ZnO-rich CdS-ZIF-8 catalyst for enhanced visible-light photocatalytic degradation of methylene blue

CdS-ZIF-8 photocatalyst was prepared by introducing a ZnO-rich zeolitic imidazolate framework-8 (ZIF-8) during synthesis of CdS by a facile solvothermal method, using ZnO-rich ZIF-8 and cadmium acetate [Cd(Ac)₂] as support and CdS precursor, respectively. The introduction of ZnO-rich ZIF-8 and the photodegradation performance of the catalyst for methylene blue (MB) organic dye were systemically investigated. The CdS-ZIF-8 catalysts were also characterized using X-ray diffraction analysis, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy, N₂ adsorption–desorption measurements, Fourier-transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV–Vis) diffuse reflectance spectroscopy (DRS), and photoluminescence spectroscopy. The results indicated that CdS-ZIF-8 contained ZIF-8, CdS, and ZnO phases. The CdS in CdS-ZIF-8 catalysts exhibited smaller particle size compared with pure CdS. Furthermore, compared with pure CdS, CdS-ZIF-8-30 with introduction of ZnO-rich ZIF-8 exhibited higher surface area (77.3 m²/g) and pore volume (0.103 cm³/g). EDX and FT-IR results suggested that a CdS/ZnO heterostructure was formed, which effectively reduced recombination of photogenerated electron–hole pairs. Radical trapping experimental data and band edge position analysis revealed that Z-scheme behavior also played a role in the system. Relying on the combined effect of their structure, the photodegradation efficiency of all the CdS-ZIF-8 catalysts was obviously superior to that of pure CdS for degradation of MB under visible-light irradiation. Photodegradation results illustrated that CdS-ZIF-8 with introduction of 30 mg ZnO-rich ZIF-8 (denoted as CdS-ZIF-8-30) exhibited optimal photodegradation activity.     

Photo-responsive nanoparticles for β-lapachone delivery in vitro

We reported a one-step encapsulation of indocyanine green (ICG) in ZIF-8 nanoparticles (NPs). The as-prepared ICG@ZIF-8 NPs possess an absorption band in the near infrared region and have the good photothermal conversion efficiency.     

CO<Subscript>2</Subscript>-responsive Polymeric Fluorescent Sensor with Ultrafast Response

Abstract Response speed is one of the most important evaluation criteria for CO₂ sensors. In this work, we report an ultrafast CO₂ fluorescent sensor based on poly[oligo(ethylene glycol) methyl ether methacrylate]-b-poly[N,N-diethylaminoethyl methacrylate-r-4-(2-methylacryloyloxyethylamino)-7-nitro-2,1,3-benzoxadiazole] [POEGMA-b-P(DEAEMA-r-NBDMA)], in which DEAEMA units act as the CO₂-responsive segment and 4-nitrobenzo-2-oxa-1,3-diazole (NBD) is the chromophore. The micelles composed of this copolymer could disassemble in 2 s upon CO₂ bubbling, accompanying with enhanced fluorescence emission with bathochromic shift. Furthermore, the quantum yield of the NBD chromophore increases with both the CO₂ aeration time and the NBD content. Thus we attribute the fluorescent enhancement to the inhibition of the photo-induced electron transfer between unprotonated tertiary amine groups and NBD fluorophores. The sensor is durable although it is based on “soft” materials. These micellar sensors could be facilely recycled by alternative CO₂/Ar purging for at least 5 times, indicating good reversibility.     

基于硅杂蒽类染料的荧光探针及其应用

近年来,荧光成像技术为人们研究活体细胞及组织内的化学生物学过程提供了有效的研究工具,可以无损、实时、原位地以高时空分辨率实现对目标物进行生物荧光成像与分析。荧光成像技术在生物学、环境监测、临床诊断和药物发现等诸多研究领域发挥着越来越重要的作用。生物荧光成像技术的最新进展对发展新型小分子荧光染料及探针提出了更高的要求。激发和发射波长位于近红外光区（600~900 nm）的荧光染料及探针由于具有光毒性低、生物分子自发荧光干扰小、光散射低、组织穿透能力强等优点,非常适合用于生物荧光成像领域。通过将罗丹明分子中O桥原子用Si代替,得到了一类新型的探针分子--硅杂蒽类荧光探针。这类染料分子在保留了氧杂蒽荧光染料优越的光学性质的同时,光谱发生明显红移,满足了近红外荧光检测的要求,具有良好的生物相容性。本文综述了近年来基于硅杂蒽及其衍生物荧光探针的合成及在金属离子、pH值、小分子、生物酶等检测方面的研究进展,并且简要阐述了基于硅杂蒽类探针分子的识别检测机理以及其在生物成像等方面的应用。     

Discovery of β-Dihydroagarofuran-Type Sesquiterpenoids from the Leaves of Tripterygium wilfordii with Neuroprotective Activities

Nine undescribed dihydro-β-agarofuran sesquiterpenoid derivatives(1—9),along with a known analogue(10),were obtained from the leaves of Tripterygium wilfordii.Their gross structures were determined via extensive spectroscopic data,and the absolute configurations were elucidated by means of single-crystal X-ray diffraction analysis and electron circular dichroism(ECD)techniques,which include ECD exciton chirality,octant rule of saturated cyclohexanone and comparison between the experimental and calculated ECD spectra.All the isolated compounds were tested for their neuroprotective activities against H2O2-induced cell injury in human neuroblastoma SH-SY5Y cells.Compounds 5 and 6 improved cell viability by 16.15%and 15.12%compared with the H2O2 treated group at 25μmol·L^-1,respectively.     

Development and testing of a Frisch-Grid Ionization Chamber for the measurement of low activity of alpha-particle emitters

Journal of Radioanalytical and Nuclear Chemistry - A Frisch-grid Ionization Chamber (FGIC) for the measurement of low activity of alpha-particle emitters has been built. The design and performance...     

HSA-Lys-161 covalent bound fluorescent dye for in vivo blood drug dynamic imaging and tumor mapping

The specific combination of human serum albumin and fluorescent dye will endow superior performance to a coupled fluorescent platform for in vivo fluorescence labeling. In this study, we found that lysine-161 in human serum albumin is a covalent binding site and could spontaneously bind a ketone skeleton quinoxaline–coumarin fluorescent dye with a specific turn-on fluorescence signal for the first time. Supported by the abundant drug binding domains in human serum albumin, drugs such as ibuprofen, warfarin and clopidogrel could interact with the fluorescent dye labeled human serum albumin to feature a substantial enhancement in fluorescence intensity (6.6-fold for ibuprofen, 4.5-fold for warfarin and 5-fold for clopidogrel). The drug concentration dependent fluorescence intensity amplification realized real-time, in situ blood drug concentration monitoring in mice, utilizing ibuprofen as a model drug. The non-invasive method avoided continuous blood sample collection, which fundamentally causes suffering and consumption of experimental animals in the study of pharmacokinetics. At the same time, the coupled fluorescent probe can be efficiently enriched in tumors in mice which could map a tumor with a high-contrast red fluorescence signal and could hold great potential in clinical tumor marking and surgical resection.

HSA lysine-161 covalent bound quinoxaline–coumarin based fluorescent dye realized in situ blood drug concentration monitoring and tumor visualization.     

Role of Tryptophan in the Active Site of Plant Esterase: Chemical Modification and Fluorometric Studies

Plant esterase extracted from wheat flour play key roles in the spectrophotometric detection of organophosphorus compounds (OPs) for food safety and human health. The purpose of the present study was to investigate the role of tryptophan residues in the activity and structure of plant esterase by chemical modification and fluorometric studies. Active site characterization of purified plant esterase showed the involvement of tryptophan in the catalytic activity. Only one was essential for the enzyme activity by the Tsou’s analysis. Substrate protection experiments further confirmed that the tryptophan residue was located at the substrate-binding site. Fluorescence quenching studies elucidated that the tryptophan residues were largely exposed to the solvent, and a smaller fraction of the surface tryptophan residues had electropositively charged amino acids around them. Experimental results obtained here are expected to promote the applications of plant esterase in OPs detection. Further confirmation of the existence of other critical residues and detailed explanation of their functions were also required for the elucidation of the mechanism involved in the detection of OPs.     

Determination of pseudo‐ginsenoside GQ in human plasma by high performance liquid chromatography–tandem mass spectrometry

A specific, sensitive and rapid method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC‐MS/MS) was developed for the determination of pseudo‐ginsenoside GQ in human plasma. Liquid–liquid extraction was used to isolate the analyte from biological matrix followed by injection of the extracts onto a C₈ column with isocratic elution. Detection was carried out on a triple quadrupole tandem mass spectrometer (API‐4000 system) in multiple reaction monitoring mode using negative electrospray ionization. The mobile phase consisted of methanol–10 mm ammonium acetate (90:10, v/v) and the flow rate was 0.3 mL/min. The method was validated over the concentration range of 5.0–5000.0 ng/mL for plasma. Inter‐ and intra‐day precisions (relative standard deviation) were all within 15% and the accuracy (relative error) was ≤9.4%. The lower limit of quantitation was 5.0 ng/mL. The pseudo‐ginsenoside GQ was stable after 8 h at room temperature, 24 h at autosampler and three freeze–thaw cycles (from ?30 to 25 °C). The method was successfully applied to the pharmacokinetic study of pseudo‐ginsenoside GQ in healthy Chinese volunteers. Copyright © 2013 John Wiley & Sons, Ltd.