A novel method of immobilizing antibodies on quartz crystals for use in immunosensors was developed using an ethylenediamine plasma-polymerized film matrix. The films formed on the quartz crystals are extremely thin and homogeneous, and they incorporate amino groups. Sensors produced using this method are more reproducible from sample to sample and exhibit lower noise and higher sensitivity than sensors made using conventional immobilization methods, e.g., via polyethylenimine and (gamma-aminopropyl)trimethoxysilane. This is, to our knowledge, the first reported application of plasma-polymerized films to quartz crystal microbalance immunosensors. Results on orientation-controlled immobilization of anti-bodies, reusability and calibration tests are also presented.

We propose a simple thin-film glucose biosensor based on a plasma-polymerized film. The film is deposited directly onto the substrate under dry conditions. The resulting films are extreme thin, adhere well onto the substrate (electrode), and have a highly cross-linked network structure and functional groups, such as amino groups, which enable a large amount of enzyme to be immobilized. Since this design allows fabrication through a dry process, with the exception of the enzyme immobilization, which is the last stage of the process, the chip fabrication can be designed as a full-wafer process to achieve mass production compatibility. The resulting sensors produced using this film are more reproducible, exhibit lower noise, and reduce the effect of interference to a greater degree than sensors made using conventional immobilization methods, e.g., via 3-(aminopropyl)triethoxysilane. The obtained film is a good interfacial design between enzyme and electrode; enzyme two-dimensionally locates very close to the electrode in a manner that is quite reproducible. Therefore, a wide dynamic range (up to 60 mM) and rapid response time (11.5+/-0.8 s) were obtained. Because of its highly cross-linking network structure, the amperometric response due to interferences such as ascorbic acid and acetaminophen was reduced by size discrimination of plasma-polymerized films.

We propose a novel ethylenediamine plasma-polymerized film matrix that is deposited on gold surfaces for use in surface plasmon resonance immunosensing. The films formed on the gold surfaces are extremely thin (∼100 nm), are homogeneous, demonstrate good adhesion, have a flat profile, and incorporate amino groups to introduce a chemical functionality. A sensor chip made with the film has many advantages when compared with conventionally used designs such as carboxylated dextran hydrogels. For example, a sensor chip made with the film shows a better sensor response than a conventional design partly because antibodies are densely and two-dimensionally immobilized onto the surface of the plasma-polymerized film.