Wenjing Qi

Facile surfactant-free synthesis and characterization of Fe3O4@3-aminophenol–formaldehyde core–shell magnetic microspheres

Fe3O4@3-aminophenol–formaldehyde (Fe3O4@APF) core–shell resin polymer magnetic nanocomposites were synthesized using a straightforward surfactant-free methodology. The shell quickly formed within 5 min and could be easily size tunable in the range from 15 to 137 nm by changing the concentrations of 3-aminophenol and formaldehyde. The morphology, composition and magnetic properties of the resulting magnetic microspheres were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis measurements. The magnetic microspheres were uniform in morphology and can be converted into Fe3O4@carbon magnetic nanocomposites because of their excellent thermal stability. Moreover, Fe3O4@APF magnetic microspheres have excelling adsorption properties in the removal of methyl blue.

An amperometric sensor for the determination of benzophenone in food packaging materials based on the electropolymerized molecularly imprinted poly-o-phenylenediamine film

Benzophenone is one of the most commonly used photoinitiators of UV-cured inks on food packaging materials and can migrate into foodstuffs. In this study, an amperometric benzophenone sensor based on molecularly imprinted polymer (MIP) was successfully constructed for the first time. The sensor was prepared by electropolymerizing o-phenylenediamine (o-PD) on a glassy carbon electrode (GCE) in the presence of template benzophenone, and then removing the template by immersing the poly-o-phenylenediamine film-modified GCE in ethanol. The molecularly imprinted sensor was tested in the presence or absence of benzophenone by cyclic voltammetry and linear sweep voltammetry to verify the changes in the redox peak currents of potassium ferricyanide. The sensor responded sensitively to benzophenone over a linear range of 0.05-5 μM with a detection limit of 10 nM. The imprinted sensor showed high recognition ability for benzophenone and was successfully applied to the determination of benzophenone in food packaging material samples.

Electrochemiluminescence Detection of TNT by Resonance Energy Transfer through the Formation of a TNT-Amine Complex

2,4,6-Trinitrotoluene (TNT) is a widely used nitroaromatic explosive with significant detrimental effects on the environment and human health. Its detection is of great importance. In this study, both electrochemiluminescence (ECL)-based detection of TNT through the formation of a TNT-amine complex and the detection of TNT through electrochemiluminescence resonance energy transfer (ECRET) are developed for the first time. 3-Aminopropyltriethoxysilane (APTES)-modified [Ru(phen)3](2+) (phen=1,10-phenanthroline)-doped silica nanoparticles (RuSiNPs) with uniform sizes of (73±3) nm were synthesized. TNT can interact with APTES-modified RuSiNPs through charge transfer from electron-rich amines in the RuSiNPs to the electron-deficient aromatic ring of TNT to form a red TNT-amine complex. The absorption spectrum of this complex overlaps with the ECL spectrum of the APTES-modified RuSiNPs/triethylamine system. As a result, ECL signals of the APTES-modified RuSiNPs/triethylamine system are turned off in the presence of TNT owing to resonance energy transfer from electrochemically excited RuSiNPs to the TNT-amine complex. This ECRET method has been successfully applied for the sensitive determination of TNT with a linear range from 1×10(-9) to 1×10(-6) M with a fast response time within 1 min. The limit of detection is 0.3 nM. The method exhibits good selectivity towards 2,4-dinitrotoluene, p-nitrotoluene, nitrobenzene, phenol, p-quinone, 8-hydroxyquinoline, p-phenylenediamine, K3[Fe(CN)6], Fe(3+), NO3(-), NO2(-), Cr(3+), Fe(2+), Pb(2+), SO3(2-), formaldehyde, oxalate, proline, and glycine.

Facile Synthesis of Porous PtM (M=Cu, Ni) Nanowires and Their Application as Efficient Electrocatalysts for Methanol Electrooxidation

Porous Pt75Cu25 and Pt73Ni27 nanowires were successfully synthesized by a one‐step wet chemical solution method without the use of any template for the first time. The combination of porous and one‐dimensional features and the addition of a second cheap metal offer high catalyst utilization, excellent catalytic activity, and better durability for the methanol oxidation reaction. Porous Pt75Cu25 and Pt73Ni27 nanowires showed mass current densities of 390 (at 0.69) and 503 mA mg−1 (at 0.70 V), respectively. These mass current densities are much higher than that of Pt nanowires (356 mA mg−1 at 0.73 V) and commercial Pt black (195 mA mg−1 at 0.73 V). During the entire 2000 s current–time test, the porous Pt75Cu25 and Pt73Ni27 nanowires also exhibited higher stability for the methanol oxidation reaction than Pt nanowires and commercial Pt black.

A Platinum Highly Concave Cube with one Leg on each Vertex as an Advanced Nanocatalyst for Electrocatalytic Applications

Platinum highly concave cubes with one leg on each vertex (HCCLV) enclosed by {7 5 0} facets were conveniently synthesized for the first time through a one‐pot solvothermal method in a mixed solvent of oleylamine and isopropanol containing platinum(II) acetylacetonate. This method can also be extended to the synthesis of Pt dendrite nanocubes at shorter reaction times. Preferential overgrowth may facilitate the formation of Pt HCCLV in the presence of oleylamine and isopropanol. The Pt HCCLV exhibit excellent electrocatalytic activity for the oxidation of methanol (7.76×) and ethanol (5.46×) compared to commercial Pt black. Furthermore, the Pt HCCLV show higher stability than Pt dendrite nanocubes and commercial Pt black. The Pt HCCLV also remarkably improve the electrochemiluminescence activity of the luminol/H2O2 system.

Wireless Electrochemiluminescence with Disposable Minidevice

Wireless electrochemiluminescence system based on the wireless energy transmission technique has been demonstrated for the first time. It has a disposable transmitter and a coiled energy receptor. The coiled energy receptor is smartly used as the electrode. The wireless electrochemiluminescence system has been used to detect hydrogen peroxide with good sensitivity, featuring advantages of easy manipulation, low cost, and small size. The handy and cheap wireless electrochemiluminescence device can use laptops as a power supply. It is promising for the development of portable or disposable electrochemiluminescence devices for various applications (e.g., such as point of care testing, field analysis, scientific research, and chemical education). These advantages enable one to integrate many wireless electrochemiluminescence minidevices with screen printing coiled electrode arrays in microwell plates and charge-coupled devices (CCD) cameras to develop electrochemiluminescence high-throughput screening systems with broad applications in clinical analysis, drug screening, and biomolecular interaction studies.

One-pot synthesis of gold nanorods using binary surfactant systems with improved monodispersity, dimensional tunability and plasmon resonance scattering properties

A facile seedless growth method for high-yield synthesis of monodisperse gold nanorods using binary surfactant mixtures is reported for the first time. In comparison with other seedless methods, the present method enables the preparation of gold nanorods with much better monodispersity. Moreover, the present seedless growth method enables the preparation of not only thin gold nanorods but also thick gold nanorods which cannot be prepared by other reported seedless methods. Dark-field microscopy measurements of a single gold nanorod indicate that the thicker gold nanorod shows enhanced scattering properties.

Increasing Electrochemiluminescence Intensity of a Wireless Electrode Array Chip by Thousands of Times Using a Diode for Sensitive Visual Detection by a Digital Camera.

Both a wireless electrochemiluminescence (ECL) electrode microarray chip and the dramatic increase in ECL by embedding a diode in an electromagnetic receiver coil have been first reported. The newly designed device consists of a chip and a transmitter. The chip has an electromagnetic receiver coil, a mini-diode, and a gold electrode array. The mini-diode can rectify alternating current into direct current and thus enhance ECL intensities by 18 thousand times, enabling a sensitive visual detection using common cameras or smart phones as low cost detectors. The detection limit of hydrogen peroxide using a digital camera is comparable to that using photomultiplier tube (PMT)-based detectors. Coupled with a PMT-based detector, the device can detect luminol with higher sensitivity with linear ranges from 10 nM to 1 mM. Because of the advantages including high sensitivity, high throughput, low cost, high portability, and simplicity, it is promising in point of care testing, drug screening, and high throughput analysis.

Detection of ozone based on its striking inhibition of tris(1,10-phenanthroline)ruthenium(II)/glyoxal electrochemiluminescence

Ozone unexpectedly dramatically suppresses the electrochemiluminescence (ECL) of Ru(phen)3(2+)/glyoxal at an ozone/glyoxal ratio of less than 0.5%. Moreover, a sensitive, simple and fast ECL method for ozone detection is developed, with a detection time within 1 min and a limit of detection of 20 nM.

A label-free and signal-on supersandwich fluorescent platform for Hg2+ sensing.

A label-free supersandwich fluorescent assay was demonstrated for the first time by taking Hg(2+) as a detection candidate. The principle of the proposed supersandwich fluorescent platform is based on the formation of supersandwich structure by T-Hg(2+)-T coordination and the fluorescence enhancement of the intercalated Genefinder (GF) in double strand DNA (dsDNA). Such supersandwich fluorescent DNA sensor exhibits a linear range of 10-300 nM for the detection of Hg(2+), with a detection limit of 2.5 nM on the basis of the 3σ/slope (σ represents the standard deviation of the blank samples), which is well below the permit of the U.S. Environmental Protection Agency (<10 nM). The detection can be fulfilled in less than 10 min. The proposed mix-and-detect fluorescent platform exhibits excellent sensitivity, selectivity, and convenient manipulation. The assay was successfully used to detect Hg(2+) in the lake water samples, which suggested its potential in practical samples.