Papers by Keyword: Gold Colloids

Abstract: The purpose of this work was to determine whether novel hybrid nanomaterials obtained in mild synthesis conditions between a Pt (II) metalloporphyrin, namely: Pt (II) 5,10,15,20-tetra (4-methoxy-phenyl)-porphyrin (PtTMeOPP) and nanoGold (n-Au) offer better recognition or detection properties toward hydrocortisone than the solely uncombined compounds. The Pt-porphyrin, gold-colloid and the hybrid nanomaterials were synthesized and characterized by UV-vis, FT-IR, ¹H-NMR, AFM and TEM microscopy. For the concentrations of hydrocortisone that have relevance for medical field, covering the range of 10^-8 to 10^-7 M, an excellent correlation of 0.99 was obtained between the intensity of absorption of the n-Au-PtTMeOPP hybrid plasmon and the hydrocortisone concentration, measured in THF-water system. So, this n-Au-PtTMeOPP conjugate system can be further developed to implement an accurate hydrocortisone optical sensor.

Abstract: ZnO nanostructures were synthesized by thermal oxidation reaction from zinc powder and then impregnated by gold colloid. The gold colloid was prepared by chemical reduction technique and had red color. The heating temperature and sintering time of thermal oxidation were 700 °C and 24 hours, respectively under oxygen atmosphere. The morphology of ZnO nanostructures and ZnO impregnated gold colloid were studied by field emission scanning electron microscope (FE-SEM). The diameter and length of pure ZnO and ZnO impregnated gold colloid were about the same value and were in the range of 100-500 nm and 2.0-7.0 µm, respectively. The ethanol sensing properties of ZnO impregnated by gold colloid were tested in ethanol atmosphere at ethanol concentrations of 1000 ppm and at an operating temperature of 260-360 °C. It was found that the sensitivity and response time were improved for gold impregnated sensor with an optimum operating temperature of 300°C due to the enhanced reaction between the ethanol and the adsorbed oxygen at an optimum temperature.