One-Pot Three Carbon Dots with Various Lifetimes Rooted in Different Decarboxylation Degrees for Matrix-Free, Anti-Oxygen, and Time-Resolved Information Encryption and Cellular Imaging.

Activating long-lived room temperature phosphorescence (RTP) in the aqueous environment and thus realizing matrix-free, anti-oxygen, and time-resolved information encryption and cellular imaging remain a great challenge. Here, we fabricated three types of carbon dots (C-dots), i.e., fluorescent C-dots (F-C-dots) and two types of phosphorescent C-dots denoted as Pw-C-dots and Py-C-dots by a one-pot strategy. Their formation was attributed to the difference in the decarboxylation degree at high temperatures using trimesic acid (TMA) as a sole precursor. Unexpectedly, the yield reached as high as ∼92%, and the proportions were ∼27% for F-C-dots, ∼17% for Pw-C-dots, and ∼56% for Py-C-dots. These nanomaterials could help implement carbon peaking and carbon neutrality. Both green RTP of the two C-dots resulted from the small energy gap (ΔEST). These two RTP C-dots had a long lifetime of over 270 ms with a relatively high quantum yield (4.5 and 6.2%). They exhibited excellent photostability and anti-photobleaching performances. The dry and wet powders of the RTP C-dots were applied to high-level information encryption. The lifelike patterns were greatly different from those of the original ones and could last for several seconds to the naked eye, demonstrating that the RTP C-dots could be potentially employed as anti-oxygen and time-resolved contrast reagents. Most significantly, the cellular imaging experiments showed that the biofriendly PVP-coated Py-C-dots could localize at lysosomes and sustain hundreds of milliseconds. This approach not only pioneers a time-resolved lysosome localization model but also opens up a promising door for anti-oxygen and time-resolved RTP cytoimaging.

Controlled manipulation of TiO2 nanoclusters inside mesochannels of core-shell silica particles as stationary phase for HPLC separation.

Based on a detailed study of the hydrolysis process of tetrabutyl orthotitanate (TBOT), TiO2 nanoclusters were modified inside the pores of SiO2 core-shell particles instead of the outside. The pore size distribution of SiO2 core-shell spheres modified with TiO2 (SiO2@dSiO2@TiO2) was analyzed by Barrett-Joyner-Halenda (BJH) method and density functional theory (DFT) method, respectively. The results of the DFT calculations demonstrate that the TiO2 nanoclusters are always first formed in bulk solution and then enter the pores. By regulating the rate of hydrolysis of TBOT, almost all of the TiO2 nanoclusters are modified into the pores and the structure of the original SiO2 core-shell sphere is hardly affected. The morphology of the particles was characterized by scanning electron microscopy and transmission electron microscopy. The crystal phase of TiO2 was measured by XRD. SiO2@dSiO2@TiO2 spheres functionalized with C18 were packed into a stainless steel column. The chemical stability of SiO2@dSiO2@TiO2 spheres under alkaline was tested by flushing of a mobile phase at pH 13 for 7 days. The efficiency of the column after the alkali solution treatment still reaches 98,430 plates m-1, which is only about 1.6% lower than that before the alkali solution treatment. A series of basic and acidic analytes were also separated on the column. Graphical abstract TiO2 nanocrystals were coated into the pore of core-shell silica spheres. The prepared particles were packed into the column and separation performance up to 98,430 plates per meter was achieved.

A composite consisting of bromine-doped carbon dots and ferric ions as a fluorescent probe for determination and intracellular imaging of phosphate.

A composite probe has been developed for fluorometric determination and imaging of phosphate in real water samples and in cells. The method is based on the use of weakly blue fluorescent bromine-doped carbon dots (C-dots) containing aromatic carbon-bromine groups and loaded with Fe3+ ions. The carboxy, phenolic hydroxy and aldehyde groups on the surface of the C-dots can coordinate with Fe3+ to form an adsorbed complex that reduces the blue fluorescence through an inner filter effect. If phosphate is added, it will capture Fe3+ on the surface of C-dots and restore fluorescence by ~88% via a displacement approach. The probe, best operated at excitation/emission maxima of 370/418 nm, has a linear response in the 0.4 to 22 µM phosphate concentration range and a 0.25 µM of detection limit. The relative standard deviation (at a phosphate level of 8.0 µM) is 3.6% (for n = 5). The method was applied to confocal imaging of phosphate in HeLa cells. Graphical abstractSchematic representation of the synthesis of bromine-doped carbon dots (C-dots) by a "one-step" approach. They are shown to be capable of (a) detecting phosphate in real water samples through the displacement approach, and (b) of imaging intracellular phosphate.

Discovery of thinopyrimidine-triazole conjugates as c-Met targeting and apoptosis inducing agents.

Five series of N-methylpicolinamide moiety and thienopyrimidine moiety bearing triazole (21-26, 27-34, 35-41, 42-47 and 48-54) were designed and synthesized. And all the target compounds were evaluated for the IC50 values against three cancer cell lines (A549, HepG2 and MCF-7) and some selected compounds (43, 49 and 52) were further evaluated for the activity against c-Met, Flt-3, VEGFR-2, c-Kit and EGFR kinases. Moreover, SARs and docking studies indicated that thieno[3,2-d]pyrimidine bearing triazole moiety was privileged structure for the activity. Especially, the Cl atom on the 4-C position of aryl group showed the best activity. The most promising compound 49 showed 3.7-5.4-fold more activity than the lead drug Foretinib against A549, HepG2 and MCF-7 cell lines, with the IC50 values of 0.9 ±â€¯0.1 µM, 0.5 ±â€¯0.1 µM and 1.1 ±â€¯0.2 µM, respectively. And The experiments of enzyme-based showed that 49 inhibitor the c-Met selectively, with the IC50 values of 16 nM, which showed equal activity to Foretinib (14 nM). What's more, According to the result of AO single staining and Annexin V/PI staining, it's claimed that the 49 could induce late apoptosis of HepG2 cells and by a concentration-dependent manner.

Alginate capped and manganese doped ZnS quantum dots as a phosphorescent probe for time-resolved detection of copper(II).

A method is described for the detection of Cu(II). It is based on the use of a room-temperature phosphorescent probe consisting of alginate-capped and manganese(II)-doped ZnS quantum dots. The carboxy groups at the surface of the probe strongly coordinate Cu(II) to form a complex. As a result, the 4T1-6A1 transition of the Mn(II) ions in the probe is quenched, and the long decay time (~2.1 ms in the unquenched state) is accordingly reduced. At excitation/emission wavelengths of 316/590 nm and a delay time of 0.1 ms, the probe shows a linear response in the 0.01 to 12 µM Cu(II) concentration range. The detection limit is 6.0 nM and the RSD is 3.2% (for n = 5). Graphical Abstract A two-step procedure is described to synthesize alginate capped manganese doped ZnS QDs. These coordinate with Cu(II) to form an absorbent complex and can be used as a phosphorescent probe for time-resolved detection of Cu(II).

Upconversion nanoparticles for ratiometric fluorescence detection of nitrite.

We have developed a selective upconversion switching method for the ratiometric fluorescence detection of nitrite using upconversion nanoparticles (UCNPs) and an efficient nitrite reaction. The green emission (λ(em) = 539 nm) of NaYF4:Yb(3+),Er(3+) nanoparticles can be selectively quenched by the neutral red (NR) dye due to the spectral overlap between the emission at 539 nm and the absorption of NR, while its red emission (λ(em) = 654 nm) remains unchanged. Nitrite reacts specifically and strongly with NR to form diazonium salt and lose the diazonium group, which sharply decreases the absorption of NR. Thus, the green emission of NaYF4:Yb(3+),Er(3+) can be recovered by increasing the amount of nitrite, leading to visible color changes from red to orange-yellow and finally green under excitation at 980 nm. The increase in the ratio of emission intensities (I539/I654) is quantitatively correlated to the concentration of nitrite ions. Moreover, the developed method has been successfully applied to nitrite detection in real samples such as drinking water, natural water and meat foods. In particular, the upconversion sensors can efficiently avoid background optical interference and thus show potential for the detection of nitrite salts in complex samples.

Selective fluorescence response and magnetic separation probe for 2,4,6-trinitrotoluene based on iron oxide magnetic nanoparticles.

Despite the rapid development of nanomaterials and nanotechnology, it is still desirable to develop novel nanoparticle-based techniques which are cost-effective, timesaving, and environment-friendly, and with ease of operation and procedural simplicity, for assay of target analytes. In the work discussed in this paper, the dye fluorescein isothiocyanate (FITC) was conjugated to 1,6-hexanediamine (HDA)-capped iron oxide magnetic nanoparticles (FITC-HDA Fe3O4 MNPs), and the product was characterized. HDA ligands on the surface of Fe3O4 MNPs can bind 2,4,6-trinitrotoluene (TNT) to form TNT anions by acid-base pairing interaction. Formation of TNT anions, and captured TNT substantially affect the emission of FITC on the surface of the Fe3O4 MNPs, resulting in quenching of the fluorescence at 519 nm. A novel FITC-HDA Fe3O4 MNPs-based probe featuring chemosensing and magnetic separation has therefore been constructed. i.e. FITC-HDA Fe3O4 MNPs had a highly selective fluorescence response and enabled magnetic separation of TNT from other nitroaromatic compounds by quenching of the emission of FITC and capture of TNT in aqueous solution. Very good linearity was observed for TNT concentrations in the range 0.05-1.5 µmol L(-1), with a detection limit of 37.2 nmol L(-1) and RSD of 4.7 % (n = 7). Approximately 12 % of the total amount of TNT was captured. The proposed methods are well-suited to trace detection and capture of TNT in aqueous solution.

Applicability of core-shell SiO2 microspheres with a high TiO2 loading as stationary phase for HPLC.

BACKGROUND: Due to its high chemical stability, sufficient rigidity and zwitterionic ion exchange properties, TiO2 can be considered as an alternative stationary phase material to SiO2 for high performance liquid chromatography. TiO2 stationary phase is usually prepared by coating TiO2 onto SiO2 support by sol-gel method. However, in the traditional coating method, in order to overcome the rapid hydrolysis rate of tetrabutyl orthotitanate, only a very low concentration of tetrabutyl orthotitanate can be used, resulting in a low loading of TiO2 on the support. RESULTS: TiO2 core-shell spheres with a good monodispersity were prepared using 0.25 mol L-1 tetrabutyl orthotitanate. The specific surface area, pore volume, pore diameter and TiO2 loading of the TiO2 core-shell spheres were 66 m2 g-1, 0.15 cm3 g-1, 9.8 nm and 57%, respectively. The core-shell spheres were derivatized with n-octadecyltrichlorosilane and then packed into a stainless steel column to test the separation performance for neutral, basic and acidic samples in liquid chromatography. A baseline separation of polyaromatic hydrocarbons was achieved, showing a column efficiency for fluorene of 118075 plates m-1. The prepared stationary phase was also used to separate acidic and basic mixtures, and column efficiencies of 54500 and 25836 plates m-1 were obtained for N,N-dinitroaniline and p-chlorophenol, respectively. The relative standard deviations of the retention times of polyaromatic hydrocarbons for run-to-run, day-to-day and column-to-column repeatability were all below 5.1%. SIGNIFICANCE AND NOVELTY: This work demonstrated that TiO2 can be coated in the pores of the shell of SiO2 core-shell spheres with high TiO2 loading using a high concentration of tetrabutyl orthotitanate as the titania source. The experimental results show that the TiO2 coated core-shell spheres can be a good alternative stationary phase for liquid chromatography.

Room-temperature phosphorescence and fluorescence nanocomposites as a ratiometric chemosensor for high-contrast and selective detection of 2,4,6-trinitrotoluene.

Reports on using complementary colours for high-contrast ratiometric assays are limited to date. In this work, graphitized carbon nitride (g-C3N4) nanosheets and mercaptoethylamine (MEA) capped Mn-doped ZnS QDs were fabricated by liquid exfoliation of bulk g-C3N4, and by a coprecipitation and postmodification strategies, respectively. Mn-doped ZnS quantum dots were deposited onto g-C3N4 nanosheets through an electrostatic self-assembly to form new nanocomposites (denoted as Mn-ZnS QDs@g-C3N4). Mn-ZnS QDs@g-C3N4 can emit a pair of complementary colour light, namely, orange room-temperature phosphorescence (RTP) at 582 nm and blue fluorescence at 450 nm. After 2,4,6-trinitrotoluene (TNT) dosing into Mn-ZnS QDs@g-C3N4 aqueous solution, and pairing with MEA to generate TNT anions capable of quenching the emission of Mn-doped ZnS QDs, the fluorescence colours of the solution changed from orange to blue across white, exhibiting unusual high-contrast fluorescence images. The developed ratiometric chemosensor showed very good linearity in the range of 0-12 µM TNT with a limit of detection of 0.56 µM and an RSD of 6.4 % (n = 5). Also, the ratiometric probe had an excellent selectivity for TNT over other nitroaromatic compounds, which was applied in the ratiometric test paper to image TNT in water, and TNT sensing under phosphorescence mode to efficiently avoid background interference. A high-contrast dual-emission platform for selective ratiometric detection of TNT was therefore established.

Lysosome-targetable brightly green fluorescence carbon dots for real-time monitoring in cell and highly efficient removal in environment of hypochlorite.

Due to the lacks of lysosome localization group and reaction/interaction site for hypochlorite (ClO-) on the surface of the carbon dots (C-dots), no C-dots-based lysosome-targeted fluorescence probes have, so far, been reported for real-time monitoring intracellular ClO-. In this work, 1,3,6-trinitropyrene (TNP) was used as a precursor to prepare C-dots with maximum excitation and emission wavelengths at 485 and 532 nm, respectively, and quantum yield âˆ¼ 27% by a hydrothermal approach at 196 °C for 6 h under a reductive atmosphere. The brightly green C-dots can sensitively and quickly respond to ClO- in aqueous solution through surface chemical reaction, showing a linear relationship in the range of 0.5-120 µΜ ClO- with 0.27 µΜ of limit of detection (LOD). Most significantly, the C-dots can localize at intracellular lysosome to image ClO- in lysosomes. Also, the magnetic nanocomposites (C-dots@Fe3O4 MNCs) were fabricated via a simple electrostatic self-assembly between Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) and C-dots for highly efficient removal of ClO- in real samples. Therefore, lysosome-targetable C-dots-based probes for real-time monitoring ClO- were successfully constructed, opening up a promising door to investigate the biological functions and pathological roles of ClO- at organelle levels.

Room-temperature phosphorescence chemosensor and Rayleigh scattering chemodosimeter dual-recognition probe for 2,4,6-trinitrotoluene based on manganese-doped ZnS quantum dots.

Rayleigh scattering (RS) as an interference factor to detection sensitivity in ordinary fluorescence spectrometry is always avoided in spite of considerable efforts toward the development of RS-based resonance Rayleigh scattering (RRS) and hyper-Rayleigh scattering (HRS) techniques. Here, combining advantages of quantum dots (QDs) including chemical modification of functional groups and the installation of recognition receptors at their surfaces with those of phosphorescence such as the avoidance of autofluorescence and scattering light, l-cys-capped Mn-doped ZnS QDs have been synthesized and used for room-temperature phosphorescence (RTP) to sense and for RS chemodosimetry to image ultratrace 2,4,6-trinitrotoluene (TNT) in water. The l-cys-capped Mn-doped ZnS QDs interdots aggregate with TNT species induced by the formation of Meisenheimer complexes (MHCs) through acid-base pairing interaction between l-cys and TNT, hydrogen bonding, and electrostatic interaction between l-cys intermolecules. Although the resultant MHCs may quench the fluorescence at 430 nm, interdots aggregation can greatly influence the light scattering property of the aqueous QDs system, and therefore, dominant RS enhancement at defect-related emission wavelength was observed under the excitation of violet light of Mn-doped ZnS QDs, which was applied in chemodosimetry to image TNT in water. Meanwhile, Mn-doped ZnS QDs also exhibited a highly selective response to the quenching of the (4)T(1)-(6)A(1) transition emission (RTP) and showed a very good linearity in the range of 0.0025-0.45 µM TNT with detection limit down to 0.8 nM and RSD of 2.3% (n = 5). The proposed methods are well-suited for detecting the ultratrace TNT and distinguishing different nitro compounds.

Pesticide-derived bright chlorine-doped carbon dots for selective determination and intracellular imaging of Fe(III).

Inspired by the conversion from organics or biomass to fluorescent carbon dots (C-dots), the use of pesticide 4-chlorophenol (4-CP) as a precursor to prepare C-dots has been reported. The as-prepared chlorine-doped C-dots display a brightly blue emission at ∼445 nm with ∼22.8% quantum yield. Also, the surface of C-dots enriches functional groups, such as phenolic hydroxyl and carboxylic acid, etc., which can capture ferric ion (Fe(III)), resulting in the quenching of blue fluorescence of C-dots through an inner filter effect. The quantitative assay for Fe(III) was therefore realized by this probe with a 0.36 µM detection limit in the 0.6-25 µM concentration range. Most significantly, the cytotoxicity on Hela cells indicates the 4-CP-derived C-dots have a negligible cytotoxicity. The C-dots were applied in detection in environmental samples and imaging in Hela cells of Fe(III), demonstrating their good applicability, low toxicity and good biocompatibility, and providing an alterative approach to totally eliminate the harm of chlorophenols (CPs).

Design, synthesis, antiproliferative activity and docking studies of quinazoline derivatives bearing 2,3-dihydro-indole or 1,2,3,4-tetrahydroquinoline as potential EGFR inhibitors.

Eight series of quinazoline derivatives bearing 2,3-dihydro-indole or 1,2,3,4-tetrahydroquinoline were designed, synthesized and evaluated for the IC50 values against three cancer cell lines (A549, MCF-7 and PC-3). Most of the forty nine target compounds showed excellent antiproliferative activity against one or several cancer cell lines. The compound 13a showed the best activity against A549, MCF-7 and PC-3 cancer cell lines, with the IC50 values of 1.09 ±â€¯0.04 µM, 1.34 ±â€¯0.13 µM and 1.23 ±â€¯0.09 µM, respectively. Eight selected compounds were further selected to evaluated for the inhibitory activity against EGFR kinase. Three of them showed equal activity against EGFR kinase to positive control afatinib. AnnexinV-FITC, propidium iodide (PI) double staining and acridine orange single staining results indicated that the compound 13a could induce apoptosis of human lung cancer A549 cells.

Enhanced photoresponsive polyethyleneimine/citric acid co-carbonized dots for facile and selective sensing and intracellular imaging of cobalt ions at physiologic pH.

Whether as an important biological element or as a radioactive source/medicine, the monitoring of trace levels of cobalt ions (Co) has become a non-negligible factor for human health and green environment. Current technologies for the detection of Co are cost-expensive and time-consuming, and require cumbersome sample pretreatment process. Herein a novel sensing platform has been developed for Co detection based on the quenching of the enhanced fluorescence signal of polyamine functionalized C-dots. Amine groups at the surface of the C-dots can capture Zn2+/Cd2+ to form coordination compound, which can inhibit the photoinduced electron transfer pathways of C-dots and then induce the fluorescence enhancement of the C-dots by ∼80% margin. Also, Co interacts with these amine groups to form an absorbent complex, which can strongly quench the enhanced fluorescence of C-dots via an inner filter effect. This C-dots-based probe showed a wide linear response to Co with a concentration ranging from 0.012 to 12 µM, and a detection limit of 8.0 nM and RSD of 5.7% (n = 5). Significantly, the C-Dots exhibit excellent properties, such as negligible cytotoxicity, excellent biocompatibility, low-cost and high photostability, etc., which make C-dots favorable for label-free monitoring of Co and then successfully applied to the confocal imaging of intracellular Co.

3-Aminopropyltriethoxysilane-functionalized manganese doped ZnS quantum dots for room-temperature phosphorescence sensing ultratrace 2,4,6-trinitrotoluene in aqueous solution.

New strategies for silica coating of inorganic nanoparticles became a research hotspot for enhancing the mechanical stability of colloidal particles and protecting colloidal particles against oxidation and agglomeration, and so on. In this paper, 3-aminopropyltriethoxysilane (APTES)-functionalized Mn doped (AF MnD) ZnS QDs was prepared to be firsyly through the use of silane coupling agents to form an active layer of silica, then sol-gel reaction of TEOS co-deposited with APTES on the surface of resultant active layer of silica. The emitted long lifetime room-temperature phosphorescence (RTP) of the resultant nanomaterials allows an appropriate delay time so that any fluorescent emission and scattering light can be easily avoided. The APTES anchored on the layer of silica can bind 2,4,6-trinitrotoluene (TNT) species to form TNT anion through acid-base pairing interaction, the TNT anion species may increase the charge-transfer pathways from the nanocrystals to nitroaromatic analytes, therefore further enhance the quenching efficiency of RTP. Moreover, APTES as capped reagents can enlarge the spectral sensitivity and enhance RTP response of nanocrystals to the electron-deficient nitroaromatic and nitrophenol species. Meanwhile, AF MnD ZnS QDs also exhibited a highly selective response toward TNT analyte through significant color change and quenching of (4)T(1) to (6)A(1) transition emission. This AF MnD ZnS QDs based sensor showed a very good linearity in the range of 0.05-1.8µM with detection limit down to 50 nM (quenching percentage of phosphorescence intensity of 8%) and RSD of 3.5% (n=5). The reported QDs-based chemosensors here open up a promising prospect for the sensitive and convenient sensing of TNT explosive.

Synthesis in aqueous solution and characterisation of a new cobalt-doped ZnS quantum dot as a hybrid ratiometric chemosensor.

In this paper, cobalt (Co(2+))-doped (CoD) ZnS quantum dots (QDs) are synthesised in aqueous solution and characterised for the first time. L-Cysteine (L-Cys) ligands on the surface of CoD ZnS QDs can bind 2,4,6-trinitrotoluene (TNT) to form Meisenheimer complexes (MHCs) mainly through acid-base pairing interactions between TNT and L-Cys and the assistance of hydrogen bonding and electrostatic co-interactions among L-Cys intermolecules. The aggregation of inter-dots induced by MHCs greatly influenced the light scattering property of the QDs in aqueous solution, and Rayleigh scattering (RS) enhancement at the defect-related emission wavelengths as well as its left side was observed with the excitation of CoD ZnS QDs by violet light. RS enhancement, combining with the quenching of the orange transition emission induced by TNT anions, resulted in a change in the ratiometric visualisation of the system being investigated. A novel CoD ZnS QD-based hybrid ratiometric chemosensor has therefore been developed for simple and sensitive analysis of TNT in water. This ratiometric probe can assay down to 25 nM TNT in solution without interference from a matrix of real water sample and other nitroaromatic compounds. Because of the excellent electron-accepting ability and strong affinity of TNT to L-Cys on the surface of CoD ZnS QDs, the CoD photoluminescent nanomaterials reported here are well suited for detecting ultra-trace TNT and for distinguishing different nitro-compounds in aqueous solution.