Time domain transmission line dielectric probe for detection of biomolecular interactions

A probe was developed to detect biomolecular binding events on a substrate in the microwave regime in real time and without labels. The probe consists of a coplanar transmission line fabricated on a glass slide that can detect dielectric changes in close proximity of the substrate-liquid interface. The probe behavior was evaluated by adsorbing polyelectrolyte monolayers of alternating charge. Biomolecular detection was demonstrated by immobilizing protein A on the glass surface and detecting rabbit IgG molecules in a flow channel. The sensitivity of the probe was conservatively estimated to be similar to100 pg/mm(2).