Patent ID: 8431336

Claim:
A dipstick for testing for the presence of a target nucleic acid in a sample solution, wherein the dipstick comprises: a chromatographic strip having a contact end for contacting the sample solution; and a capture probe that is immobilized at a capture zone of the chromatographic strip remote from the contact end, wherein the capture probe comprises an oligonucleotide capable of hybridizing to the target nucleic acid or to a hook capture probe bound to the target nucleic acid, wherein the capture probe is linked to a capture probe spacer and the capture probe spacer is linked to the capture zone, thereby immobilizing the capture probe at the capture zone and spacing the capture probe from the capture zone, wherein: i) the capture probe spacer is linked to one end of the capture probe, and the end of the capture probe that is not linked to the capture probe spacer is coupled to one or more nucleotides, which do not hybridize to the target nucleic acid when the capture probe is hybridized to the target nucleic acid or do not hybridize to the hook capture probe when the capture probe is hybridized to the hook capture probe; ii) the capture probe spacer is linked to a part of the capture probe between the ends of the capture probe, and one or both ends of the capture probe are coupled to one or more nucleotides, which do not hybridize to the target nucleic acid when the capture probe is hybridized to the target nucleic acid or do not hybridize to the hook capture probe when the capture probe is hybridized to the hook capture probe; iii) the capture probe spacer comprises a protein adsorbed directly to the capture zone, wherein the capture probe is covalently linked to the protein by a linker.