Abstract: A method of testing for the presence of a preselected target nucleic acid, protein or antigen in a biological sample by exposing nucleic acids, proteins or antigens to a probe having a catalytic element and binding element. The catalytic element catalyses at least one reaction that results in a physical change such that identifiable elements provide an indication of the presence of the target.

Abstract: An assay for detecting an analyte in a biological sample. The assay comprises a surface probe linked to the surface of a measuring electrode and the surface probe has a nucleic acid sequence complementary to a first target nucleic acid sequence. The assay also comprises a signal probe, having a nucleic acid sequence complementary to a second target nucleic acid sequence and a binding element capable of binding a ligand. The ligand is associated with a catalytic element or precursor thereof capable of reacting with a substrate to alter electrical potential of the measuring electrode.

Abstract: A method of testing for the presence of a preselected target nucleic acid, protein or antigen in a biological sample by exposing nucleic acids, proteins or antigens to a probe having a catalytic element and binding element. The catalytic element catalyses at least one reaction that results in a physical change such that identifiable elements provide an indication of the presence of the target.