Ultra bright red AIE dots for cytoplasm and nuclear imaging

An aggregation-induced emission (AIE) molecule (2-(2,6-bis((E)-2-(5-(N,N-bis(4-((E)-2-(10-((E)-4-(diphenylamino)styryl)anthracen-9-yl)vinyl)phenyl)aniline-4-yl)thiophen-2-yl)vinyl)-4H-pyran-4-ylidene)malononitrile) (TPA-AN-TPM) with near-infrared emission was synthesized by coating a disc-like red emission fluorophore with a propeller-shaped AIE fluorophore. The ultrabright red AIE dots TPA-AN-TPM@PS-PVP (TPA-AN-TPM in poly(styrene)-poly(4-vinylpyridine) nanoparticles) with an absolute quantum yield of 12.9% were fabricated by using the AIE molecule TPA-AN-TPM as the core and one biocompatible polymer PS-PVP as the encapsulation matrix. The AIE dots are mono-dispersed with an average diameter of 25 nm, and are stable in an aqueous suspension. In particular, the AIE dots can stain both the cytoplasm and the nuclei with a strong red fluorescence signal, and pose little toxicity to living cells.