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Red/near-infrared dyes are highly demanded for biological applications but most of them are far from satisfactory. In this work, a series of red/near-infrared fluorophores based on electron-withdrawing benzo[1,2-b:4,5-b′]dithiophene 1,1,5,5-tetraoxide (BDTO) are synthesized and characterized. They possess both aggregation-induced emission, and hybridized local and charge-transfer characteristics. Crystallographic, spectroscopic, electrochemical and computational results reveal that the oxidation of benzo[1,2-b:4,5-b′]dithiophene to BDTO can endow the fluorophores with greatly red-shifted emission, enhanced emission efficiency, reduced energy levels, enlarged two-photon absorption cross section, and increased reactive oxygen species generation efficiency. The nanoparticles fabricated with a near-infrared fluorophore TPA-BDTO show high photostability and biocompatibility with good performance in targeted photodynamic ablation of cancer cells and two-photon fluorescence imaging of intravital mouse brain vasculature. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Polymeric nanorods loaded with AIEgens are synthesized via nano-precipitation under ultrasound sonication, where prolonged sonication time could induce a nanodot-to-nanorod transition. These AIE nanorods, but not the nanodots, could be selectively internalized into cancer cells, which show better tumor accumulation, higher tumor penetration and more efficient in vivo cancer cell uptake.

Red/near-infrared dyes are highly demanded for biological applications but most of them are far from satisfactory. In this work, a series of red/near-infrared fluorophores based on electron-withdrawing benzo[1,2-b:4,5-b′]dithiophene 1,1,5,5-tetraoxide (BDTO) are synthesized and characterized. They possess both aggregation-induced emission, and hybridized local and charge-transfer characteristics. Crystallographic, spectroscopic, electrochemical and computational results reveal that the oxidation of benzo[1,2-b:4,5-b′]dithiophene to BDTO can endow the fluorophores with greatly red-shifted emission, enhanced emission efficiency, reduced energy levels, enlarged two-photon absorption cross section, and increased reactive oxygen species generation efficiency. The nanoparticles fabricated with a near-infrared fluorophore TPA-BDTO show high photostability and biocompatibility with good performance in targeted photodynamic ablation of cancer cells and two-photon fluorescence imaging of intravital mouse brain vasculature. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Polymeric nanorods loaded with AIEgens are synthesized via nano-precipitation under ultrasound sonication, where prolonged sonication time could induce a nanodot-to-nanorod transition. These AIE nanorods, but not the nanodots, could be selectively internalized into cancer cells, which show better tumor accumulation, higher tumor penetration and more efficient in vivo cancer cell uptake.

Red/near-infrared dyes are highly demanded for biological applications but most of them are far from satisfactory. In this work, a series of red/near-infrared fluorophores based on electron-withdrawing benzo[1,2-b:4,5-b′]dithiophene 1,1,5,5-tetraoxide (BDTO) are synthesized and characterized. They possess both aggregation-induced emission, and hybridized local and charge-transfer characteristics. Crystallographic, spectroscopic, electrochemical and computational results reveal that the oxidation of benzo[1,2-b:4,5-b′]dithiophene to BDTO can endow the fluorophores with greatly red-shifted emission, enhanced emission efficiency, reduced energy levels, enlarged two-photon absorption cross section, and increased reactive oxygen species generation efficiency. The nanoparticles fabricated with a near-infrared fluorophore TPA-BDTO show high photostability and biocompatibility with good performance in targeted photodynamic ablation of cancer cells and two-photon fluorescence imaging of intravital mouse brain vasculature. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Polymeric nanorods loaded with AIEgens are synthesized via nano-precipitation under ultrasound sonication, where prolonged sonication time could induce a nanodot-to-nanorod transition. These AIE nanorods, but not the nanodots, could be selectively internalized into cancer cells, which show better tumor accumulation, higher tumor penetration and more efficient in vivo cancer cell uptake.

Fluorescent organic dots are emerging as promising bioimaging reagents because of their high brightness, good photostability, excellent biocompatibility, and facile surface functionalization. Organic dots with large two-photon absorption (TPA) cross sections are highly desired for two-photon fluorescence microscopy. In this work, we report two biocompatible and photostable organic dots fabricated by encapsulating tetraphenylethene derivatives within DSPE-PEG matrix. The two organic dots show absorption maxima at 425 and 483 nm and emit green and red fluorescence at 560 and 645 nm, with high fluorescence quantum yields of 64% and 22%, respectively. Both organic dots exhibit excellent TPA property in the range of 800-960 nm, affording upon excitation at 820 nm remarkably large TPA cross sections of 1.2 × 106 and 2.5 × 106 GM on the basis of dot concentration. The bare fluorophores and their organic dots are biocompatible and have been used to stain living cells for one- and two-photon fluorescence bioimagings. The cRGD-modified organic dots can selectively target integrin αvβ3 overexpressing breast cancer cells for targeted imaging. The organic dots are also applied for real-time two-photon fluorescence in vivo visualization of the blood vasculature of mouse ear, providing the spatiotemporal information about the whole blood vascular network. These results demonstrate that the present fluorescent organic dots are promising candidates for living cell and tissue imaging. © 2015 American Chemical Society.

BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) is an emissive chromophore in solutions but suffers from fluorescence quenching when aggregated due to its flat molecular conformation and small Stokes shift. To create aggregate-state emissive BODIPY luminogens, tetraphenylethene (TPE), which is a popular luminogen with intriguing aggregation-induced emission (AIE) characteristic, is introduced as periphery to a methylated BODIPY core. Three TPE-BODIPY adducts are synthesized and characterized, and their photophysical properties and electronic structures are investigated. The incorporation of AIE-active TPE units alleviates aggregation-caused quenching of BODIPY core, furnishing emissive nanoparticles based on TPE-BODIPY adducts. Significantly, the two-photon absorption (TPA) and two-photon excited fluorescence (TPEF) properties are improved as more TPE units are attached. The luminogens with 3TPE units (3TPE-BODIPY) shows the strongest TPA and TPEF in the wavelength range of 750-830 nm, with cross-section values of 264 and 116 GM at 810 nm, respectively. Red emissive nanoparticles with a Stokes shift of 60 nm and a fluorescence quantum yield of 16% are attained by encapsulating 3TPE-BODIPY with 1,2-sistearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylen e glycol)-2000]. The nanoparticles are biocompatible and function well in TPEF cellular imaging and mouse brain blood vascular visualization.

BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) is an emissive chromophore in solutions but suffers from fluorescence quenching when aggregated due to its flat molecular conformation and small Stokes shift. To create aggregate-state emissive BODIPY luminogens, tetraphenylethene (TPE), which is a popular luminogen with intriguing aggregation-induced emission (AIE) characteristic, is introduced as periphery to a methylated BODIPY core. Three TPE-BODIPY adducts are synthesized and characterized, and their photophysical properties and electronic structures are investigated. The incorporation of AIE-active TPE units alleviates aggregation-caused quenching of BODIPY core, furnishing emissive nanoparticles based on TPE-BODIPY adducts. Significantly, the two-photon absorption (TPA) and two-photon excited fluorescence (TPEF) properties are improved as more TPE units are attached. The luminogens with 3TPE units (3TPE-BODIPY) shows the strongest TPA and TPEF in the wavelength range of 750-830 nm, with cross-section values of 264 and 116 GM at 810 nm, respectively. Red emissive nanoparticles with a Stokes shift of 60 nm and a fluorescence quantum yield of 16% are attained by encapsulating 3TPE-BODIPY with 1,2-sistearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylen e glycol)-2000]. The nanoparticles are biocompatible and function well in TPEF cellular imaging and mouse brain blood vascular visualization.

BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) is an emissive chromophore in solutions but suffers from fluorescence quenching when aggregated due to its flat molecular conformation and small Stokes shift. To create aggregate-state emissive BODIPY luminogens, tetraphenylethene (TPE), which is a popular luminogen with intriguing aggregation-induced emission (AIE) characteristic, is introduced as periphery to a methylated BODIPY core. Three TPE-BODIPY adducts are synthesized and characterized, and their photophysical properties and electronic structures are investigated. The incorporation of AIE-active TPE units alleviates aggregation-caused quenching of BODIPY core, furnishing emissive nanoparticles based on TPE-BODIPY adducts. Significantly, the two-photon absorption (TPA) and two-photon excited fluorescence (TPEF) properties are improved as more TPE units are attached. The luminogens with 3TPE units (3TPE-BODIPY) shows the strongest TPA and TPEF in the wavelength range of 750-830 nm, with cross-section values of 264 and 116 GM at 810 nm, respectively. Red emissive nanoparticles with a Stokes shift of 60 nm and a fluorescence quantum yield of 16% are attained by encapsulating 3TPE-BODIPY with 1,2-sistearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylen e glycol)-2000]. The nanoparticles are biocompatible and function well in TPEF cellular imaging and mouse brain blood vascular visualization.

Ultrabright organic dots with aggregation-induced emission characteristics (AIE dots) are prepared and shown to exhibit a high quantum yield, a, large two-photon absorption cross-section, and low in vivo toxicity. Real-time two-photon intravital blood vascular imaging in various tissues substantiates that the AIE dots are effective probes for in vivo vasculature imaging in a deep and high-contrast manner. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrabright organic dots with aggregation-induced emission characteristics (AIE dots) are prepared and shown to exhibit a high quantum yield, a, large two-photon absorption cross-section, and low in vivo toxicity. Real-time two-photon intravital blood vascular imaging in various tissues substantiates that the AIE dots are effective probes for in vivo vasculature imaging in a deep and high-contrast manner. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrabright organic dots with aggregation-induced emission characteristics (AIE dots) are prepared and shown to exhibit a high quantum yield, a, large two-photon absorption cross-section, and low in vivo toxicity. Real-time two-photon intravital blood vascular imaging in various tissues substantiates that the AIE dots are effective probes for in vivo vasculature imaging in a deep and high-contrast manner. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.