Self-Assembling Zeolite Crystals into Uniformly Oriented Layers

We report important progress made in the synthesis of oriented functional layers of nanochannel materials by using coordination chemistry as a tool. Zeolite L (ZL) crystals have been arranged into oriented layers through the coordinative interactions between a functional organic linker (L) and metal cations used for connecting the different parts. As organic linker we used a terpyridyl ligand bearing a urea group and a reactive siloxane part. Two strategies that lead to monolayers with different properties are described. The first consists of reacting the siloxane group of ligand L with OH groups of the substrate (S), and selectively reacting the siloxane group of L with OH groups located at the base of the ZL crystals. Next, metal cations Mn+, for example, Zn2+ or Cu2+, are coordinated to the terpy group on the modified substrate. To this the modified ZL is added and coordinatively bound by the terpy(Mnn+)terpy interaction, leading to oriented ZL layers. The second method consists of reacting substrate S and ligand L in the presence of a metal cation. A layer with reactive siloxane groups is formed on S to which the ZL crystals are bound by the reaction of the hydroxyl groups of their base. Zn2+, Cu2+, and lanthanide ions Eu3+ and Tb3+have been tested successfully, all of them leading to high-quality ZL monolayers with open channels, accessible for accepting guests, oriented perpendicularly with respect to the surface of S

Functional PEG–PAMAM-Tetraphosphonate Capped NaLnF₄ Nanoparticles and their Colloidal Stability in Phosphate Buffer

Developing surface coatings for NaLnF₄ nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH₂-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF₄ and NaTbF₄ nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH₂-PAMAM-4P ligand on oleate-capped NaLnF₄ NPs. The NPs were first treated with methoxy-poly­(ethylene glycol)-monophosphoric acid (<i>M</i>_n = 750) in tetrahydrofuran. The mPEG750-OPO₃-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH₂-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (<i>M</i>_n = 2000) and biotin-terminated PEG (<i>M</i>_n = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF₄ and NaTbF₄ NPs capped with mPEG2000–PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF₄ NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir 2012, 28, 12861−12870) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline

Beanstandungen und Beschwerden über Verstösse gegen die Patientenrechte

We report discovery of a new efficient and robust antenna composite for light harvesting. The organic dye hostasol red (HR) is strongly luminescent in aprotic solvents but only weakly luminescent in potassium zeolite L (ZL) at ambient conditions. We observed a dramatic increase of the luminescence quantum yield of HR–ZL composites if some or all exchangeable potassium cations of ZL are substituted by an organic imidazolium cation (IMZ⁺) and if the acceptor HR is embedded in the middle part of the channels, so that it is fully protected by the environment of the perylene dye tb-DXP. This led to the discovery of a highly efficient donor,acceptor-ZL antenna material where tb-DXP acts as donor and HR acts as acceptor. The material has a donor-to-acceptor (D/A) absorption ratio of more than 100:1 and a nearly quantitative FRET efficiency. Synthesis of this host–guest material is reported. We describe a successful procedure for achieving full sealing of the ZL channel entrances such that the guests cannot escape. This new material is of great interest for applications in luminescent solar concentrator (LSC) devices because the efficiency killing self-absorption is very low

Quantification of Surface Ligands on NaYF₄ Nanoparticles by Three Independent Analytical Techniques

There have been important advances in characterizing the surface coverage of ligands on colloidal inorganic nanoparticles (NPs), but our knowledge of ligand coverage on lanthanide NPs is much more limited. The as-synthesized NPs are often coated with hydrophobic ligands that need to be replaced with hydrophilic ligands such as poly­(ethylene glycol) (PEG) for biomedical applications. The two challenges in terms of characterizing ligand coverage on NPs are first to show that different analytical methods give consistent results and second to show how the sample preparation protocol affects ligand density. Here, we report a quantitative study of the native oleate content of as-synthesized NaYF₄ and NaTbF₄ NPs, as well as the surface coverage after ligand exchange with three methoxyPEG-monophosphates with <i>M</i>_n = 750, 2000, and 5000 Da. For NaYF₄, we obtained consistent results for both oleates and PEGs by three independent methods (TGA, ¹H NMR, and ICP-AES). The oleate coverage was very sensitive to the sample isolation/purification protocol, with a high surface coverage (5.5 to 8 nm^–2) for ethanol/hexane sedimentation/redispersion but only 2 nm^–2 if THF was used in place of hexanes. The surface coverages PEG750 (∼1.1 nm^–2), PEG2000 (∼1.7 nm^–2), and PEG5000 (∼0.2 nm^–2) suggest that corona repulsion limits the number of PEG5000 molecules that can graft to the surface. For NaTbF₄ NPs, we compared the surface coverage of PEG2000-monophosphate with a PEG2000-tetraphosphonate ligand shown to provide enhanced colloidal stability in PBS buffer. We found the surprising result that the footprints of these ligands were comparable, suggesting that there was insufficient room for all four phosphonate groups of the tetradentate ligand to bind simultaneously to the NP surface

Improving Lanthanide Nanocrystal Colloidal Stability in Competitive Aqueous Buffer Solutions using Multivalent PEG-Phosphonate Ligands

The range of properties available in the lanthanide series has inspired research into the use of lanthanide nanoparticles for numerous applications. We aim to use NaLnF₄ nanoparticles for isotopic tags in mass cytometry. This application requires nanoparticles of narrow size distribution, diameters preferably less than 15 nm, and robust surface chemistry to avoid nonspecific interactions and to facilitate bioconjugation. Nanoparticles (NaHoF₄, NaEuF₄, NaGdF₄, and NaTbF₄) were synthesized with diameters from 9 to 11 nm with oleic acid surface stabilization. The surface ligands were replaced by a series of mono-, di-, and tetraphosphonate PEG ligands, whose synthesis is reported here. The colloidal stability of the resulting particles was monitored over a range of pH values and in phosphate containing solutions. All of the PEG-phosphonate ligands were found to produce non-aggregated colloidally stable suspensions of the nanoparticles in water as judged by DLS and TEM measurements. However, in more aggressive solutions, at high pH and in phosphate buffers, the mono- and diphosphonate PEG ligands did not stabilize the particles and aggregation as well as flocculation was observed. However, the tetraphosphonate ligand was able to stabilize the particles at high pH and in phosphate buffers for extended periods of time

DataSheet_1_The Systemic Lupus Erythematosus Interventional Trials in Mainland China: A Continuous Challenge.pdf

ObjectivesMore than a quarter of single-country systemic lupus erythematosus (SLE) interventional randomized clinical trials (RCTs) were conducted in China. To help develop management guidelines and set benchmarks for future SLE research, a systematic review of current trials is needed.MethodsWe searched systematically three databases and four registries to summarize the interventional RCTs in mainland China and identify factors associated with participant loss. The internal validity of trials was assessed using the Cochrane risk-of-bias tool for assessing risk of bias. The odds ratio (OR) was defined as the ratio of the odds of less than 10% loss to follow-up in the presence or absence of different factors.ResultsA total of 188 trials met our inclusion criteria, and 15·5% of trials conducted in mainland China ranked low risk of bias. Participant loss was significantly higher among trials that had a defined primary outcome or were registered {primary outcome identification (0·02 [0·00-0·23]) and registration (0·14 [0·03-0·69])}. Trials examining traditional Chinese medicine (TCM) pharmacological treatments had an 8·16-fold (8·16 [1·28-51·98]) higher probability of having low participant loss than trials examining non-TCM pharmacological treatment trials, and trials that did not report masking status had a 15·95-fold (15·95 [2·45-103·88]) higher probability of having low participant loss than open-label trials. In addition, published articles in Chinese also had higher probability of having low participant loss (5·39 [1·10-26·37]).ConclusionSLE trials conducted in mainland China were of relatively poor quality. This situation, including nonrigorous design, lack of registration, and absence of compliance reporting, needs to be ameliorated. To maintain the fundamental repeatability and comparability of mainland China SLE RCTs, transparency of the clinical trial process and complete reporting of the trial data are crucial and urgently needed.</p

DataSheet_2_The Systemic Lupus Erythematosus Interventional Trials in Mainland China: A Continuous Challenge.xlsx

ObjectivesMore than a quarter of single-country systemic lupus erythematosus (SLE) interventional randomized clinical trials (RCTs) were conducted in China. To help develop management guidelines and set benchmarks for future SLE research, a systematic review of current trials is needed.MethodsWe searched systematically three databases and four registries to summarize the interventional RCTs in mainland China and identify factors associated with participant loss. The internal validity of trials was assessed using the Cochrane risk-of-bias tool for assessing risk of bias. The odds ratio (OR) was defined as the ratio of the odds of less than 10% loss to follow-up in the presence or absence of different factors.ResultsA total of 188 trials met our inclusion criteria, and 15·5% of trials conducted in mainland China ranked low risk of bias. Participant loss was significantly higher among trials that had a defined primary outcome or were registered {primary outcome identification (0·02 [0·00-0·23]) and registration (0·14 [0·03-0·69])}. Trials examining traditional Chinese medicine (TCM) pharmacological treatments had an 8·16-fold (8·16 [1·28-51·98]) higher probability of having low participant loss than trials examining non-TCM pharmacological treatment trials, and trials that did not report masking status had a 15·95-fold (15·95 [2·45-103·88]) higher probability of having low participant loss than open-label trials. In addition, published articles in Chinese also had higher probability of having low participant loss (5·39 [1·10-26·37]).ConclusionSLE trials conducted in mainland China were of relatively poor quality. This situation, including nonrigorous design, lack of registration, and absence of compliance reporting, needs to be ameliorated. To maintain the fundamental repeatability and comparability of mainland China SLE RCTs, transparency of the clinical trial process and complete reporting of the trial data are crucial and urgently needed.</p

A High-Sensitivity Lanthanide Nanoparticle Reporter for Mass Cytometry: Tests on Microgels as a Proxy for Cells

This paper addresses the question of whether one can use lanthanide nanoparticles (e.g., NaHoF₄) to detect surface biomarkers expressed at low levels by mass cytometry. To avoid many of the complications of experiments on live or fixed cells, we carried out proof-of-concept experiments using aqueous microgels with a diameter on the order of 700 nm as a proxy for cells. These microgels were used to test whether nanoparticle (NP) reagents would allow the detection of as few as 100 proteins per “cell” in cell-by-cell assays. Streptavidin (SAv), which served as the model biomarker, was attached to the microgel in two different ways. Covalent coupling to surface carboxyls of the microgel led to large numbers (>10⁴) of proteins per microgel, whereas biotinylation of the microgel followed by exposure to SAv led to much smaller numbers of SAv per microgel. Using mass cytometry, we compared two biotin-containing reagents, which recognized and bound to the SAvs on the microgel. One was a metal chelating polymer (MCP), a biotin end-capped polyaspartamide containing 50 Tb³⁺ ions per probe. The other was a biotinylated NaHoF₄ NP containing 15 000 Ho atoms per probe. Nonspecific binding was determined with bovine serum albumin (BSA) conjugated microgels. The MCP was effective at detecting and quantifying SAvs on the microgel with covalently bound SAv (20 000 SAvs per microgel) but was unable to give a meaningful signal above that of the BSA-coated microgel for the samples with low levels of SAv. Here the NP reagent gave a signal 2 orders of magnitude stronger than that of the MCP and allowed detection of NPs ranging from 100 to 500 per microgel. Sensitivity was limited by the level of nonspecific adsorption. This proof of concept experiment demonstrates the enhanced sensitivity possible with NP reagents in cell-by-cell assays by mass cytometry