Papers by Author: Yan Zhi Xia

Abstract: Stable fluorescent carbon nanoparticles (FCNPs) with excellent water-solubility were prepared firstly by one-step ultrasonic treatment from the blending of glucose and sodium hydroxide. Then, the fluorescence calcium alginate fibers were successfully prepared through wet spinning, using the mixture of FCNPs and sodium alginate solution as the spinning dope. The fluorescent property of FCNPs and fibers were investigated using fluorescence spectrophotometer. Single fiber strength tester was used to measure the strength of the fluorescence fibers. The results showed that both FCNPs and fibers emitted bright blue color under 350nm wavelength UV irradiation. The strength of the fibers was improved when the content of FCNPs in the fibers achieved certain value.

Abstract: A novel Nafion/PMB/G/GCE was prepared by firstly electro-polymerization of MB to G/GCE and then coating Nafion on PMB/G/GCE. The as-prepared modified electrode combining the advantages of Nafion, methylene blue and G was employed for the sensitive detection of rutin. The results showed that the peak current of rutin obtained on Nafion/PMB/G/GCE was obviously high compared to bare electrode and G/GCE. Under the optimized value of pH, which was pH 3.0, peak current of rutin had good linear relation with the scan rate. At the same time, peak current increased linearly with increasing concentration of rutin. The linear range was from 5×10^-7 mol/L to 1.2×10^-5 mol/L, and the detection limit was 9.5×10^-8 mol/L

Abstract: A novel composite was firstly synthesized by compositing graphenes (G) and carbon nanotubes (CNTs) and then a new composite modified electrode (G/CNTs/GCE) was prepared by coating the resulting composite on the surface of the glassy carbon electrode (GCE). The composite modified electrode G/CNTs/GCE showed great electrochemical activities which were studied by sensitive determining the electrochemistry behaviors of uric acid (UA). It revealed when the concentration range of UA changed from 1×10^-7 mol/L to 1×10^-3 mol/L, the peak currents had linear relationship with the concentration of UA in the phosphate buffer solution (PBS) which the value of pH is 7.0. And the linear equation is ip (μA) = 21.55C+28.94 (C: mmol/L), with the related coefficient 0.9964.

Abstract: Glassy carbon electrode (GCE) was modified using graphene (G), quercetin (Qu) and Nafion in this sequence to fabricate Nafion-Qu-G composite-modified GCE (Nafion/Qu/G/GCE). The as-prepared modified electrode combining the advantages of Nafion, Qu and G was employed for the selective and sensitive detection of dopamine (DA) in the presence of ascorbic acid (AA) and uric acid (UA). Compared with GCE, Qu/GCE, G/GCE and Qu/G/GCE, the Nafion/Qu/G/GCE was more electroactive and selective for DA. Differential pulse voltammetry (DPV) was used for electrochemical detection, the separations of the oxidation peak potentials for AA-DA and DA-UA were about 304 mV and 136 mV, which allowed selectively determining DA. In phosphate buffer solution (PBS) of pH 6.8, the Nafion/Qu/G/GCE provided a detection limit of 2.31×10^-8 mol/L (S/N=3) for DA. Linearity (R=0.9963) of the peak currents against the concentration of DA was found over the range of 1.0×10^-7 to 1.0×10^-3 mol/L. Furthermore, the modified electrode exhibited good reproducibility and stability.

Abstract: Temperature-sensitive calcium alginate-based microspheres were prepared in two steps. Firstly, free-radical polymerization of temperature-sensitive N-vinylcaprolactam monomer was performed in aqueous solution of sodium alginate, yielding a mixed aqueous solution bearing temperature-sensitivity composed of poly(N-vinylcaprolactam), sodium alginate-graft- poly(N-vinylcaprolactam) and sodium alginate. Then temperature-sensitive composite microspheres were prepared by inverse emulsification-crosslinking using the as-prepared solution as water phase, n-hexane as oil phase, Span-85 and Tween-85 as emulsifiers and calcium chloride as crosslinker respectively. The morphology and temperature-sensitivity of the composite microspheres were investigated by scanning electron microscope and turbidity method respectively. The controlled release behavior of the microspheres towards temperature was investigated preliminarily using berberine as a model drug.

Abstract: A novel application of carbon nanotubes (CNTs) in the field of chromogenic reactions for recognizing aminophenol isomers was described. Among the three of aminophenol isomers, only p-aminophenol could form the chromogenic system. Comparative experiments proved that the absorption of the complex increased by 23.9% in the presence of CNTs due to the presence of the intact conjugated system. A selective determination of p-aminophenol was obtained

Abstract: A new functionalized composites (PPy/c-MWNT) by carboxylic multiwalled carbon nanotube (c-MWNT) with polypyrrole (PPy) was studied. PPy/c-MWNT modified glassy carbon electrode (PPy/c-MWNT/GCE) for determination of Cd2+ and Pb2+ was described by cyclic voltammetry, electrochemical impedance spectroscopy, and anodic stripping voltammetry (ASV). PPy/c-MWNT/GCE greatly improved the sensitivity of determining Cd2+ and Pb2+. The striping peak currents changed linearly with the concentration of Cd2+ from 1.0×10-4 to 2.0×10-7 mol/L for an accumulation time of 400 s, and Pb2+ from 1.0×10-4 to 1.0×10-7 mol/L. The high sensitivity, selectivity, and stability of the PPy/c-MWNT/GCE demonstrated its practical application for a simple, rapid and economical determination of trace level of Cd2+ and Pb2+ in water samples

Abstract: A novel film of overoxidized polypyrrole and carboxylic multi-walled carbon nanotubes (c-MWNTs) was fabricated with molecular imprinted technique for dopamine by a direct and facile electropolymerization method. The resulting modified electrode surface was characterized with electrochemical impedance spectroscopy and Fourier transform infrared spectroscopy. The results demonstrated that the modified electrode not only possessed a good sensitivity but also exhibited a high selectivity toward DA which making anodic potential difference of DA and AA is 318 mV in DPV. Under the optimum conditions, the linear range of the dopamine biosensor ranges from 5.0×10−8 to 6.0×10−6 mol/L with a detection limit of 5.0×10−9 mol/L

Abstract: A glycyrrhizin decorated graphene hybrid materials (GL-G) was synthesized, which is a layer-to-layer sandwich construction. The results of characterization indicate that a photo induced electron transfer process or efficient energy transferring along the GL-G interface. Furthermore, the as-made hybrid material was used as a modifier of the glassy carbon electrode to construct a sensor (GL-G/GCE). Using p-nitrophenol as a model compound, the novel sensor demonstrated a highly enhanced electrochemical activity for it. The peak current of p-nitrophenol was significantly improved at the sensor.

Abstract: To improve the performance of traditional hydrogels, dually responsive multi-network hydrogel was designed and fabricated in two steps. Firstly, temperature-and pH-responsive copolymeric microgel of N-isopropylacrylamide, methacrylic acid and polyethyleneglycol methacrylate were prepared via precipitation polymerization in poly (vinyl alcohol) (PVA) aqueous solution. Then glutaraldehyde was added to the microgel dispersion to build crosslinks among microgels and PVA, producing multi-network hydrogel with thermo-and pH-sensitivity. The morphology of the microgel and hydrogel was characterized by electron microscope technique. Swelling and deswelling behaviors show that the obtained hydrogels exhibit good temperature-and pH-sensitivity. The hydrogel shows rapid deswelling kinetics and approaches deswelling equilibrium in ~30min.