A fluorogen named 1-decyl-1-methyl-2,5-bis{4-[(N,N-diethylamino)methyl]phenyl}-3,4-diphenylsilole (3) was synthesized. It emitted weakly as isolated molecule but strongly as supramolecular aggregate, showing a characteristic behavior of aggregation-induced emission (AIE). The molecules of 3 formed highly emissive nanoparticles in aqueous media, which quickly and selectively marked cytoplasm of HeLa cells and posed no toxicity to the living cells. The fluorogen is thus a promising candidate mate-rial for cell imaging as a sensitive, selective and cytocompatible biosensor. A fluorogen named 1-decyl-1-methyl-2,5-bis {4 - [(N, N-diethylamino) methyl] phenyl} -3,4-diphenylsilole strongly molecules of 3 formed highly emissive nanoparticles in aqueous media, which quickly and selectively marked cytoplasm of HeLa cells and posed no toxicity to the living cells. The fluorogen Thus provided a candidate mate-rial for cell imaging as a sensitive, selective and cytocompatible biosensor.