An impedance based biosensor and method for detecting a target biomolecule in a sample are provided. The biosensor has a substrate, and first and second spaced-apart electrodes disposed at the substrate. A molecular recognition element (MRE) for binding with the target is bound to the substrate between the first and second electrodes. The biosensor also has a nanoparticle having an MRE bound to its surface. In the presence of the target, the nanoparticle is immobilized between the first and second electrodes due to binding of the target biomolecule with the first MRE and binding of the target biomolecule with the second MRE. A measurable change in electrical impedance across the first and second electrodes occurs due to the immobilization of the nanoparticle between the first and second electrodes.