Visualization 2: Topological effects in anisotropy-induced nano-fano resonance of a cylinder

The synchronous resonance along the change of birefringence near quadrupole mode. Originally published in Optics Letters on 01 September 2015 (ol-40-17-4162

Solid-Phase Synthesis of Highly Fluorescent Nitrogen-Doped Carbon Dots for Sensitive and Selective Probing Ferric Ions in Living Cells

Carbon quantum dots (C-Dots) have drawn extensive attention in recent years due to their stable physicochemical and photochemical properties. However, the development of nitrogen-doped carbon quantum dots (N-doped C-Dots) is still on its early stage. In this paper, a facile and high-output solid-phase synthesis approach was proposed for the fabrication of N-doped, highly fluorescent carbon quantum dots. The obtained N-doped C-Dots exhibited a strong blue emission with an absolute quantum yield (QY) of up to 31%, owing to fluorescence enhancement effect of introduced N atoms into carbon dots. The strong coordination of oxygen-rich groups on N-doped C-Dots to Fe³⁺ caused fluorescence quenching via nonradiative electron-transfer, leading to the quantitative detection of Fe³⁺. The probe exhibited a wide linear response concentration range (0.01–500 μM) to Fe³⁺ with a detection limit of 2.5 nM. Significantly, the N-doped C-Dots possess negligible cytotoxicity, excellent biocompatibility, and high photostability. All these features are favorable for label-free monitoring of Fe³⁺ in complex biological samples. It was then successfully applied for the fluorescence imaging of intracellular Fe³⁺. As an efficient chemosensor, the N-doped C-Dots hold great promise to broaden applications in biological systems

<i>In Situ</i> Synthesis of Self-Assembled Three-Dimensional Graphene–Magnetic Palladium Nanohybrids with Dual-Enzyme Activity through One-Pot Strategy and Its Application in Glucose Probe

The self-assembled three-dimensional graphene nanohybrids with <i>in situ</i>-formed Fe₃O₄ and Pd nanoparticles on it (3DRGO_Fe₃O₄-Pd) are first synthesized by the one-pot solvothermal method, which have intrinsic peroxidase-like and oxidase-like activity. The catalytic mechanism is analyzed by the electron spin resonance (ESR), fluorescence, and electrochemical methods. The mimic enzyme catalytic activity of 3DRGO_Fe₃O₄-Pd is much higher than those of monometallic loaded nanohybrids and their physical mixture, probably caused by synergistic effect between Pd and Fe₃O₄ nanoparticles. The 3DRGO_Fe₃O₄-Pd nanohybrids was reproducible, stable, and reusable. After 10 cycles, the catalytic activity was still higher than 90%, and the morphology and structure were basically unchanged. Based on its high peroxidase-like activity, especially the enhanced affinity toward H₂O₂, a new colorimetric detection method for reduced glutathione (GSH) and glucose has been designed using H₂O₂ as an intermediary, which provides a simple, sensitive, and selective way to detect urine glucose of diabetes with a wide linear range and low detection limit

Highly selective probes of copper(II) complexes for sulfide detection and cytotoxicity assay

<p>Two probes based on novel Copper(II) complexes were developed in order to obtain H₂S molecular probes with higher selectivity. The molecular structures of the complexes were characterized by ¹H NMR, HRMS, IR and elemental analysis. The interaction of the compounds with biologically important anions and amino acids was determined by UV-vis and Fluorescence titration experiments. Results indicated that the compounds showed the highest binding ability for HS⁻ among studied anions (AcO⁻, H₂PO₄⁻, F⁻, Cl⁻, Br⁻ and I⁻) and amino acids (GSH, HCys and Cys) accompanied by blue shift phenomenon in pure DMSO and aqueous solution. The possible mechanism of host–guest interaction may be that the Copper(II) ion of complex was captured by HS⁻ and free ligand released which showed a remarkable changes in UV-vis absorption. In addition, cytotoxicity of the synthesized compounds was studied on MCF-7 cells. Results indicated that the synthesized compounds had low cytotoxicity over a concentration range of 0–150 µg⋅mL⁻¹, which exhibited that the synthesized probes could be used to detect H₂S <i>in vivo</i>.</p> <p>The probes based on novel copper(II) complexes were synthesized and obtained by the reaction of substituent salicylaldehyde with amine derivatives, and then reacted with Cu(CH₃COO)₂·H₂O, respectively. Investigation on the interference from other species suggested that copper(II) complexes have high selectivity for HS⁻ over other anions (AcO⁻, , F⁻, Cl⁻, Br⁻ and I⁻), followed by the release of the copper ion to give a remarkable increase in UV–VIS absorption in pure DMSO solution and aqueous solution.</p

In Situ Synthesis of MIL-100(Fe) in the Capillary Column for Capillary Electrochromatographic Separation of Small Organic Molecules

Because of the unusual properties of the structure, the metal organic frameworks (MOFs) have received great interest in separation science. However, the most existing methods for the applications of MOFs in separation science require an off-line procedure to prepare the materials. Here, we report an in situ, layer-by-layer self-assembly approach to fabricate MIL-100­(Fe) coated open tubular (OT) capillary columns for capillary electrochromatography. By a controllable manner, the OT capillary columns with a tailored MIL-100­(Fe) coating have been successfully synthesized. The results of SEM, XRD, FT-IR, and ICP-AES indicated that MIL-100­(Fe) was successfully grafted on the inner wall of the capillary. Some neutral, acidic and basic analytes were used to evaluate the performance of the MIL-100­(Fe) coating OT capillary column. Because of the size selectivity of lattice aperture and hydrophobicity of the organic ligands, three types of analytes were well separated with this novel MIL-100­(Fe) coating OT capillary column. For three consecutive runs, the intraday relative standard deviations (RSDs) of migration time and peak areas were 0.4–4.6% and 1.2–6.6%, respectively. The interday RSDs of migration time and peak areas were 0.6–8.0% and 2.2–9.5%, respectively. The column-to-column reproducibility of retention time was in range of 0.6–9.2%. Additionally, the 10 cycles OT capillary column (10-LC) could be used for more than 150 runs with no observable changes on the separation efficiency

The Spatiotemporal Role of COX-2 in Osteogenic and Chondrogenic Differentiation of Periosteum-Derived Mesenchymal Progenitors in Fracture Repair

<div><p>Periosteum provides a major source of mesenchymal progenitor cells for bone fracture repair. Combining cell-specific targeted <i>Cox-2</i> gene deletion approaches with <i>in vitro</i> analyses of the differentiation of periosteum-derived mesenchymal progenitor cells (PDMPCs), here we demonstrate a spatial and temporal role for Cox-2 function in the modulation of osteogenic and chondrogenic differentiation of periosteal progenitors in fracture repair. <i>Prx1Cre</i>-targeted <i>Cox-2</i> gene deletion in mesenchyme resulted in marked reduction of intramembraneous and endochondral bone repair, leading to accumulation of poorly differentiated mesenchyme and immature cartilage in periosteal callus. In contrast, <i>Col2Cre</i>-targeted <i>Cox-2</i> gene deletion in cartilage resulted in a deficiency primarily in cartilage conversion into bone. Further cell culture analyses using <i>Cox-2</i> deficient PDMPCs demonstrated reduced osteogenic differentiation in monolayer cultures, blocked chondrocyte differentiation and hypertrophy in high density micromass cultures. Gene expression microarray analyses demonstrated downregulation of a key set of genes associated with bone/cartilage formation and remodeling, namely <i>Sox9</i>, <i>Runx2</i>, <i>Osx</i>, <i>MMP9</i>, <i>VDR</i> and <i>RANKL</i>. Pathway analyses demonstrated dysregulation of the HIF-1, PI3K-AKT and Wnt pathways in Cox-2 deficient cells. Collectively, our data highlight a crucial role for Cox-2 from cells of mesenchymal lineages in modulating key pathways that control periosteal progenitor cell growth, differentiation, and angiogenesis in fracture repair.</p></div

Divinylsulfonamides as Specific Linkers for Stapling Disulfide Bonds in Peptides

A new class of <i>N</i>-phenyl-divinylsulfonamides which can be easily prepared have been successfully developed and utilized as efficient linkers in the field of disulfide bond modification. Functional divinylsulfonamides provide opportunities for the specific introduction of various functionalities, including affinity probes, fluorescent tags, and drugs, into peptides

Dysregulation of the PI3K/AKT and HIF-1pathways in Cox-2 deficient PDMPCs.

<p>Heat maps showing differentially expressed genes associated with the PI3K/AKT (A) and the HIF-1 pathway (B) in micromass cultures in the presence and absence of BMP-2 for seven days. Each column shows the relative gene expression of a sample for the indicated pathway-associated genes. RT-PCR analyses further quantitate the values for the key genes in the HIF-1 pathway at day 1 (white bars) and day 7 (black bars) (C), namely <i>VEGFA</i>, <i>EGLN1</i>, <i>EGLN3</i>, <i>HIF-1a</i> and <i>ANGPT4</i>. * p<0.05, as compared to the control.</p

Red Emission B, N, S-<i>co</i>-Doped Carbon Dots for Colorimetric and Fluorescent Dual Mode Detection of Fe³⁺ Ions in Complex Biological Fluids and Living Cells

Colorimetric and fluorescent dual mode detection methods have gained much attention in recent years; however, it is still desirable to develop new colorimetric and fluorescent dual mode nanosensors with more simple preparation procedures, low cost, and excellent biocompatibility. Herein, a colorimetric and fluorescent nanosensor based on B, N, S-<i>co</i>-doped carbon dots (BNS-CDs) was synthesized by one-step hydrothermal treatment of 2,5-diaminobenzenesulfonic acid and 4-aminophenylboronic acid hydrochloride. Using this nanosensor, a highly sensitive assay of Fe³⁺ in the range of 0.3–546 μM with a detection limit of 90 nM was provided by quenching the red emission fluorescence. It is more attractive that Fe³⁺ can also be visualized by this nanosensor via evident color changes of the solution (from red to blue) under sunlight without the aid of an ultraviolet (UV) lamp. Furthermore, the designed nanosensor can be applied for efficient detection of intracellular Fe³⁺ with excellent biocompatibility and cellular imaging capability, and it holds great promise in biomedical applications

Table_1_Metagenomic identification of pathogens and antimicrobial-resistant genes in bacterial positive blood cultures by nanopore sequencing.xlsx

Nanopore sequencing workflows have attracted increasing attention owing to their fast, real-time, and convenient portability. Positive blood culture samples were collected from patients with bacterial bloodstream infection and tested by nanopore sequencing. This study compared the sequencing results for pathogen taxonomic profiling and antimicrobial resistance genes to those of species identification and phenotypic drug susceptibility using traditional microbiology testing. A total of 37 bacterial positive blood culture results of strain genotyping by nanopore sequencing were consistent with those of mass spectrometry. Among them, one mixed infection of bacteria and fungi was identified using nanopore sequencing and confirmatory quantitative polymerase chain reaction. The amount of sequencing data was 21.89 ± 8.46 MB for species identification, and 1.0 MB microbial strain data enabled accurate determination. Data volumes greater than or equal to 94.6 MB nearly covered all the antimicrobial resistance genes of the bacteria in our study. In addition, the results of the antimicrobial resistance genes were compared with those of phenotypic drug susceptibility testing for Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus. Therefore, the nanopore sequencing platform for rapid identification of causing pathogens and relevant antimicrobial resistance genes complementary to conventional blood culture outcomes may optimize antimicrobial stewardship management for patients with bacterial bloodstream infection.</p