The present invention provides lateral flow
assay devices and methods for detecting
nicotinic acetylcholine receptor ligands in liquid samples. The device comprises a porous strip with multiple zones, including a sample deposition zone, a test
visualization zone containing an immobilized
nicotine conjugate, a
control zone, and an absorbent zone. A recombinant
acetylcholine receptor protein serves as a
mobile agent, either pre-deposited on the strip or added to the sample. The recombinant
protein comprises a ligand-
binding domain of a
nicotinic acetylcholine receptor conjugated to a visually-detectable reporter forming a
receptor-reporter conjugate. When
nicotinic acetylcholine receptor ligands are present in the sample, they competitively bind to the recombinant
receptor protein, reducing binding to the immobilized
nicotine conjugate and producing a visually detectable
signal inversely proportional to ligand concentration. The invention provides rapid, simple, and field-deployable detection of receptor ligands in environmental samples, including cyanobacterial neurotoxins in surface waters, and biological samples for pharmacological and toxicological applications.