Highly sensitive "off-on" sensor based on MXene and magnetic microspheres for simultaneous detection of lung cancer biomarkers - Neuron specific enolase and carcinoembryonic antigen.

In this work, a highly sensitive lung cancer biomarkers detection probe was developed based on Ag and MXene co-functionalized magnetic microspheres. By using carboxyl magnetic microspheres as carrier, MXene was coated repeatedly by Poly (allylamine hydrochloride) (PAH) as interlayer adhesive, and silver particles grown on the surface of MXene in situ can efficiently improve the sensitivity of the probe. The detection of neuron specific enolase (NSE) is mainly through the formation of a specific complex between NSE antigen and antibody, and the release of antibody labeled with amino carbon quantum dots (CQDs) from the surface of Ag nanoparticles (AgNPs), so that the fluorescence is restored and "OFF-ON" is formed. The biosensor exhibits excellently wide linear range (0.0001-1500 ng/mL) and the limit of detection (LOD) is up to 0.03 pg/mL, which is superior to most tumor marker probes based on fluorescence mechanism. Furthermore, we constructed dual detection strategy for NSE and carcinoembryonic antigen (CEA) simultaneously.

Ultra-stable and highly-bright CsPbBr3 perovskite/silica nanocomposites for miRNA detection based on digital single-nanoparticle counting.

Single-nanoparticle counting (SNPC) based on fluorescent tag (FT) stands out for its capacity to achieve amplification-free and sensitive detection of biomarkers. The stability and luminescence of FT are important to the sensitivity and reliability of SPNC. In this work, we developed novel perovskite/silica nanocomposites by in-situ nanoconfined growth of CsPbBr3 nanocrystals inside mesoporous structure of silica nanoparticles. PbBr(OH) was formed in an alkaline-assisted reaction triggered by water on the surface of CsPbBr3 nanocrystals. The as-obtained nanocomposites, featuring dual protection from silica matrix and PbBr(OH), exhibited high absolute photoluminescence quantum yield (PLQY) of 86.5% and demonstrated outstanding PL stability confronting with water, heat, ultrasound and UV-irradiation, which is desired by SNPC-based biosensor. Thereafter, these nanocomposites were used to construct an operationally friendly SNPC assay for the amplification-free quantification of cancer-associated miRNA. Quantitative detection of miRNA could be accomplished by directly counting the number of nanocomposites using a flow cytometer in this assay. This strategy did not ask for multiple washing steps and demonstrated specific and sensitive detection of miRNA 21, which exhibited a dynamic range of 1-1000 pM and limit of detection of 79 amol. The employment of highly stable perovskite/silica nanocomposites improved the test reliability and stability of SNPC, revealing the vast potential of perovskites in biosensing.

Lewis acid catalysed polymerisation of cyclopentenone.

A modest structural change of a ß-diketiminate-supported aluminium complex leads to dramatic differences in the reactivity towards cyclopentenone. While the bulkier complex efficiently executes Diels Alder transformations the smaller analogue performs unique polymerisation of this substrate. This observation appears to be unprecedented in the chemistry of Lewis acids and cyclic dienophiles as it represents a unique way to polymerise a functionalised olefin.

A universal mass tag based on polystyrene nanoparticles for single-cell multiplexing with mass cytometry.

Mass cytometry (MC) is an emerging bioanalytical technique for high-dimensional biomarkers interrogation simultaneously on individual cells. However, the sensitivity and multiplexed analysis ability of MC was highly restricted by the current metal chelating polymer (MCP) mass tags. Herein, a new design strategy for MC mass tags by using a commercial available and low cost classical material, polystyrene nanoparticle (PS-NP) to carry metals was reported. Unlike inorganic materials, sub-micron-grade metal-loaded polystyrene can be easily detected by MC, thus it is not essential to pursue extremely small particle size in this mass tag design strategy. An altered cell staining buffer can significantly lower the nonspecific binding (NSB) of non-functionalized PS-NPs, revealing another method to lower NSB beside surface modification. The metal doped PS-NP_Abs mass tags showed high compatibility with MCP mass tags and 5-fold higher sensitivity. By using Hf doped PS-NP_Abs as mass tags, four new MC detection channels (177Hf, 178Hf, 179Hf and 180Hf) were developed. In general, this work provides a new strategy in designing MC mass tags and lowering NSB, opening up possibility of introducing more potential MC mass tag candidates.

The preparation of novel AIE fluorescent microspheres by dispersion polymerization.

An approach to prepare monodisperse polystyrene microspheres with aggregation-induced emission (AIE) characteristics has been developed which shows promising applications in fluorescence-encoding. The micron-sized, monodisperse polystyrene microspheres with AIE molecules were perfectly synthesized by two-stage dispersion polymerization. Fluorescent AIE monomer was synthesized by Suzuki reaction, confirmed by nuclear magnetic resonance (NMR). These AIE fluorogens (AIEgens) exhibited unique properties such as bright green emission in solid state and increased emission in tetrahydrofuran (THF) solution with the increase of water content. The influence of the AIE molecules concentration to microspheres synthesis was well investigated. The reaction conditions were optimized to obtain the functional polystyrene microspheres with a size distribution around 3%. The novel microspheres were characterized by scanning electron microscopy (SEM), confocal fluorescence microscope and flow cytometry. According to these results, two-stage dispersion polymerization was proved to be an efficient pathway for the preparation of AIE fluorescent and functionalized microspheres, which could be used in many biomedical industries.

Carbodiphosphorane-Stabilized Parent Dioxophosphorane: A Valuable Synthetic HO2P Source.

Introducing a small phosphorus-based fragment into other molecular entities via, for example, phosphorylation/phosphonylation is an important process in synthetic chemistry. One of the approaches to achieve this is by trapping and subsequently releasing extremely reactive phosphorus-based molecules such as dioxophosphoranes. In this work, electron-rich hexaphenylcarbodiphosphorane (CDP) was used to stabilize the least thermodynamically favorable isomer of HO2P to yield monomeric CDP·PHO2. The title compound was observed to be a quite versatile phosphonylating agent; that is, it showed a great ability to transfer, for the first time, the HPO2 fragment to a number of substrates such as alcohols, amines, carboxylic acids, and water. Several phosphorous-based compounds that were generated using this synthetic approach were also isolated and characterized for the first time. According to the initial computational studies, the addition-elimination pathway was significantly more favorable than the corresponding elimination-addition route for "delivering" the HO2P unit in these reactions.

Imine Reduction with Me2S-BH3.

Although there exists a variety of different catalysts for hydroboration of organic substrates such as aldehydes, ketones, imines, nitriles etc., recent evidence suggests that tetra-coordinate borohydride species, formed by activation, redistribution, or decomposition of boron reagents, are the true hydride donors. We then proposed that Me2S-BH3 could also act as a hydride donor for the reduction of various imines, as similar compounds have been observed to reduce carbonyl substrates. This boron reagent was shown to be an effective and chemoselective hydroboration reagent for a wide variety of imines.

Selective homo- and cross-desilacoupling of aryl and benzyl primary silanes catalyzed by a barium complex.

Under mild conditions (25 °C, 5 mol% cat.), highly selective homo- and cross-desilacoupling of aryl and benzyl primary silanes to secondary silanes was achieved by the use of the heteroleptic barium aminobenzyl complex [(TpAd,iPr)Ba(CH2C6H4NMe2-o)] (TpAd,iPr = hydrotris(3-adamantyl-5-isopropyl-pyrazolyl)borate) (1) as a catalyst. Dihydrosilanes originating from catalytic redistribution and cross-desilacoupling reactions were isolated in fine yields, which demonstrates the feasible application of the barium complex in the syntheses of secondary aryl- and benzylsilanes.

Methylcobalamin-Loaded PLCL Conduits Facilitate the Peripheral Nerve Regeneration.

The feasible fabrication of nerve guidance conduits (NGCs) with good biological performance is important for translation in clinics. In this study, poly(d,l-lactide-co-caprolactone) (PLCL) films loaded with various amounts (wt; 5%, 15%, 25%) of methylcobalamin (MeCbl) are prepared, and are further rolled and sutured to obtain MeCbl-loaded NGCs. The MeCbl can be released in a sustainable manner up to 21 days. The proliferation and elongation of Schwann cells, and the proliferation of Neuro2a cells are enhanced on these MeCbl-loaded films. The MeCbl-loaded NGCs are implanted into rats to induce the regeneration of 10 mm amputated sciatic nerve defects, showing the ability to facilitate the recovery of motor and sensory function, and to promote myelination in peripheral nerve regeneration. In particular, the 15% MeCbl-loaded PLCL conduit exhibits the most satisfactory recovery of sciatic nerves in rats with the largest diameter and thickest myelinated fibers.

Barium tetraalkylaluminate complexes supported by the super-bulky hydrotris(pyrazolyl)borate ligand.

A heteroleptic barium aminobenzyl complex [(TpAd,iPr)Ba(o-CH2C6H4-NMe2)] (1) was obtained in excellent yield from a simple one-pot reaction. Treatment of [(TpAd,iPr)Ba(o-CH2C6H4-NMe2)] (1) with two equivalents of AlR3 (R = Me, Et) led to the formation of barium tetraalkylaluminate complexes [(TpAd,iPr)Ba(AlR4)]n (R = Me, n = 2, 2; R = Et, n = 1, 3) as dimers or monomers in the solid state. The TpAd,iPr ligand-free peralkylated barium complex [Ba(AlEt4)2]n was isolated by the addition of ten equivalents of AlEt3 under the same conditions. The donor-induced aluminate cleavage is not applicable when donor solvents are added to complexes 2 and 3. In the solution of complexes 2 and 3, the alkylaluminate moieties and TpAd,iPr ligands show a rapid fluxional behavior in [D8]toluene solution over the temperature range of -70 to 25 °C, without any significant decoalescence of the corresponding proton signals.

Super-Bulky Penta-arylcyclopentadienyl Ligands: Isolation of the Full Range of Half-Sandwich Heavy Alkaline-Earth Metal Hydrides.

Hydrogenolysis of the half-sandwich penta-arylcyclopentadienyl-supported heavy alkaline-earth-metal alkyl complexes (CpAr )Ae[CH(SiMe3 )2 ](S) (CpAr =C5 Ar5 , Ar=3,5-i Pr2 -C6 H3; S=THF or DABCO) in hexane afforded the calcium, strontium, and barium metal-hydride complexes as the same dimers [(CpAr )Ae(µ-H)(S)]2 (Ae=Ca, S=THF, 2-Ca; Ae=Sr, Ba, S=DABCO, 4-Ae), which were characterized by NMR spectroscopy and single-crystal X-ray analysis. 2-Ca, 4-Sr, and 4-Ba catalyzed alkene hydrogenation under mild conditions (30 °C, 6 atm, 5 mol % cat.), with the activity increasing with the metal size. A variety of activated alkenes including tri- and tetra-substituted olefins, semi-activated alkene (Me3 SiCH=CH2 ), and unactivated terminal alkene (1-hexene) were evaluated.

Michael Additions Catalyzed by a ß-Diketiminate-Supported Aluminum Complex.

A ß-diketiminate-supported aluminum bistriflate complex (DipLAl(OTf)2·Na[BArCl4]; DipL = CH(CMe)2(N-C6H3-iPr2)2; Tf = O2SCF3; ArCl = 3,5-Cl2-C6H3) has been identified as an efficient Lewis acid catalyst for Michael additions involving numerous electron-rich (hetero)aromatic substrates and several α,ß-unsaturated carbonyl compounds. In a vast majority of the attempted Michael reactions our catalytic system was significantly superior over the currently used methods for the same transformations in terms of reaction times and temperatures, catalyst loadings, isolated product yields, and/or selectivity.

Pursuing the active species in an aluminium-based Lewis acid system for catalytic Diels-Alder cycloadditions.

Several Al-based complexes supported by a bis(imino)aryl NCN pincer ligand have been prepared. Systematic structural and experimental evidence identified a cationic species, supported by a THF molecule, as the best Lewis acid precatalyst for a range of Diels-Alder cycloadditions. This highlighted the importance of fully isolating and characterizing the active species in any catalytic process especially when Lewis acids are used due to the presence of hidden Brønsted acids (HBAs). Finally, the control experiments conducted in order to eliminate HBA activity that involve a bulky pyridine base should be performed with caution as the corresponding protonated pyridinium salt could also serve as a proton source.

Enhanced performance in gas adsorption and Li ion batteries by docking Li(+) in a crown ether-based metal-organic framework.

Incorporating supramolecular interaction units, crown ether rings, into metal-organic frameworks enables the docking of metal ions through complexation for enhanced performance in H2 and CO2 adsorption and lithium ion batteries.

A Well-Defined Aluminum-Based Lewis Acid as an Effective Catalyst for Diels-Alder Transformations.

A catalytically active aluminum-based system for Diels-Alder transformations is reported. The system was generated by mixing a ß-diketiminate-stabilized aluminum bistriflate compound with Na[BAr(Cl) 4 (Ar(Cl) =3,5-Cl2 C6 H3). Solid-state analysis of the catalytic system reveals a unique structure incorporating a two-dimensional coordination polymer. According to the experimental results obtained from several Diels-Alder transformations, the aluminum-based system appears to be a more practical and more robust alternative to the recently reported compounds based on carbon and silicon cations.