Search

A Cu–Fe bimetallic hydrogel (2-QF-CuFe-G) was constructed through a simple method. The 2-QF-CuFe-G metallohydrogel possesses excellent peroxidase-like activity to catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. The catalytic mechanism was confirmed by the addition of •OH radical scavenger isopropyl alcohol (IPA), tert-butyl alcohol (TBA) and ˙OH trapping agent terephthalic acid (TA). Remarkably, the resultant blue ox-TMB system can be used to selectively and sensitively detect ascorbic acid (AA) with an LOD of 0.93 μM in the range of 4–36 μM through the colorimetric method. Moreover, the assay based on the 2-QF-CuFe-G metallohydrogel can be successfully applied to detect AA in fresh fruits. [ABSTRACT FROM AUTHOR]

The construction of smart materials, especially white light emitting (WLE) hydrogels with multi-stimuli responsive properties, has received widespread attention from researchers. In this study, a WLE hydrogel was obtained by the in situ doping of Eu3+ and Tb3+ into a blue emission low molecular weight gelator (MPF). Remarkably, the prepared WLE hydrogel possessed excellent stimuli responsiveness to pH, temperature and chemicals, and could be used as a soft thermometer and a selective sensor for Cu2+. The correlated color temperature of the WLE hydrogel was calculated to be 5063 K, suggesting a potential application in cool white light. Moreover, a series of metallohydrogels with different colors were obtained by modulating the ratio of MPF, Eu3+ and Tb3+ or changing the excitation wavelength, which was an excellent candidate to construct soft materials of a full-color system. Additionally, the WLE hydrogel could be used for constructing anti-counterfeiting materials. Therefore, this study provides a new approach for preparing smart WLE hydrogels with multiple functions. [ABSTRACT FROM AUTHOR]

In this study, we have synthesized a facile tyrosine derivative based compound (2-QY), which can act both as a gelator and a reducing agent. 2-QY can assemble to form a functional metallohydrogel (2-QY-Au) in the presence of HAuCl4 under mild conditions (room temperature, aqueous solution, and simple sonication treatment). Au nanoparticles (Au NPs) can be in situ formed and dispersed uniformly in the gel system, which did not require an external reducing agent and a stabilizing agent. The obtained 2-QY-Au NP@metallohydrogel can be used as a catalyst to degrade a variety of dyes, such as methyl orange, methyl green, reactive black 5, reactive orange 16, and p-nitrophenol. In particular, it exhibits excellent catalytic activity towards degradation of methylene blue in the presence of NaBH4, with a kapp value (13.23 ± 0.21 s−1) higher than those of most of the reported catalysts in the literature. Moreover, 2-QY-Au NPs have good biocompatibility and exhibit antibacterial activity against E. coli and B. subtilis. Therefore, the 2-QY-Au NP@metallohydrogel could be used as an effective catalyst for the degradation of pollution containing organic dyes, as well as for potential applications in the biomedical field. [ABSTRACT FROM AUTHOR]

3-(3,5-Dicarboxylphenyl)-5-(4-carboxylphenyl)-1,2,4-triazole (H3DBPT) as a ligand was used to synthesize four porous anionic lanthanide-based metal–organic frameworks {[Me2NH2][Ln3L3(HCOO)]·7DMF}n (Ln-MOFs, Ln = Gd, Tb, Ho, Dy, L = H3DBPT) under solvothermal reaction conditions. Single-crystal X-ray diffraction reveals that the four Ln-MOFs are isostructural and belong to the monoclinic C2/m space group. Three Ln(III) ions are connected through ten carboxylic groups to form a trinuclear [Ln3(COO)10] SBU. The SBU polyhedra share edges with each other generating a 1D inorganic chain along the a-axis, and the chains are further connected by the L3− ligands to construct the final 3D framework with tunnels parallel to the a-axis. The luminescence intensity of the Tb-MOF can be modulated using small molecule organic solvents, and the Tb-MOF exhibits significant quenching in nitrobenzene, which indicates that the Tb-MOF is a potential luminescent sensing material for nitro explosives. Furthermore, the Gd-MOF after desolvation exhibits potential for industrially important C2H2/CH4 and CO2/CH4 separation. The highly selective adsorption of C2H2 and CO2 over CH4 might be attributed to the synergistic interplay of the tunnels, the functional active sites such as open metal sites and the Lewis basic nitrogen atoms on the tunnel surface. [ABSTRACT FROM AUTHOR]

Redox cyclings between mono-/di-valent copper oxidation states occur in electron transfer reactions that underlie their biological functions. We report herein a dual channel fluorescent nanoprobe for the detection of mono- and di-valent copper ions. The probe, BSA-CDs@RBH/BCS, is designed by decorating carbon dots (CDs) on BSA encapsulated rhodamine hydrazide (RBH) and conjugating with bathocuproine disulfonate (BCS). Cu2+ catalyzes the hydrolysis of RBH, and the formed rhodamine B (RhB) shows emission at λex/λem = 360/575 nm which ensures Cu2+ detection. BSA reduces Cu2+ to Cu+ and the BCS–Cu+ chelate shows emission at λex/λem 360/450 nm which ensures Cu+ assay. Thus, the dual-channel fluorescence enables speciation of Cu2+ and Cu+. [ABSTRACT FROM AUTHOR]

A new hybrid hydrogel was constructed by in situ forming silver nanoparticles (Ag NPs) within the 3D network of a hydrogel based on a tryptophan derivative containing a phenylcarbinol side group (HAIP), which was triggered by natural light, without the need of UV-irradiation or the addition of capping reagents. Remarkably, in addition to excellent thixotropy and injectability, the hybrid Ag NPs–HAIP hydrogel exhibits broad antibacterial activities without cell cytotoxicity, which makes it a potential candidate for various biomedical applications. [ABSTRACT FROM AUTHOR]

Inspired by the structural features of native peroxidases, an artificial peroxidase was rationally designed using F43Y myoglobin with a Tyr-heme cross-link by further introduction of key residues, including both a distal Arg and a Trp close to the heme group, which exhibits an enhanced peroxidase activity similar to the most efficient native horseradish peroxidase. This study provides a simple approach for design of artificial heme enzymes by the combination of catalytic elements of native enzymes with the post-translational modifications of heme proteins. [ABSTRACT FROM AUTHOR]

Photothermal therapy following microscopic temperature detection can avoid overheating effects or insufficient heating, and thus improve therapeutic efficacy. In this study, biocompatible dual-functional nanoparticles (NPs) are constructed from polypyrrole (PPy) and rhodamine B (RB) by a one-step modified polymerization method. The polypyrrole serves as a photothemal agent, and rhodamine B acts as a temperature-sensing probe. The polypyrrole–rhodamine B (PPy–RB) NPs possess a high photothermal effect on irradiation by 808 nm laser, and a competent temperature sensitivity for the real-time temperature monitoring based on the emission intensity response of rhodamine B. After acting on HepG2 cells, the PPy–RB NPs can effectively induce cancer cell death, and the microscopic temperature is monitored by fluorescence feedback from rhodamine B during PTT by laser confocal microscopy. Hence, the proposed approach can supply a facile and promising way for the fabrication of effective theranostic nanoplatforms assisted by self-monitoring of cancer therapeutic processes. [ABSTRACT FROM AUTHOR]

Complex RNA–RNA interactions underlie fundamental biological processes. However, a large number of RNA–RNA interactions remain unknown. Most existing methods used to map RNA–RNA interactions are based on proximity ligation, but these strategies also capture a huge amount of intramolecular RNA secondary structures, making it almost impossible to detect most RNA–RNA interactions. To overcome this limitation, we developed an efficient, genome-wide method, Capture Interacting RNA and Deep Sequencing (CIRDES) for in vivo capturing of the RNA interactome. We designed multiple 20-nt CIRDES probes tiling the whole RNA sequence of interest. This strategy obtained high selectivity and low background noise proved by qRT-PCR data. CIRDES enriched target RNA and its interacting RNAs from cells crosslinked by formaldehyde in high efficiency. After hybridization and purification, the captured RNAs were converted to the cDNA library after a highly efficient ligation to a 3′ end infrared-dye-conjugated RNA adapter based on adapter ligation library construction. Using CIRDES, we detected highly abundant known interacting RNA, as well as a large number of novel targets of U6 snRNA. The enrichment of U4 snRNA, which interacts with U6, confirmed the robustness of the identification of the RNA–RNA interaction by CIRDES. These results suggest that the CIRDES is an efficient strategy for genome-wide RNA–RNA interactome analysis. [ABSTRACT FROM AUTHOR]

The first La3+-selective metallohydrogel was constructed by using a facile gelator of a phenylalanine derivative containing an imidazole group, N-(1H-imidazol-4-yl)methylidene-l-phenylalanine, namely La-ImF, which exhibits multi-stimuli responsive properties, including to heat, shearing, pH, etc. Various measurements were also carried out to obtain insights into the mechanism of gelation. Moreover, the La-ImF hydrogel can adsorb toxic dyes, making it a potential candidate for sewage treatment. [ABSTRACT FROM AUTHOR]

Two unusual metal–organic frameworks (MOFs) [CoL(4,4′-bipy)]n(1) and [Ni2L2(bpp)2(H2O)]n(2) (H2L = 1,4-benzenebis(thioacetic acid), bipy = 4,4′-bipy, bpp = 1,3-di(4-pyridyl)propane), have been synthesized and characterized by single-crystal X-ray diffraction. MOF 1can be considered as constructed by 2D layers, which consist of left- and right-handed helical chains and is further linked by L2−ligands into a 3D (4,6)-connected network with a Schläfli symbol of (42·52·62)(42·56·64·73). MOF 2is an unique 3D 8-connected self-penetrating network with a Schläfli symbol of (424·64), in which the dinuclear {Ni2} subunits are linked by L2−ligands to form 2D layers along the acplane and further expanded to a 3D network by bpp ligands. The experimental magnetic susceptibility of MOFs are interpreted with the uniform 1D chain character for 1and the dimeric nickel law for 2, yielding the exchange integral (J) values of −1.32(2) cm−1and 1.32(2) cm−1, respectively. The exchange integrals indicate weak antiferromagnetic interactions in 1, and weak ferromagnetic interactions in 2. [ABSTRACT FROM AUTHOR]

Myoglobin (Mb) was found to undergo self-oxidation when a cysteine residue was engineered at position 67 in the heme distal site. Both the X-ray crystal structure and mass spectrum confirmed the formation of a sulfinic acid (Cys-SO 2 H). Moreover, the self-oxidation could be controlled during protein purification to yield the unmodified form (T67C Mb). Importantly, both T67C Mb and T67C Mb (Cys-SO 2 H) were able to be labeled by chemicals, which provided useful platforms to generate artificial proteins., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Malachite green (MG)-contaminated wastewater resulting from industrialization causes a global problem because of its toxicity and widespread usage. Compared with traditional physical and chemical approaches, biodegradation provides a new route for the degradation of MG. As promising candidates for native enzymes, artificial enzymes have received tremendous attention for potential applications due to unlimited possibilities based on precise design. In this study, we rationally engineered artificial enzymes based on myoglobin (Mb) and neuroglobin (Ngb). We introduced an aspartic acid (H64D mutation) in the heme pocket of Mb. A distal histidine (F43H mutation) was further introduced into H64D Mb to obtain a double mutant of F43H/H64D Mb. Moreover, we used A15C/H64D Ngb as designed recently for comparison studies. The H64D Mb, F43H/H64D Mb, and A15C/H64D Ngb were found to catalyze MG degradation efficiently, with activities much higher than those of native enzymes, such as dye-decolorizing peroxidase and laccase (83-205-fold). The crystal structure of H64D Mb was solved and the interactions of MG and H64D Mb and A15C/H64D Ngb were investigated by using both experimental and molecular docking studies. The biodegradation products of MG were also revealed by ESI-MS analysis. Therefore, these artificial enzymes have potential applications in the biodegradation of MG in textile industries and fisheries., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Inspired by the structural features of native peroxidases, an artificial peroxidase was rationally designed using F43Y myoglobin with a Tyr-heme cross-link by further introduction of key residues, including both a distal Arg and a Trp close to the heme group, which exhibits an enhanced peroxidase activity similar to the most efficient native horseradish peroxidase. This study provides a simple approach for design of artificial heme enzymes by the combination of catalytic elements of native enzymes with the post-translational modifications of heme proteins.

The first La3+-selective metallohydrogel was constructed by using a facile gelator of a phenylalanine derivative containing an imidazole group, N-(1H-imidazol-4-yl)methylidene-l-phenylalanine, namely La-ImF, which exhibits multi-stimuli responsive properties, including to heat, shearing, pH, etc. Various measurements were also carried out to obtain insights into the mechanism of gelation. Moreover, the La-ImF hydrogel can adsorb toxic dyes, making it a potential candidate for sewage treatment.