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A novel quinoline fluorescent probe QNP ((E)-N′-(5-chloro-2-hydroxybenzylidene) quinoline-2-carbohydrazide) for detection of Al3+ ion was designed, synthesized and characterized. QNP displayed a high fluorescence enhancement in the presence of Al3+ ion in DMF:PBS (99:1, v/v) solution and the detection limit was as low as 1.25 μM with high selectivity and excellent sensitivity from 0 to 3 μM. The sensing ability of QNP towards Al3+ ion is attributed to the synergistic effect of PET and ICT. Furthermore, the binding stoichiometry between QNP and Al3+ ion is of 1:1 by Job’s plot and mass spectrum, and the calculated binding constant is 4.29 × 108 M−1. The detection of Al3+ ion in water samples illustrates that QNP could be applied to the detection of practical samples in the environment. Bioimaging experiments on Hela cells, zebrafish and soybean root tissues demonstrate that it has potential application to investigate biological processes involving Al3+ ion within living cells. A quinoline-based turn-on fluorescence probe for the detection of Al3+ and its bioimaging in living cells, plant, and zebrafish.

Highly luminescent nitrogen and phosphorus co-doped graphene-analogous flakes (NPCGFs) were synthesized by a one-pot simple hydrothermal reaction using β-cyclodextrin (β-CD), vinylphosphoric acid (VPA), and o-phenylenediamine (oPD) as the precursors. VPA, as an important organic P-containing monomer, was selected as the phosphorus source to generate additional conjugated and effective binding sites on the surface of the NPCGFs. This synthetic strategy not only allows enhancement of structural rigidity, but also effectively eliminates surface traps of the NPCGFs, resulting in an improved fluorescence quantum yield (FL QY) of the NPCGFs. Additionally, oPD simultaneously acts as a nitrogen source and enables amino functionalisation of the NPCGF surface in the synthesis process. The NPCGFs (QY, 32.49%) are irregularly shaped with a typical diameter of approximately 54 nm and display strong fluorescence, with excitation/emission maxima of 360/445 nm. It was found that the NPCGFs can serve as a multifunctional FL probe for pH measurement and quercetin (Qc) detection. A linear relationship exists between the decrease in FL intensity and the concentration of Qc in the range from 0.35 to 30 μg mL-1 as well as the pH variation between 4.0 and 7.0. The probe was further applied to the determination of Qc in living cells.

A fluorescent probe based on isorhamnetin (Iso)-cyclodextrin (CD) inclusion for detecting Cu2+ was synthesized. A major fluorescence emission peak at 542 nm was observed for isorhamnetin (Iso) in buffer solution (pH 7.40) when the excitation wavelength was 390 nm. It was surprisingly found that (2-hydroxypropyl)-β-cyclodextrin (β-CD) could enhance the fluorescence intensity of Iso, and the major fluorescence peak was shifted to 557 nm. UV-vis spectrum showed that the Iso-β-CD system was formed by hydrogen bond and hydrophobic interaction. And the fluorescence intensity of Iso-β-CD system was stronger and more stable compared with Iso. Further study indicated that Iso-β-CD system had good selectivity and sensitivity toward Cu2+. When Cu2+ was added, the fluorescent emission intensity of Iso-β-CD system was quenched, while other metal ions could not bring about obvious change, which meant that the Iso-β-CD system had good selectivity toward Cu2+. The fluorescence titration spectra indicated that the concentration of Cu2+ was inversely proportional to fluorescence intensity, and fluorescence emission intensity was linearly correlated with the concentration of Cu2+ in the range of 0.05–6.0 μM. The calibration equation was y = −11.66x + 781.13 (R2 = 0.996), with a limit of detection of 0.017 μM (S/N = 3). The possible reaction mechanism was studied by UV-vis spectroscopy and Job's plot method. The results indicated that Cu2+ could combine with Iso-β-CD system. The stoichiometric ratio for the complex of Iso and Cu2+ was 2:1. The formation of Iso-β-CD-Cu(II) complex led to the extension of the conjugated system and the intramolecular charge transfer (ICT) took place. Therefore, fluorescence of Iso-β-CD system was quenched. At last, the probe was successfully applied to determination of Cu2+ in water samples, vegetables and fruits with good recoveries, and the results coincided with those obtained by ICP-AES or AAS methods.

Marinepollution andindustrial wastewater have caused serious environmental pollution, thereby resulting into an alarming damage to public health in the past decades, hence the high demand for, cost effective, energy-efficient oil-water separation technologies for the removal of oil contaminants from such water. Herein, we report a facile method to fabricate superhydrophobic/superoleophilic membrane by immersing a polyimide (PI)-based nanofibrous membrane into a water/ethanol/ammonia/dopamine mixture, followed by modification with 1H, 1H, 2H, 2H-perfluorodecanethiol (PFDT). The PI-based membrane exhibited water contact angle (WCA) above 153°, while the oil contact angle (OCA) approached 0°, thereby promoting an outstanding chemical stability which sustained its superhydrophobicity when immersed in aqueous solutions at different pH values. Additionally, the PI-based membrane possesses ultrahigh flux, high separation efficiency and good reusability in oil-water separation. The aforementioned properties, as well as the easily scale-up preparation process ensure that this promising as-fabricated membrane can be applied for practical environmental applications including treatment of oily wastewater and oil spillage clean-up.

In this work, a novel fluorescent sensor (quercetin-Pluronic-F127 nano-micelles) was prepared by the facile self-assembly method with natural quercetin (Qc) and Pluronic-F127 (F127). Qc-F127 nano-micelles were characterized by TEM which indicated that Qc have successfully entered into the amphiphilic micelle. The nano micelles with sizes of 25 to 40 nm showed a strong green fluorescence (FL). The sensor exhibits high sensitivity and selectivity towards Cu2+ with a linear range of 5 × 10−8–4 × 10−6 mol L−1, the detection limit of 1 × 10−8 mol L −1. Moreover, the Qc-F127 nano-micelles can be used to detect Cu2+ in vitro due to their good biocompatibility. Besides Cu2+ sensing, when Cysteine (Cys) were added, the FL intensity of Qc-F127-Cu(II) system could be restored due to the chelation interactions between Cu2+ ions and the sulfydryl and amino groups of Cys. So, Qc-F127-Cu(II) system can used to detect Cys, and the linear range and the limit of detection of the Qc-F127-Cu2+ system were 3 × 10−7–3.5 × 10−5 mol L−1 and 6 × 10−8 mol L −1. Moreover, Qc-F127-Cu(II) has been used for imaging of Cys in cells, which demonstrates its values for potential application in biological systems.

• Fabrication of air filtration membranes via green electrospinning and thermal crosslinking

Environmentally friendly probe materials for detecting copper ions were studied in this research. Fluorescent emission of quercetin (Q) was observed in the buffer solution (pH = 7.40), and (2-hydroxypropyl)-β-cyclodextrin (CD) could enhance the fluorescence intensity of Q. The UV/Vis spectrum showed that the Q-CD system was formed. After adding copper ions into the Q-CD system, the fluorescent emission intensity of Q-CD system generated quenching, and other metal ions could not bring change, which meant the Q-CD system showed good selectivity to copper ions. The fluorescence titration spectra showed that the concentration of copper ions was inversely proportional to fluorescence intensity, and gave a good linear change in fluorescence emission intensity in response to the concentration of copper ions ranging from 5.0 × 10−8 to 8.3 × 10−6 mol L−1. The calibration curve of the relationship between the intensity and copper ions concentration was y = −9.24x + 844.51 (R2 = 0.997). The detection limit of copper ions was measured to be 2.3 × 10−8 mol L−1. The probable mechanism was studied by UV/Vis spectrum and Job's plot method. The results indicated that Q-CD-Cu(II) complex was formed and intramolecular charge transfer (ICT) took place. At last, the probe was successfully applied for determination of copper ions in water bodies, vegetables and fruits with good recovery. The study showed that Q-CD system could detect copper ions as a fluorescent probe with high selectivity, sensitivity and larger linearity range.

In this paper, we develop quercetin-coated Fe3O4 nanoparticles (QMNPS) as a sensor for the detection and removal of Pb2+ and Cu2+ based on low-field NMR. QMNPS were characterized by TEM, FTIR and XRD. The NMR sensor showed high selectivity toward Pb2+ or Cu2+. The standard curves for ΔT2-ion concentration showed good correlations, i.e., R2 = 0.9912 for Pb2+ and 0.9983 for Cu2+; the linear ranges and the limits of detection were 4.8 × 10−6–1 × 10−4 mol L−1 and 1.6 × 10−6 mol L−1 for Pb2+, and 5.0 × 10−6–1 × 10−4 mol L−1 and 2.0 × 10−6 mol L−1 for Cu2+, respectively. The calculated maximum adsorption capacity was about 71 mg for Cu2+ and 68 mg for Pb2+ per gram of QMMP, which was superior to the results of some previous reports. The detection and removal of Pb2+ or Cu2+ was based on the coordination reaction between the NMR sensor of QMNPs and Pb2+ or Cu2+, which led to the aggregation of QMNPs. As a result, the proposed NMR sensor was successfully applied for the determination and removal of Pb2+ and Cu2+ in contaminated water and urine samples with excellent recoveries and high adsorbent capacities.

Boron and nitrogen co-doped polymer carbon nanoparticles (BNPCNPs) were synthesized by a facile hydrothermal treatment using uric acid as a nitrogen source, and phenylboronic acid as a boron source for the first time. The nanoparticles with sizes in the range of 90 to 180 nm show excellent and stable fluorescence properties. Moreover, these BNPCNPs showed highly efficient fluorescence quenching ability in the presence of copper (Cu2+) ions due to the formed nonfluorescent metal complexes via robust Cu2+–O or Cu2+–N interactions with the O and N of fluorescent BNPCNPs, which allowed the analysis of Cu2+ ions in the range of 0.0033 to 80 μM. Besides Cu2+ sensing, when biothiols were added, the quenched BNPCNPs-Cu2+ system could be regained via the effective coordination/chelation interactions between Cu2+ ions and the plentiful mercapto and amino groups of biothiols. In the light of this theory, simple biothiol sensors were fabricated without complicated, costly and time-consuming operations. The linear range and the limit of detection of the BNPCNPs-Cu2+ system were 0.0078–80 μM and 2.1 nM for Lcy, 0.0085–85 μM and 2.7 nM for Hcy, and 0.013–89 μM and 4.2 nM for GSH, respectively. Especially, the nanoprobe exhibits good cell membrane permeability and excellent biocompatibility by HeLa cells assay, which is favorable for bioimaging applications. So this BNPCNPs probe can be further used for imaging of biothiols in living cells.

A natural isorhamnetin-based fluorescent sensor for highly sensitive and selective detection of copper ions had been studied. The fluorescent sensor isorhamnetin (Iso) after binding to Cu 2+ ions in pH 7.40 buffer solution generated quenching in fluorescent emission intensity. The binding constant value was obtained 1.79 × 10 6 . The sensor Iso can be applied to the quantification of Cu 2+ ion with a linear range of 1.0 × 10 −8 –1.9 × 10 −6 mol L −1 , the detection limit of 4.0 × 10 −9 mol L −1 , and the reproducibility of the sensor is good. The sensor showed high selectivity toward Cu 2+ . As a result, the isorhamnetin fluorescent sensor was successfully applied for determination of Cu 2+ in rivers, lakes, vegetables and fruits with good recovery.

A novel acylhydrazone coumarin fluorescent chemosensor C4 for detection of Ni2+ was designed and synthesized. The experimental results revealed a low detection limit of 2.1 × 10−11 M with high selectivity and excellent sensitivity towards Ni2+. C4 showed a good linear relationship with the concentration of Ni2+ from 1.3 × 10−6 to 1.6 μM. Moreover, a stable complex was formed between C4 and with Ni2+ and the binding ratio was proved to be 2: 1 by Job’s plot and mass spectrum. The sensing ability of C4 towards Ni2+ was attributed to parity-forbidden transition according to fluorescence titrations and DFT calculations. The detection of Ni2+ in water samples illustrated C4 could be successfully applied for the detection of Ni2+ in real environmental samples. What’s more, the fluorescence microscopy images of Hela cells demonstrated the high potential of the novel biosensor for the investigation of biological processes involving Ni2+, as well.

In recent years, both the increasing frequency of oil spill accidents and the urgency to deal seriously with industrial oil-polluted water, encouraged material scientists to design highly efficient, cost effective oil–water separation technologies. We report on electrospun nanofibrous membranes which are composed of core–sheath structured cellulose-acetate (CA)–polyimide (PI) nanofibers. On the surface of the CA–PI fibers a fluorinated polybenzoxazine (F-PBZ) functional layer, in which silica nanoparticles (SNPs) were incorporated, has been applied. Compared with F-PBZ/SNP modified CA fibers reported before for the separation of oil from water, the PI-core of the core–shell F-PBZ/SNP/CA–PI fibers makes the membranes much stronger, being a significant asset in their use. Nanofibrous membranes with a tensile strength higher than 200 MPa, a high water contact angle of 160° and an extremely low oil contact angle of 0° were obtained. F-PBZ/SNP/CA–PI membranes seemed very suitable for gravity-driven oil–water separation as fast and efficient separation (>99%) of oil from water was achieved for various oil–water mixtures. The designed core–sheath structured electrospun nanofibrous membranes may become interesting materials for the treatment of industrial oil-polluted water.

Based on the principle of fluorescence recovery, by the strong and specific interaction between iodide (I−) ions and nanoAg on the surface of carbon nanodots/silver (Cdots/Ag) nanocomposites, we propose a simple label-free and turn-on method for the detection of I− ions with high selectivity and sensitivity by using fluorescent Cdots/Ag nanocomposites in aqueous media.

A natural quercetin-based fluorescent sensor for highly sensitive and selective detection of copper ions has been studied. The quercetin fluorescent sensor after binding to Cu2+ ions in pH 7.40 buffered solution showed a quenching of fluorescence emission intensity. The binding constant value was obtained as 3.56 × 107. The sensor can be applied to the quantification of Cu2+ ions with a linear range of 2.0 × 10−7–3.0 × 10−6 mol L−1 and a detection limit of 1.0 × 10−7 mol L−1. The sensor showed high selectivity toward Cu2+. As a result, the proposed fluorescent sensor was successfully applied for determination of Cu2+ in water samples.

In this study we present the use of co-axial electrospinning to produce core-shell composite micro-/nano- fibers of polyurethane (PU) and cellulose acetate phthalate (CAP). The designed fibers possess enhanced mechanical properties with a tensile strength of 13.27±2.32MPa, which is a clear improvement over the existing CAP fibers that suffer from a poor mechanical strength (0.2±0.03MPa). The CAP imparts pH responsiveness to the core-shell structure giving the fibers potential for "semen sensitive" (intravaginal) drug delivery.

Highly luminescent nitrogen-doped carbonaceous nanospheres (LNCNs) were synthesized by a one-pot hydrothermal reaction of β-cyclodextrin (β-CD) and branched polyethylenimine (BPEI). Both the N-doping and amino-functionalisation of LNCNs were achieved simultaneously. The prepared LNCNs display excellent properties such as high physical and chemical stability, excitation wavelength-independent emission, and high photoluminescence quantum yields. Importantly, the LNCNs exhibit a quenching of photoluminescence in the presence of quercetin (Qc) based on the simple static quenching mechanism, making it possible to quantify concentrations from 0.5 to 80 μg mL−1 with a detection limit of 0.21 μg mL−1. Furthermore, the LNCNs probe was further used for imaging Qc in living cells.