Improved photocatalytic degradation of rhodamine B by g-C3N4 loaded BiVO4 nanocomposites.

Photocatalytic degradation has emerged as one of the most efficient methods to eliminate toxic dyes from wastewater. In this context, graphitic nitride (g-C3N4) loaded BiVO4 nanocomposites (5 wt% g-CN@BiVO4 and 10 wt% g-CN@BiVO4) have been fabricated by the wet impregnation method, and their efficiency towards photocatalytic removal of rhodamine B have been investigated under visible light irradiation. These hybrid composites have been characterized by XRD, FESEM, HRTEM, EDS-mapping, UV-Vis DRS, DLS, XPS and BET, etc. The HRTEM images revealed that BiVO4 has a decagonal shape covered by a layered nanosheet-like structure of g-C3N4. BET measurements suggest increasing the proportion of g-C3N4 results enhancement of the specific surface area. Among different photocatalysts, the 10 wt% g-C3N4@BiVO4 hybrid possesses the best catalytic activity with 86% degradation efficiency after 60 min of reaction time. The LC-MS studies suggest that the degradation reactions follow the de-ethylation pathway. Even after five cycles, the heterostructure shows only a 14% decrease in photocatalytic activity, confirming its stability. As a result, the binary composite can be regarded as a promising catalyst for the degradation of pollutants due to its ease of preparation, high stability and superior catalytic activity.

A SLC35C2 Transporter-Targeting Fluorescent Probe for the Selective Detection of B Lymphocytes Identified by SLC-CRISPRi and Unbiased Fluorescence Library Screening.

T and B lymphocytes are two major adaptive immune cells in the human defense system. To real-time monitor their diverse functions, a live-cell-selective probe for only one cell type is need to investigate the complex interaction of the immune cells. Herein, a small-molecule probe CDyB for live B cells is developed by an unbiased fluorescence library screening. The cell selectivity was confirmed by multiparametric single-cell analysis using CyTOF. Through a systematic SLC-CRISPRi library screening, the molecular target of CDyB was identified as SLC35C2 transporter based on a gating-oriented live-cell distinction (GOLD) mechanism. The gene expression analysis and knock-out experiments validated that the SLC35C2 transporter was the target for CDyB distinction. Interestingly, when CDyB was applied to study B cell development, the CDyB fluorescence and SLC35C2 expression were positively correlated with the B cell maturation process, and not involved in the T cell development.

Comprehensive and High-throughput Electrolysis of Water and Urea by 3-5†nm Nickel and Copper Coordination Polymers.

Metal-organic coordination polymers (CP) have attracted the scientific attention for electrochemical water oxidation as it has the similar coordination structure like natural photosynthetic coordinated complex. However, the harsh synthesis conditions and bulky nature pose a major challenge in the field of catalysis. Herein, 3-5 nm CP particles synthesized at room temperature using aqueous solutions of Ni2+ /Cu2+ and 2,5-dihydroxyterepthalic acid as precursor were applied for alkaline water and urea electrolysis. The overpotential required is only 300 mV at 10 mA cm-2 by Nano-Ni CP for water oxidation, with turnover frequency (TOF) of 21.4 s-1 which is around 8 times higher than its bulk-counterpart. Overall water and urea splitting were achieved with Nano-Cu (-) ∥ Nano-Ni (+) couple on Ni foam at 1.69 and 1.52 V to achieve 10 mA cm-2 , respectively. High electrochemical surface area (ECSA), high TOF, and enhanced mass diffusion are found to be the key parameters responsible for the state-of-the-art water and urea splitting performances of nano-CPs as compared to their bulk counterparts.

Correction: A combined stretching-tilting mechanism produces negative, zero and positive linear thermal expansion in a semi-flexible Cd(ii)-MOF.

Correction for 'A combined stretching-tilting mechanism produces negative, zero and positive linear thermal expansion in a semi-flexible Cd(ii)-MOF' by Prem Lama et al., Chem. Commun., 2014, 50, 6464-6467.

A Diversity-Oriented Library of Fluorophore-Modified Receptors Constructed from a Chemical Library of Synthetic Fluorophores.

The practical application of biosensors can be determined by evaluating the sensing ability of fluorophore-modified derivatives of a receptor with appropriate recognition characteristics for target molecules. One of the key determinants for successfully obtaining a useful biosensor is wide variation in the fluorophores attached to a given receptor. Thus, using a larger fluorophore-modified receptor library provides a higher probability of obtaining a practically useful biosensor. However, no effective method has yet been developed for constructing such a diverse library of fluorophore-modified receptors. Herein, we report a method for constructing fluorophore-modified receptors by using a chemical library of synthetic fluorophores with a thiol-reactive group. This library was converted into a library of fluorophore-modified adenosine-binding ribonucleopeptide (RNP) receptors by introducing the fluorophores to the Rev peptide of the RNP complex by alkylation of the thiol group. This method enabled the construction of 263 fluorophore-modified ATP-binding RNP receptors and allowed the selection of suitable receptor-based fluorescent sensors that target ATP.

A five-fold interpenetrated metal-organic framework showing a large variation in thermal expansion behaviour owing to dramatic structural transformation upon dehydration-rehydration.

A five-fold interpenetrated metal organic framework (MOF) has been shown to exhibit anomalous thermal expansion due to the combined effect of hinge-like motion and sliding of individual diamondoid networks. Upon dehydration, the MOF undergoes dramatic structural changes, thereby altering its thermal expansion behaviour to a large extent.

Hydration-dependent anomalous thermal expansion behaviour in a coordination polymer.

A coordination polymer is shown to possess anomalous anisotropic thermal expansion. Guest water molecules present in the as-synthesised material can be removed upon activation without loss of crystal singularity. The fully dehydrated form shows considerably different thermal expansion behaviour as compared to the hydrate.

Anomalous Anisotropic Thermal Expansion in a One-Dimensional Coordination Polymer Driven by Conformational Flexibility.

A one-dimensional lithium(I) coordination polymer has been characterized by variable-temperature single-crystal X-ray diffraction and differential scanning calorimetry. This compound possesses an anisotropic packing arrangement that, along with a scissor-like or hingelike movement of the pyridyl ligand side arms, results in an extremely rare combination of positive, negative, and zero thermal expansion. Designing such types of materials and understanding the mechanistic details can facilitate the design of new thermoresponsive materials.

Isolation of a structural intermediate during switching of degree of interpenetration in a metal-organic framework.

A known pillared layered metal-organic framework [Co2(ndc)2(bpy)] is shown to undergo a change in degree of interpenetration from a highly porous doubly-interpenetrated framework (2fa) to a less porous triply-interpenetrated framework (3fa). The transformation involves an intermediate empty doubly-interpenetrated phase (2fa') which has been isolated for the first time for this kind of phenomenon by altering the conditions of activation of the as-synthesized material. Interestingly, all the transformations occur in single-crystal to single-crystal fashion. Changes in degree of interpenetration have not been explored much to date and their implications with regard to the porosity of MOFs still remain largely unknown. The present study not only provides a better understanding of such dramatic structural changes in MOF materials, but also describes an original way of controlling interpenetration by carefully optimizing the temperature of activation. In addition to studying the structural mechanism of conversion from 2fa to 3fa, sorption analysis has been carried out on both the intermediate (2fa') and the triply-interpenetrated (3fa) forms to further explain the effect that switching of interpenetration mode has on the porosity of the MOF material.

In vivo detection of macrophage recruitment in hind-limb ischemia using a targeted near-infrared fluorophore.

Macrophages are an essential component of the immune system and have protective and pathogenic functions in various diseases. Imaging of macrophages in vivo could furnish new tools to advance evaluation of disease and therapies. Critical limb ischemia is a disease in which macrophages have considerable pathogenic roles, and are potential targets for cell-based immunotherapy. We sought to develop a new near-infrared fluorescence (NIRF) imaging probe to target macrophages specifically in vivo in various pathological states, including hind-limb ischemia. We rapidly screened the photostable cyanine-based NIRF library against different blood cell lines. The identified monocyte/macrophage-selective hit was tested in vitro in live-cell labeling assay. Non-invasive NIRF imaging was performed with murine models of paw inflammation by lipopolysaccharide challenge and hind-limb ischemia with femoral artery ligation. in vivo macrophage targeting was further evaluated using intravital microscopy with Csf1r-EGFP transgenic mice and immunofluorescent staining with macrophage-specific markers. We discovered MF800, a Macrophage-specific near-infrared Fluorophore, which showed selective live-cell imaging performance in a panel of cell lines and primary human blood samples. MF800 outperforms the clinically-available NIRF contrast agent ICG for in vivo specificity in paw inflammation and hind-limb ischemia models. We observed a marked overlap of MF800-labeled cells and EGFP-expressing macrophages in intravital imaging of Csf1r-EGFP transgenic mice. In the histologic analysis, MF800-positive cells also expressed the macrophage markers CD68 and CD169. NIRF imaging showcased the potential of using MF800 to understand macrophage behavior in vivo, characterize macrophage-associated diseases, and may help in assessing therapeutic responses in the clinic.

A combined stretching-tilting mechanism produces negative, zero and positive linear thermal expansion in a semi-flexible Cd(II)-MOF.

A novel semi-flexible Cd(II)-MOF has been synthesized and characterized by variable temperature powder and single-crystal X-ray diffraction. The material displays an unusual combination of thermal expansion (TE) i.e. negative, zero and positive, which is an extremely rare finding, especially for metal-organic frameworks as a result of a combined stretching-tilting mechanism.

Live cells imaging using a turn-on FRET-based BODIPY probe for biothiols.

We designed a red-emitting turn-on FRET-based molecular probe 1 for selective detection of cysteine and homocysteine. Probe 1 shows significant fluorescence enhancement after cleavage of the 2, 4-dinitrobenzensulfonyl (DNBS) unit from the fluorophore upon thiols treatment. The precursor of probe 1, BNM153, is a moderate quantum yield FRET dye which contributes a minimum emission leakage from its donor part. We synthesized this assembly by connecting a low quantum yield (less than 1%) BODIPY donor to a high quantum yield BODIPY acceptor via a 1, 3-triazine bridge system. It is noteworthy that the majority of the non-radiative energy loss of donor (BDN) was converted to the acceptor (BDM)'s fluorescence output with minimum leaks of donor emission. The fluorescence sensing mechanism of probe 1 was illustrated by fluorescence spectroscopy, kinetic measurements, HPLC-MS analysis and DFT calculations. Probe 1 is pH-independent at the physiological pH range. Finally, live cells imaging demonstrated the utility of probe 1 as a biosensor for thiols.

Multiplexing SERS nanotags for the imaging of differentiated mouse embryonic stem cells (mESC) and detection of teratoma in vivo.

Herein, we report fifty four membered, a new set of novel NIR Raman reporters and CyRLA-572 has been selected to be the best among them considering the signal intensity and stability. This new reporter molecule is an excellent partner with our in house Raman reporters (Cy7LA and Cy7.5LA). These three NIR Raman reporters are adsorbed on the gold nanoparticles to obtain their corresponding unique SERS fingerprints in which three individual characteristic peaks are capable to multiplex among them. These multiplexed Raman reporters are applied to develop biocompatible and specific targeting SERS nanotags after tagging with specific antibodies. These multiplex targeted SERS nanotags are applied to detect three targeting receptors in differentiated mouse embryonic stem cells (mESCs) consisting three germ layers such as ectoderm, mesoderm and endoderm. After successful recognition of cells by SERS techniques, we detect simultaneously three germ layers in teratoma which is a monster tumor formed from mESC cells in animal xenograft model.

Biocompatible surface-enhanced Raman scattering nanotags for in vivo cancer detection.

The advancement of surface-enhanced Raman scattering (SERS) is significantly increasing as an ultra-sensitive sensing technology in biomedical research. In this review, we focus on the most recent developments of biocompatible nanoprobes for cancer research. First, we discuss coating approaches to enhance the biocompatibility of SERS substrate and Raman reporters. Furthermore, interesting ligands such as antibodies, aptamers and polypeptides are attached to the surface of nanotags for targeting the cancerous cells in vitro. The unique multiplexing capabilities of the SERS technique have been applied for simultaneous multiple target recognition. Finally, these noninvasive, ultrasensitive tools are mostly highlighted for in vivo tumor detection. Potential application of SERS nanotags in therapeutic study and the possibility of SERS nanotags in biomedical applications are outlined briefly in this review.

Direct crystallographic observation of catalytic reactions inside the pores of a flexible coordination polymer.

A new flexible porous coordination polymer (PCP), {[Gd(2)(L)(3)(dmf)(4)]·4DMF·3H(2)O}(n) (1), was synthesized under solvothermal condition by reacting [Gd(NO(3))(3)]·6H(2)O with the ligand 2,6,2',6'-tetranitro-biphenyl-4,4'-dicarboxylic acid (H(2)L). Compound 1 had a 3D coordination polymeric structure with two types of 1D channels (A and B) that were occupied by DMF and water molecules. When crystals of 1 were separately exposed to vapors of various aromatic aldehydes, either the lattice or both the lattice and metal-bound solvent molecules were replaced by aldehyde molecules. The aldehyde molecules inside the pores spontaneously underwent cyanosilylation and Knoevenagel condensation reactions upon exposure to vapors of trimethylsilyl cyanide and malononitrile, respectively. These reactions took place at ambient temperature and pressure. Moreover, both the reactants and the products translocated from one cavity to another. The products that occupied the cavity were expunged upon exposure to the vapors of an aldehyde. Because crystallinity was maintained during these chemical transformations, direct crystallographic observation was possible. Herein, we showed that confinement of the reactants inside the void spaces of the PCP led to the products; we also assessed catalytic activities of this PCP in bulk quantities.

Domino imino-aldol-aza-Michael reaction: one-pot diastereo- and enantioselective synthesis of piperidines.

Addition of α-arylmethylidene- or α-alkylidene-ß-keto ester enolate to N-activated aldimines via the imino aldol pathway followed by intramolecular aza-Michael reaction in a domino fashion has been developed, and a highly diastereoselective route to substituted piperidines is reported. Enantiopure piperidines are synthesized from chiral sulfinyl imines. Formation and the observed stereoselectivity of the products have been rationalized by mechanistic and computational studies.