Colloidal metal labels

OPTICALLY DETECTABLE COLLOIDAL METAL LABELS PROPERTIES, METHODS, AND BIOMEDICAL APPLICATIONS... 

F. Darain, S.-U. Park and Y.-B. Shim, Disposable amperometric immunosensor system for rabbit IgG using a conducting polymer modified screen-printed electrode, Biosens. Bioelectron., 18 (2003) 773-780. M. Dequaire, C. Degrand and B. Limoges, An electrochemical metal-loimmunoassay based on a colloidal gold label, Anal. Chem., 72 (2000) 5521-5528. 

Metal labels have been proposed to resolve problems connected with enzymes. Metal ions [13-16], metal-containing organic compounds [17,18], metal complexes [19-21], metalloproteins or colloidal metal particles [22-28] have served as labels. Spectrophotometric [22,25], acoustic [25], surface plasmon resonance, infrared [24] and Raman spectroscopic [28] methods, etc. were used. A few papers have been dealing with electrochemical detection. However, electrochemical methods of metal label detection may be viewed as very promising taking into account their high sensitivity, low detection limit, selectivity, simplicity, low cost and the availability of portable instruments. 

An electrochemical immunoassay using a colloidal gold label (18 nm) that after oxidative gold metal was indirectly determined by ASV at a... 

An electrochemical immunoassay has been developed by Chu et al. [75], based on the precipitation of silver on colloidal gold labels which, after silver metal dissolution in an acidic solution, was indirectly determined by ASV at a glassy carbon electrode. The method was evaluated for a noncompetitive heterogeneous immunoassay of an IgG... 

Colloidal-metal nanoparticles have found use in biology and medicine in the last 20 years, but semiconductor nanocrystals have only recently been used for biological labelling [13, 88-90],... 

Initial studies suggested that oxygen production occurred at pH 1.4 but that it was considerably faster at pH 4.9. Other colloidal metal oxides also catalyzed the reaction. Labelling studies confirmed that O2 was derived from water but examination of the relative yields of Co and O2 when using [Co(NH3)5Cl] as acceptor, suggest that only about 20% of the [RuCbipyis] " ... 

The method of sol-particle immunoassay uses colloidal metal particles as the label. Typically these labels have been colloidal gold and colloidal silver. Detection in this type of assay is carried out visually, colorimetrically or by atomic absorption spectroscopy with electrothermal atomization. The colorimetric methods obviously offer potential in sensor development and the detection limits in the pmol 1 range are useful. 

Sol particle immunoassay was developed by Leuvering et al. of the Organon group (L6). They used inorganic (metal) colloidal particles as a label... 

---