Label-free detection of biomolecular interaction by optical sensors.

Since the first label-free optical biosensor was commercialized in 1990 a rising number of publications have demonstrated the benefits of direct biomolecular interaction analysis (BIA) for biology and biochemistry. This article first gives an overview of the historical development of different transducer principles used for the detection of BIA. Subsequently, the four major parts of a biosensor system: transducer, sample handling, surface/immobilization chemistry and test formats/data evaluation will be discussed, with a main focus on the test formats and data evaluation. The intention of this review is to present an introduction to the field and to point out the difficulties most frequently encountered.