Bioreceptors can be defined as the basic requirement for specific and sensitive biosensors. The origins of bioreceptors are rooted in biochemistry. The label-free biosensor was developed in response to the demand for a simple, reliable, low cost, rapid, screening method for the early diagnosis of cancer. A range of molecules with biorecognition powers is available naturally, such as antibodies, enzymes, cell receptors, and nucleic acid. Nucleic acid-based biosensors are the preferred choice, compared with immunosensor and enzyme-based sensors, due to their high selectivity and sensitivity. Due to the low-cost of fabrication and stability, nucleic acid biosensors are evolving as reliable and rapid detection tools in medical diagnosis. In this chapter, different transducer platforms are discussed to detect various diseases in clinical diagnosis.
