Xiaoyu Xu

Electrochemical determination of morphine at ordered mesoporous carbon modified glassy carbon electrode.

A sensitive electrochemical detection scheme for morphine has been proposed by utilizing the ordered mesoporous carbon modified glassy carbon electrode (OMC/GCE). The electrochemical behaviour of morphine at the OMC/GCE was investigated by cyclic voltammetry. The modified electrode displayed a decrease in the overpotential (ca. 82mV) and an obvious increase in the peak current (80 times) compared to the bare glassy carbon electrode (GCE). The results indicated that OMC/GCE remarkably enhanced electrocatalytic activity towards the oxidation of morphine. Linear response was found over the range from 0.1 microM to 20 microM with a high sensitivity of 1.74 microA/microM and low detection limit of 10 nM (S/N=3). And the relative standard deviation was 0.86% (n=5). Moreover, combining with a medium-exchange procedure, the OMC/GCE has also been successfully applied to the selective determination of morphine in urine samples with a low detection limit of 50 nM and satisfied recovery of 96.4%. The good results indicate that the OMC/GCE holds great promise in practical application.

Micelle-assisted synthesis of polyaniline/magnetite nanorods by in situ self-assembly process

Polyaniline/magnetite nanocomposites consisting of polyaniline (PANI) nanorods surrounded by magnetite nanoparticles were prepared via an in situ self-assembly process in the presence of PANI nanorods. The synthesis is based on the well-known chemical oxidative polymerization of aniline in an acidic environment, with ammonium persulfate (APS) as the oxidant. An organic acid (dodecylbenzenesulfonic acid, DBSA) was used to replace the conventional strong acidic (1 M HCl) environment. Here, dodecylbenzenesulfonic acid is used not only as dopant, but also as surfactant in our reaction system. So, DBSA can excellently control the morphology and size of PANI nanorods and magnetite particles. Magnetite particles were formed simultaneously during sedimentation, and the formed nanorods were also decorated by the particles. The resulting PANI/magnetite composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). It is found that PANI/magnetite nanorod composites have uniform size, superparamagnetism and a small mass fraction of magnetite, thermal stabilization even at a higher temperature.

One step to detect the latent fingermarks with gold nanoparticles

A simple and environment friendly chemical route for detecting latent fingermarks by one-step single-metal nanoparticles deposition method (SND) was achieved successfully on several non-porous items. Gold nanoparticles (AuNPs) synthesized using sodium borohydride as reducing agent in the presence of glucose, were used as working solution for latent fingermarks detection. The SND technique just needs one step to obtain clear ridge details in a wide pH range (2.5-5.0), whereas the standard multi-metal deposition (MMD) technique requires six baths in a narrow pH range (2.5-2.8). The SND is very convenient to detect latent fingermarks in forensic scene or laboratory for forensic operators. The SND technique provided sharp and clear development of latent fingermarks, without background staining, dramatically diminished the bath steps.

Synthesis and characterisation of novel imidazolium‐based ionic liquid crystals with a p‐nitroazobenzene moiety

A novel series of compounds with different counter anions, i.e. 1‐{[4‐(4‐nitrophenylazo)phenyloxy]}alkyl‐3‐methyl‐1H‐imidazol‐3‐ium bromide salts (Cn , n = 3, 6, 10) and tetrafluoroborate salts (Dn , n = 3, 6, 10), were synthesised by the incorporation of an imidazolium group into paraffin side chain‐terminated 4‐nitroazobenzene derivatives. Their chemical structures were determined by 1H NMR, 13C NMR, UV spectroscopy and elemental analysis. The thermotropic liquid crystalline properties of these materials were further studied by polarising optical microscopy, wide‐angle X‐ray diffraction and differential scanning calorimetry. The results show that Cn and Dn (n = 6, 10) exhibit smectic liquid crystalline phases. The ionic liquid groups play an important role in forming the smectic layer structure, via enhancement of the thermal stability of the smectic state.