Synthesis of V-shaped Thiophene Based Rotor-Stilbene: Substituent Dependent Aggregation and Photophysical Properties.

Thiophene core V-shaped rotor-stilbene derivatives have been synthesized utilizing two-fold Heck coupling reaction. These compounds are blue emitters with moderate quantum yield in dilute solution. Rotor nature of the synthesized stilbenes supports aggregation induced emission (AIE) behaviour and they show substituent dependent emission behavior in aggregate state. In presence of donating groups (e.g., tert-butyl, methoxy, diphenylamine group) in stilbenes, they exhibit AIE property. But with the introduction of electron withdrawing group (nitro group), they shows aggregation caused quenching (ACQ) behavior. Different types of nano-aggregates formation is observed in aggregated state, which was confirmed by dynamic light scattering (DLS) and scanning electron microscopy (SEM) studies. The details photophysical (absorption, fluorescence, and lifetime), electrochemical property (cyclic voltammetry) and thermal stability have been investigated. Optimized structure, energy and electronic distribution of molecular orbitals have been studied by theoretical calculation.

Biodegradable Poly(trehalose) Nanoparticle for Preventing Amyloid Beta Aggregation and Related Neurotoxicity.

Trehalose is a disaccharide that is capable of inhibiting protein aggregation and activating cellular autophagy. It has been shown that a polymer or nanoparticle form, terminated with multiple trehalose units, can significantly enhance the anti-amyloidogenic performance and is suitable for the treatment of neurodegenerative diseases. Here, we report a trehalose-conjugated polycarbonate-co-lactide polymer and formulation of its nanoparticles having multiple numbers of trehalose exposed on the surface. The resultant poly(trehalose) nanoparticle inhibits the aggregation of amyloid beta peptides and disintegrates matured amyloid fibrils into smaller fragments. Moreover, the poly(trehalose) nanoparticle lowers extracellular amyloid ß oligomer-driven cellular stress and enhances cell viability. The presence of biodegradable polycarbonate components in the poly(trehalose) nanoparticle would enhance their application potential as an anti-amyloidogenic material.

A NANOG-pERK reciprocal regulatory circuit regulates Nanog autoregulation and ERK signaling dynamics.

The self-renewal and differentiation potential of embryonic stem cells (ESCs) is maintained by the regulated expression of core pluripotency factors. Expression levels of the core pluripotency factor Nanog are tightly regulated by a negative feedback autorepression loop. However, it remains unclear how ESCs perceive NANOG levels and execute autorepression. Here, we show that a dose-dependent induction of Fgfbp1 and Fgfr2 by NANOG activates autocrine-mediated ERK signaling in Nanog-high cells to trigger autorepression. pERK recruits NONO to the Nanog locus to repress transcription by preventing POL2 loading. This Nanog autorepression process establishes a self-perpetuating reciprocal NANOG-pERK regulatory circuit. We further demonstrate that this reciprocal regulatory circuit induces pERK heterogeneity and ERK signaling dynamics in pluripotent stem cells. Collectively our data suggest that NANOG induces Fgfr2 and Fgfbp1 to activate ERK signaling in Nanog-high cells to establish a NANOG-pERK reciprocal regulatory circuit. This circuit regulates ERK signaling dynamics and Nanog autoregulation in pluripotent cells.

Generation of Cdx2-mCherry knock-in murine ES cell line to model trophectoderm and intestinal lineage differentiation.

Caudal-type homeobox 2 (.Cdx2) transcription factor is an essential regulator of differentiation to the intestinal epithelium, somatic mesoderm and trophectoderm function in the mouse. However, the regulation of Cdx2 in these processes is poorly understood. Separation of viable Cdx2 expressing cells during differentiation for downstream experiments is not possible due to its nuclear localization, limiting experimental possibilities and studying Cdx2 regulation. Here, we report generation of a Cdx2-mCherry knock-in reporter mouse embryonic stem cell line (TCMC), for modeling and studying in vitro differentiation of mESCs to intestinal epithelia, somatic mesoderm, and trophectoderm.

Supramolecular Aggregates of Tetraphenylethene-Cored AIEgen toward Mechanoluminescent and Electroluminescent Devices.

Luminescent materials possessing both the mechanoluminescence (MCL) and electroluminescence (EL) properties are the quest for sensing and optoelectronic applications. We report on the synthesis of a new tailor-made luminogen, 1,2-bis(4-(1-([1,1'-biphenyl]-4-yl)-2,2-diphenylvinyl)phenyl)-1,2-diphenylethene (TPE 5), using Suzuki coupling reaction with high yield. An aggregation-induced emission (AIE) active complex TPE 5 forms supramolecular spherical aggregates at the air-water interface of a Langmuir trough. As a consequence, a large enhancement of luminescence is obtained from the mono- and multilayer Langmuir-Blodgett films of TPE 5 owing to the AIE effect. The luminogen TPE 5 exhibits a reversible MCL response, displaying photoluminescence switching due to change in the crystalline states under external stimuli. The unique feature of luminescence enhancement upon aggregate formation is utilized for the fabrication of light-emitting diodes with low threshold voltage using supramolecular aggregates as the active layer. This work demonstrates an efficient strategy for obtaining controlled supramolecular aggregates of AIEgen with a potential in the dual applications of MCL and EL.

Detection and Monitoring of Amyloid Fibrillation Using a Fluorescence "Switch-On" Probe.

Amyloid protein fibrillation is associated with a variety of neurodegenerative and other diseases, and their efficient detection and monitoring can greatly advance early diagnosis and therapy. Herein, we report a fluorescent "switch-on" probe for the reliable detection and monitoring of amyloid fibrils. The probe consists of a peptide component for binding with amyloid structure and a color component with an aggregation-induced green emission property. This probe is nonfluorescent in the presence of amyloid forming monomer protein/peptide, but fluorescence "switch-on" occurs after binding with amyloid fibrils. Compared to conventionally used thioflavin T, this probe offers a high signal-to-noise ratio, which is unaffected by the quencher ion/nanoparticle. The proposed new probe has been used for the detection and monitoring of amyloid fibrils produced by a wide variety of amyloid protein/peptides and can be extended for in vitro diagnostic applications.

Planar-rotor architecture based pyrene-vinyl-tetraphenylethylene conjugated systems: photophysical properties and aggregation behavior.

Four pyrene-vinyl-tetraphenylethylene based conjugated materials were synthesized and characterized by FT-IR, NMR, and mass spectroscopy. The photophysical (including absorption, fluorescence, and fluorescence lifetime) and aggregation properties in tetrahydrofuran were investigated. The photophysical and aggregation behavior depends on the spacer, substituent, and also the architecture (mono or tetra-branched) of the molecule. The vinyl spacer mono-branched compound is aggregation induced emission (AIE) active (αAIE = ∼6). Vinyl spacer tetra-branched compounds are AIE inactive, but their emitting efficiency is good in both solution (Φfl = 63%) phase and in the aggregated state (Φfl = 43%). Phenylvinyl spacer tetra-branched compounds emit light strongly in solution (Φfl = 92%), but not in the aggregated state (Φfl = 8%). They are shown to be thermally stable and emit light in the green region (500-550 nm). The results of cyclic voltammetry measurements of these materials showed irreversible oxidation waves, and have high HOMO energy levels (-5.66 to -5.53 eV).