Zaide Zhou

Preparation and Characterization of Fe3O4/Ag Composite Magnetic Nanoparticles

Fe3O4 magnetic nanoparticles being used as seeding materials, Ag+ ions on the Fe3O4 magnetic nanoparticles reduced to the metal form by tartaric acid using heated treatment. Thus, Fe3O4/Ag composite core-shell magnetic nanoparticles were synthesized. The products were characterized by transmission electron microscope (TEM) and x-ray diffraction (XRD). Both TEM and XRD results showed that the Ag nanoparticles were well distributed on the surface of Fe3O4 magnetic nanoparticles. The size for Fe3O4/Ag composite magnetic nanoparticles which were spherical shape was ≃40 nm. Furthermore, the magnetic properties of samples were characterized on a vibrating sample magnetometer. Under optimal conditions, Fe3O4/Ag composite nanoparticles showed higher magnetism than pure Fe3O4 nanoparticles.

Clinical determination of glucose in human serum by a tomato skin biosensor

BACKGROUND Glucose biosensors based on enzyme reaction of glucose oxidase were studied because the symptomatic therapy of diabetes mellitus requires reliable assessment of blood glucose level at frequent intervals. Tomato skin membranes have been successfully employed to entrap glucose oxidase for fabrication of glucose biosensor. METHODS Glucose oxidase was immobilized onto the tomato skin and the enzyme membrane was then positioned on the surface of an oxygen electrode. The glucose concentration was quantified by the change of dissolved oxygen. All the serum samples were also simultaneously determined by a Hitachi 7060 chemistry analyzer. RESULTS The response of the biosensor showed a linear relationship with a concentration range of 1.0-30.0 mmol/l glucose. The limit of detection was 0.20 mmol/l. Error Grid analysis demonstrated that 100% of the results fell within clinically acceptable zones A and B. The F- and t-tests showed no significant differences between the 2 methods. The recovery was 95.0-110.0% for 30 serum samples analysis. CONCLUSIONS The tomato skin biosensor possesses the advantages of simple fabrication, fast response time, low cost and high sensitivity. The results of our method are more accurate than and match well with the current clinical instrument method.

Flow injection analysis of resorcinol using inhibited Rhodamine B/Cerium(IV) chemiluminescence system

The fluorescent dye Rhodamine B (RhB), in combination with a strong oxidant Ce(IV), was used to investigate the properties of three important polyphenols, resorcinol, catechol, and hydroquinone. The reaction of RhB with Ce(IV) solution in acidic medium was found to elicit strong chemiluminescence (CL). The CL signal remarkably weakened in the presence of resorcinol whereas the two other isomers, catechol, and hydroquinone, hardly had any effect in the same range of concentrations. Based on these observations, a new flow-injection CL method was developed for the determination of resorcinol. In addition, a brief discussion of possible mutual interaction mechanism between the three polyphenols and the components of the system is also presented.