Analyte assay using particulate labels

A population of specifically detectable metal-like light scattering particles formed from at least one light scattering material, said particle comprising at least one additional material on its surface to provide chemical stability and an ability to said particle to bind to an analyte, wherein said population of particles is adapted to sufficient homogeneity in size so that one or more specific light scattering properties of the individual particles in said population are similar from particle to particle.

A specifically detectable light scattering particle reagent formed from at least one light scattering material selected from the group consisting of a metal, a metal compound, a metal oxide, a semiconductor, and a superconductor having a diameter between 1 and 500 nanometers wherein said particle reagent comprises a base molecule adapted to bind to the surface of the particle and adapted to bind to a binding agent, said particle reagent capable of binding to an analyte.

Apparatus for analysis of a solid phase sample, comprising:

• a light source angled such that light is delivered to said sample and the scattered light from any particles bound to said sample can be maximally detected, wherein said apparatus is constructed and arranged such that any said particles associated with said sample can be illuminated with said light under conditions which produce scattered light from said particles and in which light scattered from one or more said particles can be detected by a human eye with less than 500 times magnification and without electronic amplification.