Patent ID: 6413786
Filing Date: 2002-07-02
Classification: C12Q,G01N,Y10S

Abstract:
A method for determining binding of a ligand comprising the steps of:providing colloidal particles having a complex index of refraction and showing optical resonance at a resonant wavelength, said particles coated with a receptor for the ligand, wherein the resonant wavelength is a wavelength at which a real part n(&lgr;) of the index of refraction approaches zero while an imaginary part n(&lgr;) of the index of refraction simultaneously approaches 2, and wherein diameter of said particles is less than about {fraction (1/10)} of the resonant wavelength; contacting the colloidal particles with a sample solution; and measuring light scatter and/or light absorption at the resonant wavelength whereby a decrease in light scatter and/or light absorption at the resonant wavelength is representative of binding of the ligand to the colloidal particles.