Patent ID: 7700744

Claim:
A method for detecting a protein or a nucleic acid from a complex sample comprising a virus, prokaryotic cell or eukaryotic cell, the method comprising: (a) contacting the complex sample with magnetic colloidal particles to form a mixture, said magnetic colloidal particles comprising a core and an envelope, wherein: the core is magnetic and is coated with an organic polymer; said organic polymer is a homopolymer or copolymer of monomers selected from the group consisting of acrylamide, acrylate, styrene, methyistyrene, ethyistyrene, tert-butyl-styrene, chloromethylstyrene, and vinyltoluene; the organic polymer comprises functional groups selected from the group consisting of amine, hydroxyl, thiol, aldehyde, ester, anhydride, acid chloride, carbonate, carbamate, isocyanate, isothiocyanate groups, and mixtures thereof; and at least a fraction of the functional groups reacts with other functional groups of the envelope; and wherein: the envelope comprises a polymer that is a hydrophilic homopolymer or copolymer of monomers selected from the group consisting of acrylamide, methacrylamide, acrylic acid, methacrylic acid, allylamine, and styrene; if the polymer is a homopolymer, then the homopolymer comprises at least one member selected from the group consisting of polysaccharides, polypeptides, linear or branched polyethyleneimine, and dendrimers; the hydrophilic homopolymer or copolymer comprises ionizable functional groups that are identical or different; the ionizable functional groups are selected from the group consisting of amine, carboxylic acid, ester, anhydride, aldehyde, thiol, disulfide, α-halocarbonyl, sulfonic acid, maleimide, isocyanate, and isothiocyanate groups; and the ionizable functional groups partially react with the functional groups of the core; (b) homogenizing the mixture; (c) complexing said magnetic colloidal particles with said virus, prokaryotic cell, or eukaryotic cell; (d) applying a magnetic field to separate from the mixture said virus, prokaryotic cell or eukaryotic cell complexed on said magnetic colloidal particles; and (e) detecting said protein by an immunoassay or detecting said nucleic acid by hybridization.