Papers by Keyword: Thionine

Abstract: Graphene is a material that has been heavily investigated in many researches due to its beneficial characteristics such as large surface area, low manufacturing cost, high electro conductivity and incredible mechanical strength. Applying the graphene in water-based solvents however can cause agglomeration due to its hydrophobic properties. Researchers have composited the graphene with other materials in overcoming its hydrophobicity. In this research, graphene was nanocomposited with thionine to make it disperse well in water-based solvents while preserving its intrinsic properties. The nanocomposition process involves mixing of both graphene oxide with thionine and were reduced by hydrazine hydrate while reflux heating. The produced mixture was then filtered to obtain the Thionine-Graphene nanocomposite. The obtained sample was then characterized to confirm the composition of both graphene and thionine. Fourier transfer infrared spectroscopy was operated to investigate the chemical bonds and hence concluding the presence of both graphene and thionine in the sample. The preservation of the intrinsic properties of graphene was also investigated through observing the absence of functionalized graphene bonds. Post-investigation reports that the chemical bonds from both of the materials, graphene and thionine were detected confirming the successfulness of the nanocomposition.

Abstract: In the development of new processes to use the potential of iron reducing bacteria, Acidiphilium cryptum, the main bacteria involved in the reduction of Fe (III) compounds in acidic environments, could play an important biohydrometallurgical role. Thus, the bioleaching of hematite, goethite and a low-grade manganese ore was assayed, in vials and columns, using three different media; two of which included a ligand, oxalate, or a redox mediator, thionine.Although the presence of A. cryptum was essential for promoting the dissolution of both iron oxides and the bioleaching of manganese ore, the addition of oxalate to the media tripled and quadrupled the microbial dissolution of hematite and goethite, respectively. Oxalate also had a positive effect in assays performed in columns, however, the addition of thionine to the medium allowed to reach significant hematite dissolution.

Abstract: A label-free immunosensor was developed to detect the presence of an antigen. This immunosensor was based on the modulation of the electrochemistry of the surface bound redox species thionine (Thi). The model antigen was carcinoembryonic antigen (CEA) and the model epitope was the antibody of CEA (anti-CEA). Glassy carbon electrode surfaces were first drop-coated with a mixture of graphene, Thi and Nafion and air-dried. The electrode surface was then electrodeposited in HAuCl₄ solution to form Au nanoparticles (AuNPs). The resulted AuNPs were used to immobilize anti-CEA. Binding of CEA to the surface bound epitope resulted in the attenuation of the Thi electrochemistry. Under optimal conditions, the response of the label-free immunosensor had a liner range from 10 fg/mL to 100 ng/mL with a detection of 3.5 fg/mL (S/N=3).

Abstract: This paper describes the electrocatalytic oxidation of nitrite by poly-thionine /gold nanoparticle modified glassy carbon electrode. Due to the synergistic effect of poly-thionine and gold nanoparticle, the modied electrodes could oxide nitrite with enhanced oxidation current and a decrease in the required overpotential compared with bare electrode without poly-thionine and gold nanoparticles layer coated. The influence factors for nitrite assay such as polymer film thickness, adsorption time of gold nanoparticles onto the poly-thionine film, different buffers and pH，interferent ions were discussed elaborately. Under the optimal conditions, the oxidation current signal was proportional to the concentration of nitrite from 3.0×10-6 to 1.0×10-3 mol/L with a detection limit of 1.0×10-6 mol/L. The proposed method has been applied to determine nitrite concentration in real samples and the results were satisfactory. The poly-thionine/gold nanoparticles composites modied electrode has been proved to possess high sensitivity, good storage stability, reproducibility and anti-interference ability.

Abstract: A novel amperometric immunosensor for the determination of alpha-fetoprotein (AFP) was constructed using multi-wall carbon nanotubes modified glass carbon electrode.thionine as the mediator,were immobilized by DNA throngh the layer-by-layer method. Thionine was first fabricated on carbon nanotubes modified glass carbon throngh 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-hydroxysuccinimide(EDC/NHS).then a negatively charged DNA film was absorbed on the positively charged thionine,and the DNA was uesd as cross-linker to immobiled amount thionine.nano-Au-was used to immobilized anti-AFP.The electrochemical sensor have a relatively low detection limit of 0.02ng/ml.