Surface engineering of Al2O3 nanotubes by ureasolysis method for activating persulfate degradation of antibiotics.

Though ecofriendly, pure Al2O3 has never been used for activation of peroxodisulfate (PDS) to degrade pollutants. We report the fabrication of Al2O3 nanotubes by ureasolysis method for efficient activating PDS degradation of antibiotics. The fast ureasolysis in aqueous AlCl3 solution produces NH4Al(OH)2CO3 nanotubes, which are calcined to porous Al2O3 nanotubes, and the release of ammonia and carbon dioxide engineers the surface features of large surface area, numerous acidic-basic sites and suitable Zeta potentials. The synergy of these features facilitates the adsorption of the typical antibiotics ciprofloxacin and PDS activation, which is proved by experiment results and density functional theory simulation. The proposed Al2O3 nanotubes can catalyze 92-96% degradation of 10 ppm ciprofloxacin within 40 min, with chemical oxygen demand removal of 65-66% in aqueous, and 40-47% in whole including aqueous and catalysts. Ciprofloxacin at high concentration, other fluoroquinolones and tetracycline can also be effectively degraded. These data demonstrate the Al2O3 nanotubes prepared by the nature-inspired ureasolysis method has unique features and great potentials for antibiotics degradation.

Cr3+-ZnGa2O4@Pt for Light-Triggered Dark Catalytic Regeneration of Nicotinamide Coenzymes without Other Electron Mediators.

Photocatalysts for regeneration of reduced nicotinamide adenine dinucleotide (NADH) usually work with continuous lighting and electron mediators, which causes impracticability under dark conditions, risk of NADH reoxidation, and complex separation. To solve these problems, we present a new catalyst of tiny Pt nanoparticles photodeposited on chromium-doped zinc gallate (CZGO@Pt). Upon being light-triggered, the photogenerated electrons are stored in the traps of CZGO and then gradually released and transferred by Pt to directly reduce NAD+ after stoppage of illumination. Three lighting modes are compared to demonstrate the feasibility and advantage of this light-triggered dark catalysis. Within 4 h of reaction, the in-the-dark NADH yield reaches 75.0% under prelighting CZGO@5%Pt and it reaches 80.0% under prelighting CZGO@5%Pt and triethanolamine (TEOA). However, the NADH yield is only 53.5% under continuous lighting of CZGO@5%Pt, TEOA, and NAD+. Consequently, the light-triggered dark catalytic regeneration of NADH not only saves energy and operates easily but also significantly elevates the NADH yield. It thus would secure wide interests and applications in places where no light or only intermittent light is available.

Porous Ga2 O3 Nanotubes Derived from Urease-Mediated Interfacially-Grown NH4 Ga(OH)2 CO3 for High-Efficient Hydrogen Evolution.

The authors proposed a novel template-free strategy, urease-mediated interfacial growth of NH4 Ga(OH)2 CO3 nanotubes at 20-50 °C, to fabricate the porous Ga2 O3 nanotubes. The subtlety of the proposed strategy is all the products from urea enzymolysis are utilized in formation of NH4 Ga(OH)2 CO3 precipitates, and the key for interfacial growth of NH4 Ga(OH)2 CO3 nanotubes is the dynamic match between the rate of CO2 bubble fusion and NH4 Ga(OH)2 CO3 precipitation. The proposed strategy works well for the doped porous Ga2 O3 nanotubes. As a proof-of-concept, the porous ß-Ga2 O3 and ß-Ga2 O3 :Cr0.001 nanotubes are used as photocatalysts or co-catalysts with Pt, for H2 evolution from water splitting. The H2 evolution rate of porous ß-Ga2 O3 nanotubes reach 39.3 mmol g-1 h-1 with solar-to-hydrogen (STH) conversion efficiency of 2.11% (Hg lamp) or 498 µmol g-1 h-1 with STH of 0.03% (Xe lamp) respectively, both about 3 times of ß-Ga2 O3 nanoparticles synthesized at pH 9.0 without urease. The Cr-doping enhances the in-the-dark H2 evolution rate pre-lighted by Hg lamp, and Pt co-catalysis further elevates the H2 evolution rate, for instance, the H2 evolution rate of Pt-loaded ß-Ga2 O3 :Cr0.001 nanotubes reaches 54.7 mmol g-1 h-1 with STH of 2.94% under continuous lighting of Hg lamp and 1062 µmol g-1 h-1 in-the-dark.

Afterglow Resonance Energy Transfer Inhibition for Fibroblast Activation Protein-α Assay.

Traditional photoluminescence resonance energy transfer (PRET)-based sensors are widely applied, but still suffer from the severe background interference from in situ excitation. The afterglow nature of the persistent luminescence nanoparticles (PLNPs) allows optosensing after the stoppage of in situ illumination, and thus subtly overcomes that interference. We proposed a simple strategy for functionalizing PLNPs for bioanalytical applications and the new afterglow resonance energy transfer (ARET)-based assay for quantitative determination and imaging of fibroblast activation protein-alpha (FAPα) in live cells using Au-decorated Cr3+0.004:ZnGa2O4 as donor and Cy5.5-KGPNQC-SH as acceptor. The ARET between the donor and acceptor quenches the afterglow of the donor, and the cleavage of peptide KGPNQC by FAPα inhibits the ARET and restores the afterglow of the donor. The ARET-based assay of FAPα, with the linear range of 0.1-2.0 mg·L-1 (1.2-22.9 nM), LOD of 11 µg·L-1 (115 pM), and RSD of 3.9% (for 0.5 mg·L-1 FAPα, n = 5), displays higher sensitivity, lower limit of detection (LOD), and better anti-interference capability than the corresponding PRET-based assay. Besides, the ARET-based sensors are lighted up by the FAPα-positive U87MG and MDA-MB-435 cells, but kept in the dark when incubated in the FAPα-negative AD293 cells. The proposed ARET-based sensor can detect FAPα of U87MG and MDA-MB-435 living cells in human serum with the spiked recoveries of 95.6-103%. Our data demonstrated a simple and effective strategy for bridging PLNPs to bioanalytical applications, and an attractive ARET assay of FAPα.

Engineering Persistent Luminescence Nanoparticles for Biological Applications: From Biosensing/Bioimaging to Theranostics.

Persistent luminescence nanoparticles (PLNPs) are unique optical materials emitting long-lasting luminescence after ceasing excitation. Such a unique optical feature allows luminescence detection without constant external illumination to avoid the interferences of autofluorescence and scattering light from biological fluids and tissues. Besides, near-infrared (NIR) PLNPs have advantages of deep penetration and the reactivation of the persistent luminescence (PL) by red or NIR light. These features make the application of NIR-emitting PLNPs in long-term bioimaging no longer limited by the lifetime of PL. To take full advantage of PLNPs for biological applications, the versatile strategies for bridging PLNPs and biological system become increasingly significant for the design of PLNPs-based nanoprobes. In this Account, we summarize our systematic achievements in the biological applications of PLNPs from biosensing/bioimaging to theranostics with emphasizing the engineering strategies for fabricating specific PLNPs-based nanoprobes. We take surface engineering and manipulating energy transfer as the major principles to design various PLNPs-based nanoprobes based on the nature of interactions between nanoprobes and targets. We have developed target-induced formation or interruption of fluorescence resonance energy transfer systems for autofluorescence-free biosensing and imaging of cancer biomarkers. We have decorated single or dual targeting ligands on PLNPs for tumor-targeted imaging, and integrated other modal imaging agents into PLNPs for multimodal imaging. We have also employed specific functionalization for various biomedical applications including chemotherapy, photodynamic therapy, photothermal therapy, stem cells tracking and PL imaging-guided gene therapy. Besides, we have modified PLNPs with multiple functional units to achieve challenging metastatic tumor theranostics. The proposed design principle and comprehensive strategies show great potential in guiding the design of PLNPs nanoprobes and promoting further development of PLNPs in the fields of biological science and medicine. We conclude this Account by outlining the future directions to further promote the practical application of PLNPs. The novel protocols for the synthesis of small-size, monodisperse, and water-soluble PLNPs with high NIR PL intensity and superlong afterglow are the vibrant directions for the biomedical applications of PLNPs. In-depth theories and evidence on luminescence mechanism of PLNPs are highly desired for further improvement of their luminescence performance. Furthermore, other irradiations without tissue penetrating depth limit, such as X-ray, are encouraged for use in energy storage and re-excitation of PLNPs, enabling imaging in deep tissue in vivo and integrating other X-ray sensitized theranostic techniques such as computed tomography imaging and radiotherapy. Last but not least, PLNPs-based nanoprobes and the brand new hybrids of PLNPs with other nanomaterials show a bright prospect for accurate diagnosis and efficient treatment of diseases besides tumors.

EDTA etching: a simple way for regulating the traps, size and aqueous-dispersibility of Cr3+-doped zinc gallate.

Traps, size and aqueous-dispersibility are the most important parameters that affect the features and applications of persistent luminescent nanoparticles (PLNPs). However, simultaneous controlling of these parameters is rather difficult and has not been reported yet. We present the first exploration on adjusting the traps, size and aqueous-dispersibility of PLNPs via simple ethylenediaminetetraacetate (EDTA) etching. Cr0.004 3+:ZnGa2O4 (ZGO) was used as the PLNP model. EDTA etching of the sintered ZGO results in effective reduction of the size and great improvement in the aqueous-dispersibility. In addition, EDTA etching alters the density of mediate traps and generates new deep traps, thus achieving the massive production of (ultra)small ZGO-EDTA with fine aqueous-dispersibility, suitable mediate/deep traps and superlong bright afterglows (51 days). As EDTA can interact with most metals, this simple EDTA etching strategy is prospectively amenable to other PLNPs, and the resulting PLNPs-EDTA have wide applications in both biological field and information storage.

Fluorescence Anisotropy as a Reliable Discrimination of Ligand-Asymmetric and Symmetric Mn-Doped ZnS Quantum Dots.

We presented a novel fluorescence anisotropy (FA) method for the noninvasive, effective, simple, and convenient discrimination of the symmetric and asymmetric distribution of the ligands on Mn-doped ZnS quantum dots (QDs). The symmetric or asymmetric distribution of mercaptopropionic acid (MPA) and NH2-polyethylene glycol-CH3 (PEG-m, MW 2000) was controlled by the condensation reaction of the carboxyl of MPA and the amino of PEG-m with or without the masking by the amino-functionalized silica nanoparticles. The ligand-asymmetric Janus-QDs were obtained with the masking, whereas the ligand-symmetric PEG-QDs were gained without masking. The FA values of the QDs could not only distinguish the ligand symmetric PEG-QDs from the ligand asymmetric Janus-QDs but also discriminate the QDs with a different PEG-m amount. Besides, the FA assay also has superiority over the dynamic light scattering (DLS) and photoluminescence (PL) methods in discriminating the interaction of Janus-QDs or PEG-QDs with protamine (the sensitivity of Janus-QD-3 over PEG-QD-3 was 1.60, 1.24, and 1.11 in the FA, DLS, and PL methods, respectively).

Magnetic Separation-Assistant Fluorescence Resonance Energy Transfer Inhibition for Highly Sensitive Probing of Nucleolin.

For the widely used "off-on" fluorescence (or phosphorescence) resonance energy transfer (FRET or PRET) system, the separation of donors and acceptors species was vital for enhancing the sensitivity. To date, separation of free donors from FRET/PRET inhibition systems was somewhat not convenient, whereas separation of the target-induced far-between acceptors has hardly been reported yet. We presented here a novel magnetic separation-assistant fluorescence resonance energy transfer (MS-FRET) inhibition strategy for highly sensitive detection of nucleolin using Cy5.5-AS1411 as the donor and Fe3O4-polypyrrole core-shell (Fe3O4@PPY) nanoparticles as the NIR quenching acceptor. Due to hydrophobic interaction and π-π stacking of AS1411 and PPY, Cy5.5-AS1411 was bound onto the surface of Fe3O4@PPY, resulting in 90% of fluorescence quenching of Cy5.5-AS1411. Owing to the much stronger specific interaction of AS1411 and nucleolin, the presence of nucleolin could take Cy5.5-AS1411 apart from Fe3O4@PPY and restore the fluorescence of Cy5.5-AS1411. The superparamagnetism of Fe3O4@PPY enabled all separations and fluorescence measurements complete in the same quartz cell, and thus allowed the convenient but accurate comparison of the sensitivity and fluorescence recovery in the cases of separation or nonseparation. Compared to nonseparation FRET inhibition, the separation of free Cy5.5-AS1411 from Cy5.5-AS1411-Fe3O4@PPY solution (the first magnetic separation, MS-1) had as high as 25-fold enhancement of the sensitivity, whereas further separation of the nucleolin-inducing far-between Fe3O4@PPY from the FRET inhibition solution (the second magnetic separation, MS-2) could further enhance the sensitivity to 35-fold. Finally, the MS-FRET inhibition assay displayed the linear range of 0.625-27.5 µg L(-1) (8.1-359 pM) and detection limit of 0.04 µg L(-1) (0.05 pM) of nucleolin. The fluorescence intensity recovery (the percentage ratio of the final restoring fluorescence intensity to the quenched fluorescence intensity of Cy5.5-AS1411 solution by 0.09 g L(-1) Fe3O4@PPY) was enhanced from 36% (for nonseparation) to 56% (for two magnetic separations). This is the first accurate evaluation for the effect of separating donor/acceptor species on the FRET inhibition assay.

Ionic strength assay via polyacrylate-ferriferrous oxide magnetic photonic crystals.

Convenient reading out and/or determination of ionic strength (IS) is of great significance for both scientific research and real life applications. We presented here a novel method for the rapid and sensitive IS assay based on the electrolyte-induced sensitive wavelength blueshifts of the reflection spectra of polyacrylate capped Fe3O4 magnetic photonic crystals (PA-Fe3O4-MPCs). For HCl, MgSO4 and the common electrolytes corresponding to the salinity of seawater (including NaCl, KCl, MgCl2, CaCl2, Na2SO4 and their mixtures), the PA-Fe3O4-MPCs displayed wavelength blueshifts identical to the total IS of the aqueous solutions, regardless of the kind of above-mentioned electrolytes in the solutions. Besides, the PA-Fe3O4-MPCs exhibited relatively high sensitivity (an average of 294 nm L mmol(-1) in the range of 0.05-0.30 mmol L(-1), and an even higher value of 386 nm L mmol(-1) at 0.05-0.15 mmol L(-1)) and fast response (within 8 s) to the IS of aqueous solutions. The relative standard deviation (RSD) for IS (NaCl, 0.1 mmol L(-1)) was 4.4% (n = 5). The developed method was applied to determine the salinity of seawater samples, and the determined results were validated by the traditional standard chlorinity titration and electric conductimetry method. The recoveries were in the range of 92-104%. The proposed PA-Fe3O4-MPCs based reflectometry method would have great potential for IS and salinity assays.

Bioinspired nanocomplex for spatiotemporal imaging of sequential mRNA expression in differentiating neural stem cells.

Messenger RNA plays a pivotal role in regulating cellular activities. The expression dynamics of specific mRNA contains substantial information on the intracellular milieu. Unlike the imaging of stationary mRNAs, real-time intracellular imaging of the dynamics of mRNA expression is of great value for investigating mRNA biology and exploring specific cellular cascades. In addition to advanced imaging methods, timely extracellular stimulation is another key factor in regulating the mRNA expression repertoire. The integration of effective stimulation and imaging into a single robust system would significantly improve stimulation efficiency and imaging accuracy, producing fewer unwanted artifacts. In this study, we developed a multifunctional nanocomplex to enable self-activating and spatiotemporal imaging of the dynamics of mRNA sequential expression during the neural stem cell differentiation process. This nanocomplex showed improved enzymatic stability, fast recognition kinetics, and high specificity. With a mechanism regulated by endogenous cell machinery, this nanocomplex realized the successive stimulating motif release and the dynamic imaging of chronological mRNA expression during neural stem cell differentiation without the use of transgenetic manipulation. The dynamic imaging montage of mRNA expression ultimately facilitated genetic heterogeneity analysis. In vivo lateral ventricle injection of this nanocomplex enabled endogenous neural stem cell activation and labeling at their specific differentiation stages. This nanocomplex is highly amenable as an alternative tool to explore the dynamics of intricate mRNA activities in various physiological and pathological conditions.

Glucose oxidase-catalyzed growth of gold nanoparticles enables quantitative detection of attomolar cancer biomarkers.

Ultrasensitive and quantitative detection of cancer biomarkers is an unmet challenge because of their ultralow concentrations in clinical samples. Although gold nanoparticle (AuNP)-based immunoassays offer high sensitivity, they were unable to quantitatively detect targets of interest most likely due to their very narrow linear ranges. This article describes a quantitative colorimetric immunoassay based on glucose oxidase (GOx)-catalyzed growth of 5 nm AuNPs that can detect cancer biomarkers from attomolar to picomolar levels. In addition, the limit of detection (LOD) of prostate-specific antigen (PSA) of this approach (93 aM) exceeds that of commercial enzyme-linked immunosorbent assay (ELISA) (6.3 pM) by more than 4 orders of magnitude. The emergence of red or purple color based on enzyme-catalyzed growth of 5 nm AuNPs in the presence of target antigen is particularly suitable for point-of-care (POC) diagnostics in both resource-rich and resource-limited settings.

Aminophenylboronic-acid-conjugated polyacrylic acid-Mn-doped ZnS quantum dot for highly sensitive discrimination of glycoproteins.

Discrimination of glycoproteins with different glycans is a significant but difficult issue. We presented here a new strategy for strengthening the discrimination of glycoproteins by introducing a new signaling channel, fluorescence polarization (FP), into a "single probe with three signaling channels" sensor array. The single probe was aminophenylboronic-acid-conjugated poly(acrylic acid)-Mn-doped ZnS quantum dots, and the three signaling channels were FP, room temperature phosphorescence and light scattering. Ten glycoproteins, including ovalbumin, fibrinogen, transferrin, horseradish peroxidase, vascular endothelial growth factor, immunoglobulin G, avidin, hyaluronidase, cellulase R-10, and glucose oxidase, were involved for evaluating the discriminating capability. The introduction of the FP signaling channel improved the discriminating power of the sensor array, so that the 10 glycoproteins at 0.15 µM could be well discriminated both in PBS buffer and in the presence of human serum sample. The identification accuracy of the unknown samples was 96.25% (77 out of 80) at the 0.15 µM level and 97.50% (78 out of 80) at the 0.2 µM level. The integration of the signaling patterns with different responsive principles was demonstrated as the promising way to enhance the discrimination power of the single-probe-based sensor arrays.

Metal-organic framework polymethyl methacrylate composites for open-tubular capillary electrochromatography.

Metal-organic frameworks (MOFs) are attractive as novel separation medium due to their distinguished properties including large surface area, accessible tunnels and diverse structures. Here, we report the incorporation of MOF CAU-1 (CAU=Christian-Albrechts-University) into polymethyl methacrylate (PMMA) to produce a new composite (CAU-1@PMMA), and the fabrication of CAU-1@PMMA coated capillary for open tubular capillary electrochromatography (CEC). CAU-1 contains unprecedented [Al8(OH)4(OCH3)8](12+) clusters connected by twelve aminoterephthalic acid linkers, and is highly porous and stable in a variety of buffer solutions. The incorporation of CAU-1 into PMMA not only increases surface area, but also electroosmotic flow (EOF). As a result, the CAU-1@PMMA coated capillary column gives higher column efficiency, larger column capacity, and shorter separation time for baseline separation of two groups of aromatic carboxylic acids than the PMMA coated capillary column. Besides, the incorporation of CAU-1 also improves the resolution for the CEC separation of basic sulfa drugs and structurally related peptides. The run-to-run, day-to-day and column-to-column precision for the EOF of CAU-1@PMMA coated capillary column is 0.3%, 0.4%, and 2.2% (relative standard deviation), respectively. The results show that MOFs composites are promising stationary phases for CEC applications.

Ultrathin-yttrium phosphate-shelled polyacrylate-ferriferrous oxide magnetic microspheres for rapid and selective enrichment of phosphopeptides.

Rapid and selective enrichment of phosphopeptides from complex biological samples is essential and challenging in phosphorylated proteomics. We present the direct growth of the ultrathin YPO4 shell on the surface of polyacrylate capped secondary Fe3O4 microspheres (PA-Fe3O4@YPO4) for the rapid and selective trapping phosphopeptides from complex samples. The prepared PA-Fe3O4@YPO4 could be rapidly harvested in the presence of an applied magnetic field and easily re-dispersed in solutions after removing the external magnet. The ultrathin YPO4 shell on super-hydrophilic PA-Fe3O4 has the advantages of fast adsorption/desorption dynamics and low non-specific adsorption, thus trapping of phosphopeptides from the tryptic digests mixture of ß-casein/BSA with molar ratio of 1/300 is achieved in 20s adsorption/desorption time. Two phosphopeptides can still be detected with a signal to noise ratio (S/N) over 3 when the amount of ß-casein was as low as 8 fmol.

Heparin-mediated fluorescence anisotropy assay of antithrombin based on polyethyleneimine capped Mn-doped ZnS quantum dots.

We presented a homogeneous heparin-mediated fluorescence anisotropy (FA) assay of antithrombin (AT) based on long-lived luminescent polyethyleneimine capped Mn-doped ZnS (PEI-Mn-ZnS) QDs. The PEI-Mn-ZnS QDs with long lifetime luminescence at 585 nm displayed a very low background of FA value, which was very helpful for FA assaying of large molecules. The medium heparin was crucial for AT determination, and different heparin amounts resulted in different linear range of detection and sensitivity. For example, the limit of detection (LOD) of 0.9 nM AT with a detection linear range from 8.6 nM to 21.5 nM was found when the heparin concentration was 75 µM. The proposed method also exhibited high selectivity over the coexisting or related proteins such as human serum albumin and thrombin.

Mn-doped ZnS quantum dot imbedded two-fragment imprinting silica for enhanced room temperature phosphorescence probing of domoic acid.

A novel strategy was presented to construct the enhanced molecularly imprinted polymer (MIP)-based room temperature phosphorescence (RTP) probe by combining the RTP of Mn-doped ZnS quantum dots (Mn-ZnS QDs) and two-fragment imprinting. Two fragments or structurally similar parts of the target analytes were used as the dummy templates. Polyethyleneimine capped Mn-ZnS (PEI-Mn-ZnS) QDs, offering the binding sites to interact with the carboxyl groups of templates, were imbedded into MIPs by the hydrolysis of tetraethoxysilane. The rebinding of the target analytes to their fragments' cavities (recognition sites) modulated the selective aggregation of Mn-ZnS QDs in QDs-MIPs and resulted in the RTP enhancement. This new method was suitable for the selective enhanced RTP detection of nonphosphorescent analytes without any derivatization and inducers. The proposed methodology was applied to construct the high selective enhanced MIP-based RTP probe for domoic acid (DA) detection. The RTP enhancement of two-fragment imprinting silica was about 2 times of one-fragment imprinting silica and 4 times of the nonimprinting silica. The two-fragment imprinting silica exhibited the linear RTP enhancement to DA in the range of 0.25-3.5 µM in buffer and 0.25-1.5 µM in shellfish sample. The precision for 11 replicate detections of 1.25 µM DA was 0.65% (RSD), and the limit of detection was 67 nM in buffer and 2.0 µg g(-1) wet weight (w/w) in shellfish sample.

Room-temperature phosphorescent discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots.

A room-temperature phosphorescence (RTP) strategy was developed for direct, additive-free discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots (STPP-Mn-ZnS QDs). The RTP response of STPP-Mn-ZnS QDs to the three isomers was pH-dependent, and the greatest difference in the RTP response to the isomers was observed at pH 8.0: catechol enhanced the RTP intensity of the QDs, while resorcinol and hydroquinone had little effect on the RTP intensity of the QDs. The enhanced RTP intensity of 1 µM catechol was not affected by the coexistence of 30 µM resorcinol and 50 µM hydroquinone at pH 8.0. The detection limit of this RTP method was 53 nM catechol, and the precision was 3.2% (relative standard deviation) for five replicate detections of 1 µM catechol. The discrimination mechanism was ascribed to the weak bonded ligand of STPP-Mn-ZnS QDs and the different interaction between the three isomers and STPP-Mn-ZnS QDs. The strong binding of catechol to Zn resulted in the extraction of Zn from the surface of STPP-Mn-ZnS QDs and the generation of holes that were trapped by Mn(2+) to form Mn(3+). Catechol also promoted the reduction of Mn(3+) into Mn(2+) excited state, thus ultimately inducing the enhanced RTP response of STPP-Mn-ZnS QDs.

Metal-organic framework ZIF-8 nanocrystals as pseudostationary phase for capillary electrokinetic chromatography.

The outstanding properties such as large surface area, diverse structure, and accessible tunnels and cages make metal organic frameworks (MOFs) attractive as novel separation media in separation sciences. However, the utilization of MOFs in EKC has not been reported before. Here we show the exploration of zeolitic imidazolate framework-8 (ZIF-8), one of famous MOFs, as the pseudostationary phase (PSP) in EKC. ZIF-8 nanocrystals were used as the PSP through dispersing in the running buffer (20 mM phosphate solution containing a 1% v/v methanol (pH 9.2)) to enhance the separation of the phenolic isomers (p-benzenediol, m-benzenediol, o-benzenediol, m-nitrophenol, p-nitrophenol, and o-nitrophenol). ZIF-8 nanocrystals in the running buffer were negatively charged, and interacted with the phenolic hydroxyl groups of the analytes, and thus greatly improved the separation of the phenolic isomers. Inclusion of 200 mg L-(1) ZIF-8 in the running buffer as the background electrolyte gave a baseline separation of the phenolic isomers within 4 min. The relative standard deviations for five replicate separations of the phenolic isomers were 0.2-1.1% for migration time and 4.5-9.7% for peak area. The limits of detection varied from 0.44 to 2.0 mg L-(1) . The results show that nanosized MOFs are promising for application in EKC.

The stable and water-soluble neodymium-doped lanthanide fluoride nanoparticles for near infrared probing of copper ion.

Neodymium (Nd(3+)) doped nanomaterials exhibited the unique near infrared (NIR) luminescence properties. However, the application of Nd-doped nanomaterials to chemosensors was rarely explored. Herein, the water-soluble 2-aminoethyl dihydrogen phosphate stabilized Nd-doped LaF(3) (ADP-Nd-LaF(3)) nanoparticles were explored as the NIR probe for chemosensors. The NIR emission intensity at 1061 nm of ADP-Nd-LaF(3) nanoparticles kept stable in the aqueous solution of various pH and coexisting of most common metal ions except copper ion, consequently, the ADP-Nd-LaF(3) nanoparticles were developed as a high selective NIR probe for Cu(II). The NIR emission of ADP-Nd-LaF(3) exhibits a linear quenching response to Cu(II) in the range 5-100 µM, with a detection limit of 0.8 µM. The precision of eleven replicate detections of 5 µM Cu(II) was 0.5% (RSD). The recovery of spiked Cu(II) in human urine and waste water samples ranged from 102 to 109%. The possible mechanism of Cu(II)-induced fluorescence quenching of ADP-Nd-LaF(3) nanoparticles was also discussed.

High-performance liquid chromatographic separation of position isomers using metal-organic framework MIL-53(Al) as the stationary phase.

Metal-organic framework MIL-53(Al) was explored as the stationary phase for high-performance liquid chromatographic separation of position isomers using a binary and/or polar mobile phase. Baseline separations of xylene, dichlorobenzene, chlorotoluene and nitrophenol isomers were achieved on the slurry-packed MIL-53(Al) column with high resolution and good precision. The effects of mobile phase composition, injected sample mass and temperature were investigated. The separation of xylene, dichlorobenzene, chlorotoluene and nitrophenol isomers on MIL-53(Al) were controlled by entropy change.