Influence of the substituents of the thiol ligand on the optical properties of AuCu14.

Detailed photophysical processes of two AuCu14 clusters with different substituents (-F or -C(CH3)3) of the thiol ligand were studied in this work. The electronic effect of the substituents led to structural shrinkage, thus enhancing the luminous intensity. The internal conversion (IC) and intersystem crossing (ISC) rates in the AuCu14-C(CH3)3 crystal were slower compared with the AuCu14-F crystal, which was caused by the steric effect.

Filling the gaps in icosahedral superatomic metal clusters.

Chemically modified superatoms have emerged as promising candidates in the new periodic table, in which Au13 and its doped M n Au13- n have been widely studied. However, their important counterpart, Ag13 artificial element, has not yet been synthesized. In this work, we report the synthesis of Ag13 nanoclusters using strong chelating ability and rigid ligands, that fills the gaps in the icosahedral superatomic metal clusters. After further doping Ag13 template with different degrees of Au atoms, we gained insight into the evolution of their optical properties. Theoretical calculations show that the kernel metal doping can modulate the transition of the excited-state electronic structure, and the electron transfer process changes from local excitation (LE) to charge transfer (CT) to LE. This study not only enriches the families of artificial superatoms, but also contributes to the understanding of the electronic states of superatomic clusters.

Staggered Assembly of a Dimeric Au13 Cluster: Impacts on Coupling of Geometric Isomerism.

The specific states of aggregation of metal atoms in sub-nanometer-sized gold clusters are related to the different quantum confinement volumes of electrons, leading to novel optical and electronic properties. These volumes can be tuned by changing the relative positions of the gold atoms to generate isomers. Studying the isomeric gold core and the electron coupling between the basic units is fundamentally important for nanoelectronic devices and luminescence; however, appropriate cases are lacking. In this study, the structure of the first staggered di-superatomic Au25 -S was solved using single-crystal X-ray diffraction. The optical properties of Au25 -S were studied by comparing with eclipsed Au25 -E. From Au25 -E to Au25 -S, changes in the electronic structures occurred, resulting in significantly different optical absorptions originating from the coupling between the two Au13 modules. Au25 -S shows a longer electron decay lifetime of 307.7 ps before populating the lowest triplet emissive state, compared to 1.29 ps for Au25 -E. The experimental and theoretical results show that variations in the geometric isomerism lead to distinct photophysical processes owing to isomerism-dependent electronic coupling. This study offers new insights into the connection between the geometric isomerism of nanosized building blocks and the optical properties of their assemblies, opening new possibilities for constructing function-specific nanomaterials.

High-Efficiency Pure Blue Circularly Polarized Phosphorescence from Chiral N-Heterocyclic-Carbene-Stabilized Copper(I) Clusters.

Circularly polarized luminescence (CPL) materials have attracted considerable attention for their promising applications in encryption, chiral sensing, and three-dimensional (3D) displays. However, the preparation of high-efficiency, pure blue CPL materials remains challenging. In this study, we reported an enantiomeric pair of triangle copper(I) clusters (R/S-Cu3) rigidified by employing chiral N-heterocyclic carbene (NHC) ligands with two pyridine-functionalized wingtips. These chiral clusters emitted pure blue phosphorescence that overlapped with that of the commercial blue phosphor having Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.14, 0.10), and the films exhibited an unprecedented photoluminescence quantum yield (PLQY) of ∼70.0%. Additionally, the solutions showed very bright circularly polarized phosphorescence (CPP) with a dissymmetry factor of ±2.1 × 10-3. The excellent solubility and photostability endowed these pure-blue-emitting chiral clusters with promising applications as pure blue CPP inks for 3D printing white objects, such as precise-atomic-enlarged models of metal clusters and a lovely white stereoscopic "rabbit". The intricate mechanism underlying blue phosphorescence in this small cluster and across various states is elucidated through a comprehensive approach that integrates thorough analysis of luminescence properties, controlled experiments, and theoretical calculations. For the first time, we propose that the dominant high-energy emission center is constituted by delocalized hybrid orbitals over multiple atomic centers, encompassing both the metal and the coordinated atoms. This challenges stereotypical assumptions that the cluster center solely supports low-energy emissions. This work expands the currently limited range of CPP functional materials and provides a new direction for CPP applications involving NHC-stabilized metal clusters.

Carbene-stabilized enantiopure heterometallic clusters featuring EQE of 20.8% in circularly-polarized OLED.

Bright and efficient chiral coinage metal clusters show promise for use in emerging circularly polarized light-emitting materials and diodes. To date, highly efficient circularly polarized organic light-emitting diodes (CP-OLEDs) with enantiopure metal clusters have not been reported. Herein, through rational design of a multidentate chiral N-heterocyclic carbene (NHC) ligand and a modular building strategy, we synthesize a series of enantiopure Au(I)-Cu(I) clusters with exceptional stability. Modulation of the ligands stabilize the chiral excited states of clusters to allow thermally activated delayed fluorescence, resulting in the highest orange-red photoluminescence quantum yields over 93.0% in the solid state, which is accompanied by circularly polarized luminescence. Based on the solution process, a prototypical orange-red CP-OLED with a considerably high external quantum efficiency of 20.8% is prepared. These results demonstrate the extensive designability of chiral NHC ligands to stabilize polymetallic clusters for high performance in chiroptical applications.

Smart Reversible Transformations between Chiral Superstructures of Copper Clusters for Optical and Chiroptical Switching.

Superstructures made from nanoscale clusters with new collective properties are promising in high-tech applications; however, chiral superstructures remain elusive, and the limited intercluster coupling effect at room temperature hampers the tailoring of collective properties. Here, we show that from chiral monomeric copper clusters to two enantiomeric pairs of supercrystals with distinct phases, the absorption band edge red-shifts by over 1.3 eV, with photoluminescence and circularly polarized phosphorescence from visible (572 nm) to near-infrared (NIR, 858 nm). These supercrystals with high NIR quantum yields of up to 45% at room temperature are prototyped for night-vision imaging. In response to solvent and temperature stimuli, chiral supercrystal-to-supercrystal transformations occurred, concomitant with high-contrast optical/chiroptical switching. In situ single-crystal X-ray diffraction (SCXRD), steady-state and time-resolved optical spectroscopy, and response experiments combined with theoretical calculations demonstrate that distance-sensitive intercluster orbital interactions contribute to the exceptional collective optical responses. Such chiral supercrystals built from subnanoscale metal clusters with novel collective chiroptical responses would be useful in the fields of information storage and NIR optical devices.

Identification of Kv4.2 protein complex and modifications by tandem affinity purification-mass spectrometry in primary neurons.

Proteins usually form complexes to fulfill variable physiological functions. In neurons, communication relies on synapses where receptors, channels, and anchoring proteins form complexes to precisely control signal transduction, synaptic integration, and action potential firing. Although there are many published protocols to isolate protein complexes in cell lines, isolation in neurons has not been well established. Here we introduce a method that combines lentiviral protein expression with tandem affinity purification followed by mass-spectrometry (TAP-MS) to identify protein complexes in neurons. This protocol can also be used to identify post-translational modifications (PTMs) of synaptic proteins. We used the A-type voltage-gated K+ channel subunit Kv4.2 as the target protein. Kv4.2 is highly expressed in the hippocampus where it contributes to learning and memory through its regulation of neuronal excitability and synaptic plasticity. We tagged Kv4.2 with the calmodulin-binding-peptide (CBP) and streptavidin-binding-peptide (SBP) at its C-terminus and expressed it in neurons via lentivirus. Kv4.2 was purified by two-step TAP and samples were analyzed by MS. MS identified two prominently known Kv4.2 interacting proteins [dipeptidyl peptidase like (DPPs) and Kv channel-interacting proteins (KChIPs)] in addition to novel synaptic proteins including glutamate receptors, a calcium channel, and anchoring proteins. Co-immunoprecipitation and colocalization experiments validated the association of Kv4.2 with glutamate receptors. In addition to protein complex identification, we used TAP-MS to identify Kv4.2 phosphorylation sites. Several known and unknown phosphorylation sites were identified. These findings provide a novel path to identify protein-protein interactions and PTMs in neurons and shed light on mechanisms of neuronal signaling potentially involved in the pathology of neurological diseases.

Achiral-Core-Metal Change in Isomorphic Enantiomeric Ag12Ag32 and Au12Ag32 Clusters Triggers Circularly Polarized Phosphorescence.

Understanding how the chiral or achiral section in chiral nanostructures contributes to circularly polarized light emission (CPLE) at the atomic level is of fundamental importance. Here, we report two pairs of atomically precise enantiomers of homosilver (R/S-Ag12Ag32) and heterometal (R/S-Au12Ag32) clusters. The geometrical chirality of R/S-Ag12Ag32 arises from the chiral ligand and interface consisting of positive moieties of Ag32(R/S-PS)24. The circular dichroism of R/S-Ag12Ag32 is active, but CPLE-silent. A complete metal change from Ag12 to Au12 in the achiral core section of S2-@M12@S8 engenders isomorphous heterometal R/S-Au12Ag32, which activates CPLE. We further quantify the contributions of achiral and chiral sections and for the first time unveil that heterometal bonding (Au12-Ag32) at the linkage varies the delocalization of orbitals and proportion of achiral and chiral section in electron transition-involved orbitals, thus activating CPLE. Based on these unique atomically precise homochiral metal clusters, our work provides a new insight into the contributions of achiral and chiral sections to the origin of chiroptical response of chiral metal clusters, paving the way to advance the development of CPLE nanoparticles.

Aminal-Linked Porphyrinic Covalent Organic Framework for Rapid Photocatalytic Decontamination of Mustard-Gas Simulant.

Covalent organic frameworks (COFs) are appealing photocatalysts for toxic chemical degradation. Great efforts have been devoted to regulate the photocatalytic performance of COFs by tuning their organic building blocks, but the relationship between COF linkage and photochemical properties has rarely been explored. Herein, we report the synthesis and characterisation of a novel aminal-linked porphyrinic COF, namely Por-Aminal-COF. Por-Aminal-COF (0.25 mol %) showed excellent photocatalytic activity toward the detoxification of the sulfur mustard simulant with a half-life (t1/2 ) of 5 min, which is far lower than that of traditional imine-linked Por-COF (t1/2 =16 min). Transient absorption spectroscopy indicated that the aminal linkages of Por-Aminal-COF facilitated the intersystem crossing process. Thus, Por-Aminal-COF showed higher triplet-state generation efficiency compared with Por-COF, consequently promoting the activation of oxygen molecular to singlet oxygen.

Silver Cluster-Porphyrin-Assembled Materials as Advanced Bioprotective Materials for Combating Superbacteria.

Superbugs are bacteria that have grown resistant to most antibiotics, seriously threating the health of people. Silver (Ag) nanoparticles are known to exert a wide-spectrum antimicrobial property, yet remains challenging against superbugs. Here, Ag clusters are assembled using porphyrin-based linkers and a novel framework structure (Ag9 -AgTPyP) is produced, in which nine-nuclearity Ag9 clusters are uniformly separated by Ag-centered porphyrin units (AgTPyP) in two dimensions, demonstrating open permeant porosity. Ag9 -AgTPyP eliminates over 99.99999% and 99.999% methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa (P. aeruginosa) within 2 h upon visible-light irradiation, which are superior to a majority of bacteria inactivation photocatalysts. The novel-established long-term charge-transfer states from AgTPyP to adjacent Ag9 cluster that has preferential affinity to O2 greatly promote reactive oxygen species (ROS) production efficiency; and its unique framework accelerates the ROS transportation. Personal protective equipment (masks and protective suits) incorporating Ag9 -AgTPyP film also shows excellent performances against superbugs. This superbugs-killing efficiency is unprecedented among silver complexes and porphyrin derivatives. Utilizing efficient photogenerated electrons and holes between metal cluster and linkers can open up new interests of research in photocatalytic areas.

P38 Regulates Kainic Acid-Induced Seizure and Neuronal Firing via Kv4.2 Phosphorylation.

The subthreshold, transient A-type K+ current is a vital regulator of the excitability of neurons throughout the brain. In mammalian hippocampal pyramidal neurons, this current is carried primarily by ion channels comprising Kv4.2 α-subunits. These channels occupy the somatodendritic domains of these principle excitatory neurons and thus regulate membrane voltage relevant to the input-output efficacy of these cells. Owing to their robust control of membrane excitability and ubiquitous expression in the hippocampus, their dysfunction can alter network stability in a manner that manifests in recurrent seizures. Indeed, growing evidence implicates these channels in intractable epilepsies of the temporal lobe, which underscores the importance of determining the molecular mechanisms underlying their regulation and contribution to pathologies. Here, we describe the role of p38 kinase phosphorylation of a C-terminal motif in Kv4.2 in modulating hippocampal neuronal excitability and behavioral seizure strength. Using a combination of biochemical, single-cell electrophysiology, and in vivo seizure techniques, we show that kainic acid-induced seizure induces p38-mediated phosphorylation of Thr607 in Kv4.2 in a time-dependent manner. The pharmacological and genetic disruption of this process reduces neuronal excitability and dampens seizure intensity, illuminating a cellular cascade that may be targeted for therapeutic intervention to mitigate seizure intensity and progression.

Activity-dependent isomerization of Kv4.2 by Pin1 regulates cognitive flexibility.

Voltage-gated K+ channels function in macromolecular complexes with accessory subunits to regulate brain function. Here, we describe a peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1)-dependent mechanism that regulates the association of the A-type K+ channel subunit Kv4.2 with its auxiliary subunit dipeptidyl peptidase 6 (DPP6), and thereby modulates neuronal excitability and cognitive flexibility. We show that activity-induced Kv4.2 phosphorylation triggers Pin1 binding to, and isomerization of, Kv4.2 at the pThr607-Pro motif, leading to the dissociation of the Kv4.2-DPP6 complex. We generated a novel mouse line harboring a knock-in Thr607 to Ala (Kv4.2TA) mutation that abolished dynamic Pin1 binding to Kv4.2. CA1 pyramidal neurons of the hippocampus from these mice exhibited altered Kv4.2-DPP6 interaction, increased A-type K+ current, and reduced neuronal excitability. Behaviorally, Kv4.2TA mice displayed normal initial learning but improved reversal learning in both Morris water maze and lever press paradigms. These findings reveal a Pin1-mediated mechanism regulating reversal learning and provide potential targets for the treatment of neuropsychiatric disorders characterized by cognitive inflexibility.

Identification of circRNA-miRNA networks for exploring an underlying prognosis strategy for breast cancer.

Aim: Circular RNAs (circRNAs) still have many potential functions in the process of tumor development that are not completely understood. The study aims to explore novel circRNAs and their mechanisms of action in breast cancer (BCa). Materials & methods: A combination strategy of RNA-sequencing (RNA-seq) technique, quantitative real-time PCR and bioinformatic analysis was employed to identify the potential mechanisms involving differentially expressed circRNAs in the serum exosomes and tissues of BCa patients. Results: The expression levels of hsa-circRNA-0005795 and hsa-circRNA-0088088 were significantly different both in serum exosomes and tissues and might function as competing endogenous RNAs and play vital roles in BCa development. Conclusion: We constructed two circRNA-miRNA networks and provided new insight into the prognosis and therapy of BCa using circRNAs from serum exosomes.

The emerging role of circular RNAs in breast cancer.

Breast cancer (BCa) is one of the most frequently diagnosed cancers and leading cause of cancer deaths among females worldwide. Circular RNAs (circRNAs) are a new class of endogenous regulatory RNAs characterized by circular shape resulting from covalently closed continuous loops that are capable of regulating gene expression at transcription or post-transcription levels. With the unique structures, circRNAs are resistant to exonuclease RNase R and maintain stability more easily than linear RNAs. Recently, an increasing number of circRNAs are discovered and reported to show different expression in BCa and these dysregulated circRNAs were correlated with patients' clinical characteristics and grade in the progression of BCa. CircRNAs participate in the bioprocesses of carcinogenesis of BCa, including cell proliferation, apoptosis, cell cycle, tumorigenesis, vascularization, cell invasion, migration as well as metastasis. Here we concentrated on biogenesis and function of circRNAs, summarized their implications in BCa and discussed their potential as diagnostic and therapeutic targets for BCa.

A novel bungarotoxin binding site-tagged construct reveals MAPK-dependent Kv4.2 trafficking.

Kv4.2 voltage-gated K+ channel subunits, the primary source of the somatodendritic A-type K+ current in CA1 pyramidal neurons of the hippocampus, play important roles in regulating dendritic excitability and plasticity. To better study the trafficking and subcellular distribution of Kv4.2, we created and characterized a novel Kv4.2 construct encoding a bungarotoxin binding site in the extracellular S3-S4 linker region of the α-subunit. When expressed, this construct can be visualized in living cells after staining with rhodamine-conjugated bungarotoxin. We validated the utility of this construct by visualizing the spontaneous internalization and insertion of Kv4.2 in HEK 293T cells. We further report that Kv4.2 colocalized with several endosome markers in HEK 293T cells. In addition, Kv4.2 internalization is significantly impaired by mitogen-activated protein kinase (MAPK) inhibitors in transfected primary hippocampal neurons. Therefore, this newly developed BBS-Kv4.2 construct provides a novel and powerful tool for studying surface Kv4.2 channel localization and trafficking.

Circular RNA circASS1 is downregulated in breast cancer cells MDA-MB-231 and suppressed invasion and migration.

AIM: The study aimed to investigate the role of circular RNA circASS1 in breast cancer cells. MATERIALS & METHODS: Circular RNAs microarray expression profile were analyzed in MCF-7, MDA-MB-231, and qRT-PCR and western blotting were used to quantify expression of circASS1 and its parental gene ASS1. Wound healing, migration and invasion assay were performed. Luciferase assay system was used to detect harbored miRNA. RESULTS: CircASS1 in MDA-MB-231 is downregulated comparing to MCF-7, and overexpression of circASS1 could suppress invasion and migration. While silence, it could promote invasion and migration. MiR-4443 functioning as a tumor promoter gene could be captured by circASS1. ASS1 is upregulated in loss-of-function experiments, while downregulated in gain-of-function experiments. CONCLUSION: CircASS1 suppresses invasion and migration capacity of breast cancer cells and harbored miR-4443.

MiR-29a: a potential therapeutic target and promising biomarker in tumors.

MiRNAs, small non-coding RNA molecules, were recognized to be associated with the incidence and development of diverse neoplasms. MiRNAs were small non-coding RNAs that could regulate post-transcriptional level by binding to 3'-UTR of target mRNAs. Amongst which, miR-29a was demonstrated that it had significant impact on oncogenicity in various neoplasms through binding to critical genes which enhanced or inhibited the progression of cancers. MiR-29a participated in kinds of physiological and pathological processes, including virus replication, cell proliferation, differentiation, apoptosis, fibrosis, angiogenesis, tumorigenicity, metastasis, drug-resistance, and so on. According to its sufficient sensitivity and specificity, many studies showed that miR-29a might serve as a potential therapeutic target and promising biomarker in various tumors. In this review, we discussed the functions of miR-29a and its potential application in the diagnosis, treatment and stages of carcinoma, which could provide additional insight to develop a novel therapeutic strategy.

FRMPD4 mutations cause X-linked intellectual disability and disrupt dendritic spine morphogenesis.

FRMPD4 (FERM and PDZ Domain Containing 4) is a neural scaffolding protein that interacts with PSD-95 to positively regulate dendritic spine morphogenesis, and with mGluR1/5 and Homer to regulate mGluR1/5 signaling. We report the genetic and functional characterization of 4 FRMPD4 deleterious mutations that cause a new X-linked intellectual disability (ID) syndrome. These mutations were found to be associated with ID in ten affected male patients from four unrelated families, following an apparent X-linked mode of inheritance. Mutations include deletion of an entire coding exon, a nonsense mutation, a frame-shift mutation resulting in premature termination of translation, and a missense mutation involving a highly conserved amino acid residue neighboring FRMPD4-FERM domain. Clinical features of these patients consisted of moderate to severe ID, language delay and seizures alongside with behavioral and/or psychiatric disturbances. In-depth functional studies showed that a frame-shift mutation, FRMPD4p.Cys618ValfsX8, results in a disruption of FRMPD4 binding with PSD-95 and HOMER1, and a failure to increase spine density in transfected hippocampal neurons. Behavioral studies of frmpd4-KO mice identified hippocampus-dependent spatial learning and memory deficits in Morris Water Maze test. These findings point to an important role of FRMPD4 in normal cognitive development and function in humans and mice, and support the hypothesis that FRMPD4 mutations cause ID by disrupting dendritic spine morphogenesis in glutamatergic neurons.

Behavioral and Neurochemical Phenotyping of Mice Incapable of Homer1a Induction.

Immediate early and constitutively expressed products of the Homer1 gene regulate the functional assembly of post-synaptic density proteins at glutamatergic synapses to influence excitatory neurotransmission and synaptic plasticity. Earlier studies of Homer1 gene knock-out (KO) mice indicated active, but distinct, roles for IEG and constitutively expressed Homer1 gene products in regulating cognitive, emotional, motivational and sensorimotor processing, as well as behavioral and neurochemical sensitivity to cocaine. More recent characterization of transgenic mice engineered to prevent generation of the IEG form (a.k.a Homer1a KO) pose a critical role for Homer1a in cocaine-induced behavioral and neurochemical sensitization of relevance to drug addiction and related neuropsychiatric disorders. Here, we extend our characterization of the Homer1a KO mouse and report a modest pro-depressant phenotype, but no deleterious effects of the KO upon spatial learning/memory, prepulse inhibition, or cocaine-induced place-conditioning. As we reported previously, Homer1a KO mice did not develop cocaine-induced behavioral or neurochemical sensitization within the nucleus accumbens; however, virus-mediated Homer1a over-expression within the nucleus accumbens reversed the sensitization phenotype of KO mice. We also report several neurochemical abnormalities within the nucleus accumbens of Homer1a KO mice that include: elevated basal dopamine and reduced basal glutamate content, Group1 mGluR agonist-induced glutamate release and high K+-stimulated release of dopamine and glutamate within this region. Many of the neurochemical anomalies exhibited by Homer1a KO mice are recapitulated upon deletion of the entire Homer1 gene; however, Homer1 deletion did not affect NAC dopamine or alter K+-stimulated neurotransmitter release within this region. These data show that the selective deletion of Homer1a produces a behavioral and neurochemical phenotype that is distinguishable from that produced by deletion of the entire Homer1 gene. Moreover, the data indicate a specific role for Homer1a in regulating cocaine-induced behavioral and neurochemical sensitization of potential relevance to the psychotogenic properties of this drug.