldehyde azine(SA) polymers were prepared and investigated for cellular imaging applications. First, a diazido derivative of SA was synthesized and subsequently PEGylated with polyethylene glycol monomethyl ether(mPEG) by metal-free azide-alkyne 1,3-dipolar cycloaddition reaction. The formed triazole group in niPEG-SA was then converted into cationic triazolium group by N-alkylation reaction. Botli the synthesized polymers, niPEG-SA and N-alkylated niPEG-SA, showed good dispersibility in water, but differences in self-assembly of nanostructures. The niPEG-SA with triazole groups self-assembled into micelles, while the N-alkylated mPEG-SA with triazolium groups sell-assembled into vesicles. Furthemiore, mPEG-SA and N-alkylated niPEG?SA naiioparticles showed bright fluorescence due to the aggregation of AIE-active SA molecules in the nanoparticles and could be successfully used as fluorescent naiioprobes for bioimaging applications in HeLa cancer cells. Finally, both the synthesized polymers showed minimal cytotoxicity and low hemolytic activity. Therefore, these PEGylated SA polymers proved to be promising bioimaging nanoprobes or traceable dnig delivery vehicles.