Reduction of the hook effect in assay devices
View Patent ↗A membrane-based assay device for detecting the presence or quantity of an analyte residing in a test sample is provided. The device utilizes conjugated probes that contain a specific binding member for the analyte of interest. The specific binding member preferentially complexes with the analyte within a test sample when contacted therewith. Excess analyte that remains uncomplexed with the specific binding member undergoes non-specific binding, such as to a hydrophobic domain. As a result, the ability of the uncomplexed analyte to compete with the complexed analyte at the detection zone of the device is restricted. Thus, the incidence of “false negatives” is limited in a simple, efficient, and relatively inexpensive manner.
1. A flow-through assay device for detecting the presence or quantity of an analyte residing in a test sample, the flow-through assay device comprising:
a porous membrane in communication with particles that are labeled with a signal-producing substance and conjugated with a specific binding member, the specific binding member being capable of preferentially binding to the analyte to form analyte/probe complexes, wherein the particles comprise pores that have an average size of less than about 100 nanometers and block the analyte/probe complexes but allow an uncomplexed analyte to pass therethrough, and further wherein the particles contain a hollow interior within which a domain is located, the domain non-specifically binding to the uncomplexed analyte that passes through the pores, the hollow interior constituting at least about 20% of the spatial volume occupied by the particle, wherein the particles comprise a shell polymer containing a nonionic ethylenically unsaturated monomer and an ethylenically unsaturated monomer that includes at least one carboxylic acid group;
wherein the porous membrane of the flow-through assay device defines a detection zone within which a receptive material is immobilized, the receptive material being configured to bind to the analyte/probe complexes, and further wherein the particles are capable of generating a detection signal when present within the detection zone that corresponds to the presence of the analyte within the test sample.
2. The flow-through assay device of claim 1 , wherein the hollow interior constitutes at least about 30% of the spatial volume occupied by the particle.
3. The flow-through assay device of claim 1 , wherein the domain is located on a surface of the particles.
4. The flow-through assay device of claim 1 , wherein the particles have a spherical shape.
5. The flow-through assay device of claim 1 , wherein the particles are formed by electrostatic layer deposition.
6. The flow-through assay device of claim 1 , wherein the particles comprise the shell polymer and a core polymer, the core polymer containing polystyrene.
7. The flow-through assay device of claim 1 , wherein the average size of the particles ranges from about 0.1 nanometers to about 100 microns.
8. The flow-through assay device of claim 1 , wherein the average size of the particles ranges from about 1 nanometer to about 10 microns.
9. The flow-through assay device of claim 1 , wherein the pores have an average size of from about 5 to about 100 nanometers.
10. The flow-through assay device of claim 1 , wherein the pores have an average size of from about 0.1 to about 60 nanometers.
11. The flow-through assay device of claim 1 , wherein the signal-producing substance is selected from the group consisting of chromogens, catalysts, fluorescent compounds, chemiluminescent compounds, phosphorescent compounds, radioactive compounds, direct visual labels, liposomes, and combinations thereof.
12. The flow-through assay device of claim 1 , wherein the specific binding member is selected from the group consisting of antibodies, antigens, haptens, biotin, avidin, streptavidin, protein A, protein G, carbohydrates, lectins, nucleotide sequences, peptide sequences, effector and receptor molecules, hormone and hormone binding protein, enzyme cofactors and enzymes, enzyme inhibitors and enzymes, and derivatives thereof.
13. The flow-through assay device of claim 1 , wherein the receptive material is selected from the group consisting of antigens, haptens, antibodies, protein A or G, avidin, streptavidin, secondary antibodies, and complexes thereof.
14. The flow-through assay device of claim 6 , wherein the domain is hydrophobic.
15. The flow-through assay device of claim 1 , wherein the ethylenically unsaturated monomer that includes at least one carboxylic acid includes (meth)acrylic acid, acryloxypropionic acid, (meth)acryloxypropionic acid, itaconic acid, aconitic acid, maleic acid or anhydride, fumaric acid, crotonic acid, monomethyl maleate, monomethyl fumarate, monomethyl itaconate, or a combination thereof.