Fluorescent labeling techniques have been widely used in cell imaging, protein detection and DNA probing because it offers a highly sensitive visualization tool for detecting biological macromolecules and monitoring biological events under real, living conditions. However, fluorescence quenching effect will occur when conventional luminescent materials are used in high concentrations.

In contrast, we discovered the novel phenomenon of aggregation-induced emission (AIE): nonemissive dyes with propeller-shaped molecular structures such as silole, tetraarylethene, fulvene, pyran and polyaryl are induced to emit efficiently by aggregate formation. These intriguing properties of the AIE fluorogens prompted us to explore the possibility of utilizing them as fluorescence biosensors....[ Read more ]

Fluorescent labeling techniques have been widely used in cell imaging, protein detection and DNA probing because it offers a highly sensitive visualization tool for detecting biological macromolecules and monitoring biological events under real, living conditions. However, fluorescence quenching effect will occur when conventional luminescent materials are used in high concentrations.

In contrast, we discovered the novel phenomenon of aggregation-induced emission (AIE): nonemissive dyes with propeller-shaped molecular structures such as silole, tetraarylethene, fulvene, pyran and polyaryl are induced to emit efficiently by aggregate formation. These intriguing properties of the AIE fluorogens prompted us to explore the possibility of utilizing them as fluorescence biosensors.

Synthetized lipophilic silole derivatives can readily pass through cell membranes, stain only the cell cytoplasm, and form highly emissive nanoaggregates in aqueous media without any obvious cytotoxicity against living cells. The compound molecules were found to be retained inside of the cells without noticeable leakage to the outside. Thus, these new AIE-based compounds can be used as selective and cell-compatible fluorescent dyes for long-time living cell imaging.

Tetraphenylethane (TPE) fluorogens with amine-reactive functional group and thiol-reactive fuctional group were also synthesized and used to specifically label lysine (Lys) residues and cysteine (Cys) residues of proteins, respectively. Because of the AIE characteristics, the fluorescent detection of proteins through functionalized TPE fluorogens does not exhibit the fluorescence quenching effect which traditional fluorescent detection methods usually suffer from.

Fluorescent DNA segments are prepared by using silole labeled aminoallyl-dUTP through enzymatic incorporation methods. Fluorescent products with extremely high degree of labeling (DOL) can be obtained with no fluorescence quenching effect. The products can be further used as fluorescent DNA probes in many bioapplications.