Patent ID: 8535950

Claim:
A method for determining the binding constant of two interacting molecular species by Laser Light Scattering (LLS) comprising the steps of: providing a colloidal aqueous suspension of particles containing perfluoropolymer or a latex suspension of particles containing perfluoropolymer with an average diameter between 5 and 200 nm; measuring the intensity, l 0 , of the light scattered by the colloidal aqueous suspension or latex; sequentially adding to the colloidal aqueous suspension of particles or the latex suspention of particles, an aqueous solution of a mixture of an amphiphilic nonionic surfactant and a surfactant ended with a receptor to form a first mixture comprising perfluoropolymer particles that comprise on their surface an amphiphilic nonionic surfactant and a surfactant ended with a receptor; measuring the intensity of the light, l r ,scattered by the first mixture by LLS after each addition of the aqueous solution to the colloidal aqueous suspension of particles or the latex suspension of particles; repeating the addinq of an aqueous solution of a mixture of amphiphylic nonionic surfactant and surfactant ended with a receptor step and the measuring of the intensity, l r , step until reaching an asymptotic value of intensity; sequentially adding an aqueous solution of a ligand to the first mixture to form a second mixture comprising perfluoropolymer particles that comprise on their surface an amphiphilic nonionic surfactant, a surfactant ended with a receptor and a ligand having interacted with the receptor; measuring the intensity of the light, l, scattered by the second mixture by LLS after each addition of the aqueous solution of the liqand to the first mixture; repeating the adding of a ligand aqueous solution step and the measuring of the intensity, l, step until reaching an asymptotic value of intensity; correlating the measured light intensity of the first mixture and the second mixture with the ligand solution additions; and determining the binding constant of two interacting molecular species based on the correlation, wherein the two interacting molecular species are the surfactant ended with the receptor and the ligand for the receptor, wherein the amphiphilic nonionic surfactant and the surfactant ended with a receptor can be the same or different surfactant, and wherein the wavelength of the laser light is greater than the average diameter of the particle.