Dongmei Deng

Nonenzymatic glucose sensor based on nickel(II)oxide/ordered mesoporous carbon modified glassy carbon electrode

A highly sensitive and selective nonenzymatic glucose sensor based on electrodepositing NiO nanoparticles on ordered mesoporous carbon (named as NiO/OMC) modified glassy carbon electrode (GCE) was constructed. The synthesized OMC was characterized by X-ray diffraction, and the morphology images of OMC nanoparticle and NiO/OMC nanocomposite were characterized by scanning electron microscope. Electrochemical behaviors of glucose at the NiO/OMC/GCE were investigated by cyclic voltammetry and amperometry, and the modified electrode showed excellent electrochemical activity toward the oxidation of glucose. At the optimum conditions, the calibration curve for glucose determination was linear in the range of 2-1000 μM with a fast response time (<2 s), and a high sensitivity of 834.8 μA mM(-1) cm(-2) and a low detection limit (S/N=3) of 0.65 μM were obtained. In addition, the proposed sensor was successfully applied to analyze glucose level in human blood serum samples.

Synthesis of MnCo2O4 nanofibers by electrospinning and calcination: application for a highly sensitive non-enzymatic glucose sensor

Spinel-type MnCo2O4 nanofibers (MCFs) were successfully synthesized by electrospinning and sequential calcination. The crystal structure, composition and morphology of the synthesized MCFs were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. Due to the outstanding electron-transfer ability of spinel MnCo2O4 and the large surface area of nanofibers, the synthesized MCFs were employed as electrocatalysts for the oxidation of glucose. Cyclic voltammetry and amperometry were used to evaluate the electrocatalytic activities of the MCFs towards glucose. The non-enzymatic glucose sensor showed a wide linear range of 0.05-800 μM with a low detection limit of 0.01 μM (S/N = 3).

Electrospun graphene decorated MnCo2O4 composite nanofibers for glucose biosensing

Graphene decorated MnCo2O4 composite nanofibers (GMCFs) were synthesized by electrospinning and subsequent calcination in an Ar atmosphere. The structural and morphological characterizations of GMCFs were performed using X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, energy-dispersive spectroscopy, scanning electron microscopy and transmission electron microscopy. The synthesized GMCFs combine the catalytic activity of spinel-type MnCo2O4 with the remarkable conductivity of graphene. In addition, electrospinning can process MnCo2O4 materials into nanosized architectures with large surface area to prevent magnetic nanoparticles from aggregating. The obtained GMCFs were applied as a novel platform for glucose biosensing. Electrochemical studies show that the developed biosensor exhibits excellent electrocatalytic activity towards glucose oxidation over a wide linear range of 0.005-800µM with a low detection limit of 0.001µM.

Electrochemical determination of nitrobenzene using bismuth -film modified carbon paste electrode in the presence of cetyltrimethylammonium bromide

Electrochemical behavior of nitrobenzene (NB) at a bismuth-film modified carbon paste electrode (BiF/CPE) in the presence of cetyltrimethylammonium bromide (CTAB) was investigated by square wave voltammetry. The electrochemical response of NB was apparently improved by CTAB due to the enhanced accumulation of NB at the electrode surface. Operational parameters including the deposition potential and time of bismuth film, pH of solutions and concentration of CTAB were investigated and optimized. Under optimized conditions, the cathodic peak current was proportional to the concentration of NB in the range of 1.0 × 10−6 to 1.0 × 10−4 mol L−1 with the detection limit of 8.3 × 10−7 mol L−1. The proposed BiF/CPE revealed good stability and reproducibility for rapid, simple and sensitive analysis of NB.

Label-free electrochemical impedance genosensor based on 1-aminopyrene/graphene hybrids

In this work, we proposed a novel simple protocol for preparing 1-aminopyrene/graphene (ApG) hybrids for fabricating label-free electrochemical impedance genosensor. Graphene, with the structure of a single-atom-thick sheet of sp(2)-bonded carbon atoms, was anchored to 1-aminopyrene (1-Ap) with the pyrenyl group viaπ-stacking interaction. The morphology, conductivity, and interaction of ApG hybrids were characterized by transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), UV-visible (UV-vis) and fluorescence spectra. The amino-substituted oligonucleotide probe was conjugated to 1-Ap by the cross-linker glutaraldehyde. The DNA hybridization reaction of oligonucleotide probe with target DNA was monitored by EIS. Under optimum conditions, the proposed biosensor exhibited high sensitivity and a low detection limit for detecting the complementary oligonucleotide. The target oligonucleotide could be quantified in a wide range of 1.0 × 10(-12) to 1.0 × 10(-8) M with good linearity (R = 0.9900) and low detection limit of 4.5 × 10(-13) M (S/N = 3).

Tryptamine functionalized reduced graphene oxide for label-free DNA impedimetric biosensing

A novel simple protocol of synthesizing tryptamine-functionalized reduced graphene oxide (TRA-rGO) was proposed to fabricate label-free electrochemical impedance DNA biosensor. TRA was anchored to rGO with its indole ring via π-stacking interaction. The morphology, conductivity and interaction of TRA-rGO were characterized by atomic force microscopy, high resolution transmission electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy (EIS) as well as Raman and fluorescence spectroscopy. The amino-substituted oligonucleotide probe was conjugated to TRA by cross-linker glutaraldehyde for preparing an electrochemical biosensing platform. The DNA hybridization reaction of oligonucleotide probe with target DNA was monitored by EIS. Under optimum conditions, the proposed biosensor exhibited high sensitivity and low detection limit for detecting complementary oligonucleotide. The target oligonucleotide could be quantified in a wide range of 1.0 × 10(-12)-1.0 × 10(-7)M with low detection limit of 5.2 × 10(-13)M (S/N=3).

Enzyme mimics of spinel-type CoxNi1−xFe2O4 magnetic nanomaterial for eletroctrocatalytic oxidation of hydrogen peroxide

A series of spinel-type Co(x)Ni(1-x)Fe2O4 (x=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) magnetic nanomaterials were solvothermally synthesized as enzyme mimics for the eletroctrocatalytic oxidation of H2O2. X-ray diffraction and scanning electron microscope were employed to characterize the composition, structure and morphology of the material. The electrochemical properties of spinel-type Co(x)Ni(1-x)Fe2O4 with different (Co/Ni) molar ratio toward H2O2 oxidation were investigated, and the results demonstrated that Co0.5Ni0.5Fe2O4 modified carbon paste electrode (Co0.5Ni0.5Fe2O4/CPE) possessed the best electrocatalytic activity for H2O2 oxidation. Under optimum conditions, the calibration curve for H2O2 determination on Co0.5Ni0.5Fe2O4/CPE was linear in a wide range of 1.0×10(-8)-1.0×10(-3)M with low detection limit of 3.0×10(-9)M (S/N=3). The proposed Co0.5Ni0.5Fe2O4/CPE was also applied to the determination of H2O2 in commercial toothpastes with satisfactory results, indicating that Co(x)Ni(1-x)Fe2O4 is a promising hydrogen peroxidase mimics for the detection of H2O2.

Simultaneous determination of epinephrine and uric acid at ordered mesoporous carbon modified glassy carbon electrode

An ordered mesoporous carbon modified glassy carbon electrode was employed for the simultaneous determination of epinephrine and uric acid by differential pulse voltammetry. The modified electrode exhibited excellent electrocatalytic ability for the oxidation of epinephrine and uric acid, and two well-defined oxidation peaks towards two species with a potential difference of 170 mV appeared at the modified electrode. Under optimum conditions, linear responses of epinephrine and uric acid were obtained in the concentration ranges of 0.5 to 200 μM, and 0.25 to 100 μM, with detection limits of 0.2 μM and 0.07 μM (S/N = 3), respectively. The proposed modified electrode displayed high selectivity, good stability and reproducibility, and was successfully applied for the determination of epinephrine in epinephrine hydrochloride injection and uric acid in human urine samples.

Nitidine chloride-assisted bio-functionalization of reduced graphene oxide by bovine serum albumin for impedimetric immunosensing

A novel protocol of label-free electrochemical impedance immunosensor based on bovine serum albumin-nitidine chloride-reduced graphene oxide (BSA-NC-rGO) nanocomposite was proposed for quantitative determination of carcino-embryonic antigen (CEA). BSA was anchored to rGO via the aromatic plane of NC by π-stacking interaction to realize bio-functionalization of rGO, and then gold nanoparticles (AuNPs) were electrodeposited onto the surface of BSA-NC-rGO nanocomposite. The morphology, conductivity and interaction of different nanocomposites were characterized by scanning electron microscopy, cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and UV-vis spectrum. CEA monoclonal antibody (anti-CEA) was conjugated to AuNPs via gold-thiol chemistry to construct electrochemical immunosensing platform, and the specific immunoreaction between CEA and anti-CEA was monitored by EIS. Under optimum conditions, CEA could be quantified in a wide range of 0.1-200 ng mL(-1) (R=0.9948) with low detection limit of 0.067 ng mL(-1). The proposed immunosensor exhibited great potential for detecting blood samples.

Effective immobilization of Au nanoparticles on TiO2 loaded graphene for a novel sandwich-type immunosensor

A novel and sensitive sandwich immunosensor for amperometric determination of carcinoembryonic antigen (CEA) was designed using Au nanoparticles-titanium dioxide-graphene (AuNPs-TiO2-graphene) nanocomposites. Dopamine-functionalized graphene was firstly prepared by π-stacking interaction, and TiO2 was then attached to the surface of dopamine-graphene by the specificity and high affinity of enediol ligands to Ti (IV). Afterwards, AuNPs-TiO2-graphene nanocomposites were synthesized with photo-reduction approach under ultraviolet irradiation. The morphology and conductivity of the as-prepared nanocomposites were characterized by transmission electron microscopy, Fourier transform infrared spectra, X-ray powder diffraction, cyclic voltammetry and electrochemical impedance spectroscopy. Taking the advantage of large specific surface area and excellent biocompatibility, AuNPs could covalently link horseradish peroxidase labeled secondary antibody (HRP-Ab2) through the interaction between AuNPs and mercapto or primary amine groups of HRP-Ab2 for sandwich-type immunosensor construction. Under optimum conditions, the modified electrode exhibited a linear current response to CEA concentration in a wide range of 0.005-200ngmL-1 (R2 = 0.994) with low detection limit of 3.33pgmL-1 (S/N = 3).