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Abstract: 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. [ABSTRACT FROM AUTHOR]

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(polyethylene glycol)-2000]. The nanoparticles are biocompatible and function well in TPEF cellular imaging and mouse brain blood vascular visualization. [ABSTRACT FROM AUTHOR]

Integration of tetraphenylethene featuring aggregation‐induced emission and a conventional chromophore furnishes efficient red luminescent materials. As discussed on page 481, Zujin Zhao and co‐workers fabricate biocompatible nanoparicles that show great potential for use in two‐photon excited fluorescence cellular imaging and three‐dimensional vascular visualization. [ABSTRACT FROM AUTHOR]

The study of blood brain barrier (BBB) functions is important for neurological disorder research. However, the lack of suitable tools and methods has hampered the progress of this field. Herein, we present a hybrid nanodot strategy, termed AIE-Gd dots, comprising of a fluorogen with aggregation-induced emission (AIE) characteristics as the core to provide bright and stable fluorescence for optical imaging, and gadolinium (Gd) for accurate quantification of vascular leakage via inductively-coupled plasma mass spectrometry (ICP-MS). In this report, we demonstrate that AIE-Gd dots enable direct visualization of brain vascular networks under resting condition, and that they form localized punctate aggregates and accumulate in the brain tissue during experimental cerebral malaria, indicative of hemorrhage and BBB malfunction. With its superior detection sensitivity and multimodality, we hereby propose that AIE-Gd dots can serve as a better alternative to Evans blue for visualization and quantification of changes in brain barrier functions. [ABSTRACT FROM AUTHOR]