Review on recent trends and prospects in π-conjugated luminescent aggregates for biomedical applications

Metal-free organic molecules with structurally diverse aggregation-induced emission(AIE)behavior and new functional photophysical properties reveal unique structure-property relationships,especially bright luminescence,and have attracted extensive attention in the past few decades.Despite tremendous progress on fluorescent molecules development,the extended π-conjugated organic AIE probes with their nanorange self-assembly,coassembly,unique morphology,high biocompatibility,and light-harvesting capabilities enable them as potential candidates in numerous translational application perspectives.In particular,a few important classes of AIE light up small molecules,supramolecules,oligomers,polymers,including nanoparticles and photosensitizer molecules,with their emerging properties of thermally activated delayed fluorescence,room temperature phosphorescence,including emission switching stimuli-responsive behavior and multifunctional properties,have been boosted by the rare features of aggregation at their condensed or solid states.This review highlights salient features of AIE-based emitters,encompassing molecular design strategies,stimulating photophysical properties,mechanistic aspects,and their efficacy in various electronic and biomedical applications,broadly covering properties of small molecules to oligomers,macromolecules to polymers.