tellurium and stannic-oxide

An ultrasensitive label-free photoelectrochemical (PEC) immunosensor was developed to detect amyloid β-protein (Aβ) based on CdS/CdTe-cosensitized SnO2 nanoflowers. Specifically, SnO2 with a flower-like porous nanostructure was utilized as a perfect substrate for the construction of PEC immunosensors, and the SnO2-modified electrode was first coated with CdTe quantum dots (QDs) and then further deposited with CdS by successive ionic layer adsorption and reaction techniques. The formed SnO2/CdS/CdTe-cosensitized structure exhibited excellent photocurrent intensity and was employed as an excellent photoactive matrix to immobilize Aβ antibody to further construct the immunosensor. Under optimal conditions, the as-constructed PEC immunosensor was used to detect Aβ and exhibited a wide linear concentration range from 0.5 pg mL-1 to 10 ng mL-1, with a low limit of detection (LOD, 0.18 pg mL-1, S/N = 3). Meanwhile, it also presented good reproducibility, specificity, and stability and may open a new promising platform for the clinical detection of Aβ or other biomarkers.

Topics: Amyloid beta-Peptides; Antibodies, Monoclonal; Biosensing Techniques; Cadmium Compounds; Electrochemical Techniques; Humans; Immunoassay; Limit of Detection; Photochemical Processes; Quantum Dots; Sulfides; Tellurium; Tin Compounds

In this paper the humidity sensing properties of layers prepared by a new method for obtaining doped tin oxide are studied. Different techniques-SEM, EDS in SEM, TEM, SAED, AES and electrical measurements-are used for detailed characterization of the thin layers. The as-deposited layers are amorphous with great specific area and low density. They are built up of a fine grained matrix, consisting of Sn- and Te-oxides, and a nanosized dispersed phase of Te, Sn and/or SnTe. The chemical composition of both the matrix and the nanosized particles depends on the ratio R(Sn/Te) and the evaporation conditions. It is shown that as-deposited layers with R(Sn/Te) ranging from 0.4 to 0.9 exhibit excellent characteristics as humidity sensors operating at room temperature-very high sensitivity, good selectivity, fast response and short recovery period. Ageing tests have shown that the layers possess good long-term stability. Results obtained regarding the type of the water adsorption on the layers' surface help better understand the relation between preparation conditions, structure, composition and humidity sensing properties.

Topics: Humidity; Microscopy, Electron, Scanning; Molecular Probe Techniques; Nanostructures; Sensitivity and Specificity; Tellurium; Temperature; Tin Compounds