Acousto-optic tunable filter—based surface plasmon resonance biosensor for determination of human factor B

A surface plasmon resonance (SPR) biosensor based on wavelength modulation with a fixed angle of incidence incorporating an acousto-optic tunable filter (AOTF) is described. The AOTF is used as the wavelength selector of the AOTF–SPR biosensor system. The wavelength range of the AOTF is 440–790 nm. The wavelength is modulated by inputting AOTF 0–5 V voltage and one voltage corresponds to one wavelength. The SPR spectrum is shown in terms of reflected light intensity versus voltage supplied to AOTF. The intensity of reflected light is the minimum at the resonant voltage. Molecular self-assembling on the surface of the sensor is applied to form the sensing membrane on the gold substrate. The staphylococcal protein A (SPA) is modified on the gold substrate. The temperature effect of human factor B (Bf) antibody and antigen reaction was studied. The human factor B was determined in the concentration range of 2–80 (mu)g/ml.