Buhong Gao

Core–sheath structured electrospun nanofibrous membranes for oil–water separation

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.

A natural quercetin-based fluorescent sensor for highly sensitive and selective detection of copper ions

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.

A label-free and turn-on fluorescence sensor for sensitive and selective detection of iodide using carbon nanodots/silver nanocomposites

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.

Boron- and nitrogen-doped photoluminescent polymer carbon nanoparticles as nanosensors for imaging detection of Cu2+ and biothiols in living cells

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.

Durable superhydrophobic and superoleophilic electrospun nanofibrous membrane for oil-water emulsion separation

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.

Quercetin-coated Fe3O4 nanoparticle sensors based on low-field NMR for determination and removal of Pb2+ and Cu2+ in biological samples

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.